Hi everyone-

This is the first time that I have posted here, but I have been reading the previous posts for the last several months.

I finally decided to start building my cnc plasma table. I decided to build a 6 x 12 table. I have read many posts that said that I should build a smaller practice table, but I really don’t have the time to build two tables.

My table is built out of 4 x 6 tubing that is resting on a piece of ½ inch plate. I am planning on building a water table, to try to eliminate some of the smoke in my shop.

So far I have the 4 x 6 tubes welded together, and tacked to the plate, and the 7 legs welded on.

I have to do some welding on the gussets, and then I can flip the table onto the legs.

I am planning on welding a piece of 2 inch angle on the inside perimeter of the 4x6 tube for the support slats to rest on.

I am sure that I am going to have many, many questions during the next few months.

Once I get the main portion of the table fully welded together, and the table flipped over, I will post some pictures of my progress


Steve

Sounds great, glad to see you taking the plunge!
Keep us all updated on how it goes, hopefully you will be burning metal real soon.
Never be afraid to ask questions, there is a wealth of knowledge available here, thanks to a large number of dedicated members.
Good luck!

Am I understand you correctly? The 1/2" plate is going to be welded to the bottom of your 4 X 6 tube to create your water chamber?

That is the plan for now. I have the 4 x 6 tubes tacked together, the plate on top of that, then a total of 7 legs under the table. I also welded 4 pieces of 6 inch channel on the plate to help with the deflection.

I was going to flip the table over, but I have decided to finish the legs before I turn it over. I still need to cap the legs and install the feet. After that, I will turn it over. (I hope)



Steve

I still have not had the time to finish the legs of my table and flip it over. So I took some pictures of it upside down.

I am going to try to post these pictures.


Steve

Looks good, I love retarded overkill...

DSL- When it is left over scrap-- you use what you have


Steve

I need a 5x10 scrap piece of 1/2" plate.......
Got any more? :D

How are you going to drain & clean the water chamber when needed?

One thing is for sure, You will not have to worry about rapid direction changes on the gantry moving the table base around.

& I agree if it's cheap or even better "FREE" it's for me.

How are you going to drain & clean the water chamber when needed?

One thing is for sure, You will not have to worry about rapid direction changes on the gantry moving the table base around.

& I agree if it's cheap or even better "FREE" it's for me.


I agree. That is one heck of a base for the table.
Better to over do it than under do it!:cheers:
The only way it gets better than free is if someone pays you to take it:D

This is the first time that I have posted here, but I have been reading the previous posts for the last several months.


Welcome, :wave:

Your study & reading has paid off by giving a great start to the new machine.

Thanks for the photos.
They certainly help to follow your progress, keep them coming.

This weekend, I finally had some free time to work on my plasma table. I flipped the table over, and started to stitch weld the inside. I am welding about 3-4 inches, and then moving to the other side. I am trying to keep the table from warping. Here are some pictures I took today.


Steve

There will be warping, but there's always a solution to fix it. I calculated with some warping when I welded my steel frame and then I lined it up with epoxy. Works like a charm.
You've got a crazy machine coming, looks good! :)

Regards,
Sven

I don't know what to say about all this.

I finally ordered my leveling feet for the table. They have 3/4 inch threads, and a 3 inch base.

I have made the mounts using a piece of 3 inch channel, with a welded 3/8 inch piece of plate on top. I then welded a 3/4 inch structural nut on the back side of the channel.

Here is a picture of the feet. I can't find the picture of the mounts I made.

The feet are finally on, and i can now level the table! Once the table is level, I am going to fill it with water and then check for leaks.


Steve

First, that table is looking great... If I may suggest before you level the table put a little water in it and "tilt" it with the forklift to check your welds. A lot less water to deal with if there is a leak.
Also a nice addition would be the ability to raise and lower the water level at the touch of a switch... just need a tank that will hold all the water for your table (old compressor tank), two solenoid or manual valves, a little pipe a few fittings and some compressed air. Plumb from table to lowest point on tank, then on the highest point on tank, add short piece of pipe with Tee on top, one side of the Tee will be a valve for air fill the other will be a valve for air vent to atmosphere. Close vent side open fill side, water will rise in table, close fill valve at desired water level. Open vent valve when ready to drop water...

Again very nice table.

James

Time for am update-

I am trying to decide on what type of linear rails to purchase. I called http://www.superiorbearing.com (http://www.superiorbearing.com/) and received a quote of $78.69 per meter for the size 25 linear rail, and a price of $88.82 per meter for the size 30.

Or should I go with a named brand like THK or Thomson rail?


Any suggestion would be greatly appreciated.



