Newbie with questions on DIY plasma table controls

[mpascino]

Hello all, I've been on the DIY CNC Plasma table for a long while now. The mechanics of the project don't scare me much, I just have a lack of understanding of the electronics and computer interface. I have a fairly in depth controls background, however I have never worked with a setup along these lines. Where is the best place to read up on the control system aspect? I am looking to build a bare bones 2 axis table (4'x4') to start. Head height will be controlled manually for now. What is the most cost effective way to accomplish this? I understand I will likely need to purchase software, but is there a brain or main controller outside of the servo/stepper motor drives. I'm sure there is a DYI CNC for dummies post on here somewhere, I just am having trouble finding it right now. Any help is greatly appreciated.
Thanks,
Mike

[jcc3inc]

Sir,

Are you looking for the CNC controller to run the sterpper/servomotors, or do you want an auto torch height control? Both are available for very reasonable sums. A most popular CNC controller is the Mach 3 series. And others on this site can recomment a ready made THC. Note that you will need the table and carriage, Z axis mechanism, motors and gearboxes and gear rack, stepper or servo drivers, interface cards, and plasma unit to accomplish this.

Give us more info as to where you are at this time.

Regards,
Jack C.

[mpascino]

Thanks for the reply. I am looking for more information regarding how the PC and electronics work. I can handle the table, carriage, racks, gearboxes, etc with no concerns. For what I plan to use the equipment for as a start I don't see why I will need a torch height control, hence the two axis. I'm sure that could change do the road. I already have a Thermal Dynamics Pak 50 which I have used manually for a few years. I mostly cut 1/4 steel plate. Gaining the ability to cut out brackets and such with the table would be extremely helpful.

I understand the theory of how everything works together. I don't understand what controllers there are to chose from and how they interface with the drives and servo motors. Are all of the controllers configurable for different ratios or steps per length? Where is the best place to start to further educate myself on how the electronics work together. Thanks again.

[mpascino]

So I have read up a bit on the mach 3 controller. What is the prefered controller to pair up with the Mach 3 for a plasma table? Even if I started off with a two axis machine I would want to add a THC later on. Are Gecko drives the prefered units or is there another supplier that is cost competitive?

I haven't discovered anyone running a plasam table with a Thermal Dynamics Pak Master 50xl. Is there a reason for this? Are certain units not compatiable with a THC?

Sorry for all the questions, I'm a little lost on how all of this works together. Thanks,
Mike

[jcc3inc]

Sir,

Geckos have a good reputation, so I'd probably go with them.

There is no reason that the Thermal plasma will not work with a CNC table. Any plasma should be adaptable.

Wher we started building plasma cuttiing machines, it was immediately obvious that we needed a THC. Our first one was simple, it controlled height only during cutting; that is there was no initial height sensing. While control was a great help, initial height sensing allowed more automation - the operator didn't have to have frequent manual inputs to the height controller.

You need to decide whether you will use steppers or servomotors. I like steppers for smaller machines, servos for larger systems. You will need a power supply for whatever you choose, and some sort of optical isolation for input/outputs. Plasma is a noisy medium.

Regards,
Jack C.

[jemmyell]

Hi,

Talk to Tom Caudle at www.candcnc.com about plasma electronics. He also has a yahoo group with a wealth of DIY plasma information.

-James Leonard

[cidteach]

Hope this is ok , I dont mean to hijack this thread. I am a machine shop teacher at a trade and tech school and i am mulling over the idea of building a cnc plasma. We participate in US First Robotics, team 2344, and this would most certainly help our team be more competitive as well as teach the students very real manufacturing and automation.
My questions are regarding the controls of a table. I think i get it, but after reading many many threads, it seems i may be missing info.
What is needed to control a 2 axis table, my understanding is stepper motors to something like a gecko drive, to a pc that is running mach 3 with sheetcam. What are breakout boards used for, is there a need for an interface card??

Heres the thing, i have checked out CandCNC and the plasma package is out of our budget. Our school does not support these types of projects and barely supports our efforts with robotics. My students literally sell boxes of candy to raise money for our events and material costs.

I have many more questions, but i feel this will start us off on the right path.
Many thanks
Mr. C

[jcc3inc]

Cidteach,

If you would like to contact me, I may be able to help you in making a plasma table. I used to be in that business and could prob enable you to do it "on a shoestring" if that is what it takes. Would need the parameters; size X,Y, speed, which plasma, etc.

jccinc-at-owc-dot-net

Regards,
Jack C.