[howling60]

Wanted to poke my head in, and say i have just uploaded some photos of machines we have built (cnc plasma table) and retrofit (bridgeport series II) running Mach 3. Wanted to show off the capabilities. Let me know what you think!

check out my photo gallery for the photos

-Nate

[Weldtutor]

Nate
The spiral cut on an angle shows good contol. An explanation of your THC might be interesting.
Do you have photos of the plasma table itself you could post?
Thanks WT

[howling60]

I do indeed have some photos of the machine itself i could post, just need to do alot of resizing.... something about the forums not liking my 1 mb files :stickpoke

the THC system that has been used: I'll have to get back to you on the specifics (esp regarding hardware) as I came into the project towards the end, and have been working on the software side of things. What i can tell you, is that we are feeding an automation direct dl05 plc with an analogue input card, with a scaled tip voltage signal.

To keep the kerf on the cut correct, the torch tip must be kept at an "ideal" cutting height. After running some testing the deadband voltage signifying an "ideal" cut height was approximated. From there, we/I were able to write a macro that would raise the z axis if the tip voltage was below the deadband, and would lower the z if the tip voltage was above the deadband. From there, it is/was a matter of tightening up the deadband until the torch would maintain ideal cutting height while cutting a possibly out-of-level part.

As of right now, the machine has been able to compensate very well at a feedrate of 18 ipm, cutting through 1/4" plate. Almost had it compensating enough to cut a 1/2" wall, 12" iron pipe, traveling up & down the sides

The only issue at the moment, is producing a feed/speed table for the various materials that will be cut on this machine.

I'll see if i can't get more exact details regarding the hardware end of things & post them up. For now, it's time to go and tighten the deadband more, get this thing to be absolutely mint

-nate

[Torchhead]

18IPM?? My Hypertherm cuts 1/4" at 80IPM and 1/8" has to be cut at 100+ IPM to get a clean cut. Slower cuts leave a ragged edge, lots of dross and a wide kerf. The ideal deadband is about 1% or less of the cut voltage. Normal cut voltage is around 135VDC so you need to hold +- 1.3 VDC. Several other critical parameters while cutting are important to control. You need to reference to get a correct pierce height. If the controller software is not involved in the Z (torch head) movement in real time then you need to reference (touch off) before every pierce. For constant quality cuts the pierce time needs to be set from an Arc Good signal so the machine doesn't over pierce or fail to pierce and start moving. IF your plasma unit does not have the Arc Good signal output you need to devise a way to obtain it and feed it back to the control to inhibit movement until its active (and the torch is on). A simple delay during pierce produces mixed results.

Using an external PLC with analog input seems to be a lot of extra work and expense to do something that the Campbell THC300 is designed to do (I'm biased since I designed it).

The new MP1000-THC we have developed holds deadband at +-1VDC and is fully digital with realtime interface to the THC inputs in MACH3.

[Barker806]

Nate works with me
He is learing about plasma and Mach3 at the same time... There is a place to get the "good arc" out of the plasma but we have not hooked it up because we wanted to test the table. The cost of the DL06 is about 200.00 with everything and we get to use it for the I/O and analog feed/jog over ride. You know how it is when you need to have a machine done to get that job out The DL06 will also be set up to run the Oxy/map with all the valves...

As for the Feed of the plasma... The plasma will not cut that fast But it did a great job in 3/4".

How did you like the 3D milling

Thanks
Brian

[kburn]

How does the MP1000-THC compare to the Torchmate controller on Ebay? Is the MP1000-THC a interface between the pc and the z-axis drive using steps in direction?

Thanks,
Kevin

[Torchhead]

There is quite a bit of difference. The Z is not driven directly from the THC but through MACH3. We elected to integrate the MP1000-THC tightly with MACH3 since it gives us sophisticated toolpath capabilites for plasma. An example is a recent change that gives you an option to add in a pause until THC takes control after a pierce. This prevents head bounce right after the pierce. Since MACH3 is controlling the other axis as well, we can have it involved in making the plasma cutting process seamless. See details on the MP1000-THC (it is also a powered port one breakout) at www.CandCNC.com. March special: Get a free handheld handwheel control with an MP1000-THC purchase.

PS it also controls our optional Power Control