Steve

p.s. I am mounting the rail on 2x 2 cold roll steel

Damn dude that is a serious table ya got goin, but what really impresses me is that other table in the back ground, looks like you used 12" I beams, seriously solid.

Time for am update-

I am trying to decide on what type of linear rails to purchase. I called http://www.superiorbearing.com (http://www.superiorbearing.com/) and received a quote of $78.69 per meter for the size 25 linear rail, and a price of $88.82 per meter for the size 30.

Or should I go with a named brand like THK or Thomson rail?


Any suggestion would be greatly appreciated.



Steve

p.s. I am mounting the rail on 2x 2 cold roll steel



There really isn't much point in spending more money. I have seen machines put together using the 15mm size. IMHO, 25mm is more than fine.

Check HIwin (sp?) as well. THK, IKO and others make a nice product, but they are not the only players in the game anymore.:)

I finally ordered my leveling feet for the table. They have 3/4 inch threads, and a 3 inch base.

Did you get a good deal on them? Where did you buy them from?

DeviousMW

DeviousMW-

I paid $22.00 for each leveler, and I ordered them through Graingers. I ordered them on Tues. and they were here on Wed. Not too bad.

The only thing this I would have changed would be to order levelers with longer thread.

I welded a structural 3/4 nut on the insided of the channel, plus the width of the channel, then the the 1/4 inch plate, then the jam nut.

So after all the pieces were added together, I only had a little more than an inch of adjustment.

The good thing is my floor is level :)

Steve

When I first saw this I was like, 'how can someone put so much material into a table?!,' now I'm building my own and it would make your table look light-weight.

My ship finally came in! Actually it was more like a slow boat from Taiwan. My linear rails and bearings are here. Hopefully now we will start to make progress. I have posted a few pictures just as proof. J

Steve

wow, they took some time to deliver :(

what kind of rails did u use and how much did they cost?


what drivers/motors/software are u going to use?

looks like a great project.

After several weeks of nothing happening on the plasma cutter, my wife gave me a few hours on the weekend to work on it! J I have the 2 x 2 cold roll mounted and it is now time to mount the linear rail. I have 1 question though. Should I mount the joints for the linear rail at the same end of the table or should I stager the joints with 1 at each end?

I have attached a few pictures to show how the cold roll is attached to the table and the splice plate. I remove the splice plate so that I can re level the cold roll before I install the linear rails.


Steve

It shouldn't matter.

My table is similiar to yours.

3 I beams spanning longidutinally. 4 hss holding each I beam up giving a total of 12 legs. Each leg has adjustable feet with swivelling capabilities by use of trailer ball hitches (cheap on ebay and looks beefy). The table has a waterbath but using 1/8" sheet (you dont need it to be too thick to hold the water). I used I beams so that I could mount linear shafts on the sides for the gantry to slide on. The table is a 12x6 allowing a cutting capacity of 10x5. The gantry is all aluminum to keep the wieght down as it is the part that moves. Shafts span laterally at both ends turning belts. 1 motor turns 1 shaft (headshaft) and the tailshaft is at the other end. My buddy and I choose this design as it keeps everything looking very clean. Very little wires, hoses etc will be visible. The only hoses and wires that will be seen is at the top where the plasma cutter and cutting torch mount. The Z axis is moveable for THC compatibility and has a double mount for both a oxy torch and plasma. I can mount a 12 inch high HSS or ibeam on top of my table and cut bolt holes or whatever on top as the z axis can move up high enough (which explains why the gantry is so high). The water bath walls is constructed of angle iron welded at all 4 corners to make a rectangular frame. This frame is then siliconed to the table and tightened down by drill, tapped and bolts. The electronics are all gecko / mach III based and were created by mike laws on this board. Pics at www.ubcustom.com/cnc . Good luck with your table and hopefully my buddy and my table can give you some ideas. Erik

WOW those are some thick slats! Did you get this table up and running?

Carbidecraters and Energyforce- My table is still a work in progress. It has just been too hot to work in the shop much. I do have the linear rails mounted, but that is about as far as I have gotten. I have more pictures to post once my DSL is fixed.

The next step is to make the support for the gantry.

Energyforce- I saw your plasma cutter last year, then it just seamed like you quit working on it. I am glad you are still working on it.


Steve

Just to let you know my DSL is still down, so I can't post my pictures.

I have been thinking about changing my set-up. Instead of building 1 large gantry to mount the plasma cutter, oxygen acetaline torch, and spindle on. How about a small gantry for the plasma, and a second larger gantry for the torch and the spindle?


The big question is if it is possible to program the machine to drill holes in the plate and then use the plasma to cut the shape out??

