View Full Version : Need Help! Torch moves up at pierce? need help

04-24-2011, 12:09 AM
Need a little help:

I am running the MP3000 DTHC on my plasma table. It is a self constructed table.

The problem that I have been trying to solve for the last month is a random move up in the Z axis right at the same time the torch fires. This move up should not happen as I have a THC delay setting long enough to delay for the pierce, the plunge to cut height and a second or so of the cut move.

The move is not due to any g-code, nor is it due to any noise getting into my system. The reason I know this is because when I run a set of g-code with the THC turned off the program will execute perfectly. Noise can be eliminated from the equation due to the plasma unit being off and the up move still happens when the torch on/off is triggered in Mach - with the THC on only.

The THC seems to be working fine other than this issue, it one could call it fine.

The scenario is this: The torch moves to pierce position, touches off the material, pulls up to pierce position, fires and simultaneously moves up (there is a stop a the pierce height then the move right at the torch on command), executes the pierce delay if there is one, moves to cut height if it can and starts to cut, then the THC delay comes out of the set delay time and Mach starts to see the THC signals the Z moves accordingly to those signals.

When the torch moves up at the torch on command it usually ends up around .170 - .250”. If I have the tip saver feature set at a low percentage, say 2%, the torch will never get down to the cut height. If I turn off the tip saver I get a crash into the material.

Besides the move up at pierce everything else in the THC functioning seems to be operating as designed, however the move up on torch on throws everything else off and there is usually a fault error stopping the system or the cut is no good due to the extra height during the cut.

I took a few quick videos that better illustrate the problem I am trying to fix. Sorry for the narrow screen and lower resolution, I only had my phone with me today when I was working on this issue.

YouTube - eMotionCNC's Channel (http://www.youtube.com/user/eMotionCNC?feature=mhum#p/a/u/2/zgnKx9WFzl4)

YouTube - eMotionCNC's Channel (http://www.youtube.com/user/eMotionCNC?feature=mhum#p/a/u/1/tkOL6rNBFsA)

YouTube - eMotionCNC's Channel (http://www.youtube.com/user/eMotionCNC?feature=mhum#p/a/u/0/JGajnfKXGSw)

If anyone has and idea of what might be causing this I would appreciate the help..


04-24-2011, 11:41 PM
Torchead should be able to diagnose this problem better than anyone else....

I had this same problem but it only lasted for a few hours... my connector on my limit switch came loose when the z traveled all the way down and pulled the wire off the connector... (same exact problem that your having but diagnosed quickly)

I guess lets start out with simple questions. It sounds to me that your z home switch which runs the thc on the floating head is not connected or something in this area....

Is your z home limit switch connected to your floating head, dthc, table i/o card???

Usually next to your z axis the red light will be green if it is working properly...

04-25-2011, 12:21 AM
Yep, the Z home is connected and working correctly. When I ref down to do a touch off the material everything works as designed.