Plasma Torch Height Control

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17 May 2013 18:33 #34233 by mariusl
Replied by mariusl on topic Plasma Torch Height Control
John,
Something I am not to clear about if you can explain please. When I look at the thcud code the correction velocity is simply added to the z_pos. So the increments are are the actual correction_velocity. How is the actual velocity determined then?

Secondly, when I disable the thc the z_pos_requested is just passed through. Does the component latency not influence the reaction on a request?

Lastly, what settings do you recomend I use. I have a nema23 3.0nm on a 4mm pitch screw on the z axis.

Regards
Marius


www.bluearccnc.com

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17 May 2013 21:02 #34237 by PCW
Replied by PCW on topic Plasma Torch Height Control
Dont know how fast is fast in this context
(cutting corrugated metal would need fast)
But a fast THC probably needs to use a standard PID loop working
on the actual voltage and setpoint voltage for the Z control.
(and real time voltage data)

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17 May 2013 21:09 #34238 by BigJohnT

John,
Something I am not to clear about if you can explain please. When I look at the thcud code the correction velocity is simply added to the z_pos. So the increments are are the actual correction_velocity. How is the actual velocity determined then?

Secondly, when I disable the thc the z_pos_requested is just passed through. Does the component latency not influence the reaction on a request?

Lastly, what settings do you recommend I use. I have a nema23 3.0nm on a 4mm pitch screw on the z axis.


Well velocity might have been a poor choice for the pin name.

I'm not sure what your asking about reaction on a request?

I just experimented with a number that gave me good response with no hunting(too high and it will hunt).

JT

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17 May 2013 22:20 #34245 by mariusl
Replied by mariusl on topic Plasma Torch Height Control

Dont know how fast is fast in this context
(cutting corrugated metal would need fast)
But a fast THC probably needs to use a standard PID loop working
on the actual voltage and setpoint voltage for the Z control.
(and real time voltage data)


@ Peter, I am getting the voltage information from the usb at 115200 and at the rate of whatever the user component is serviced. My settings are BASE_THREAD = 35000, SERVO_THREAD = 1000000.
The voltage is checked against the set voltage and a up or down signal is set. I have a hysteresis window of 0.5v set at this time. This is done in a realtime component.

Regards
Marius


www.bluearccnc.com

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17 May 2013 22:24 #34246 by mariusl
Replied by mariusl on topic Plasma Torch Height Control


Well velocity might have been a poor choice for the pin name.

I'm not sure what your asking about reaction on a request?

I just experimented with a number that gave me good response with no hunting(too high and it will hunt).

JT


John, I meant if you jog up or down. The other axis are very responsive but the Z axis has a sluggish almost delayed action. This happens even if I disable the thc. My question is then, is it possible that the component causes the delay as it grabs the zpos request (even when jogging)?

Regards
Marius


www.bluearccnc.com

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17 May 2013 23:10 #34254 by BigJohnT


Well velocity might have been a poor choice for the pin name.

I'm not sure what your asking about reaction on a request?

I just experimented with a number that gave me good response with no hunting(too high and it will hunt).

JT


John, I meant if you jog up or down. The other axis are very responsive but the Z axis has a sluggish almost delayed action. This happens even if I disable the thc. My question is then, is it possible that the component causes the delay as it grabs the zpos request (even when jogging)?


I don't have any sluggish movement on my Z axis. It jogs up and down at the maximum speed I set it at with no hesitation at all. I have my Z set at 60IPM.

Do you have latency issues or memory issues?

JT

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18 May 2013 01:45 #34262 by mariusl
Replied by mariusl on topic Plasma Torch Height Control
I dont have memory or latency problems. The other two axis are fine. When I say sluggish I mean that when I jog the axis in continuous mode, the z will continue to move long after I stopped jogging. I have to jog in the opposite direction to get it to stop

Regards
Marius


www.bluearccnc.com

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18 May 2013 01:55 #34266 by BigJohnT
How are you jogging?

JT

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18 May 2013 01:57 #34267 by mariusl
Replied by mariusl on topic Plasma Torch Height Control
Page up and down on the keyboard

Regards
Marius


www.bluearccnc.com

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18 May 2013 02:05 #34268 by BigJohnT
Remove the thc component from the equation and test your jog. I just jogged mine up and down with both the USB game pad and the page up/down keys and it stops sharply.

JT

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