Steve

Hi

Have to say nice work , and very heavy duty machine , keep up the good work

cheers

Just to let you know my DSL is still down, so I can't post my pictures.

I have been thinking about changing my set-up. Instead of building 1 large gantry to mount the plasma cutter, oxygen acetaline torch, and spindle on. How about a small gantry for the plasma, and a second larger gantry for the torch and the spindle?


The big question is if it is possible to program the machine to drill holes in the plate and then use the plasma to cut the shape out??

Steve

Hmm. I don't know if you could do it with Mach, unless you were wanting to do a bunch of cable swapping in the middle of every job.
A 5 or 6 axis controller could do it, though.

Well it is finally time to start working on the gantry for my table. I have to choose between several different sizes of tube to use. I have 2x4 with 3/8 wall thickness, 4 x 4 with 1/8 wall, or 6x6 with 5/16 wall. any suggestions? I am leaning on the 6x6 so that 3 have enough room to mount the rails and the Igus cable bearer.Steve

Nice build!

On the gantry - one time-honored rule in machine building is if the part doesn't move, make it heavy. If it does move, keep it light.

Since this is a plasma cutter, your forces are going to be next to nothing - I would suggest going light for the gantry. Even 6X6x5/16 seems a bit heavy for it's intended purpose.

Scott

Seeing the table flipped over makes it look like the meanest pool table ever. Haha. Very nice work, I'll definately be keeping my eye on this thread.

Hi everyone-

It has been a while since I have worked on my plasma table. I finally have the linear rails installed and squared. I have also painted, sealed the inside of the water table and filled it with water. Zero Leaks!!!!

I am going to finish the painting, and then start designing the gantry.

If anyone has any ideas, I would like to hear them.


Steve

Very nice. I can't wait to see the completed table. It took me two test fills ,on my water table, before I got all of my welds leak free.:)

Wow. Your project looks awesome. What are you planning to cut and make with it when you're done?

Jcar- I guess I got lucky ( and that tube of silicone did not hurt either!)

Lcard989- My family is in the steel erecting business. We are planning on starting to fabricate some of the smaller jobs. That is why I am planning on mounting a oxygen/acetylene torch and a large Milwaukee drill also.

Hey Steve, How's progress on your water table?, have you gotten the rolling stock on yet? Cutting plate yet? I agree about the scrap, actually if you just let the scrap sit there too long (like 7 years like I did) then it is almost worse taking up valuable space.

-Mike

Mike—

For the most part my project is slow going, but mostly it has stopped. My wife and I had our second baby is 13 months in October. So my free time is non-existent! I have managed to get the base of the table painted, and the slats installed. I am in the process of getting the gantry supports cut, so once that is installed I will post some more pictures. As far as a time frame--- who knows. Once baby #2 starts sleeping through the night, I can go back to working on it at night when I get home from work.


Steve

what size are the bearings and rails. Where did you buy them? how much did they cost?

Hi Bigtoy, Were you asking me about bearings & rails, or Steve?, Nice work Steve. That Silicone works wonders doesn't it? I was curious about your rails too. ??
I just got my bearings at www.reidsupply.com
PRB-280 X & Y axis bearings 16 1 ea $4.96
3/4" id, 1.75" od, 1/2" thick, case hardened steel ball bearings
prb-247 z-axis bgearings 8 1 ea $3.11
1/2"idx 1.25"od, 3/8" thick, case hardened sealed ball
&, Steve you saw, I'm using 3 1/3" sch 40 pipe for my rails (also the table structure.) Gives me a 4.00" od.

--Mike

Hi Bigtoy, Were you asking me about bearings & rails, or Steve?,

--Mike
No, I was asking Steve.

Ryan

Mike and Bigtoy-

I purchased all of my linear rails and bearing blocks from Superiorbearing.com. The person I dealt with was Rick Hoback, and he was great to work with. His E-mail is Rick Hoback [rick@superiorbearing.com].

The total price for all of my stuff was $2,400.00 ish. Here is a list of all I recieved

2 pc. 16.5 foot long size 30mm linear rail. Ends were EDM cut at the butt splice
8 pc. 30 mm bearing blocks
4 pc. 8 foot size 25mm linear rail
8 pc. 25mm bearing blocks

The manufacturer of all of these parts is AMT.


If you have any other questions just let me know.


Steve

Mike and Bigtoy-

I purchased all of my linear rails and bearing blocks from Superiorbearing.com. The person I dealt with was Rick Hoback, and he was great to work with. His E-mail is Rick Hoback [rick@superiorbearing.com].

