Plasma torch dragging on metal during cut

[xotech]

Good morning,

I am cutting a table design on my Arcmax 5x10. It is 3/8ths metal sheet and I am using 65 Amp head. I have a powermax 85 and sheetmax gave me 45 ipm for this cut and my soft pierce is at 80%. I zero the table and zero the torch and started cutting but torch height during the cut goes to -2.3 or over slowly and dragging on the metal and stopping. I re zero the Y and torch many times and start cutting from the line but it still drags. Powermax has no errors and voltage is around 135-140 range. When I put in 45A head it does not cut all the way through. No errors on the screen Please help. Am I doing something wrong

[adbuch]

If you are using thc, perhaps it needs to be calibrated. What happens if you turn off thc and set you cut height to a fixed 0.060?
David

[TJS]

What system is this. I thought arcLight uses commandCNC.

[adbuch]

I know that some of the legacy Arclight Dynamics tables used Mach3. I had assumed that they all did since they offer the Auto Tracer attachment which uses Scanything which only runs on Mach3, Eding cnc, or Linuxcnc. It does appear that the newer Arclight Dynamics tables run from either Command cnc or Flashcut cnc and they still offer the Scanything auto tracing software with their auto tracer attachment as shown in their 2021 Auto Tracer Demo video.

So I assume they have one of the requisite programs (Mach3 or Linuxcnc) loaded onto their supplied pc and use that strictly for the Scanything interface. The Scanything program shown in their demo video looks exactly the same to me as the Scanything version I run on my Mach3 controlled AvidCNC router.

David

[weldguy]

Your problem is with the auto torch height control, either it is not set up correctly or it is malfunctioning. If you are not familiar with how the auto height control operates it can be frustrating to resolve.

I would suggest that you turn the auto height control OFF just to finish the job and then we can load some thinner scraps onto your table and work on figuring out what is going on with the auto height.

It could be as simple as increasing your height controls voltage setpoint, I would try 10volts or so to start but again you will want to do this on some scrap material and just cut simple straight lines until you get it resolved.

Best of luck and let us know how it goes.

[TJS]

I do not see the OP responding. I have viewed some ArchLight vids and it looks like they are using Command CNC. Cuttting thicker material with Command CNC has been a challenge I think for many. It is recommended that another profile be built and slowing down all acceleration axis and max's as well. Also slowing the DTHC response time to SLOW helps. I did create a new "Thick Material" profile with all the suggested parameters to combat the torch diving. The main complaint I had was the torch bouncing up and down on thick stuff. This is when it was suggested to slow the DTCH response time down to slow. Then the torch would still dive. I then was told to slow all accel and axis down by 50% I think. I still have issues with the torch height getting real close and not holding the .060 cut height. I am now playing with voltages.

[adbuch]

I do not see the OP responding. I have viewed some ArchLight vids and it looks like they are using Command CNC. Cuttting thicker material with Command CNC has been a challenge I think for many. It it recommened that another profile be built and slowing down all acceleration axis and max's as well. Also slowing the DTHC response time to SLOW helps. I did create a new "Thick Material" profile with all the suggested parameters to combat the torch diving. The main complaint I had was the torch bouncing up and down on thick stuff. This is when it was suggested to slow the DTCH response time down to slow. Then the torch would still dive. I then was told to slow all accel and axis down by 50% I think. I still have issues with the torch height getting real close and not holding the .060 cut height. I am now playing with voltages.

TJ - what thickness metal are you cutting when you say "Thicker'"? I would think that if the material is flat thicker plate (say 1/4" or thicker) you could just turn off your thc and maintain your set cut height.
David

[TJS]

Yes it is 1/4" plate or thicker. Next time I cut thicker I am going to turn it off.

[adbuch]

Yes it is 1/4" plate or thicker. Next time I cut thicker I am going to turn it off.

[asuratman]

so on thick material (>1/4" or 6mm) suggested not to use thc ...

[adbuch]

so on thick material (>1/4" or 6mm) suggested not to use thc ...

That is my takeaway here. If the material is flat and level to the xy plane of motion, then thc is not necessarily needed. And cutting results may be better without it.
David

[TJS]

I just cut some 1/4" plate the other day and Disabled THC in Sheetcam. It worked fine. I am making brackets for my engine run stand. Holes came out good as well.
T.J.

[adbuch]

What kind of engine are you running on your stand? Pictures please.
Thanks,
David

[TJS]

I am building this one to be able to run a few manufactures of engines. I am getting an older 6.2 Chevy diesel ready to put in a 79 square body. So that is first. But the mounts and the bellhousing are the same for small block chevy, Big Block Chevy and I will adapt to LS as well. I should be able to switch to small block ford/Big Block Ford and Dodge as well when I come to the need. I made it long enough to hold a 5.9 Cummins as well. Just need to make engine adapter mounts to my uprights.
Not much CNC plasma cutting with this project. Just a few plates. I will start a new thread with pics soon.
Thanks.
T.J.

[Dakotab2507]

What amperage where you cutting this 1/4 out with? What is your preset volts? What plasma cutter (Hypertherm model) are you using? you should be able to cut 1/4 with torch height control without problems if you have some pictures of the parts you're cutting I also might be able to help with preventing this happening in the future on this plate. Thanks!

[TJS]

I just cut out a 3/8" address sign with the THC off and it worked great. Nice clean cuts, minimal or no bevel.