My Newb Plasma Table Attempted Build
- tommylight
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16 May 2020 10:11 #167944
by tommylight
Replied by tommylight on topic My Newb Plasma Table Attempted Build
Should have said lower all Z axis speeds, by half, just to be on the safe side.
it seems your Z axis is loosing position while working, can you try setting a lower probe speed, please ?
It only does this when THC is enabled. When THC is disabled it never does. I can try it, willing to try anything to make it work right.
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16 May 2020 10:29 #167946
by phillc54
Replied by phillc54 on topic My Newb Plasma Table Attempted Build
Could you do a short cut with THC disabled and the material ramping down slightly as the torch moves. So the material should be closer to the torch at the start then further away at the end. Can you observe what the arc voltage does as the cut progresses. Maybe then do another with the ramp opposite, so finish closer than the start.It only does this when THC is enabled. When THC is disabled it never does. I can try it, willing to try anything to make it work right.
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16 May 2020 15:48 #167977
by dvn4life1972
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
I did the cut from the higher side (closest) first, 4in long. Once the arc voltage stabilised it started to increase as the work piece got farther from the torch tip, and the opposite going the other way (eventually touching the workpiece at the end due to no THC).
Pat
Pat
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16 May 2020 16:45 #167979
by tommylight
Replied by tommylight on topic My Newb Plasma Table Attempted Build
Did the torch move at all down for the first case and up for the second ?I did the cut from the higher side (closest) first, 4in long. Once the arc voltage stabilised it started to increase as the work piece got farther from the torch tip, and the opposite going the other way (eventually touching the workpiece at the end due to no THC).
Pat
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16 May 2020 16:56 #167981
by dvn4life1972
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
I had the THC disabled, Phil requested the test with it off. I can do it again with it on. It usually doesn't dive until after a long run though (somewhere beyond 12 or more inches of linear cutting travel).
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16 May 2020 17:02 #167982
by tommylight
Replied by tommylight on topic My Newb Plasma Table Attempted Build
Again, did the torch move up or down during that test?
What were the readings on voltage display during that ?
What were the readings on voltage display during that ?
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16 May 2020 17:20 #167986
by dvn4life1972
Replied by dvn4life1972 on topic My Newb Plasma Table Attempted Build
The torch did not move up or down. Pierce was about 185v, then moving from high/closest end to low/farthest end it started at 140v and ended at 155v.
Going the opposite direction it started at about 144v (after pierce) and dropped to about 138v by the end when it was physically touching the steel
Pat
Going the opposite direction it started at about 144v (after pierce) and dropped to about 138v by the end when it was physically touching the steel
Pat
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16 May 2020 18:46 #167993
by tommylight
Replied by tommylight on topic My Newb Plasma Table Attempted Build
That all seems very reasonable, so that is good.
Can you do a dry run of some gcode with at least 20 to 50 probes/piercings and note when it happens and what exactly happens ?
Can you do a dry run of some gcode with at least 20 to 50 probes/piercings and note when it happens and what exactly happens ?
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16 May 2020 22:28 #168009
by rodw
So this just confirms arc behaviour where arc voltage increases about 10 volts per mm change in cut height.
Or in my test on one plasma cutter it was 7.53 volts/mm over 16000 readings.
Replied by rodw on topic My Newb Plasma Table Attempted Build
I did the cut from the higher side (closest) first, 4in long. Once the arc voltage stabilised it started to increase as the work piece got farther from the torch tip, and the opposite going the other way (eventually touching the workpiece at the end due to no THC).
Pat
So this just confirms arc behaviour where arc voltage increases about 10 volts per mm change in cut height.
Or in my test on one plasma cutter it was 7.53 volts/mm over 16000 readings.
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16 May 2020 23:21 #168012
by phillc54
You will probably need to set up halscope and hopefully we can see what is happening.
Replied by phillc54 on topic My Newb Plasma Table Attempted Build
Well that seems to behave correctly, I have no idea why it would decide to drive the torch down, maybe noise or moon phase.I did the cut from the higher side (closest) first, 4in long. Once the arc voltage stabilised it started to increase as the work piece got farther from the torch tip, and the opposite going the other way (eventually touching the workpiece at the end due to no THC).
You will probably need to set up halscope and hopefully we can see what is happening.
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