The total price for all of my stuff was $2,400.00 ish. Here is a list of all I recieved

2 pc. 16.5 foot long size 30mm linear rail. Ends were EDM cut at the butt splice
8 pc. 30 mm bearing blocks
4 pc. 8 foot size 25mm linear rail
8 pc. 25mm bearing blocks

The manufacturer of all of these parts is AMT.


If you have any other questions just let me know.


Steve

Were the 16.5' pieces 1 individual length? Or is that what you are saying were EDM cut, so that splicing joints are precision mated?

Millman-

The longest piece of linear rail that they sold was 4,000mm (12.5 ish feet). So I had to splice the two pieces together.

When I roll a bearing across the joint with zero weight, I can kinda feel the joint. With weight on the bearing, it is as smooth as glass.


Steve

I have 15mm rail on my gantry, I scrounged up some used rail & had to splice 2 pieces to get enough for a 5' useable area. I ground the ends square for a matched fit on my tool grinder.

I purchased 2 new bearings. That's what happened with mine. Could feel the joint with nothing attached but when the Z carrier went on can't feel it at all.

I had to snug the screws in the rail & then bump each rail till I got as smooth a transition from rail to rail as possible then tighten the rail screws fully.

Steve,I E-mailed Rick and got a price of $94/meter for the 25mm rail and$48for the short blocks and $68 for the long blocks.Still good prices,possibly 1/2 THK's price.
Did you have to pay shipping from Tiwan?How much was the shipping?
BTW nice table.Any gantry ideas?Are you planning steppers or servos?
Good work Steve
Larry

Larry- I only had to pay FED EX freight form Ohio to Lexington, KY. I picked the boxes up at the terminal.

I am planning on using servos. I have the gantry designed in my head, now if I can only get it out!

Update time—

During the last two weeks or so, the work on the table has been slow at best. I had everything planned to cut the gantry side plates this weekend. A person here on the Zone was going to cut them with his table. As luck would have it, one of my daughters caught a virus, so I needed to stay home. The next 4 weeks are already planned for me, so I can not work on the table for about a month.

I did manage to take a few pictures of the paint job. I have also started cutting the angle that I am going to us for slats. I used all that I had at the house, so I have to go to the shop and get more.

Now for a serious problem. I went outside today and I found everything in the shop dripping with water! The shop has zero leaks, so I know it is not the roof. Everything that is metal was covered with water, the forklift, the steel rack, the plasma table. It and has rained here for the last three days, and the humidity is high. Any ideas how to keep it from raining inside?? I need to figure this out before everything starts to rust.


Steve

Update time—



Now for a serious problem. I went outside today and I found everything in the shop dripping with water! The shop has zero leaks, so I know it is not the roof. Everything that is metal was covered with water, the forklift, the steel rack, the plasma table. It and has rained here for the last three days, and the humidity is high. Any ideas how to keep it from raining inside?? I need to figure this out before everything starts to rust.


Steve

Sounds to me like you have that age old problem of condensation.

Most likely been cool there for a few days/nights. Warms up, air is much warmer that the steel. Just like a glass of iced tea in the summer. Moisture from the air collects on the cool steel surfaces.

To help the problem you'll have to either Heat your building to stabelize the environment. (reduce moisture inside your shop + keep the steel from getting so cold.) For most people with a home or part time shop gets to expensive.


Second option. If your shop is somewhat sealed, depending on it's size, dehumidifier(s) fairly energy efficient. Down side(s) when it gets very cold the condensing coil in them will freeze. Even with the dehumidifier(s). If your shop is cold & you open up the doors on a warmer day, warm humid air will rush in from outside & still have the problem.

Insulation on those metal walls will go a long way to help with the condensation problem. I assume you have 2" of insulation on the inside of the roof like most metal buildings. I hope you also have a vapor barrier under the concrete floor, that also helps immensely. My shop has sprayed foam insulation of the walls and a vapor barrier. I have never had a condensation problem.
I am curious why you are using angles for work support versus flat strips that insert into a holder on the sides?

I agree Bill Insulation wil help to a cretain degree.

To a large part it depends on the climate in the regon of the country you live. In my area I have a very well insulated building, work in it every day, have heat in winter.

I still have some problem in the Spring & Fall It always seems to happen when the temp is getting pretty low at night, but not enough to warrant heat being on. Then getting really warm the following day. Or over a weekend & it getting cool with no heat in the building.

I don't have a severe case of condensate problems but I do have the once in a while thing happen.

OK time for a new project.

Since I am having to wait a few weeks to cut my gantry side plates, I am going to start gathering pieces and parts for the cable bearer.

Is there any rule of thumb that I should follow? I am planning on using Igus cable chain.

