Arc stops for a second RTech 50cnc

[Jb_engineering]

Hi, my plasma torch recently went down, so i bought a replacement (which i told was a replacement part). It cuta ok on large cuts, but when cutting more detailed cuts, the arc fires, and then goes out for a second, and then fires again. But during this time, the torch starts to move, so i have cuts that are not finished cutting. I was using a pm70 torch, but the replacement ive been given is a ptm-100. Im just wondering if something need tweaking to for it to run correctly.

Before my torch went down the arc would fire, and then continue throughout its cut. I didnt know if anybody else has had a similar issue.

[adbuch]

What make and model of plasma cutter do you have?
David

[weldguy]

Very strange that it does not have this problem on larger parts, only small ones. On off signal is the same regardless of part size. For the time being a longer pierce delay to prevent the torch from moving before the second arc. Does it only do this when small cut are close together? If you let the machine rest until the post flow air stops then start the next cut does the problem still exist?

[Jb_engineering]

Its an rtech 50cnc. The thing is ive used some old designs that were never a problem, but with the new torch im having the issue. Ive tried adjusting the delay, but its asif the arc fires, then stops then starts again. Its strange, as once its fired its ok.

[adbuch]

Its an rtech 50cnc. The thing is ive used some old designs that were never a problem, but with the new torch im having the issue. Ive tried adjusting the delay, but its asif the arc fires, then stops then starts again. Its strange, as once its fired its ok.

Perhaps go back to your dealer and return the new torch and get the same model you had before that you know works for you.
David

[adbuch]

Or make your pierce lead-ins extra long so that the misfire/re-fire occurs in the lead-in and not the actual part. For small inside circles, you could do a spiral lead-in. I would do some tests to see how far the torch moves between the initial pierce and the location it actually starts cutting after the delay. That would tell you how long a lead-in length you need. If it is too long, then the long lead-in approach may not work.

David

[Jb_engineering]

Thanks for the info, ive been on to the dealer, maybe getting a swap for the correct torch as could have been miss sold this one. I didnt know if needed to set this torch up differently. It misses about 1/16, doesnt sound alot but it is enough for the cut part not to fall away from the work piece.

[adbuch]

Thanks for the info, ive been on to the dealer, maybe getting a swap for the correct torch as could have been miss sold this one. I didnt know if needed to set this torch up differently. It misses about 1/16, doesnt sound alot but it is enough for the cut part not to fall away from the work piece.

Does it use the same consumable stack as the other torch? What was wrong with the other torch?
David

[tcaudle]

Do you have anything on that system that shows you the actual torch fire status (like an LED) at the torch to see if the signals cutting out or if its 100% in the torch. I have see a minor Blip (on-off-on that cause the torch to turn off then refire a second later. Sometimes its even had to catch it with the indicators because it can dropout and turn back on really fast BUT the torch has to cycle before it restarts.. One way to diagnose THAT is to send a hard torch on signal with a switch wired in and see if it happens then. Only that as a last resort.

Make sure you clamp the worklead to the material and not just to the table or the slats .

ON one old table we had to put a 10mfd cap across the torch fire pair to stop the drop out . It could have been the torch fire circuit in the plasma or some form of noise issue but the cap did the trick and acted as a filter and a delay .

[Jb_engineering]

Everything seemed fine, ive sorted a replacement out dor it now, waiting on it to arrive. Thanks for the help and info guys.