[JTH]

I've just started my first CNC project, a 4'x6' plasma table, and would like some input on the electronics/software side of things. I've got the mechanical design portion under control.

This is the current direction I'm leaning....

1) Mach 3 $160
- This scares me the most, there doesn't seem to be many plasma guys running this. Is that true?

2) Xylotex 4 Axis Drive Box Complete with Motors and Cables $525
- I plan on two motors for the long axis, slaved together in Mach 3.

3) Cambell Designs THC 300 $390

4) I've already got SolidWorks 2003 and a decent PC running XP.
- I'm assuming Mach 3 will take DXF files from SW or do I need to generate the G-Code first, then import that to Mach 3?

5) Thermal Dynamics Cutmaster (51, 81, or 101) with CNC interface and machine torch. $2000+


Am I overlooking anything? What would you do differently? Is anybody using a similiar configuration? Any comments would greatly appreciated.

John

[GaryCorlew]

You should check into sheetcam, I have heard good things about it, and I believe it will nest parts, which you will want to do. Also you may want to check out http://www.candcnc.com

[grinder_gary]

You should go to the mach support group and see how many use mach for plasma. Alot use it for lathe and mill but alot use it for plasma. I am currently setting up a 10 x 5 table for myself. Lots of support if you ask. Try the site at http://www.machsupport.com/, then go to the yahoo site and get lots of support.
http://groups.yahoo.com/group/mach1mach2cnc/

Sheetcam is a good program also.

Gary

[massajamesb]

I don't currently use Mach, though I have it on my home computer for reference.
I use
Dcad, Sheetcam, and Quickstep 4 (Quickstep instead of Mach)

I use plasma on 1/4" and thinner, and oxyacet above that.

The thickness of material you mainly cut will decide the size of your plasma. I use a Cutmaster 50, 40 amp machine. Cuts 1/4 fine.

Don't be scared of Mach. It is a great plasma program. I just didn't have the money to invest in a computer nice enough to support Mach.
Quickstep4 runs fine under Win98 on my flea market computer.

Check out www.candcnc.com for another nice ATHC. Great service and product.

[JTH]

Thanks guys.

Is SheetCam a subsitute for Mach 3?

The thickness of material you mainly cut will decide the size of your plasma. I use a Cutmaster 50, 40 amp machine. Cuts 1/4 fine.

What travel rates are you running for 1/4" mild steel? How about 3/8" with the plasma, ever tried it? Dross? What's about thin sheet like 1/16"?

I'd like to achieve 150 IPM for smooth/fast cutting of 1/16". Do you know your max travel?

[massajamesb]

Thanks guys.

Is SheetCam a subsitute for Mach 3?

no. Sheetcam takes a part or design in, and converts it into a file that Mach understands (Gcode). Mach "tells " your motors where to go, in laymans terms by processing the "Gcode". It is a little more complicated than that, but you get the idea

What travel rates are you running for 1/4" mild steel? How about 3/8" with the plasma, ever tried it? Dross? What's about thin sheet like 1/16"?

Yes, I can cut up to 1/2" with plasma, but I hate the bevel. Oxyfuel leaves no bevel, but it cuts slower.

I run anywhere from 45-75 IPM on 3/16 and 1/4, as my duty cycle at 40 amps doesn't allow for real big items.
I don't have any pics of items I cut with plasma on here yet, but here is a couple of pieces done with oxyfuel.

1/4 plate bracket with almost no dross

Attachment 29598

Attachment 29599



I ground the rust off of the top of the plate so you could see the cut better. I did not grind any dross, nor did I grind the cut edge.


Here is a 1/2 " piece done with oxyacet

Attachment 29600

I'd like to achieve 150 IPM for smooth/fast cutting of 1/16". Do you know your max travel?

with 28 volts, I now rapid at about 300 IPM, thanks to the Pulsepacer attachment on Quickstep4. Before I got that, I could get 200-250 max on 24 volts. I only have one motor driving X, and one driving Y. My setup originally was chain driven, it is now rack and pinion with timing belts and pulley for gear reduction. I just don't like spending money I don't have to, and I built my table on a strict budget. My table looks nothing like my old pics on here, it is completely different now. Originally, I built it for about 550 bucks. I now have about 900 in it, minus the plasma cutter. With it, I have about 1800 in the whole mess, including a bunch of leftover parts, driver boards, etc.

That help a little?

[massajamesb]

I should also mention, you will want higher cutting speed for 16 gauge than 150 IPM, as you will have too much heat in one area for too long that way.

Edit: here are a few plasma cut pieces. The smaller one is 3/16, and the larger one is 1/4 plate. No dross, no grinding on either one. Sorry for the crappy pics, all my money is in my cnc, not in my camera.
Attachment 29604

Attachment 29605



Attachment 29608

Attachment 29609

[Torchhead]

Your target for top cutting speed should be a min of 200 IPM. There is always a tradeoff between speed and torque. Only problem with the Xylotex (we sell an complete 4 axis integrated motor controller using Xylotex) is its limited to 30VDC absolute max (including backemf). We don't run ours above 28VDC.

The voltage somewhat limits the top speeds. On steppers voltage = RPM. Most of the motors perform better at 48 to 68VDC.

IMO The Xylotex is really intended for smaller applications like table top milling and routing and that is what we sell our units for.

Moving bigger loads at quick rapids takes more power (torque & speed) than you can expect from 24VDC.

Also be aware that the THC300 is a port 2 solution (you need a 2nd parallel port). You then need to use the first parallel port for your motors and table switches. The Xylotex will run directly off your port 1 output BUT the inputs are not isolated and running plasma is a very noisy environment. If you get the table ground tied to the computer ground you will end up cutting "random art". You will end up fighting noise problems. I would recommend a port1 interface/breakout with buffers for the step & dir and opto isolated inputs for your Homes, limits and e-stop.

As for users running MACH3 with plasma: I know there has to be at least 450 because that is how many THC300 and MP1000-THC have been sold and they only run with MACH (well, there are 2 or 3 running with EMC but that's all).

You are welcome to join the CandCNCSupport yahoo forum and ask any technical questions about either of the THC products listed and/or MACH3, SheetCAM and general plasma cutting.

We still do that as a business (cut steel) and have over the past five years figured out how to do it the most profitable way (hardware & software).

Our formula is pretty simple:

CorelDraw12 (running DXFTool) -> SheetCAM -> MACH3.

Tom Caudle
www.CandCNC.com