Are there any suggestions on how I need to separate the servo cables, the I/O cables, and the other wires. Or should I not worry about it an cram all the wires in one big bundle.

Any suggestions about the size of the Igus cable chain I should look for?


Thanks for all the help



Steve

OK time for a new project.



Any suggestions about the size of the Igus cable chain I should look for?


Thanks for all the help



Steve



Boy it's a bit confusing to figure the size(s) of that stuff out. Seems that on ebay most list it with the OE # system Even after going on Igus site, There are so many different styles of it, I gave up trying to cross the #'s into something meaningful to me. www.mcmastercarr.com carries E chain but doesn't specify brand name...:drowning: Again No Help trying to figure out the stuff on ebay. Best thing there is ask for internal measurments from the seller. To me the stuff is unbelieveably expensive new.

I finally came across many feet of it, all the same size, & stacked 2 runs of it as the pic below shows. It was a bit of a challenge to anchor the ends with it stacked but it stays nice & tight together. The inner & outer loop does not seperate throughout it's entire movement. As far as length it only takes slightly more than 1/2 the length of your axis movement to do the job. Couple of pics showing that on My Y axis.

I have enough of the Igus to run it along the X, but I decided to use a festoon to get the cables/hoses out of harms way as well as save space beside the table. I didn't want to have to drag burned parts out over top of cable carriers. Maybe not the most elegant looking arrangement, But it works great. It is also next to no friction. I made the rollers on the lathe & pressed a ball bearing in the center of the wheels. The cable is Nylon coated 3/16" steel, the OD with the nylon is 1/4"

As you can tell from the pics my machine is still a work in progress.

Hope this may help a bit.

Neil

On Saturday, I was iced in and could not leave the house. So my wife felt sorry for me and let me go to the shop and work for 5 hours without any interruptions. I started to clean the shop, and the whole time I had to work around the piece of plate that I was going to get cut for my gantry plates. I finally had enough and I started working on the plates with a torch and a metal saw!!!

I wanted to have the plates cnc plasma cut to insure that both were identical. After I cut the plates I can not see any differences in the plates, so I hope that I did not rush my project and hurt the overall accuracy.

The pictures show the gantry temporarily assembled, I have taken it back apart so that I can drill the Y axis linear rails.

The gantry rolls really easy and smoothly.


Steve

How much z-axis travel are you going to have Steve? Also what do you think that gantry will weigh with the z-carriage & torch on?
--Mike

Gee Steve, I'm afraid that gantry might sag........ When you park your truck on it!!!! I guess it's 1/2" wall thickness too!

I don't see that your carriers should cause any problems with accuracy. Line up as best you can on the holes for your box tube. Tack the 2 pieces together & drill both plates at once.

Looking good :cheers:

Millman52- No it is not 1/2 inch, that would be over kill-- it is only 5/16 :)

Mike the distance from the bottom of the tube to the top of the angle is 10 inches. So my Z axis should be less than that.

As far as weight go the tube is 23.13 pounds per foot ish. So 24 x 7 feet = 168 LBS

The supports and bearings are 25 LBS each.

The gantry is about 218 LBS as it sits now. I am hoping that it does not go over 300 LBS when it is finished.

I am planning on using 850 oz servos, but if I have to I can use 1100 oz steppers.

I am also planning on using something close to 10 to 1 reducers. But everything is subject to change !


Steve

Steve,JFG or jerry fly guy is using 640 Oz steppers with 10/1 reducers moving a ton gantry to 800IPM.Check his posts.No need for 1100 oz steppers.
Larry

Steve,

Looking good. I can't wait to see the finished machine. I think the 850 oz servo's will be more than enough. Hope the little ones are doing better.

Hi everyone-

It has been a few months since I really have worked on the plasma table, but it is now time to start buying parts to bolt onto the table.

I have a chance to buy 4 Dura True 115 planetary gearboxes that have a 5 to 1 ratio.
2 of the gearboxes are 90 degree gearboxes. All 4 of the gearboxes are rated to have a backlash not to exceed 8 arc minutes.
So what does everyone think about the planetary gearboxes? Do you think I will have problems with them?
I know I will have to make adapter plates, but that should not be a problem (I hope). I am also planning on either using 850 OZ. or 1125 OZ. motors.

Steve

hi

have to tell u again, u got a beutifull table there.

i don't think the gearboxes are such a good ideea, also don't overpower the motors, i have 1 800OZ motor and 1 1200OZ. At low speeds (200mm/m) the bigger motor vibrates. I'm going to change the gearing from 1/1 to 1/3 , hope this will make some vibration disapear.

Steve,

I checked the specs, and man, those are some big gearboxes. The only concern I would have is the output shaft diameter. From what I could tell, it's 24mm (.945"). All of the pinions that I've found in that range have pitch diameter over 3". In my opinion 3" is way to much, even with the 5:1 gear ratio. McMaster has a 16 pitch pinion with a pitch diameter of 1 1/2" and a body diamter just over 1 1/4", that's made for a 1/2" shaft. You could bore these out to fit your shafts. With a pitch diameter of 1 1/2" and a gear ratio of 5:1 you'll get around .942" of travel per motor revolution, which should be fine. My system has more than enough accuracy at .642" per motor revolution.

Jody,

Bekx- Thanks for the complement on the table. I am hoping to get some additional pictures posted this weekend.

Jody- I have talked to my machinist, and he said that there won’t be any problems making any of the adapters, or boring and broaching the pinion gear. What do you think about the gearbox? Good/bad why

I still have some concerns with what I am doing. Since this is my first project, I am kinda winging it. I don’t want to buy one component and then learn the hard way that I should have done something else.

My biggest concern is with the overall weight of the gantry. Right now it weighs close to 175-200 pounds, then when I add the motors, gearboxes (If I decide to go this way), Igus cable chain, the plasma torch, the oxygen/propane torch, and other parts—I am going to be close to 300-350 pounds. Once this is running, that is a lot of weight being thrown around, stopping and reversing. How much abuse can a rack gear take before teeth start disappearing?

Right now at close to 200 pounds, I can pull the gantry with very little effort. I am going to purchase a fish scale this weekend so that I can measure the actual force.

Any comments on the motor size? I have read that too big is bad, and that too small is bad. The two sizes that I have been thinking about are the 850 oz. and the 1125 oz. motors. According to the specs for both of these motors, the continuous output rating for both of these is about ¼ the peak force (850 and 1125 oz.).

I am planning on ordering either ¾ or 1 inch rack gear in about three weeks, so that is the next big problem to solve!

Thanks for the suggestions and help


Steve

Do not use 1100oz steppers. I have these babys on my gantry, it weighed about 120lbs from memory...

I have severe resonance and motor cogging at certain speeds. But if you run it through a reduction of at least 4:1 I think it would work much better.

As you gantry weighs so much, the rapid acceleration and decceleration could possible make the whold table jump anound and vibrate etc...It did on mine. Often bigger is not better.

As to worrying about not being able to make the gantry move cause of the weight, don't. It will move around fine, especially if gearing it down.

What is the backlash on the gearboxes? How many arc minutes or seconds etc?

Peter

Steve,

The gearboxes look nice. If I could get a good deal on 4 of them, I'd jump on it. Based on experience with my machine, I don't think you'll have a problem with power or acceleration. You'll have 354 lbs of force being applied to your 300-350 lb gantry. Assuming your using a 1.5" diameter pinion, dual 850 oz motors and a 5:1 gear ratio. My 100-150 lb gantry has 165 lbs of force being applied to it. As for gear strength, take a look at this link http://www.pic-design.com/tech/gear_calc/gear_calc.htm. For example, according to Method 2, a 20 pitch - 32 tooth pinion with a face width of 1/2" can handle approx. 4256 oz/in of torque (unhardend 1018 with a yield strength of 40,000 psi). You'll probably be using gears with a wider face, larger pitch, and made from harder matherial. Strength shouldn't be an issue. Backlash won't be a problem either. 8 arc minutes applied to a 1.5" diameter pinion will give you backlash of approx. .0017".

Jody,

OK- so I made a decision. I decided to go with the gearboxes. I picked them up and have 2 straight and 2 90 degree 5 to 1 ratio gearboxes.


Now time for the motors and encoders. Where is the best place to buy them from?

Is there a better brand or manufacture to go with? Is there a brand to stay away from? I know I want NEMA 34 for the mounting size, and I am going to use Geckos for the drives.

Is there anything special I need to know about the encoder?


Thanks for the help

Steve


p.s. once I get home I will post some pictures of the gearboxes. It is kinda hard to do that from my phone!

Steve here a link for steppers real cheap.http://www.kelinginc.net/SMotorstock.html
As apples says stay away from the monster sizes.Steppers don't have encoders.
Here is another link for gear rack.These guys are really cheap and sell small quanity direct
http://www.stdsteel.com/
Larry

o.k. Here is a picture of each type

Time for the next step.

While I am waiting for the adapters for my gearboxes to be made, I decided to start working on a way to route all the cables for my table. I have two different sizes of Igus cable chain. The first is about 3x5 inches and 20 ish feet in length, and the second is about 1 x 1 inch and 20 ish feet long.

