Another plasma component...

Rod,

There are a few pins used here:

- ohmic-max-attempts - input - maximum ohmic probe attempts before fallback to float switch
- ohmic-probe - input - ohmic probe input
- ohmic-test - input - when on attempt a single ohmic probe (shorted torch test)
- ohmic-enable - output - on only while probing

Cheers, Phill.

Phill

I may not get to live cutting today but here is what I found so far.

I think that the Torch Enable button should be in the disabled state on startup of LinuxCNC. I know this is personal preference sort of thing.

The torch did a dry run with the torch disabled.

The torch is still moving to Z Max after traversing at Safe Z height before probing from Z Max. Think is that the probing sequence should be:
Move from Z max or safe Z to Probe Height at G0 speed. Slow to probe speed and probe. At end of cut torch should return to Safe Z or Z Max as appropriate (I think this works correctly).

I am not sure now what the Probe Height setting is supposed to be. If it is the height that the torch slows to probe speed then the current range of values is too small for an imperial machine. I think the default value should be about .75" and the setting range should be .25" to 1.25".

When probing and the float switch actuates first plasmac treated this as an ohmic probe failure. So on my setup every probe try using the float switch resulted in 5 tries before moving to pierce height. I think if the float switch actuates first it should be the signal to use the float switch height for the probing.

I will try to get to making a video and doing live cutting today but it doesn't look good.

John

Just thinking about this because I want you guys to succeed. When probing, the machine should recognise either the ohmic input or the float switch input but then adjust for cut height depending on which input was triggered. I'm not sure you need to retry. The only float switch probing failures I get in my gcode routine is if the probing distance would exceed limits or not long enough to touch off. When doing it outside of gcode, I can't see these errors could occur.

But if John says its required, go with him as he probably cuts more in one day than what I've cut since I built my table.

islander261 wrote:
I think that the Torch Enable button should be in the disabled state on startup of LinuxCNC. I know this is personal preference sort of thing.

Will do, if this is a problem for others I will make it an ini file setting.

The torch did a dry run with the torch disabled.

Yay!!!

The torch is still moving to Z Max after traversing at Safe Z height before probing from Z Max. Think is that the probing sequence should be:
Move from Z max or safe Z to Probe Height at G0 speed. Slow to probe speed and probe. At end of cut torch should return to Safe Z or Z Max as appropriate (I think this works correctly).

I will check this out later today.

I am not sure now what the Probe Height setting is supposed to be. If it is the height that the torch slows to probe speed then the current range of values is too small for an imperial machine. I think the default value should be about .75" and the setting range should be .25" to 1.25".

Height above zero point (top of slats?) Z moves at setup-speed (in config tab) to this height then moves at probe speed.

When probing and the float switch actuates first plasmac treated this as an ohmic probe failure. So on my setup every probe try using the float switch resulted in 5 tries before moving to pierce height. I think if the float switch actuates first it should be the signal to use the float switch height for the probing.

If ohmic-max-attempts is set to zero then it should use the first signal as you described, I will check later.


Cheers, Phill.

I have just pushed an update:
- add torch enable/disable.
- remove dry-run (to do a dry run press run while torch is disabled).
- GUI's start with torch disabled.
- minor fixes to Axis native button press events.

A question...
At the moment if there is Z axis motion before beginning a job then if the Z axis is lower than safe height the offsets get confused and this can lead to errors and gcode unable to be run. Basically you need to re home the machine.
A fix for this is to reset the offsets at the end. This will cause the Z axis to move to the actual starting height rather than Z max.
I feel this is the lesser of two evils. If someone has moved their Z axis they probably have a good reason...
I would like to hear what others think.

Cheers, Phill.

Sorry guys,
I broke safe height before probing a little while ago, it is fixed and an update pushed...

Another question:
Instead of specifying probe-height as the height above the slats, would it be reasonable to specify probe-height as the height above the top of the stock. This would mean the very first probe would be slow as it would run at probe-speed from wherever the start Z is. After this all subsequent probes would be from probe-height above the top of stock as measured from the last cut.


Cheers, Phill.