[eddieburnsii]

I am a newbie to the forums not to plasma systems. I have ran various large industrial machines for many years. I have been studying a lot lately on building my own smaller scale home shop machine. I have started tinkering in my cad program and have a few early design pics I'd like to get input on. Please feel free to ask any questions. I plan to be able to cut 5x10 sheets up to 3/4 for the most part.

Attachment 198336Attachment 198338Attachment 198340Attachment 198342

Thanks, Eddie

[eddieburnsii]

If this particular design or a close variation of it is used I guestimate the total gantry weight to be <250lbs. My question is, will a single NEMA 23 stepper motor handle moving that much weight? Or will I need a NEMA 34?

[Arthurmetal]

I recommend a Nema 34 on each side of your gantry. You will need some acceleration.

[jason_alex]

Are you going to have complicated parts that are long? If so I would recommend going to a servo drive. You dont want to be cutting along it loose a few steps here and there and you miss cut a hole by 3/16 of an inch or more and have to go back and try to fix it. Just my opinion

[eddieburnsii]

I recommend a Nema 34 on each side of your gantry. You will need some acceleration.

Is there a certain weight these motors are rated for? I could change the materials and drop the weight considerably on the gantry. If the cost of materials will exceed the cost of going up on the motor size I will just stick with the original materials and go with the larger motors.

[eddieburnsii]

Are you going to have complicated parts that are long? If so I would recommend going to a servo drive. You dont want to be cutting along it loose a few steps here and there and you miss cut a hole by 3/16 of an inch or more and have to go back and try to fix it. Just my opinion

I understand the servo motors are more accurate. Do they use encoders? I am pretty sure all of the industrial machines I have used in the past have had stepper motors and I never had a problem.

[Shed Hunter]

I would stick with steppers unless $ doesn't matter to you. Also, Make the gantry as strong/stiff as you can, but at the same time make the gantry as light as possible. There is not a weight limit for a stepper... But keep in mind the less friction...the better. If you are doing plasma only, the gantry doesn't need to be super rigid. However, if you want to add a router...then it will need to be much more rigid.

[eddieburnsii]

I would stick with steppers unless $ doesn't matter to you. Also, Make the gantry as strong/stiff as you can, but at the same time make the gantry as light as possible. There is not a weight limit for a stepper... But keep in mind the less friction...the better. If you are doing plasma only, the gantry doesn't need to be super rigid. However, if you want to add a router...then it will need to be much more rigid.

Money is very crucial to me as I don't have much to spare. Steppers it is. I do not plan to use a router but I would like to add an oxy/gas torch and possibly an air scribe in the future. I would like to make it nice and rigid as I plan to only use one motor per axis.....X,Y,Z.

[Arthurmetal]

One motor per axis? You will have to drive your gantry on both sides to prevent raking.
Either with a shaft, belt drive or two motors. On my previous plasma table I had one motor with a driving shaft along the gantry with belt drive on both sides.
This table was too light weight, to much backlash, to much vibration and therefore a serious limitation in cutting speed. This was also intended to be a cheap build.
I recommend to spend the extra bucks on driving your gantry with two motors; will be worth your investment.

You might want to have a look at the candcnc systems, they have the entire motor issue already sorted out for you.

[eddieburnsii]

Arthurmetal I have looked at several 4 axis kits prepackaged. I like them but not sure yet what direction I want to go there. I read stories where people have trouble with the slave drive motor. Maybe it isn't really that bad of a deal?

[Arthurmetal]

Any descend prepacked system should support slaved axis.
Configuration in mach3 it is no problem.

Maybe with some cheap chinese sets you could run into problems.
On our local forum I learned that, for example, this particular board does (or did) not support slaved axis.
4 Axis CNC Breakout Board, Mach3 USB Interface Board Capable with Windows2000/XP/Vista etc., View interface board, sunwin Product Details from Shenzhen Sunwin E-Commerce Co., Ltd. on Alibaba.com

Another aspect you might want to research in an early stage is your torch height control. In case you want to assemble your drive system from separate parts. Integrating a stand-alone THCunit after you are up and running might be a challenge. Those kit systems should have sorted this out for you as well.
Unless you want to go into this electronic stuff for the learning experience. I didn’t.

Don’t let anyone tell you you can run your plasma table without a THC, especially because of the plate sizes you intend to cut.

[eddieburnsii]

Thanks for that info on the non support of the slave axis boards.

I think I will try to scrounge enough to buy a complete 4 axis kit from candcnc or the likes. I too do not relish the idea of doing all that wiring.

Actually you CAN run a torch without a THC, not that I would want to but it can be done. When I first started running industrial machines back around 1993 the machine I used had a toggle switch to control the Z-axis. I had to stand there the entire time looking at it and adjust the torch height manually. Not fun but I didn't know any better till the company sprung for a new ESAB water table with everything you could imagine on it....lol. The old table had a 100 amp power pack and all programming was in g-code. I could cut 16ga at 600 IPM and 1" at 24 IPM. I also started stack cutting and increased production much to the dismay of management. They said the machine wasn't designed to do it.....lol

[Arthurmetal]

I have a hard time imagining you (or myself) staring at 600 IPM with a toggle switch in your hand.
Some of the art stuff I do, does about 300 pierces and 45 minutes of cutting in a piece of 11ga (3 mm) steel 20 x 50 inch.
Only the warping involved in jobs like this, led me to the statement that you can't do without a THC.
Maybe I am just spoiled by modern technology. I run my plasma table(s) for 4 years now and still have the old analog THC300.
Latest digital thc are even far more advanced.

[eddieburnsii]

Yeah only that first old machine I started out on was without a THC. The rest have had it and I couldn't go back unless I was cutting 1/4" and thicker all the time on a good level table....lol