This is what I have planned for

I am going to run the two cable chains next to one another, and in the larger chain run the plasma torch cable in 1 compartment and all the power, e-stop wires, limit switches, and hosing in the other compartment. That would leave the servo encoder wires in their own cable chain.

Now I have some questions.

1 Is this a good idea or am I going to create more problems? If this is a good idea how far apart should I space the cable chain?

2 On most servo encoder wires, how many wires are required for each encoder?

3 I know I need shielded wire for the encoders, but are all shielded wires created equal? Where is the best place to buy the wire?

That is enough. This information should keep me busy for a week or two!!!!



Thanks for the help



Steve

It has been several months since I have updated my progress. To be honest, I had to take 3 giant steps back!!!

When I was assembling my gantry, I discovered that the tube was warped, and the mounting holes were not square from one side to the other. OOPS

So I had to cut the hole gantry apart and start over. I decided to weld a piece of plate to each side of the tube and then have the whole thing ground. I should have done this the first time. Over the 7.5 length of the tube it is off .01 from side side.

Next I sent the tube to a shop with a large cnc horz. mill with a rotating table. They drilled the linear rail mount holes on both sides. Now the gantry is plumb, straight, square, and true, and can shim it any way necessary to get the travel with the x axis correct.

I have also finished the z axis, and i am reassembling it now. Once I get the servo motors, I have to remove 1 of the supports, and cut some holes it it for the moters to pass through.

It is almost time for the motors and electronics!!!



Steve

Hi everyone-

It has been a while since I have worked on my plasma table. I finally have the linear rails installed and squared. I have also painted, sealed the inside of the water table and filled it with water. Zero Leaks!!!!

I am going to finish the painting, and then start designing the gantry.

If anyone has any ideas, I would like to hear them.


SteveWOw nice table, what did you use to seal the inside of the water table ????


Ben88ner

Ben88ner

I welded the table both inside and outside. Then I cheated and used paintable silicone caulk. After that I just painted it with an enamel paint.

Lo and behold--- it holds water



Steve

Hi everyone-

I think I have decided on my electronics for my plasma cutter. I have changed my mind several times, and I might still change my mind.

I think I am going to use the Larkin Viper 200 servo drivers. The main reason was the voltage. I want to make sure I can get all that I can out of my servo motors. The maximum voltage on the servos is 90 volts. http://www.larkencnc.com/viper/v200.htm

I am using three different servos. These are from Kelinginc.
2 KL34-180-90 (NEMA 34) for the x axis http://www.kelinginc.net/KL34-180-90.pdf
1 KL34-170-90 (NEMA 34) for the y axis http://www.kelinginc.net/KL34-170-72.pdf
2 KL34-150-90 (NEMA 34) for the z axis http://www.kelinginc.net/KL34-150-90.pdf

I am also planning on using 3 power supplies, one for each axis. For the x axis a 90 volt and 1500 watts. The other 2 axis have a 90 volt and 1000 watts. One power supply has a regulated 5 volts dc, and the other has a regulated 24 volts dc. http://www.antekinc.com/PS-10N90R.pdf

For the breakout boards, I am going to use the C23 from cnc4pc. http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=182

I am also going to use the I/O boards from cnc4pc
http://www.cnc4pc.com/Store/osc/product_info.php?cPath=39&products_id=151
http://www.cnc4pc.com/Store/osc/product_info.php?cPath=39&products_id=184

I though about using one of the all in one BOBs but I think I have to much going on for that.

For the plasma controller I am going to use the THC 300B form soundlogic.com
http://soundlogicus.com/THC300B/tabid/115/Default.aspx

How does this sound?

Anything I need to change? I am going to place the order tomorrow.


Steve

I think you'd be much happier w/ a VSD-E card from Granite Devices..

www.Granitedevices.fi

No affiliation, other than I'm a happy customer [four of their VSD-A drives on my router]..

I've blown up two of the vipers in the last week and a half.. on a plasma system.. don't know as of yet what when wrong.. but I wouldn't design a system around them.. the granites would be my first pick..

Fwiw

J

Jerry,

I have been going between the two drives for about a month. I diot know anyone was having problems with the vipers.

decisions decisions :)


What do you think about the other parts?

Steve

Well I look at it this way, I've yet to hear of anyone not happy w/ the VSD boards.. that pretty much says it all for me.. plus I've used them.. and LOVE them..

No comment to offer on the rest [other than why 2 motors on the Z axis?]

Jerry-

The reason for the two z axis is because on one side of the gantry is the oxy / fuel torch and the plasma cutter. The other side of the gantry has a 3/4 inch Millwaukee drill. The idea is that the plasma will blow a small starter hole, and then the drill will drill the correct size hole. Next the plasma will cut the outside of the part out.

or atleast that is what I am hoping will happen.


