THC futures for Plasma

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THC futures for Plasma

Postby shad » Sat Sep 24, 2016 12:34 am

As you know, one of the main problems for the torch height control is the need to turn off THC at the corners, at the end of the cut, at the small holes.
Now most of the users use the rules when creating a cutting program in SheetCam or other CAM program. But the rules often do not work properly, especially when they overlap. It is a headache.
If we look at it more globally, we can define the following THC control rules during cutting.

    Turn off THC when machine accelerate/decelerate - I guess this is UCCNC antidive future, but now only for internal THC, no way to send this signal to the external device
    Turn off THC before end of cut - the value of the distance before end can be settable
    Turn off THC on the small holes and down cutting speed - the values of the hole diameter and slowdown feedrate as percents from cutting speed can be settable
    These features must be able to operate for the built-in THC logic and able to have hardware output to the external THC (for example one combined output for this futures and for M205/M206 macros - "OR" logic) .

Balazs,what you think about this?
Also it's will be great to add to the UCCNC CAM module Plasma profile with settable kerf width.
Thank you!
-- Andrew
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Re: THC futures for Plasma

Postby beefy » Sat Sep 24, 2016 7:12 am

Hi Andrew,

Turn off THC when machine accelerate/decelerate - I guess this is UCCNC antidive future, but now only for internal THC, no way to send this signal to the external device
I've suggested to Balazs that in addition to M205/206 having a synchronous output, that any other internal feature that disables THC, also affects the same output. But I have no idea how easy or difficult that is to implement.

Turn off THC before end of cut - the value of the distance before end can be settable
Turn off THC on the small holes and down cutting speed - the values of the hole diameter and slowdown feedrate as percents from cutting speed can be settable

Like Terry said this is normally done in Sheetcam (or other cam). Why would it be better to put it in UCcnc.

Can you give an example of this "overlapping" problem with Sheetcam path rules. I'd be interested in trying to get these problems to happen, always good to know about problems I haven't experienced. I've tried path rules where I have a feedrate change and M205/206 put together in gcode. Sheetcam inserted them correctly and UCcnc implemented them correctly. I injected THC UP/DOWN pulses into UCCCNC and monitored the Z and XY pulse stream with a logic analyser and everything went smoothly when the M205/206 and the feedrate change happened.

Keith.
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Re: THC futures for Plasma

Postby shad » Sun Sep 25, 2016 10:19 am

Keith, you right about addition to M205/M206 having a synchronous output, that any other internal feature that disables THC, also affects the same output. Just will wait new release.
About others futures - yes, this is normally can done in CAM program and it's will be great to add this futures to the UCCNC CAM module.
Two issue in the sheetcam was posted here http://forum.sheetcam.com/viewtopic.php ... light=rule
But this is small part of all issues from my customers. It forced us to write own Sheetcam postprocessor and LUA script (based on the acc/dec, control of the small holes and making hole center marking without moves holes for marking on the separated layer) for generating cutting program. Now it's works perfect.

Terry, now I know, that all THC state LEDs in the UCCNC has 60 msec update time. It makes no sense to read state Of the THC inside plugin and send to the external device. It will be a long delay. Hardware output and M205/206 this is the best way.
Also we always disable THC on the holes less 25 mm diameter and decrease cutting speed to 75%. Holes are cut better.
-- Andrew
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Re: THC futures for Plasma

Postby shad » Mon Sep 26, 2016 8:49 am

Most of those type features are not needed with low end AIR Plasma. I have tested them all and most did nothing to improve the cutting that I could not achieve by paying attention to the original setup.

Yes, you right.This is true and the main purpose of these futures to protect the torch and nozzle from damage during cutting. This futures are not make cutting more quality, but make more safely.
Everything else is handled by the THC and CNC machine.
-- Andrew
UC400ETH
UC300ETH-5LPT
NEURON Lite THC
http://neuroncnc.com/
shad
 
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