[homerswitch]

Recently purchased the cncrp pro4848 with plasma plug and play package. This includes the TMC3in1 THC. Product version 4.4.0.0 File version 2018.1.4.1

The THC functions as expected under normal circumstances. The problem occurs when the torch encounters a gap in the material (or runs off the edge). The tip voltage jumps up about 50V and the THC dives the torch.

The TMC3in1 is configured:
Target Band 0.25V
Linear Response Band 20.1V
THC offset 0V
Mode delay after arc ok 0.4s (did same thing at 1.1sec)
Stop THC < 97% feedrate...checked\
Enable anti-dive based on tip volts...checked
ATV buffer 800ms (still dives if set to 200ms)...This item is different in the setup literature, which allows 1-128 tip-voltage data points instead of time-based buffer.
4% change in tip volts before anti-dive
0% thc response when anti-dive active
Disable thc when tip volts >25V
<25V...from target v (did same at 20v default value.

Any suggestions would be greatly appreciated.

Thanks!

[mattcnc123]

If you reduce the z axis speed that could help you a lot.


Matt

[ahren]

Give us a call and we'd be happy to help you with this issue. In particular, it will be helpful to enable logging on your plasma system so that it records all of the THC data. We can then put this through our THC data analyzer (available for you as well -- we can walk you through downloading and installing this). This program graphs torch voltage and the response of the THC (including anti-dive settings) over time, so you can tweak the anti-dive settings to balance THC coming on at the right time, while still detecting events like unexpected gaps in the material.

In terms of the average tip volts setting, the time-based version is the newer and more reliable version, so you are using the correct settings.

Best regards,

Ahren
CNCRouterParts

[homerswitch]

Thanks to both Ahren and Matt for the recommendations.
Okay, I have enabled logging and, using the data analyzer, it looks like the thc down signals are okay, but the thc up signals get ignored.
Attachment 402652
I looked at a number of different cuts and this seems consistent...down okay but no up. On longer cuts the torch continues to drift downward but never raises by thc command even though the thc is commanding higher and higher positive velocities.
I'm totally new on this analyser software, but I believe I'm reading the graph correctly.
Not really sure how to proceed from here, though. Thoughts, anybody?

Thanks!

[homerswitch]

Thanks to both Ahren and Matt for the recommendations.
Okay, I have enabled logging and, using the data analyzer, it looks like the thc down signals are okay, but the thc up signals get ignored.
Attachment 402652
I looked at a number of different cuts and this seems consistent...down okay but no up. On longer cuts the torch continues to drift downward but never raises by thc command even though the thc is commanding higher and higher positive velocities.
I'm totally new on this analyser software, but I believe I'm reading the graph correctly.
Not really sure how to proceed from here, though. Thoughts, anybody?

Thanks!

I did stretch, compress, and offset different parameters on the graph to make it more readable.



Here is how the graph was set for the pic:
z axis x10
tip volts /10
commanded vel. Z /10
thc allowed /100, offset +2