4x4 plasma plan in progress

[Big-D]

This is a thread for the true beginner.

Some of you know me as the guy who started this project with no knowledge of the electronics, software or the mechanical components of a cnc plasma table. Since then I have learned, primarilly through this forum, a basic overview of those components and processes. There is an imense amount of information available here. I have found, however, that the majority of the build logs are from people with experience in some form of machining, metal working, or other field involving linear motion, electronics, or drive systems. I have only one ingredient necesary to design and build a cnc plasma cutting table- ambition. I suspect I am not alone. The more I read on this forum, the stronger my interest in this project gets.

When I started gathering information, I found that about the time I asked a question on this forum, I would find at least part of the answer while waiting for a reply. I was asking questions that have been answered dozens of times already, many times by the same people. The members of this forum have vast amounts of patience with beginners.

I have spent a great deal of time on another site, http://www.cncinformation.com, where I found text and video tutorials decribing the cnc components and processes. Many of my questions were answered there. I could have saved a lot of time if I would have found this site about 3 months ago.

Now for my latest questions.

I've settled the software and electronics issues of my table plan by what I considder sound recommendations from millman, torchhead, mlaws, weldtutor and others who frequent the forum.

-I plan to use coreldraw 12, sheetcam and mach 3 for the software.
-A plasma package from http://www.candcnc.com, should take care of most of the electronics and motor issues.
-Linear motion system is being designed with products from http://cncrouterparts.com. Seemed like a good, sound shortcut that may change as the project progresses.

Now for the drive systems.

I need to put together a reduction system and rack & pinion drive for both sides of the table and the y-axis. If I go with a 1" pinion gear, than a 5:1 (3/4" pinion- 4:1) reduction should do. (I didn't come up with this on my own) I have tried to decipher the various belt and pulley combos availeable to do this, but there are literally thousands of variables. Belt width, length, pitch, composition. Pulley diameter, bore, flange, double flange, composition, shaft mount system. Rack and pinion have similar variables. With my dial-up isp, I don't have enough hours in the day for research, and with the price of these things I don't want to make too many mistakes when I order.

I need to match up a drive pulley for a 1/2 inch motor shaft with a proper belt and reduction pulley on a shaft that will accept the proper pinion gear with bearings and mounting blocks in between. (whew) I want to mount this on a 1/4" spring tensioned pivot plate- similar to the millman52 table. I have visitted some of the recommended sources of these components online, but I'm a bit confused as to what exactly I should order and where from, for the best price and service. Suggestions please!

I gather the r&p should be straight geared with 20 pitch and 14.5 degree pitch angle. That's as far into specifics that Ive gotten.

Eventually I'll need a small ballscrew drive for the z, but I'll address that another time.

Thanks a lot for all the advice up to now and in the future. Any help I can be to other "true beginners", feel free to ask. I've learned a ton, but it's just a scratch on the surface of this field. Don

[millman52]

What is the projected cutting size of your table? Plasma only? Plasma, Ox/Fuel? Plasma, Router?

How heavy do you expect your gantry will be when complete with everything mounted?

Are you going to be cutting very thin material as well as thicker, say 1/2" steel? Stainless? aluminum?

If you get a good straight table (no binding on rails) & the gantry doesn't weigh 300# when completely outfitted. It doesnt take much to move it.

The problem is in the motors having the ability to stop the motion of the gantry in 1 direction & head back the opposite way without loosing steps (if you're using stepper motors). All the above questions pretty much need answered, or at least closest best guess. To help determine gear/drive ratios. The heavier it is & the more friction the motors have to overcome all comes into play.

If you have started your frame construction & have the ability to post a few pictures. That always helps others to understand your problems.

[Big-D]

What is the projected cutting size of your table? Plasma only? Plasma, Ox/Fuel? Plasma, Router?

How heavy do you expect your gantry will be when complete with everything mounted?

Are you going to be cutting very thin material as well as thicker, say 1/2" steel? Stainless? aluminum?

[/I]

Neil,

For now I plan on a 54" X 54" working surface with a water table. I don't know if it's practical to use it for a router also, but I would like to try. Some say you should'nt mix the two (fire hazard) but maybe with the water it would work. For now I'll try plasma only.

I'm not sure how much the motors weigh, but I have extruded aluminum ordered for the main gantry frame. With everything, I can't see the gantry going over 125#- 150# tops even with steel reinforcement if it becomes neccessary.

Mostly I plan on 1/16" steel for artwork and some aluminum. I don't plan on anything too thick, but who knows what the future brings. This is strictly for hobby purposes. If I want to build a gate or something of the sort, 1/4" steel would be more than enough.

I hav'nt started to build yet. I figured on building the gantry first and building the table to accomodate it.

Don

[Weldtutor]

Fantastic research you have done Big-D!

I was a little afraid you were scared away earlier, but you took the advice given to read & study & now have a great knowledge base to work with.

Your selections for software, electronics & mechanical drives seem to all be good choices.

Speed reduction is certainly important. Try to keep your design for that simple & effective. For your concern for shaft size changes from the 1/2" motor to another size, a flex coupling (Lovejoy or other brand) might be a simple solution to consider.

A water table for plasma "dust" control is usually a good solution when cutting steel. Cutting aluminum over water can lead to hydrogen accumulation which has serious safety concerns.

[millman52]

The 740 oz motors from www.CandCNC.com are strong motors. Same as what I used. You'll have plenty of power for your size/weight machine.

