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Author Topic: Floating torch head, how?  (Read 3109 times)

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Offline Davek0974

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Floating torch head, how?
« on: January 31, 2014, 01:26:12 PM »
Looking ahead with my plasma table build, I'm trying to find out how a floating z head works with mach3?

If I understand it correctly, there is a switch on the head slide that holds the torch, when the cycle is started, the head drops until the switch opens, then raises until it closes, then raises a preset amount more and zeroes the Z DRO. The cut then starts as normal.

Is that correct?

If so, where is the input fed into mach software and does it actually reset the Z DRO??

Any tips appreciated.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Floating torch head, how?
« Reply #1 on: January 31, 2014, 04:31:26 PM »
Well I've found some gcode that goes into sheetcsm  to be run before a cut is made, but I can't find any info on the switch?

Is it just another limit switch?

I would have thought that this would have just caused an e-stop though so I maybe wrong there.

If it's a separate signal coming in through the BOB, then how is it related to the g-code so it knows when it's hit to lift the torch back up??


Dave
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Floating torch head, how?
« Reply #2 on: January 31, 2014, 05:28:07 PM »
Hi Dave,
 Go to the HOME page and put      floating      in the search box.

Gads of good research info there.

If you can't find what you need, post again.

Regards,
Russ :)

Offline Davek0974

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Re: Floating torch head, how?
« Reply #3 on: February 01, 2014, 06:29:27 AM »
Thanks overloaded, I hadn't searched from the home page before, just this page, my bad.

I now have some research to do regarding the G31 code and I believe my switch is wired to an input connected to the "probe" input in mach?

This means I can keep my "home all" to zero the z axis to the top limit switch, this is what I would like to do.

I see I need to switch to a THC post processor in sheetcam and edit it to insert the G31 codes??

Am I on the right path now??
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Floating torch head, how?
« Reply #4 on: February 01, 2014, 09:25:10 AM »
I've had a look at the mach/THC post processor file in sheetcam and it's all laid out ready for a couple of variables to be set and it should ref the top of material at the start and then every 500mm I think. I will look at altering this so it ref's at the start of every pierce as I don't have THC yet and time is of no importance.

If I understand things properly, I connect the head switch to the probe input in mach.

I have also just ordered the full license for mach :)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Floating torch head, how?
« Reply #5 on: February 02, 2014, 04:21:12 AM »
Well I've been searching and found some ideas but keep getting conflicting replies, the post processor in sheetcam uses offsets apparently and I have been told these are not good as they remain in place after the job has been run therefore risking messing up the next job etc unless a G92.1 code is issued.

I was told to search for macros but found little that made sense and what I did find seemed to use the same G31 offset coding??

So  I'm getting a bit baffled now, is there a working code that sheetcam can trigger before every cut that will sensibly probe the top of the metal using the floating head switch??

One idea I did have was alter the post processor to insert a G92.1 code after the job finishes??
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Floating torch head, how?
« Reply #6 on: February 03, 2014, 01:34:30 PM »
Well I've got the floating head working using the G31 method, can someone explain why this might not be a good idea, or at least tell me where it can go wrong?

It's all embedded into sheetcam post processor and seems to work but where are the pitfalls if any?

Here's what I've been feeding it today...

G31 Z-100 F300 this lowered the head from wherever it was sitting and stopped when the probe switch closed.
G92 Z0 Set offset to zero.
G00 Z20 This moved the head back up by the amount of float head travel I have.
G92 Z0 Set offset to zero.
G00 Z1 This raised the head a further millimetre.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives