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View Full Version : Low-cost 4x4 plasma table, finished.



Fiero Addiction
04-27-2008, 11:17 AM
I just finished building my plasma table and have been running it for about a week, I figured I'd show a few pictures. I spent a lot of time here looking at pictures of other people's builds for ideas, hopefully someone can get something from mine. My initial goal was to spend $1000. It ended up being closer to $1500.

The table is made from 4"x2" 14 ga steel tubing, fully welded. It's 64" long by 60" wide. The material support slats are 1/8" x 2" flat bar on end, 4" apart, supported at each end and in the center. The table has a built-in water tray, 18 ga steel sheet welded to the bottom of the table. The air tank underneath the table is the air bladder to adjust the water level.

For the X axis linear guides I'm using a 72" ground Vee rail and Vee rollers on one side, bolted to 1x1 steel tubing which is welded to the main frame of the table. The opposite side is the same except that it uses flat rollers on a flat rail. The X carriages are cut from 1/4" steel plate. Each carriage has two fixed rollers on top and two smaller rollers in adjustable slots on the bottom. The gantry is made from 2"x2" uprights and 4"x2" cross beam, welded to the carriages. The Y axis uses two V rails, one bolted to the top and one bolted to the bottom of the 4"x2" gantry tube. I have rails on both sides of the gantry, the second set will be for a drilling head.

The X and Y axis are driven by timing belts and steppers. The belts are 3/8" width .2" pitch XL series polyurethane with kevlar strands. The belts are fixed at each end, wrapped over drive pulleys and tensioned using two double skate bearings as idlers on each belt. Both axis are direct drive with 15 groove pulleys on 210 oz/in NEMA 23 stepping motors, two on the X and one on the Y.

More later...

Fiero Addiction
04-27-2008, 11:45 AM
The Z axis is a linear stage assembly that I found on Ebay. I think it's from some kind of silicon wafer handling machine. I got two of them for ~$120 including the motors. I made the plasma torch holder from a block of aluminum, it's mounted on some miniature THK linear rails to activate the tip contact switch.

The control box is 12"x12"x6", should have been larger but it's what I had. It holds a Cosel 24V 15 amp power supply, A Mechatronics 4 axis driver board, a four output isolated relay board, E-stop relay, cut/drill switching relays, 5V power supply with 5 optoisolated input channels, Torch height control board, two fans, and front panel controls and indicators.

I can traverse at 200ipm. The X has trouble going any faster than that with these little motors. The Y will do 300ipm without any problems. I'm driving the motors at twice the rated current and 4 times the rated voltage, they don't even get warm. I'd like to push them harder, but I'm just about at the limit of the drivers. I haven't noticed any missed steps yet and it moves faster than my plasma cutter can cut, so I guess there's no need to change anything.

Weldtutor
04-27-2008, 12:44 PM
I just finished building my plasma table and have been running it for about a week...

Nice looking project you have completed.

Thanks for sharing the construction information & finished pictures.

"Happy cutting." :)

madmike357
04-30-2008, 12:14 AM
thats a good lookin table how many gallon is your water tank?

lamicron
04-30-2008, 08:00 AM
Do you use any chemical to keep the water clean of rust ? My water table is full of it...

Fiero Addiction
04-30-2008, 03:59 PM
The table volume is about 60 gallons, plus about 15 gallons excess in the tank, so the 80 gallon air tank is nearly full when the table is empty. I added about .05% by weight of sodium nitrite (not sodium nitrate!) as a corrosion inhibitor. I'm using n-alkyl dimethyl benzyl ammonium chloride and n-alkyl dimethyl ethylbenzyl ammonium chloride as an algaecide. These chemicals are both widely used for cooling water treament. I also added an ounce of blue dye so I remember not to drink the water! :eek:

Here's the recipe for home-made PlasmaQuench
1/4 pound of sodium nitrite powder ($15/pound)
1 teaspoon of Physan 20 ($8/8oz bottle)
1 oz Ultramarine blue food-grade dye ($5/oz.)
Mix well, treats 75 gallons of water.
All prices include tax and/or shipping.

It seems to be working very well, the slag in the bottom of the table is not rusted at all, and it also prevents the sheets and cut-outs from rusting. I haven't been using it for very long, but the water is as clear as the day I put it in. The blue dye is starting to settle out, maybe I should have used liquid dye instead of powder, but it's not important anyway, the color was just for fun.

Edited to post some pictures of the bottom of the water bed.. no rusty muck, just shiny beads and black dust. The slats were rusted before I installed them.

txcowdog
04-30-2008, 11:14 PM
Excellent build at an affordable price. You have done a great job. Now I'm jealous.

DRL
05-01-2008, 12:49 AM
Fiero,
Thanks for the recipe. You named 2 different ammonium chlorides, are they both in the Physan 20? What about a source for them?
Great looking table. I love your belt drive. I've been thinking of doing that with small roller chain, just like your Y axes, with the chain laying flat, supported, instead of hanging in midair like if it were a loop. Easier to adjust tension.

DRL

Fiero Addiction
05-01-2008, 06:49 PM
The Physan 20 is marketed for home and garden applications as a general purpose disinfectant, fungicide, virucide, and algaecide. It contains both of the amonium chlorides. You can get it at a garden center or greenhouse supply, or online retailers such as Amazon.com. The label gives instructions for treating pools, you can scale it down for whatever size your plasma table is.
The Sodium Nitrite should be about .05% by weight. Just calculate the weight of the water in your table, multiply by .0005, and add that much Sodium Nitrite.

Check Ebay seller quartzpegmatite for Sodium Nitrite
Check Ebay seller heavenlyorchids for Physan 20

http://www.physan.com/

I've been using the table just about every day since I finished it. The fun hasn't worn off yet. I'm running out of metal.

Fiero Addiction
05-16-2008, 06:21 PM
Well after a few weeks of use and an upgrade to an Esab 875 plasma cutter, one of the allegro 3977 chips on the Mechatronics board let it's smoke out! I just replaced it with Keling 5042 drivers and it was a huge improvement to the machine. I can now get 700 IPM from the X and 1200 IPM from the Y, accelleration at 100 IPS/S with lots more power than it ever had. I had blamed the little 210 oz/in motors for the poor performance when it was really the drivers. The acceleration is still not fantastic, but it's satisfactory.

I'm noticing some minor white corrosion on the galvanized bed of the water table. The steel slag and dropouts are still not showing any rust, and the water is still clear. It gets a nasty muck on the surface after cutting, but after a down/up cycle it's clean again.

Jon

TT350
07-02-2008, 07:05 PM
Man that is a first class job!!
I like the belt setup.
Why did you choose belts over
rack and pinion?

Fiero Addiction
07-03-2008, 02:05 PM
I used belts for a couple reasons. They are easy to tension and virtually backlash-free, no need for the spring-loaded pinion to keep gears in tight mesh. Belts don't wear (much) and don't require lubrication. If a belt gets damaged, it's cheap and easy to replace. They were about half the price of rack, at least from the suppliers I was dealing with. The 3/8" belts are a little small for the X axis, I can visibly see some belt stretch when accelerating or decelerating at high rates. I would go 1/2" or 3/4" if I did it again.

I was a little concerned about direct driving the belts when I was building the machine, most of the info you read on this forum will tell you that you need further reduction, but for plasma cutting you really don't. My resolution is more than good enough for plasma cutting, and it has plenty of torque to move the heavy gantry and torch around. I can put a pen in the torch holder and draw shapes on paper with no visible steps.

TT350
07-03-2008, 03:01 PM
Thanks for the info.

TT350
07-03-2008, 06:26 PM
Where did you get your THC?

Fiero Addiction
07-04-2008, 09:55 AM
I made my own THC based on the schematics in the older Mach user manual. It has been working very well.

TT350
07-04-2008, 10:15 AM
Is there a link to the info?

Mongkol
07-05-2008, 12:41 AM
Hi Fiero,
Do you use the plasma cutter with manual torch to link with your plasma table? What brand and model do you use?

Mongkol

Fiero Addiction
07-05-2008, 10:27 AM
TT350, The schematic for the THC can be found in the Mach2 user manual, section 12.2.
http://machsupport.com/docs/Mach2Mill_6.11.pdf
I made some changes to mine, but if built the way it's shown, it should work just like the THC-300. It provides torch-up, torch-down, and arc-good outputs. I'm using Mach3 and it integrates very well with the built in controls. Figure 12.2 is the voltage divider and filtering circuit that mounts in or on your plasma source. Figure 12.3 is the circuit that compares the scaled arc voltage to the set voltage and generates the appropriate up/down output signal. It also has fault detection and voltage display circuitry.

Mongkol, I started out with a Thermal Dynamics 35C and hand torch (seen in pictures) but I now use an Esab PCM-875 with a hand torch. The Esab has connections for the torch-on and arc-good signals, as well as a 20:1 scaled arc voltage.

lamicron
08-22-2008, 08:14 PM
How are your belts working? Is there any backslash? I´m building a new plasma table and really want to work with belts! You tell about using the 1/2 " in belt ( H ?) Is it ok? i was thinking to use a t5 o t10 ( 5mm or 10mm) which one you thimk will be better<?
Thanks
Luis

510rob
08-23-2008, 05:36 PM
Fiero,

I looked up the specs on your ESAB PCM-875, and specs are 10-60 amps output range. What is the maximum thickness of steel that you have cut with that plasma machine? What kind of thickness could you get from your original plasma machine?

Oh yeah, your machine looks very well constructed too - nice job!

Fiero Addiction
08-24-2008, 12:49 PM
lamicron,
The belts are close enough to zero backlash that it can be considered zero for this kind of application. I also have no drive reduction, so there is no extra backlash from that. I haven't had to replace or re-tension any belts yet, so I am very satisfied.

510rob,
The Esab PCM-875 is rated to cut 7/8" steel according to the manual that came with it, but I'm betting 5/8" is a more realistic limit. The heaviest matarial I've cut is .4" mild steel and if I have everything set up right it does a nice job with very little taper, but more often I get more taper than I like. I'm still figuring out the best settings as far as cut speed and height. I have to run it quite a bit slower than the recommended cut speeds in the manual. I think the kerf is wider than most, it runs about .9". It uses high frequency pilot arc starting, which hasn't been a problem for me. I got the unit on Ebay for $1200, brand new with warrany.
The Thermal Dynamics 35C is discontinued, but it's the same as the Drag-Gun Plus that they still sell. It's a small 35 amp portable unit with a built-in compressor. I still have it around for manual cutting jobs. It's rated for 1/2" steel, but I found 3/8" was a more reasonable limit, and even that was too much most of the time. The TD torch seems to work a lot better than the Esab, finer kerf, cleaner cuts, better consumables life, but a lot of that probably has to do with the lower output current. If I never had to cut anything over .25" I may have stuck with the 35C. The high frequency start on this unit did give me some trouble too, and it was never intended for mechanized cutting.

hugoglez7210
09-22-2008, 12:33 AM
I recently bought some machine called a mega-plotter the owner toldme that it works good, so I tough I coul do some modificacions and use it as a plasma table, he gave a box with step motor driver alredy plug to a the step motor it turns on but I'm stuck with the driver for the computer he gave me the drivers on a flopy disk he said those are from ability systems, but the flopys are just blank. can you help me what kain of drives i can use

radioactive
09-23-2008, 05:49 PM
Nice job on the build it looks like it turned out great...

I would like to build one almost identical to yours. Do you mind sharing where I could find most of the material other than the steel? vee rails, steppers, belts, pulleys, etc.?

Also did you have any pieces plasma cut for you that you possibly still have the drawing for? Like the side plates for the gantry portion...

Is the table opening 4'x4' or slightly larger? I wasn't sure if I should make the opening exactly 4x4 or if it needs to be slightly larger to prevent the torch from cutting above the edge of the table...

Thanks!

Fiero Addiction
09-23-2008, 09:53 PM
McMaster Carr - fasteners, open end belt, V rails, adjustable feet
Stock Drive Products - pulleys, belt clamps
Modern Linear - V rollers (size 2)
VX Bearings - skate bearings

I have the X and Y carriage plates drawn in CAD. I'll upload them.

My table inside area is 56" x 60". I don't know what the actual cutting capacity is, the torch cannot quite travel all the way to the edges except on the far end of the X axis where it could go over. Notice how the X rails extend beyond the ends of the table to increase the travel.

I had an occasional problem with the belts running off the edge of the double 608 bearings that are used for idlers. I replaced some of them with back to back flanged 608 bearings to form a sort of pulley.

Jon

Fiero Addiction
09-29-2008, 01:44 PM
I just wanted to add a few notes for anyone who is considering using the drawings I posted. The gantry end plate is sized to use #2 V rollers in the top holes and 608 bearings on the slotted lower holes to hold the gantry down on the rails. The rails are #2 V rail bolted to 1x1 steel tubing.

The Y carriage plate uses #2 V rollers top and bottom. The top ones are fixed and the bottom ones are adjustable via eccentric bushings. The dimensions are to fit #2 V rail bolted to 4" tall tubing.

Jon

kermit582
12-10-2008, 09:45 AM
hi I was just wondering if you are driving the table from both sides or just one side on the x axis

Fiero Addiction
12-10-2008, 08:04 PM
Both sides are driven; two motors, two drivers for the X axis.

kermit582
12-14-2008, 09:00 PM
I was wondering if anyone has ever tryed a belt drive on a 4x8 table? would it work? or is that to far of travel for a belt drive

matttargett4
12-15-2008, 03:15 PM
kermit,

ive just finished my 10 x 5 table, belt drive works great i wouldnt do it different if i did it again, i have a 12Nm nema 34 each side, 2:1 reduction onto a 14 tooth 1/2 inch pitch belt, ds 10m /min no sweat, great acceloration, no backlash, brilliant repeatablility, i found it to be much cheaper than the rack ad pinion option.

kermit582
12-18-2008, 11:10 AM
do you have any pics or a build log onhere?

matttargett4
12-18-2008, 02:14 PM
kermit,

icant say that i do no, im just in the finishing stages so will post pictures when all is tidied up if you like, is a simple system really, on my x axis the belt is fixed at both ends in a clamp, the gantry uses two nylon rollers to tension the belt and wrap it around the drive pinion, i ve tried to sketch it in paint underneath, the rollers are 75mm apart horizontally and vertically, ive just put a groove in the outside of the roller to help the belt run in the middle, only 3.5mm deep to encourage it to the middle, appears to do its job. any more questionsgive me a shout

matt

bamwa
12-19-2008, 02:17 AM
hello, i'm curious as to what you mean by a groove. Why not use a washer on each side of the roller. Can you post a pic? Thank you in advance.

matttargett4
12-19-2008, 08:48 AM
hi,

all it ive done is turned down the central 30mm of the roller by 7mm dia with a 45 degree slope on each side to try to make the elt self centre, the profile should be in the attatchment below, excuse the paint drawing, its all i had o hand.

ill probably get shot down for ths big time, but form what i hav learnt from this forum and through a very small amount of practical experience compared to some members i think the most important thing in designing / building your own machine is to not be frightened to have a go at what you think might work and see what happens, particularly with the general mechanical engineering stuff like this, i tried a flat roller, it worked ok but i thought it could be better so i changed it, why did i put a 3.5mm groove in the roller, because it looked kinda right, and it does pretty well what i want it to, maybe it would be better if it were deeper i dont know, my main piece of advice would be keep you design pretty simple, complication causes failure in my experience aftr that give it a go and enjoy it since it is after all a hobby for most of us.

Here endeth the gospel according to me! dont be afraid to ask if you want to know something else, quite cool to think somone else is interested in my messing about!

Torchhead
12-20-2008, 04:56 PM
You may find instead of a "groove" in the idler pulleys that a "Crown" works better if you run them against the flat side of the belt. Something to do with a belt under tension moving to the high spot but I can't give you the engineering justification because I am just an old beat-up EE (:0

TOM CAUDLE
www.CandCNC.com

Richard Honey
12-27-2008, 03:47 PM
I agree with your crown idea Tom.

As a kid on a farm in Western Australia we had a lot of machinery and equipment driven with flat belts. Invariably the pulleys were not flat but had a slight crown.

The flat belts ran true even with significant misalignment of the drive and driven pulleys. In many cases we simply drove our old International W30 tractor up to the machine, looped the flat belt over the two pulleys and reversed the tractor to tension the belt. No high tech alignment there.

As far as I can work out the belt creeps towards the part of the pulley with the biggest diameter' and as the crown of the pulley is the giggest diameter; that where it tries to stay.

If we imagine a flat belt running on a tapered pulley; the belt will only be making proper contact with the bigger part of the taper. If there is sullicient belt slackness, the belt will automatically climb up the taper until it runs right off the high side of the pulley.

A pulley with a crown is similar to a pulley with two tapers; hence once the belt climbs to the top of the taper it will stay there, because to go further would be to start to go down the other taper and belts don't like doing that.

So there we have it. A beautiful union of flat belt drive, steam engine technology married with computerised digital control and drive technolgy.

A marriage made in heaven!

Degrom
01-08-2009, 02:42 AM
Hi there..

Great design!!! Do you have any pictures of some of the cuts you have made and what was the thinnest sheet metal you have cut with it?

Thanks for sharing your design with us.
Bert.


I used belts for a couple reasons. They are easy to tension and virtually backlash-free, no need for the spring-loaded pinion to keep gears in tight mesh. Belts don't wear (much) and don't require lubrication. If a belt gets damaged, it's cheap and easy to replace. They were about half the price of rack, at least from the suppliers I was dealing with. The 3/8" belts are a little small for the X axis, I can visibly see some belt stretch when accelerating or decelerating at high rates. I would go 1/2" or 3/4" if I did it again.

I was a little concerned about direct driving the belts when I was building the machine, most of the info you read on this forum will tell you that you need further reduction, but for plasma cutting you really don't. My resolution is more than good enough for plasma cutting, and it has plenty of torque to move the heavy gantry and torch around. I can put a pen in the torch holder and draw shapes on paper with no visible steps.

Torchhead
01-08-2009, 01:14 PM
I was a little concerned about direct driving the belts when I was building the machine, most of the info you read on this forum will tell you that you need further reduction, but for plasma cutting you really don't. My resolution is more than good enough for plasma cutting, and it has plenty of torque to move the heavy gantry and torch around. I can put a pen in the torch holder and draw shapes on paper with no visible steps.

If you are not concerned with the low resolution, low torque, and inaccuracy of direct drive then a little belt flex should not be of concern. You can never get more accuracy than you have resolution (smallest distance the tool travels with one step). If you are cutting out rough brackets for welding were you can have 1/16 margin, then build a machine to meet those standards. Since plasma is not "precision" cutting, it negates some of the need for accuracy, but remember that all the errors are cumulative. So if your table accuracy is only .030 then add the flame inaccuracy to that (maybe .020) and you are at .050 Plenty good for stuff that gets welded together. For other types of cutting (like decorative with fine cut) it limits you ability to do detailed cuts.

TOM CAUDLE
www.CandCNC.com
Totally Modular CNC Electronics.

Fiero Addiction
01-08-2009, 04:18 PM
Prior to building this machine I was paying to have parts cut for me, and I later found out that they were cut on a Torchmate by a member of this forum. I can say that the same parts cut on my machine look just as good as those that were cut on the Torchmate. It did take me a long time to figure out what settings work best, and I don't use the machine that often so I'm still learning every time I use it. I did make a lot of scrap metal and waste a lot of consumables in the beginning. It was very frustrating at times, but it was well worth it.

Santa brought me a new camera for Christmas, I'll have to try cutting some artistic type stuff and post a few pictures. I normally make parts that are not extremely dimensionally critical. Automotive engine mounts and such, 10ga to .375" steel. It might be fun to try something different.

Jon

Degrom
01-08-2009, 08:20 PM
Hi There,

I agree that Plasma is not accurate compare to a CNC mills or laser cutters. But I keep on asking do I really need that accuracy from a budget machine. This kind of table opens up a lot of opportunities to get your foot in the door...

I am not form the US so even the cheapest machine, if I have to import it will cost almost double the price its worth when it gets here.(Making this DIY machine worth a lot more if you really think about it.. :)

Best regards,
Bert.




If you are not concerned with the low resolution, low torque, and inaccuracy of direct drive then a little belt flex should not be of concern. You can never get more accuracy than you have resolution (smallest distance the tool travels with one step). If you are cutting out rough brackets for welding were you can have 1/16 margin, then build a machine to meet those standards. Since plasma is not "precision" cutting, it negates some of the need for accuracy, but remember that all the errors are cumulative. So if your table accuracy is only .030 then add the flame inaccuracy to that (maybe .020) and you are at .050 Plenty good for stuff that gets welded together. For other types of cutting (like decorative with fine cut) it limits you ability to do detailed cuts.

TOM CAUDLE
www.CandCNC.com
Totally Modular CNC Electronics.

Degrom
01-08-2009, 08:28 PM
Thanks Jon,

Pictures would be much appreciated. I would like to build a machine that would be able to cut proper straight line and circle cuts out of 2mm(0.07") sheet metal. If it can do more detailed cuts it would be a bonus to me.

I know thicker material will not be a problem... :)

Thanks again.
Bert.


Prior to building this machine I was paying to have parts cut for me, and I later found out that they were cut on a Torchmate by a member of this forum. I can say that the same parts cut on my machine look just as good as those that were cut on the Torchmate. It did take me a long time to figure out what settings work best, and I don't use the machine that often so I'm still learning every time I use it. I did make a lot of scrap metal and waste a lot of consumables in the beginning. It was very frustrating at times, but it was well worth it.

Santa brought me a new camera for Christmas, I'll have to try cutting some artistic type stuff and post a few pictures. I normally make parts that are not extremely dimensionally critical. Automotive engine mounts and such, 10ga to .375" steel. It might be fun to try something different.

Jon

Fiero Addiction
01-11-2009, 11:46 AM
This is a piece I cut last week, 10ga HRS, cut at 60 amps and 75 IPM. The big hole is about .8" diameter. There is excessive taper on the small outside corners due to the speed, but it is not critical for this part.

http://www.fieroaddiction.com/images/plasma/100_0016.jpg

Fiero Addiction
01-11-2009, 11:57 AM
Here is two pieces of .375" HRS on top of a piece of .25" HRS, all without any secondary finishing. I don't recall the settings I use for these.

http://www.fieroaddiction.com/images/plasma/100_0020.jpg


This next one is four pieces of .375" HRS after finishing the edges with a 2" roloc flap disc and paint.

http://www.fieroaddiction.com/images/plasma/100_0025.jpg

Jon

Fiero Addiction
01-11-2009, 12:14 PM
Here's a picture of the scribe I use for marking holes to be drilled. It's a standard Blue Point pneumatic scribe mounted on a single acting pneumatic slide with spring return. A single solenoid activates the scribe and brings the point down to the plate. When the solenoid closes, the air bleeds off through the scribe and it retracts. I haven't used it for marking lines, but it works great for marking points, and makes a nice center mark for drilling. I wrote a custom post file for Sheetcam to handle the tool offset and use Sheetcam's drill function, so it's all automatic.

http://www.fieroaddiction.com/images/plasma/100_0021.jpg

bamwa
01-11-2009, 03:04 PM
Hello Fiero, those parts look like S$$T! Just kidding. (notice I used dollar signs? )

Congrats on a sweet table. I was wondering what size is your drive pulley, and did you ever research a chain drive setup? I am currently building a table. Belts are going to be around $300, but I found 100' spool of roller chain for $100. I think it's for atv's. This would save a little money as I also am attempting to break the $1000 table barrier.
I have seen 3 ideas for the chain. One being your setup but with chain instead of belt, another being a fixed motor on the table frame with the chain being looped around a pulley on each end and attached to the gantry, and thirdly the chain welded to the rail thereby acting as gear rack. To eliminate stretching the third way seems best. Your thoughts? Also, where did you get started in learning g code and running the software (converting dxfs, checking g code, nesting parts, torch up and down, you know, the basics). This learning curve looks like a cliff from here!

Thanks, Bamwa

Degrom
01-11-2009, 03:15 PM
Hey... Those parts look great!!!

Forgive me but I am still in the dark ages and parts like that takes for ever to make it in my little work shop.(Lots of manual labor involved and then its not even close to that quality)

Keep up the good work!!!

Regards,
Bert.


This is a piece I cut last week, 10ga HRS, cut at 60 amps and 75 IPM. The big hole is about .8" diameter. There is excessive taper on the small outside corners due to the speed, but it is not critical for this part.

http://www.fieroaddiction.com/images/plasma/100_0016.jpg

maglinvinn
01-11-2009, 03:18 PM
will it be possible to see a picture of how you anchored your belts?

you used belts on the x axis and the y axis both, correct?

Some more upclose photos of your mounting bracket for the tourch head would be great too!

Would you mind sharing with us who you bought the belts from?

Fiero Addiction
01-11-2009, 05:28 PM
Hello Fiero, those parts look like S$! Just kidding. (notice I used dollar signs? )

Congrats on a sweet table. I was wondering what size is your drive pulley, and did you ever research a chain drive setup? Also, where did you get started in learning g code and running the software (converting dxfs, checking g code, nesting parts, torch up and down, you know, the basics). This learning curve looks like a cliff from here!

Thanks, Bamwa

The drive pulleys are 15 tooth. I did look at chain and consider all three variations. I think your choice really depends on how you want to lay it out and what you are comfortable working with. I don't like the design that uses a motor fixed to the table with a moving chain, it seems like it would take a lot of extra power just to accelerate and decelerate the chain.
I taught myself how to use the software. I'm certainly not an expert, I just know enough to make it do what I need. I can hardly look at g code and tell what the machine is going to do, but you really don't need to know it to run one of these. Sheetcam takes your DXF and converts it to g code, load that into Mach3 and press start. There are a lot of settings to learn in the beginning, but once you have profiles set up for different materials, it's pretty easy. All of my nesting is done manually in Sheetcam. The software forums are really helpful when you get stuck with something.

Fiero Addiction
01-11-2009, 05:50 PM
will it be possible to see a picture of how you anchored your belts?

you used belts on the x axis and the y axis both, correct?

Some more upclose photos of your mounting bracket for the tourch head would be great too!

Would you mind sharing with us who you bought the belts from?

Yes, belts on X and Y, type XL belt from McMaster Carr Supply. The belt clamps are from Stock Drive Products.

This first picture shows the Y belt on top of the gantry. It's also set up for a second belt to run a carriage on the other side of the gantry as well (not installed). Here you can also see how I did the home and limit switches.
http://www.fieroaddiction.com/images/plasma/100_0026.jpg
http://www.fieroaddiction.com/images/plasma/100_0027.jpg

The X belts are under the rails to prevent damage when loading sheets.
http://www.fieroaddiction.com/images/plasma/100_0032.jpg
http://www.fieroaddiction.com/images/plasma/100_0033.jpg

In addition to the Z axis slides, the torch holder is on four tiny ball slides with about 1" travel for initial height sensing.
http://www.fieroaddiction.com/images/plasma/100_0029.jpg
http://www.fieroaddiction.com/images/plasma/100_0028.jpg

maglinvinn
01-11-2009, 06:06 PM
OOH!

you used a tongue and groove rail on that... didn't see that in the original pics. where'd you get the tongue and groove set up from?

Fiero Addiction
01-11-2009, 07:10 PM
OOH!

you used a tongue and groove rail on that... didn't see that in the original pics. where'd you get the tongue and groove set up from?

You mean the main linear motion rails? They're V rails from McMaster Carr.

Jon

maglinvinn
01-11-2009, 08:56 PM
You mean the main linear motion rails? They're V rails from McMaster Carr.

Jon

hmm... when i went to the McMaster Carr site i searched for V Rails, and couldn't quite find the style you're using in this rig.

what category rails is it under?

I'm trying to price the component costs of something like this, because i'm 99% positive i'm going to end up building somehting a lot like it within the next 3 months. less if i have my way. haha.

Fiero Addiction
01-11-2009, 09:27 PM
It's page 1092 of their current online catalog, Preceision Ground Rails. The stuff I used is $6 per foot. They have rollers on page 1091, but I got my rollers from Modern Linear for much less. Search "track Rollers" if you can't find it. Modern Linear also sells the same type of rails and some other neat stuff. http://www.modernlinear.com/

plain ol Bill
01-11-2009, 10:15 PM
I used Superior bearing for my V rails and wheels.
http://www.superiorbearing.com/

maglinvinn
01-11-2009, 11:04 PM
It's page 1092 of their current online catalog, Preceision Ground Rails. The stuff I used is $6 per foot. They have rollers on page 1091, but I got my rollers from Modern Linear for much less. Search "track Rollers" if you can't find it. Modern Linear also sells the same type of rails and some other neat stuff. http://www.modernlinear.com/

6 bucks a foot is a price i could never say no to! lol.

now, i realllllly hate to be a bother, but when i was looking at the modern linear for the v bearings, i didn't see one spec'd as #2.

Guide Roller, 52100, sealed (VW-2X)


Price: $14.87

Qty: Max: 100

i did see that one however... is that the same?

Fiero Addiction
01-12-2009, 03:23 PM
I did get a quote from Superior Bearing, and I think they may have been less expensive for the rollers, but I ended up ordering from Modern Linear for some reason, probably for ease of ordering (online).

All of the suppliers of this type of track and rollers seem to have four standard sizes, 1 thru 4 from smallest to largest. It shouldn't matter where you get them from, Bishop Wisecarver, Superior, Modern or McMaster, they all interchange. You can even use a size 1 roller on a size 2 track, etc.. Look for the number designation in the part number (modern Linear VW-2X = Superior T2, etc.) or look at the dimensions to figure out what you need. I used the VW-2.

Jon

mcArch
04-01-2009, 11:44 PM
Hi Fiero Addiciton, very nice work there on that table! What sort of trouble and solutions did you have and come up with for the hi frequency start on that ESAB? I have an ESAB pcm1125 that I am having a heck of a time with - that Hi Freq. is really messing up my THC interface.

Thanks for sharing.

Fiero Addiction
04-07-2009, 07:00 PM
mcArch, I haven't had any trouble with the ESAB. I have an 8 foot rod driven into the ground (through the floor) right next to the table. From the rod I have a ground cable running to the case of the ESAB, and another cable to a stud welded to the frame of the table. The work lead from the ESAB is also conncted to that stud. The PC and power electronics are isolated from the table ground and are grounded only through the power cords.

The only time I have a problem is if I have a programming error that causes it to fire over a cutout or too high above the plate, it will light for a few seconds and then MACH3 will go to E-stop. I just hit reset and it's ready to go again.

Jon

Dirtbos
04-15-2009, 03:01 PM
I am sure you put in a great deal of time and effort into your design. It is well thought out, in my opinion.

Thank you for posting the design and all of the related information. It has been a great help to me (and I am sure to many others).

I will be building my table along the lines of yours, with some variations, shortly. It will serve my needs very well.

Thank you again,

Mike :cheers:

Dirtbos
04-17-2009, 12:56 PM
One question if you don't mind. Are you using regular angle iron for the flat rail on the X axis? If so, did you do anything to improve the surface quality? If not, what did you use for that rail?

Thanks,
Mike

Fiero Addiction
04-20-2009, 10:52 AM
It's just plain 1/2" x 1/2" x 3/16" angle that I had laying around. The surface is a lot smoother than the typical angle iron I'm used to, maybe because of the smaller size. It was smooth enough for the rollers to ride on without doing anything to it, but you could polish it if you feel the need.

I'm not sure if I said it before, but I originally had a V rail on that side and it caused problems because it wasn't perfectly parallel to the other side. I realized there was no need for V rail on both sides, and the angle iron was the perfect solution with the least amount of changes to other parts.

millman52
04-20-2009, 04:15 PM
I'm not sure if I said it before, but I originally had a V rail on that side and it caused problems because it wasn't perfectly parallel to the other side.
I realized there was no need for V rail on both sides, and the angle iron was the perfect solution with the least amount of changes to other parts.


I've recomended to new builders to use only 1 rail for tracking. I feel you are asking for problems having 2 guided rails & it's money spent for no more accuracy in the table.

I've seen many on here with rails on both sides I admire those who have the patience to get them in the near perfect alignment they have to be.

I've always wondered what would happen when the gantry is held by precision linear rail on both ends, if you were cutting small parts from 1 1/2" steel with Ox/Fuel. I can't help but believe something would bind or warp as heat begain to build up & the gantry grows.

Dirtbos
04-21-2009, 02:20 PM
Fiero Addiction,

A cumulative error in part size accuracy of as much as .050 has been suggested by a previous poster. What has your experience been so far? How close does your table cut to dimension?

Mike

DennisCNC
04-30-2009, 11:30 PM
How is the home made plasma quench working?

Dustin407
05-01-2009, 04:13 AM
[QUOTE][Originally Posted by Fiero Addiction

I'm not sure if I said it before, but I originally had a V rail on that side and it caused problems because it wasn't perfectly parallel to the other side.
I realized there was no need for V rail on both sides, and the angle iron was the perfect solution with the least amount of changes to other parts.


I've recomended to new builders to use only 1 rail for tracking. I feel you are asking for problems having 2 guided rails & it's money spent for no more accuracy in the table.

I've seen many on here with rails on both sides I admire those who have the patience to get them in the near perfect alignment they have to be.

I've always wondered what would happen when the gantry is held by precision linear rail on both ends, if you were cutting small parts from 1 1/2" steel with Ox/Fuel. I can't help but believe something would bind or warp as heat begain to build up & the gantry grows.
04-20-2009 10:52 AM
/QUOTE]

Modern linear has an answer to this problem. If you use 2 v-rails, one on each side, shim the one perfectly straight. The other let flow with your steel tube. On the shimed v-rail use the fixed wheel bushings. On the other side used the ecentric elongated bushings, this allows the wheel to go in and out without binding and keeping the same height. To clarify for example, the wheel may be 1/2" thick and the bushing 5/8" long, this allows for 1/8" of in/out play. You have to ask him for this, because it is a prototype part(that is not listed) and he is willing to give them out for free for people to try. He only wishes for feedback, eventually it will become a catalog part.

millman52
05-01-2009, 02:22 PM
Fiero Addiction,

A cumulative error in part size accuracy of as much as .050 has been suggested by a previous poster. What has your experience been so far? How close does your table cut to dimension?

Mike

I can't speak for others But my table will hold a 2" diameter hole through 3/4" plate to within .005 of round using Oxy/fuel. & will increase or decrease hole size by exactly the change you make in your CAD drawing.

I am literally burning 49/64" holes in 3/4" plate & going straight to the radial drill & tapping them 7/8"-9 without any other cleaning other than grinding or chipping off dross.

If you pay attention to detail & don't allow backlash when you build a torch table can be as accurate as a milling machine. It's the cutting process itself that will make you chase your tale. In the above burning-tapping hole process I have to use the same exact tip. When a new tip is necessary I have to waste a bit of material to be sure the hole is close enough to size again. Although the tip size lists .060 kerf. 1 tip will take .070 & the next .055

Dirtbos
05-02-2009, 02:06 AM
Modern linear has an answer to this problem. If you use 2 v-rails, one on each side, shim the one perfectly straight. The other let flow with your steel tube. On the shimed v-rail use the fixed wheel bushings. On the other side used the ecentric elongated bushings, this allows the wheel to go in and out without binding and keeping the same height. To clarify for example, the wheel may be 1/2" thick and the bushing 5/8" long, this allows for 1/8" of in/out play. You have to ask him for this, because it is a prototype part(that is not listed) and he is willing to give them out for free for people to try. He only wishes for feedback, eventually it will become a catalog part.

Millman52,

Thanks for the info. I'll check that out. :)

Dustin407
05-02-2009, 03:02 PM
Dirtbos,

I wrote that paragraph about the prototype wheel bushings. I thought it would help you out if you use two rails. But millman is correct you only need on side it is not a big advantage at all to have two. I am going to use two rails on mine, thats because I found this solution, without it I would have only used 1 rail. Here is the link if you wanna check them out.



http://www.modernlinear.com/index.html

millman52
05-03-2009, 01:33 AM
Dirtbos,

I wrote that paragraph about the prototype wheel bushings. I thought it would help you out if you use two rails. But millman is correct you only need on side it is not a big advantage at all to have two. I am going to use two rails on mine, thats because I found this solution, without it I would have only used 1 rail. Here is the link if you wanna check them out.



http://www.modernlinear.com/index.html

Below is a sketch of what I will do when I build again. My current table uses the CR flat bar & (4) double row angular contact bearings #5201-2RS. like the right side of the sketch. http://www.vxb.com/page/bearings/PROD/Kit6934

Although there is certainly nothing wrong with the V rail down both sides. I feel it is spending money for something you don't really need. I worried about wear on the CR strap & bolted the strap to the frame rail so I could change or flip the rail if wear developed. I have run my table now for over 16 months (estimated 30 hrs per week) There isn't anything more than a gray line the width of the bearings in the CR flat.. A couple months back I polished it up with some 220 grit emory just to see if it was wearing a groove down in the strap. Nothing you can feel. I'm convinced it will last for years.

Probably don't neeed the angular contact bearings. I'm sure less expensive single row double sealed bearings would be fine. I used the double row bearings because I had a surplus of them stashed away from another job.

Dustin407
05-03-2009, 11:08 PM
Well how much was the bearings and cr flat? I think a 9' stick of v-rail and two v-wheels are $120.00. Its still more expensive but not real bad. The main reason I am using v-rails on each side is to have a mirrored design. I will be running two motors on the same axis as the v-rails and just wanted to be able to build two motor brackets that are the same( build everything in twos).

millman52
05-04-2009, 07:21 PM
Well how much was the bearings and cr flat? I think a 9' stick of v-rail and two v-wheels are $120.00. Its still more expensive but not real bad. The main reason I am using v-rails on each side is to have a mirrored design. I will be running two motors on the same axis as the v-rails and just wanted to be able to build two motor brackets that are the same( build everything in twos).

You have a point from the building standpoint. 1/4" X 3" X 12' CR flat $70.00 no need for it to be 3" wide though. The 3" is all I have e recent price of. (10) 12mm ID bore sealed bearings $15.00. I think they were about $3.00 each individually from VXB.

"I think a 9' stick of v-rail and two v-wheels are $120.00."

I don't remember what size you're planning to build. If 8' you'll need more than 9' of rail to allow adequate spacing between the V wheels & run off room to get your gantry clear of the cutting surface.

My build was for 5' X 10'. Actual cutting surface is 5' 2" X 10' 2" I have to be extremely careful loading a 10' sheet of thicker steel on the table. If I had it to do over I'd allow at minimum a foot of extra room 2 would be even better.

If you are in the situation that you don't have the extra room for it, then there just isn't much you can do about it. Unless you want to build an annex for the table :D

mcArch
05-18-2009, 06:09 PM
Hi Jon, what THC system are you using?

-Mike

mcArch
05-18-2009, 07:55 PM
Hi Jon, never mind about the thc, I remember now, you made your thc based on the mach manual schematic that Tom C did. I cannot get my pcm1125 to work with the thc, I'm trying to connect to get raw tip volts because Tom's thc needs the raw tip volts & not the 20:1 division that the terminal block provides. I connect to work lead and torch lead, no too dificult I thought. Just trying to find something in your summary here that will give me a clue as to what I'm missing here.

grayman74
07-07-2009, 01:09 PM
Jon / Fiero Addiction,

I am very impressed with the way your table works and looks! You have given me hope that this can be done inexpensively!

tof1
07-23-2009, 04:52 PM
How is the home made plasma quench working?

I would also like to know...?

Fiero Addiction
07-23-2009, 06:43 PM
I would also like to know...?

It's been over a year and it's still working great! The water is still clear, there's no rust anywhere, and no foul smell. I haven't done anything except add water to replace what evaporates. It works better than I could have imagined! The only thing that didn't hold up is the blue dye, it disappeared completely.

tof1
07-23-2009, 09:44 PM
It's been over a year and it's still working great! The water is still clear, there's no rust anywhere, and no foul smell. I haven't done anything except add water to replace what evaporates. It works better than I could have imagined! The only thing that didn't hold up is the blue dye, it disappeared completely.

Very nice! I just ordered the chemicals to add to my water table when it's ready. Do you have a schedule set for when to more chemicals?

Fiero Addiction
07-24-2009, 10:46 AM
No schedule, I figured I'd flush and replace it when it starts turning brown or smelling funky. In a production shop I would expect it to go bad much faster, but mine looks like it's going to go at least two years before needing service. I have enough chemicals left over to treat it at least once more.

I'm slowly putting together a new control cabinet that will house the PC and an 18" touch screen monitor. I'll also be automating the water level control so I just have a fill/drain switch instead of using ball valves. I'm trying to eliminate some clutter from my shop, the computer cart takes up a lot of space, it will be nice to have everything in one self-contained unit without all the cords dangling.


Jon

Fiero Addiction
07-24-2009, 01:27 PM
If you are not concerned with the low resolution, low torque, and inaccuracy of direct drive then a little belt flex should not be of concern. You can never get more accuracy than you have resolution (smallest distance the tool travels with one step). If you are cutting out rough brackets for welding were you can have 1/16 margin, then build a machine to meet those standards. Since plasma is not "precision" cutting, it negates some of the need for accuracy, but remember that all the errors are cumulative. So if your table accuracy is only .030 then add the flame inaccuracy to that (maybe .020) and you are at .050 Plenty good for stuff that gets welded together. For other types of cutting (like decorative with fine cut) it limits you ability to do detailed cuts.

TOM CAUDLE
www.CandCNC.com
Totally Modular CNC Electronics.

Low resolution, low accuracy, low torque......all relative terms. Compared to the hand guided cutting I was doing before I had the machine, this is highly accurate! :D We are talking about home-made hobby type machines here. I don't think anyone believes they are going to replace a mega-buck high def commercial unit with something they made in their garage, but certainly one could hope to match the capabilities of a $10k Torchmate they saw on Powerblock TV. But you are right, the belt stretch doesn't concern me, especially since it only happens at higher than cutting speeds and is self correcting.

The basic resolution with my direct drive is .015" per step. I understand microstepping is not always very accurate, but it theoretically should increase the resolution to .0019". From there I could only guess at accuracy. Gear reduction would increase resolution and torque, but adds complexity and cost which is generally not a welcome addition in home-built machines.

Stepper motors create maximum torque at minimum RPM. Using gear reduction increases motor speeds. Some of the torque gained in gear reduction must be lost to increased motor speed, and if you run the motor too fast it will miss steps or just stall. My thought is that you want to run the motor at the lowest speed that allows you to obtain the desired resolution. If you can meet your resolution and torque requirements without gear reduction, then don't use gear reduction. Gear reduction to gain resolution beyond what is needed is just inefficient.

It takes a considerable amount of force to stop my machine, and since there are no forces acting to stop it (other than it's own weight and friction), it has plenty of torque for a plasma cutting machine. If you push hard enough on the gantry it will stop, so I just don't push on it when it's running. :D

I've never measured accuracy, never had a reason to. I'm able to make parts that fit the way I need them to, and bolt holes that bolts fit through. Circles are round and squares are square. It fit's my needs. I don't do production work, I'm doing prototypes and one-off custom pieces for my own projects and for my company. It saves me a lot of time and I'm making better parts than I ever could without the machine. I've never made a part and then wished I had better accuracy. Less taper and longer consumable life would be nice, but that's a different story.

Jon

Fiero Addiction
07-24-2009, 02:37 PM
Check out my latest video

YouTube - Homebrew Plasma Quench

tof1
07-24-2009, 05:18 PM
Wow, pretty amazing how clear the water is. Thanks for the info!

rusmannx
07-24-2009, 05:59 PM
very impressive. lets see some video of that thing in action!

MARKG
07-25-2009, 01:00 AM
I agree, can we see a video of your fabulous machine working? Great job!

Fiero Addiction
07-25-2009, 12:06 PM
YouTube - Home Made CNC Plasma Cutter with Plate Marker - Part 1

Fast forward to about 1:40 to see the plate marker!

Fiero Addiction
07-25-2009, 12:15 PM
One more....


YouTube - CNC Plasma Cutter - Part 2

Fiero Addiction
07-25-2009, 12:25 PM
YouTube - CNC Motion and Plate Marking Demo

tof1
07-25-2009, 01:47 PM
I wonder what causes that brown looking foam?

Fiero Addiction
07-25-2009, 02:35 PM
I don't know what causes it but it disappears.

Mongkol
07-25-2009, 07:59 PM
Fiero,
After cut, Do you get a free dross in the bottom of material?

Mongkol

Fiero Addiction
07-25-2009, 08:52 PM
I get a normal amount of dross that is easy to clean off. If I have the speed and height just right, and a new tip, it does really well with hardly any dross. I have my 10ga settings down pretty good, the video is 1/4" and judging by the sparks it looks like something wasn't quite right, but it still cut fine.

Mick40
07-25-2009, 09:00 PM
Wow, nice job! Tell us more about the plate maker...How do you interface the two. Did you build it yourself? WE (group) need to know more!!!!!!

Fiero Addiction
07-25-2009, 10:36 PM
Wow, nice job! Tell us more about the plate maker...How do you interface the two. Did you build it yourself? WE (group) need to know more!!!!!!

I made it. See my post #43 on page 4. I'll need to write a different post processor to do engraving, when the need arises. Right now I just use it to mark holes that are too small to be burned.

Mick40
07-26-2009, 12:16 AM
I re-read the post and missed it! I'm really impressed, your cuts are fantastic. I'm looking to build but will only cut 1/8 steel, what would you recommend for a plasma?

Fiero Addiction
07-26-2009, 08:48 AM
I re-read the post and missed it! I'm really impressed, your cuts are fantastic. I'm looking to build but will only cut 1/8 steel, what would you recommend for a plasma?

30 amps should be plenty for 1/8", but you should get the best one you can afford. I would avoid the cheap China units.

Mick40
07-26-2009, 11:12 AM
Hypertherm has a good track record, I will spent the extra money in the long run it will same me aggravation.

thanks!

skippy
07-26-2009, 04:03 PM
Hey thanks for sharing and for the videos, nice build. I especially liked the marking device. I work in 2mm (14 guage) sheet cutting large pieces from 3000 x 1500mm (10' x 5') sheets and would love to build a suitable machine with a marking device for the rivet holes. Yours is a very inspiring project!
By the way, anyone know if plasma cuts pre-galvanised sheet without problems?

adscnc
07-26-2009, 04:18 PM
Fiero, really nice build, you're a tallented man.
If you built again would you still use the same "210 oz/in NEMA 23 stepping motors" or would go a bit bigger ? You do refer to them as smal.

Fiero Addiction
07-26-2009, 10:42 PM
Hey thanks for sharing and for the videos, nice build. I especially liked the marking device. I work in 2mm (14 guage) sheet cutting large pieces from 3000 x 1500mm (10' x 5') sheets and would love to build a suitable machine with a marking device for the rivet holes. Yours is a very inspiring project!
By the way, anyone know if plasma cuts pre-galvanised sheet without problems?

I've cut 18ga galvanized sheet with the plasma, no problems.

I use the marker for marking holes that are too small to burn, or ones that need to be threaded. The plasma makes the holes a little hard to tap, so I mark them and drill them.

Fiero Addiction
07-26-2009, 10:51 PM
Fiero, really nice build, you're a tallented man.
If you built again would you still use the same "210 oz/in NEMA 23 stepping motors" or would go a bit bigger ? You do refer to them as smal.

Thanks!
I would probably get bigger motors, maybe step up to the next frame size. I'm driving them pretty hard and they get very hot within a few minutes. I got 5 of them for $80 on Ebay, so I have two spares before I have to buy any more, but so far no failures.

MARKG
07-26-2009, 10:59 PM
Thanks for the videos, inspiring, great machine!

MARKG
11-08-2009, 01:53 PM
A quick question for Fiero Addiction or anyone else who may be able to help; where do you source the multiwire plugs used to connect and quick disconnect the motors to the controller we see in the photos of your machine in the first couple of posts.

thanks!

Mark

Fiero Addiction
11-08-2009, 06:24 PM
I salvaged a lot of my connectors from some scrap cables (dumpster diving). The rest of them I ordered from either Digi-Key or Mouser. They are AMP CPC type connectors which are pretty common.

MARKG
11-08-2009, 10:34 PM
Thanks!

BruceArnn
12-16-2009, 01:40 PM
Very nice. Clean, straightforward and hardcore DIY. Especially like how you devised your own THC circuits. Care to share the changes you came up with? Keep us posted. Bruce

Fiero Addiction
12-18-2009, 04:09 PM
Very nice. Clean, straightforward and hardcore DIY. Especially like how you devised your own THC circuits. Care to share the changes you came up with? Keep us posted. Bruce

Thanks Bruce. I made some changes that were required to interface my ESAB unit. Also changed the relays' wiring and functions slightly. My LCD display shows arc voltage while cutting, IIRC the original did not. I also eliminated the fault indicating portion, I did not feel it was necessary. There were a few other minor tweaks, but I do not remember the details. If you want specific details I'll need to dig up my notes, I think I drew a schematic of my final design.

BruceArnn
12-21-2009, 08:23 AM
If you want specific details I'll need to dig up my notes, I think I drew a schematic of my final design.


Well yea, I would like to see it and it might help me (us) to think of something we've overlooked. I started the steel part of my build yesterday. I'm following quite a bit of what you came up with. Some variations of course. I had to come back and re-read the part of this thread about V-groove bearings due to sticker shock on my McMaster-carr shopping cart. ;]
Also, the last time I etched a circuit card, I think Reagan was in the white house, did you do something creative there?...Bruce

Fiero Addiction
12-22-2009, 08:45 PM
Well yea, I would like to see it and it might help me (us) to think of something we've overlooked. I started the steel part of my build yesterday. I'm following quite a bit of what you came up with. Some variations of course. I had to come back and re-read the part of this thread about V-groove bearings due to sticker shock on my McMaster-carr shopping cart. ;]
Also, the last time I etched a circuit card, I think Reagan was in the white house, did you do something creative there?...Bruce

I used a small prototyping board, no etching necessary. I usually keep several of them around for small projects like this when I don't want to etch. I think I had to buy the relays and the digital panel meter, but I had all the other components around. My schematic and connecting diagrams are scribbled on paper and I don't have time to draw them in CAD right now. If I ever do I will post them here. Here's a shot of the main THC board. The bottom right quadrant is the incoming arc voltage signal conditioning, then to the left is a quad comparator ic, transistors to drive the LEDs, optoisolators, etc. Top right you'll notice one of the relays has been relocated from the interface card. I did that because it now also switches the output to the display, from preset volts to actual volts while cutting. It's not really necessary, but for some reason when I was building it I thought it would be nice to see something on the display while it's cutting, instead of just going blank as in the original design. In fact I do occasionally make THC adjustments while cutting, and it's nice to see the changes on the display. It tells me it's working, and it also lets me know how much of a change I'm making instead of just twisting the knob. Below the relay is the 7805 voltage regulator ic and filter caps. I left out the bridge because it's being fed from the 24v DC power supply for my stepper drives.

http://www.fieroaddiction.com/images/plasma/100_0897.jpg

BruceArnn
12-23-2009, 07:05 AM
Good info...Gracias..bruce

OKIE J.O.A.T.
01-09-2010, 11:38 PM
Greetings Fiero Addiction,
As Forrest Gump would say, "I like it alot."
I do industrial automation and would like to share a link with you for automating your machine further.
http://flash.ezautomation.net/

Rhinorider
01-10-2010, 01:33 PM
Fiero, Great build, I am just starting and my table will be very similar to yours, except I am going to use rack & pinion. I would also like to add the plate marker to mark small holes as you have and to mark plates that will later be bent in a brake. Where did you find the marker itself, (Manufacutrer, model, supplier?)

jeffz1
02-23-2010, 11:36 AM
Fiero,
Thats a great looking table. The Flat rail on Flat roller on the x axis. Is that just a flanged ball bearing and a piece of small angle Iron bolted to the 1x1 tubing?

jeffz1
02-23-2010, 01:37 PM
I see now on post 60 where you used 1/2x1/2 x 3/16 angle iron for the rail

adiozmm
02-28-2010, 11:43 AM
Hello, very nice facility.
what is the max speed

mkweiss222
03-04-2010, 11:30 AM
Low resolution, low accuracy, low torque......all relative terms. Compared to the hand guided cutting I was doing before I had the machine, this is highly accurate! :D We are talking about home-made hobby type machines here. I don't think anyone believes they are going to replace a mega-buck high def commercial unit with something they made in their garage, but certainly one could hope to match the capabilities of a $10k Torchmate they saw on Powerblock TV. But you are right, the belt stretch doesn't concern me, especially since it only happens at higher than cutting speeds and is self correcting.

The basic resolution with my direct drive is .015" per step. I understand microstepping is not always very accurate, but it theoretically should increase the resolution to .0019". From there I could only guess at accuracy. Gear reduction would increase resolution and torque, but adds complexity and cost which is generally not a welcome addition in home-built machines.

Stepper motors create maximum torque at minimum RPM. Using gear reduction increases motor speeds. Some of the torque gained in gear reduction must be lost to increased motor speed, and if you run the motor too fast it will miss steps or just stall. My thought is that you want to run the motor at the lowest speed that allows you to obtain the desired resolution. If you can meet your resolution and torque requirements without gear reduction, then don't use gear reduction. Gear reduction to gain resolution beyond what is needed is just inefficient.

It takes a considerable amount of force to stop my machine, and since there are no forces acting to stop it (other than it's own weight and friction), it has plenty of torque for a plasma cutting machine. If you push hard enough on the gantry it will stop, so I just don't push on it when it's running. :D

I've never measured accuracy, never had a reason to. I'm able to make parts that fit the way I need them to, and bolt holes that bolts fit through. Circles are round and squares are square. It fit's my needs. I don't do production work, I'm doing prototypes and one-off custom pieces for my own projects and for my company. It saves me a lot of time and I'm making better parts than I ever could without the machine. I've never made a part and then wished I had better accuracy. Less taper and longer consumable life would be nice, but that's a different story.

Jon

Well put...and a very nice machine. I dont think your taper problem is a direct result of how your table performs, but a result of the cutter itself.

jeffz1
03-05-2010, 02:00 AM
Fiero,
Could you show some more pics on how you did your overhead cable support system I have looked at all the images and watched all of your videos and havent seen any clear images of that part of the table. I am trying to build a table similar to yours.

HamerDownJustin
03-06-2010, 01:26 AM
Very nice.I wish I had half your talent.

Fiero Addiction
04-15-2010, 04:12 PM
Fiero,
Thats a great looking table. The Flat rail on Flat roller on the x axis. Is that just a flanged ball bearing and a piece of small angle Iron bolted to the 1x1 tubing?

Yes, but it's just a standard bearing, not a flanged bearing. I initially built it with V rail/rollers on both sides, but the table is about 1/16" wider on one end and it was causing some binding. Then I realized that only one side needs to be guided by V rail. The 3/16" angle was just to take up the space after removing the V rail on that side.

Fiero Addiction
04-15-2010, 04:15 PM
Hello, very nice facility.
what is the max speed

I don't remember anymore, several hundred inches per minute, many times faster than the plasma cutter can cut most material.

MetalHead6263
05-31-2010, 09:46 PM
Awesome , you got any plans you can share yet ?

MBG
09-17-2010, 11:13 AM
I am going to try and duplicate your machine if you don't mind.

I priced the steel and it is about $200 for the frame.

I am puzzled how you built this for $1500.

ilvaporista
09-20-2010, 04:15 AM
Looks great and some really good ideas in there. To avoid accidents and burnt fingers I use a small magnet screwed on a wooden stick to lift parts out after cutting. Saves crashes and keeps fingers out of the way.

Fiero Addiction
10-03-2010, 02:35 PM
I am going to try and duplicate your machine if you don't mind.

I priced the steel and it is about $200 for the frame.

I am puzzled how you built this for $1500.

My frame is 4" x 2" x 14ga., exactly 30 feet of it, 3.293 pounds per foot, at about $.80 per pound that's $80. Add the gantry, sheet for water bed, slats, and misc other pieces. I would guess there's not more than $300 in steel for the whole machine, but I did not pay for any of the steel, the entire machine was built from surplus steel that was laying around my shop or scrounged from wherever I could find it. I did buy the material support slats, but they were from a scrap yard for a very low price. I spent a lot of time searching around for the best prices on all of the other components. I would guess I have at least $2000 into it now with upgrades, and that does not include the actual plasma cutter.

pinjas
10-04-2010, 05:03 AM
I have been studying your table for at least a few weeks and I feel that I am a pretty big fan of it's design. I appreciate you sharing your work. I have about a million questions every time I look over this thread but I feel like I am slowly answering these questions on my own.
My big questions that I cannot answer on my own concern designs. Are you very happy with the layout you chose? I read that you would have used wider belts, anything else?

Have you been happy with the accuracy? Accuracy is my number one goal. How exactly did you setup the on/off for the torch?

Fiero Addiction
10-05-2010, 02:37 PM
I should have used wider belts, but it's been over two years with no failures. I am happy with the accuracy. Circles are round, squares are square, dimensions are true to drawings.

pinjas
10-05-2010, 05:02 PM
Did you ever consider using V belts instead?
I've imagined they might need a fair amount more tension, but that might translate to finer movement? I have no idea. I doubt you'd need very wide V belts as they are far thicker, perhaps less likely to form any sort of stretching?
If I do go with timing belts I will definitely go with, at least, 1/2 inch and I am considering 3/4ths wide belts.

millman52
10-05-2010, 06:25 PM
Did you ever consider using V belts instead?
I've imagined they might need a fair amount more tension, but that might translate to finer movement? I have no idea. I doubt you'd need very wide V belts as they are far thicker, perhaps less likely to form any sort of stretching?
If I do go with timing belts I will definitely go with, at least, 1/2 inch and I am considering 3/4ths wide belts.

V belts in my opinion will always walk to a certain extent no matter how tight they are. This would lead to lots of accumulated error by the end of a lengthy program.

I have took the time on multiple v belt pulleys, to align in a straight row, the part #'s on the outer side of the belt. Run a machine even with no load for a couple min. & the #'s are never still aligned.

pinjas
10-05-2010, 07:22 PM
V belts in my opinion will always walk to a certain extent no matter how tight they are. This would lead to lots of accumulated error by the end of a lengthy program.

I have took the time on multiple v belt pulleys, to align in a straight row, the part #'s on the outer side of the belt. Run a machine even with no load for a couple min. & the #'s are never still aligned.

Hah, alright. Thanks for clearing that up for me.

pinjas
10-22-2010, 12:36 AM
Hello,

Here to bug people some more. I have some questions.

What is the purpose of those secondary outer 2x4 rails on
the x axis? It looks like you made the table, and then bolted on another set of 2x4 14 gauge tubes.

I've been trying to compare the difference between v rails and steel angle, is there any?

Why are there bearings on 'top' and 'bottom'? I hope I am being clear in all of my inquiries. I guess another way of putting it is, why are there upper and lower bearings?

Would there be any benefit or difference in using square steel bar instead of rectangular tubing?

Thanks a bunch.

Fiero Addiction
10-25-2010, 12:20 PM
What is the purpose of those secondary outer 2x4 rails on
the x axis? It looks like you made the table, and then bolted on another set of 2x4 14 gauge tubes.


I have no idea what you are talking about.



I've been trying to compare the difference between v rails and steel angle, is there any?


I don't know how to answer that question. They are two completely different things with different purposes.




Why are there bearings on 'top' and 'bottom'? I hope I am being clear in all of my inquiries. I guess another way of putting it is, why are there upper and lower bearings?


The upper bearings guide the gantry, they define the axis. The lower bearings prevent the gantry from tipping over or getting off track.



Would there be any benefit or difference in using square steel bar instead of rectangular tubing?


Solid bar vs. tube? It's unnecessarily heavy.
Square vs. rectangular? Makes no difference other than the obvious dimensional difference.

MARKG
10-25-2010, 07:16 PM
"....What is the purpose of those secondary outer 2x4 rails on
the x axis? It looks like you made the table, and then bolted on another set of 2x4 14 gauge tubes...."

Pinjas, to clarify , the add-ons you are referring to, I think, are the track and belt carriers only. Yes the table is welded up and made water tight, then the x axis tracks are bolted/welded to the table. They are easy to fab this way and can be adjusted/shimmed while you install them, there is no need to have them as a structural part of the table. I would recommend you see post #1, page 1, third paragraph. and read the build through carefully.

Also, my two cents on v belts - using them will give 0 accuracy. Don't do this!

Fiero Addiction, this is a really nice design, easy to build and well thought out. I have all of the parts gathered to build mine to your design, thanks for sharing with us!

pinjas
10-27-2010, 10:40 PM
I think I am starting to understand things, thanks for the information, I really appreciate it. I had an idea though and I am hoping to run it past some people with clarity.
I've been thinking that I might make my table 3x6 or 4x6 or 4x8 or something like that. I've realized and learned that the X axis is a pretty expensive portion of a table. The idea I was wondering about was making the Y axis the X and the X the Y. The longer portion being the Y axis would probably cut down in cost at least a little, is there a reason why this is never done?

tulsaturbo
10-28-2010, 01:53 AM
I prefer the gantry to be the longest part of the table. Its a personal preference. My son and I are in the process of building a new table (3x6) in which the gantry will be 6 feet in length. It will look similiar to what you have pictured.

pinjas
10-28-2010, 01:59 AM
I prefer the gantry to be the longest part of the table. Its a personal preference. My son and I are in the process of building a new table (3x6) in which the gantry will be 6 feet in length. It will look similiar to what you have pictured.

You are saying that the only reason people almost always do it the other way is because of some sort of logic associated with vanity or personal preference? There is no purpose or reason other than that?
I am looking for unforeseen consequences to building a table this way, like, oh it's a bad idea because it causes giant robots to magically build themselves and cut off your big toes, or something like that.

It seems like a good idea in my mind right now, but who hasn't said, "It seemed like a good idea at the time."?

I've been trying to figured out, what to use to secure the belting to the table. http://www.mcmaster.com/#catalog/116/1043/=9gy3cf I found end plates on this page, but at 50 bucks a pop, I'd rather gouge my eyeballs out. I don't understand how a tiny rectangle of aluminum could be 50 bucks. Maybe there is a supplier that charges significantly less or an alternative to this.

outofoperation
10-28-2010, 02:10 PM
is there a reason why this is never done?

Hi pinjas,

who said, it´s never done? Squeeze me (http://www.cnczone.com/forums/plasma_edm_other_similar_machine_project_log/94823-not_so_cost_effective_plasma_table.html)

regards, Steff

http://www.cnczone.com/forums/attachment.php?attachmentid=94563&amp;d=1260122786

vdoug
10-30-2010, 03:27 PM
your machine is sweet. i built a real cheap model(video on youtube under d9electro1) http://www.youtube.com/results?search_query=d9electro1&aq=f just to see how cheap i could go.never putting a pencil on it i would say i got 600 bucks in it,maybe 650. and that includes electronics.(motors,driver,powersupply etc..). i used chain drive and instead of ground rails i used flat plate. i found a couple of deals on ebay on things like idler pulleys and have notice since i bought them the v groove bearings have gone down on price.i think with a lot of luck i havent had any binding on rails or anything with the table.although i dont think its as acurate as yours and i love the side tool of yours as well.you made me feel great about myself when you said hey this is garage build for less and you are more than happy with your products.my problem is finding parts for less.i hate finding the same part or better for less money.but thats my catch 22. i go for less less less so much that a few dollars more i would be more happy sometimes.example:building my second sawmill even after an upgrade on the first one.its close to finished as well. i also have trouble with paint. its called impatence. but now i was thinking of an up grade on my cnc.you gave me more ideas and with my other machine i can do more/better work/parts thank you doug
if anyone can give sugestions on finding the best price on belts and spur gears please post thanks
and yes i know in my videos i start my torch to high, but i have gotten better. still working with speeds though. i got a machine but i'm still a newb

Fiero Addiction
11-28-2010, 05:36 PM
The longer portion being the Y axis would probably cut down in cost at least a little, is there a reason why this is never done?

The biggest reason is that you want to keep the moving mass as small as possible. Less mass means you can use smaller motors/drives and run higher speeds.

Torchhead
11-28-2010, 07:28 PM
More important than speed (unless you are just out to impress your buddies) is acceleration. Good acceleration means sharp corners with less rounding. Acceleration is the mass of the gantry (weight) times the force (rotational torque converted to linear force) applied in a given period of time (typically one sec). You gain torque by either a reduction transmission (belt drive) or with bigger motors. To get more acceleration you either increase torque or lower the mass of the load (gantry).

TOM caudle
www.CandCNC.com

Fiero Addiction
11-28-2010, 09:25 PM
Yes, when I said higher speeds I was implying better acceleration, but perhaps I should have worded it differently.

ptcplasma.sc11
03-30-2011, 11:01 PM
hey fiero addiction, can you explain me with more details how do you control the torch height!? I read before that you did your own THC system, but, can you explain me with more details how it exactly works!?

Fiero Addiction
03-31-2011, 08:05 AM
The THC board receives a scaled and filtered arc voltage signal from the plasma power source. It compares this voltage with the preset voltage determined by the position of the torch height setting potentiometer. If actual arc volts is greater than preset it sends torch down signal to Mach3. If arc volts is less than preset it sends torch up signal to Mach3. Mach 3 does the rest. There is a small range of voltage where it's "just right" and doesn't output any up or down signal.

That's how it works, don't ask me how to build it.

Fiero Addiction
05-29-2011, 02:35 PM
I've finished my new control panel and have been using it for a couple months. I've taken all the internals from the PC and mounted them into a large electrical cabinet along with the power supplies and drivers for the machine, a 19" touch screen monitor, miniature keyboard, card reader, and ATHC controls. The PC was full of black dust, so I put a nice big air filter on the new cabinet.

The ATHC has become problematic and is no longer usable until I can repair it. I don't know if I'll repair it or build a new improved version.

One of my stepper motors has failed. It's actually been giving me trouble for a long time but I hadn't been able to pinpoint the problem until now. It worked fine when cold, but as it heated up it would start to do strange things. I swapped it out and the problem is gone. The motors get super hot and I'm surprised any of them have lasted this long.

I've been cutting a lot of 3/4" A36 steel with surprisingly good results. I was going through a lot of tips trying to figure out the pierce settings so we decided to drill 1/8" holes at the starting points to avoid damaging tips during piercing. I'm near max capacity for the Esab PCM875, Cutting is slow at 8 inches per minute.

http://www.fieroaddiction.com/images/plasma/100_1613.jpg

http://www.fieroaddiction.com/images/plasma/100_1612.jpg

http://www.fieroaddiction.com/images/plasma/100_1603.jpg

http://www.fieroaddiction.com/images/plasma/100_1608.jpg

WSS
05-29-2011, 09:57 PM
That is a really nice cabinet! Very clean. I might steal a few of those ideas.....
WSS

MARKG
05-29-2011, 10:29 PM
Wow FA, very nice work. So it would appear that the water table does not get all of the soot / crud/ dust, good to know.

What are the 3/4" thick parts for if you don't mind telling us.

thx
Mark
Montreal

Fiero Addiction
05-30-2011, 09:55 AM
The parts are for a power hammer.

I'm not sure all of the dust/dirt inside the PC was from plasma cutting ,but it was a disturbing amount. I used a panel filter for a Ford F-series truck, plenty of flow and replacements are 5 or 6 bucks at WalMart.

http://www.fieroaddiction.com/images/plasma/100_1614.jpg

plain ol Bill
05-30-2011, 06:35 PM
:cheers:Ok - good looking job, now for the important part! Tell me about the power hammer:banana:
I have a Sahinler 110# hammer and love it.

Fiero Addiction
05-30-2011, 09:22 PM
The power hammer is someone else's project, I don't know too much about it. It's a big sheet metal forming machine based on a Yoder.

cobretti
05-30-2011, 10:04 PM
I love that control cabinet of yours and with my limited space could really use the same idea albeit on a smaller scale. Would I get that electrical cabinet at any electrical supply store?

thanks

Fiero Addiction
05-31-2011, 09:27 AM
You should be able to order a similar enclosure from any electrical supply, but they are quite expensive. I bought mine at surplus, but I don't remember where. Mine is a NEMA 4 with sealed door, you may find another type more suitable. There are many types available in any size you need. Here's a useful link, or just google NEMA Enclosures.

NEMA Electrical Enclosures and Industrial Cabinets (http://www.automationdirect.com/adc/Overview/Catalog/Enclosures;jsessionid=5e30efcabaa2fab1fbd77537a366a37137a3?source=google&keyword=NEMA%20enclosures&type=search&gclid=CLzCs6ajkqkCFUWA5QodVDTwqQ)

bearings
06-07-2011, 05:07 PM
I am looking at your build and can say Great job and thats one good looking machine. How are your 3/8 belts holding up on the x and y axis? I am looking for some wider sizes but not having much luck. Thanks

Fiero Addiction
06-08-2011, 04:45 PM
I haven't had any problems with the belts. As long as I keep the rapid speeds conservative I think they'll last forever. If I try to cut thin sheet metal at 60 amps, the speed required to make a good cut results in some noticeable oscillations in the cut after a direction change (belt stretch). To prevent this I turn down the current and lower the speed accordingly. I don't do production work so I can afford to run a little slower. I rarely cut anything thinner than about .120" so it's not really an issue for me, but if your goal is to cut a lot of thin sheet at high speeds the belts may not work for you. Keep the moving parts as light as possible.

mabod
02-07-2012, 10:20 AM
Very nice build, great concept and idea, and a very low cost. It's impressive.

XM381A2
03-31-2012, 06:45 PM
Very nice setup and great info.