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Author Topic: THC Codes upset corners???  (Read 16788 times)

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Offline Davek0974

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Re: THC Codes upset corners???
« Reply #20 on: April 08, 2014, 04:58:53 AM »
No idea, as I said Terry and Ian are the guys that can most likely answer your questions regarding Plasma.
Hood

Thanks Hood, I am trying but little or no response, if this were shareware I could live with it but I bought the license ;)
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Offline stirling

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Re: THC Codes upset corners???
« Reply #21 on: April 08, 2014, 11:35:36 AM »
No idea, as I said Terry and Ian are the guys that can most likely answer your questions regarding Plasma.
Hood

Thanks Hood, I am trying but little or no response, if this were shareware I could live with it but I bought the license ;)

 ???

I don't need external outputs just a way to switch Anti-dive on and off from g-code without introducing a delay which would cause issues when plasma cutting.

You appear to have the wrong end of the stick regards anti-dive. You turn it on at the beginning and leave it to do it's thing. IT turns THC on and off automatically as required by the %feed setting.

Offline Davek0974

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Re: THC Codes upset corners???
« Reply #22 on: April 08, 2014, 01:47:00 PM »
No idea, as I said Terry and Ian are the guys that can most likely answer your questions regarding Plasma.
Hood


Thanks Hood, I am trying but little or no response, if this were shareware I could live with it but I bought the license ;)

 ???

I don't need external outputs just a way to switch Anti-dive on and off from g-code without introducing a delay which would cause issues when plasma cutting.

You appear to have the wrong end of the stick regards anti-dive. You turn it on at the beginning and leave it to do it's thing. IT turns THC on and off automatically as required by the %feed setting.

Ah, thanks, that is indeed different to what I presumed.

So what happens when sheetcam sets a reduced speed for say a circle, mach will not see a deceleration as the speed change was programmed, will the torch dive or not?

I can't fathom how it will work with a "dumb" THC like I am in the middle of fitting? It only has up and down outputs (can't use arc ok as I have no more inputs). By embedding on off codes in my g-code I could see how it might work but without that I can't.

Using edited m10/11 macro codes does not introduce a delay so that is one good thing, but if anti-dive is just on, what is left to control torch dive when anti-can't work because it's a coded speed reduction?
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Offline BR549

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Re: THC Codes upset corners???
« Reply #23 on: April 08, 2014, 07:42:41 PM »
First WHY do you think you need to slow down in a corner ??  Plasma wants a consistant cutting speed.  Mach3 is going to slow down on its own as it cannot make corners wide open most times based on the accel/deaccel parameters of the drives. SO when it down slow down on its own the anti dive will kick in and take care of diving due to slower speeds.

IF you let Sheetcam slow the corner speeds THEN you have ZERO anti dive controls on a simple plasma. AS soon as the feedrate drops the arc voltage will go UP and the THC will send the4 torch DOWN to correct the voltage change.

The setup in Sheetcam is for units that control the preset arc voltage parameters on the fly so WHEN you change the feedrates you also change the arc voltage preset as well and then the cuttting stays consistantly good.

CandCNC has a good setup for doing this on the fly. A simple Mach3 plasma cannot. The only solution is to JUST turn off the THC if you make a programmed speed change that is going to effect cutting quality then turn it back on when you return to the proper cutting speeds.


Here I do not require constant tweeking the speeds for corners or circles.

Just a thought, (;-) TP
(;-) TP

Offline Davek0974

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Re: THC Codes upset corners???
« Reply #24 on: April 09, 2014, 02:17:30 AM »
Thanks for that, this is all new to me so forgive me for asking about things that may never happen :)

I presume in a torch dive, it cannot dive below the minimum level set in Mach i.e. 0mm or material surface?

Is there an OEMButton code set for THC on & off, i couldn't see one in the list.




Thanks again
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Offline Davek0974

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Re: THC Codes upset corners???
« Reply #25 on: April 09, 2014, 02:37:33 AM »
I also thought it customary to program a speed reduction on small circles to say 60% ?

Surely here I would need to program in a THC off command and on again at the end as Mach has no auto-slowdown for small circles feature.
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Offline stirling

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Re: THC Codes upset corners???
« Reply #26 on: April 09, 2014, 07:02:22 AM »
If you DO get torch dive it should ONLY be at the start as it gets up to commanded feed and at the end as it slows to a stop. With good accel you shouldn't even get it then.

There is a caveat to this in that you can get dive on a kerf crossing - Mach's anti-dive won't help you there as it's purely speed dependent.

OEM 123 toggles THC on/off. Curiously labelled "Torch Enable Toggle" in the spreadsheet.

Offline Davek0974

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Re: THC Codes upset corners???
« Reply #27 on: April 09, 2014, 07:14:31 AM »
If you DO get torch dive it should ONLY be at the start as it gets up to commanded feed and at the end as it slows to a stop. With good accel you shouldn't even get it then.

There is a caveat to this in that you can get dive on a kerf crossing - Mach's anti-dive won't help you there as it's purely speed dependent.

OEM 123 toggles THC on/off. Curiously labelled "Torch Enable Toggle" in the spreadsheet.

Thanks for that, making more sense now.

The start should be ok as the unit has a built in delay before its starts sending signals.

I did notice the toggle OEM but was looking for an on/off pair, it will work though.

Was i right that it can't dive below THCMin though??
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Offline stirling

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Re: THC Codes upset corners???
« Reply #28 on: April 09, 2014, 08:57:50 AM »
Z can not be driven lower than THC min by THC - i.e. No. However I have to wonder why you ask. Tell me a value for THC minZ that will achieve something useful.

Offline Davek0974

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Re: THC Codes upset corners???
« Reply #29 on: April 09, 2014, 09:35:09 AM »
:)

What i meant was that if THC Min is zero, and the torch is running say 1.2mm, a torch dive would/could NOT send the torch below THC min, i.e it can only dive as low as zero in this case.

As you said, it cannot so that answers my question and makes sense.

Thanks
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