I would think you could easily use a 1" DP pinion. I used a 3/4" DP pinion but had to turn 1 end of my 1/2" pinion shafts to a .375 diameter for a press fit of the pinions to the shaft. Then use a 4:1 belt reduction. If you think you'll be needing to run large cutters on your router you might want the extra torque a 5:1 reduction would give. If you should decide to go plasma only, I'm fairly confident 3:1 would be enough.

I took the liberty to look up a few part #'s & prices on L series timing pulleys on Quality Transmission Components. Best I remember they had the best prices when I was doing research. Someone else may know of a better source.

QPELA75010F16 10 tooth double flange Al. ................. @ $7.86
QPELA75030F16 30 tooth double flange steel ............. @ $25.31
QPELS75040F16 40 tooth double flange steel ............. @ $19.17
QPELS75050N16 50 tooth No Flanges steel ............. @ 24.67

These part #'s are for 1/2" bore pulleys & will accept up to a 3/4" wide belt.

I purchased my R & P from Mcmaster Carr. I think others on here say www.stdsteel.com has better prices Pretty sure I used 20 pitch 20 angle R & P.

[MBG]

I NEED to contact you on the phone. I am doing the SAME project.


Please let me know if you are interested. I will call you if you are afraid of charges.

[Big-D]

MBG

I NEED to contact you on the phone. I am doing the SAME project.


Please let me know if you are interested. I will call you if you are afraid of charges.

MBG,

I've been looking at other build logs on this forum for only about 3 months, and I have found dozens of linear motion systems, drive systems, table designs and sizes, and electronics configurations. I don't spend a lot of time online- 1-2 hours a week average. I would encourage you to peruse the build logs of the metal working machines forum as well as the router table build logs. The linear motion system I am considdering for my plasma table comes from a router table parts producer. From the look of your posted threads, you are more looking to build a table with 4-5 axis for milling Ice or granite sculptures. That's way out of my league.

I would be glad to help you with any specific questions you have, although bear in mind you know a great deal more about metal working and cnc than I do. I'm just a veterinarian with an interesting hobbie in mind.

If you still want to talk, let me know and I'll pm my #. This is one of the busiest times of the year for me, but I enjoy this subject and will be glad to talk about it.

Good Luck, Don

[MBG]

MBG

MBG,

I've been looking at other build logs on this forum for only about 3 months, and I have found dozens of linear motion systems, drive systems, table designs and sizes, and electronics configurations. I don't spend a lot of time online- 1-2 hours a week average. I would encourage you to peruse the build logs of the metal working machines forum as well as the router table build logs. The linear motion system I am considdering for my plasma table comes from a router table parts producer. From the look of your posted threads, you are more looking to build a table with 4-5 axis for milling Ice or granite sculptures. That's way out of my league.

I would be glad to help you with any specific questions you have, although bear in mind you know a great deal more about metal working and cnc than I do. I'm just a veterinarian with an interesting hobbie in mind.

If you still want to talk, let me know and I'll pm my #. This is one of the busiest times of the year for me, but I enjoy this subject and will be glad to talk about it.

Good Luck, Don

Don, yes please pm me your number.

[MBG]

I am doing a plasma table also. I am not doing the CNC machine right now.

[Big-D]

I still have not started to build this table. I'm one of those visual/tactical oriented guys who need to see and feel the parts and not just look at a plan. My plans are all in my head. This may seem totally impractical to a lot of you because machinists inherently work from spec drawings. Most of what I do is made up as I go, or on-the-fly.

I've got my linear motion parts on hand for all 3 axis. 80/20 aluminum is ordered for the gantry frame. Gear rack and spur gears are on order as well as belts and pulleys for the speed reduction. Gonna be like Christmas around here for a while!

I've seen pictures in build logs of r&p z axis drives directly run from the motor with no speed reduction. I ordered an extra spur gear with the idea of doing this on mine. Since then I have asked two of my reliable sources about this and it was discouraged. I thought from the beginning that it would produce too rapid speeds. This thought was confirmed and the explanation was that the thc would not keep up with the speed and be continuously "hunting" for the ideal height. Makes sense to me.

Anyhow, now a screw drive. I've seen pictures, but I don't get all the bearings, couplings, nuts and bolts of these drives. There are dozens of different kinds of screws. I searched for a 1/2" 10 tpi(turns per inch) acme screw at Mcmaster-carr because it seems to be the popular source. They only had 30" minimum length. Next I tried ebay. I found several screws, but they were either machined or used. I figured the machining would be necessary for mounting to bearings. I got tired of staring at the pc monitor and called a phone # from one of the ebay stores. I got a very nice lady in Florida who took the time to explain the components of the acme screw drive system. I know there are many forms, but hers made sense. She also pointed me to her most reliable sources for the parts I would need. Maybe I'm just a sucker for a female voice on the line, but I liked it and it didn't hurt my eyes like this monitor. Yeah, I bought everything she had that she said I needed. I think she gave me a good deal too- probably due to my irresistible charm, but I digress... Seriously, the explanation was enough to make a lot of the illustrations and pictures clearer to me.

Another step taken in the table plans. Will be building soon. Now to clean the garage...

[millman52]

Well sounds like you are well on your way. A small lathe & even a bench top milling machine would really be helpful at this point too. Might have to expand your hobby LOL

[DRL]

Big-D,
Your about to the point that you need to get out your camera and post some pixs of your project.

"I still have not started to build this table. I'm one of those visual/tactical oriented guys who need to see and feel the parts and not just look at a plan. My plans are all in my head. This may seem totally impractical to a lot of you because machinists inherently work from spec drawings. Most of what I do is made up as I go, or on-the-fly."

Don't worry about that I'm the same way. Does not matter how, just as long as the project gets done.

Doug