Steve

I think your going to have a dickens of a time drilling down a plasma pierce. I run a HPR260 here at work and there is no way I'd try and drill down the pierce hole.. the material is terribly hard from all that heat.. you'd be much better off to just drill the hole and plasma the exterior.. We do not allow shop personnel to use our plate shear on any material that has been plasma cut for this reason..

Fwiw..

J

I think your going to have a dickens of a time drilling down a plasma pierce. I run a HPR260 here at work and there is no way I'd try and drill down the pierce hole.. the material is terribly hard from all that heat.. you'd be much better off to just drill the hole and plasma the exterior.. We do not allow shop personnel to use our plate shear on any material that has been plasma cut for this reason..

Fwiw..

J

Another fact that gets greatly ignored but is widely publicised on welding sites. Plasm cut edges that are going to be welded should be ground to remove that hardened edge.

As I understand it it's not as much the heat as it is a change in the molecular structure of the steel itself.

If memory serves me the hardened edge is only a few thousandths thick. But still enough to ruin or at least greatly shorten the life of a HSS drill bit.


Steve,

How large a hole are you needing to drill? Could you possibly use slug cutters, like are so popular on magnetic base drills these days? Those slug cutters require very little down pressure & would cut outside the pierced hole in softer material.

Neil

We don't require all of the parts we cut to have cleaned edges, but in certain situations we do it to allow better penitration into the plate when welding. Our plasma has multi gas cutting so we can control the oxidation at the cut to some degree.

Rotabroach cutters [for mag drills] are pretty impressive. I've used them several times [we've got several mag drills at work]. However they are expensive to replace and typically they are used in cutting larger holes, the smaller cutters are less common. Typical mag drills only run 4-500rpm which is way to slow for small holes, hence there is a limit at the lower end of the size scale.. For this reason I think they would be of limited use in this application..

Personally I'd just mount a drill quill as the second axis and use that to drill my holes.. forget about doing it w/ the plasma.. or... cut them w/ the plasma.. depending on what unit is used and how thick the mat'l is, the cut may be such that it's usable right off the torch..

I just cut some 1" 44w last night.. 4 x 8 sheet into 45 parts.. 23minutes and the plate left over was hand size chunks.. they are impressive when they are set up correctly.. :)

Jerry,Neil-

We call those cutters -annular- cutters. They work great. Right now we use them for holes that are between 3/4 and 1 1/2 inch. The Millwaukee drill motor that I have will easly switch between an annular cutter, a morise taper bit, and a twist drill bit. I also have a VFD to control the speed of the drill.

Steve

I've blown up two of the vipers in the last week and a half.. on a plasma system.. don't know as of yet what when wrong.. but I wouldn't design a system around them.. the granites would be my first pick..

Jerry, when did i sell you those drives, I can't find any customer named Jerry in the last 2 years ?

If you do have viper drives that have failed, I offer a warantee and will repair them for $30 each.
I've had very few Viper 200 drives fail in the last year and am getting great customer feed back.

Looks like it is time for an update-

I have made a little bit of progress over the last month. I have most of the parts painted, and I am putting it back together. I have pictures that show how the Z axis is put together, some pictures of the conduit I ran, and there are pictures of some of the electronics that have arrived. I am still waiting on the Smooth Stepper board, and the other break out boards.

Now for some questions

1. I am looking at Renco encoders, what resolution should I buy? and why.
2. I am needing to order the timing gears and belt for the z axis. What ratio should I buy?
3. Are there any do’s or don’t I need to worry about when setting up the enclosure box that has the transformers and the Granite Devices servo drives?

I am going to have all the wires running in conduit where ever possible. I have two runs of conduit, one for the power stuff (noisy) and one for the other stuff (less noisy)

What am I missing????


Thanks


Steve

more pictures

Time for an Update-

I started working on the control cabinet. I decided to use two cabinets, one for the power supplies, and one for the otherstuff.

I have everything mounted to the back plane for the enclosure box, and it is time to start wiring.

How does this layout look? Anything I need to change before I start adding wires?


Thanks


Steve

Update-

Over the weekend, I had a chance to do some wiring. Here are two pictures so far. The second picture showes the wire markers that I am using.


Steve

Steve - Very impressive machine. Panel work is going to look good to. - Ron

Thanks Ron.

I will try to post more pictures this weekend.



Steve

Hi Scrambled,
Do you need to run 2 motors on x axis or not, since your table is big? Thanks. Asuratman.

asuratman-

My x axis has 2 servo motors. This should be more than enough to move the gantry.


Steve