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Author Topic: Help w/ cnc plasma issue  (Read 3790 times)

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Help w/ cnc plasma issue
« on: May 01, 2011, 11:20:27 PM »
Having some issues I am hoping you all can help. I am running my software on a cnc plasma. If I run the g code without the plasma it runs clean. The minute I run with the torch the machine takes on a mind of it's own. However if I run without the torch, and manually fire it mid code it runs flawlessly? Could this be an ground/noise issue? Controller is a c and cnc unit.

Offline BR549

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Re: Help w/ cnc plasma issue
« Reply #1 on: May 02, 2011, 10:30:58 AM »
Describe "takes on a mind of its own"

(;-) TP
Re: Help w/ cnc plasma issue
« Reply #2 on: May 03, 2011, 09:14:20 AM »
Sounds like lots of HF noise.  Which plasma are you running?  Does it have HF or contact arc start?

Offline jve

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Re: Help w/ cnc plasma issue
« Reply #3 on: May 03, 2011, 11:18:19 AM »
for me it sound that you have noise try to sheld the plasma torch cable and try to avoid the plasma torch cable to the other cables like motors ,limits ecc

Offline BR549

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Re: Help w/ cnc plasma issue
« Reply #4 on: May 03, 2011, 11:31:47 AM »
One would think if it were HF noise then when he fired it mid program it would cause trouble as well ???

Please describe "it has a mind of its own"

(;-) TP
Re: Help w/ cnc plasma issue
« Reply #5 on: May 03, 2011, 12:31:07 PM »
Mind of it's own = torch head shuts off, move -y until limit switch. Totally aborts the intended cut path. As for HF noise, plasma and computers are on separate power panels, no wires were touching the plasma line.
Re: Help w/ cnc plasma issue
« Reply #6 on: May 03, 2011, 12:33:53 PM »
I believe it is arc start

Offline BR549

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Re: Help w/ cnc plasma issue
« Reply #7 on: May 03, 2011, 01:15:02 PM »
Can you post the starting portion of your Gcode where it acts up?? Does it do it on all gcode programs? Does it act the SAME way each time ?

(;-) TP

Offline kf2qd

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Re: Help w/ cnc plasma issue
« Reply #8 on: May 03, 2011, 02:13:57 PM »
Grounding. I used to install commercial machines and we had a couple locations where we had problems because of gounding problems. You need to make sure everything on your carriage is grounded to a common point on the carraige, then run a ground wire to a common point with the rails and table. then run a ground from that point to a good earth ground. Depending on your location you may need to water the the ground rod as excessive drought can affect teh quality of your ground. You might also look for a copper shield to run your torch leads in.  A woven copper sleeve around your torch lead and the it tied top the common ground at one end.

Every location will not have this problem. I have installed machines with no groundimng and had ZERO problems. One of the machines with a grounding problem would move erratically and unpredictably. The other machine would blow encoders. Get a bad ground and an encoder would fail.