Remember Arc Lost position

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Re: Remember Arc Lost position

Postby Robertspark » Fri Oct 21, 2016 6:29 am

When running overburn on sheetcam, can you not turn off thc at the same time as issuing m11 to turn off the plasma, and then continue the overburn.

I have my overburn set at 10mm for example (although deceleration has already started from 4500mm/sec), and I add a code snippet in 10mm before end of cut to issue an m11.
Rob
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Re: Remember Arc Lost position

Postby beefy » Fri Oct 21, 2016 9:40 am

Robertspark wrote:When running overburn on sheetcam, can you not turn off thc at the same time as issuing m11 to turn off the plasma, and then continue the overburn.

I have my overburn set at 10mm for example (although deceleration has already started from 4500mm/sec), and I add a code snippet in 10mm before end of cut to issue an m11.


Rob, that's pretty much along the lines of what I'd do too. I love the code snippets (and everything else in Sheetcam).

Of course this assumes the user has Sheetcam and for what it costs and the features it gives I can't understand why anyone doing plasma would not buy Sheetcam. I couldn't live without it.

Andrew,
I'm all for new useful features but if the same thing can be achieved in cam software like Sheetcam, should we be asking Cncdrive to try and do it in UCcnc ?? Apologies if I'm misunderstanding what you are asking for.

Keith.
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Re: Remember Arc Lost position

Postby Robertspark » Fri Oct 21, 2016 11:48 am

Andrew, the only negative I see with the neuron is that you've only got one digital input which is the thc on/off.

Given the torch on/off is Ethernet controller, there is some latency there, hence your overburn is likely to be slightly inconsistent (we are obviously talking milliseconds here)

For the feature you asked for, you will need a cam software with overburn built in. I do not profess to know all cam software, but without overburn in cam that function is going to be limited in use is it not?
Hence you should be using a snippet (or whatever other cam software calls it) to I sent the THCOff and m11 which ignores the arc Ok signal and continues the motion as required.

Does anyone have any recommendations of what overburn they run and why? Do you go to the point of calculating your deceleration distance from say 60% feedrate and that is the optimum overburn (too technical, law of diminishing returns??)
Rob
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...working my way through the 1000+ ways things don't work to find the one that does
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Re: Remember Arc Lost position

Postby shad » Fri Oct 21, 2016 2:01 pm

Rob, Keith, you do not understand me.
I mean, to add delay between two events: UCCNC will have arc lost signal and then Feedhold (or stop) of the XY motion (because ArcOK signal will be lost). I hope you understand me if you have many time of the Cut.
This task only for UCCNC. Not for CAM.
I am talk about regular THC like Proma.
If we talk about the Neuron - now I have 10 msec for send Torch ON/OFF and ArcOK command to/from the controller. To be honest it's less then denounce time for hardware IO. And it' works fine. :D
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Re: Remember Arc Lost position

Postby beefy » Fri Oct 21, 2016 8:54 pm

shad wrote:It often happens that an arc is lost on the end of cut, especially when overburn future used or when the cutter is turned off for a few milliseconds before cutting end for prevent divot forming. It's normal situation and CNC control does not have to stop XY motion.

Just when arc will lost, first - UCCNC has to catch current position, store position in the API and start ArcLostDelay timer. When delay time will ended, UCCNC stop XY motion.


Hi Andrew,

I'm guessing I'm not fully understanding what it is you want to achieve.

When you say, "arc is lost on the end of cut", do you mean accidentally or deliberately.

Example for divot prevention you turn off the torch (deliberately) a short distance during before the cut path ends. Therefore you are turning off the torch DURING motion and you do not want the loss of Arc OK to stop motion. That is completely achievable with cam by inserting M206 (THC Off) just before the torch is turned off. Then any THC Up/Down signals are ignored and loss of Arc OK will not stop motion.

The same with an overburn situation, this is a deliberate action, and you can put M206 in the code just before the overburn path starts.

Are there also any non-deliberate situations you are thinking of ??

As for stopping XY motion, because you are talking about the end of a cut, the motion will stop regardless (at the end of the cut path). So yes, I'm confused why you would need UCcnc to stop motion when this ArcLostDelay timer has timed out.

Also, because you are talking about the end of a cut I am confused why you would want to catch the current position.

Keith
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Re: Remember Arc Lost position

Postby Robertspark » Fri Oct 21, 2016 9:39 pm

beefy wrote:
Example for divot prevention you turn off the torch (deliberately) a short distance during before the cut path ends. Therefore you are turning off the torch DURING motion and you do not want the loss of Arc OK to stop motion. That is completely achievable with cam by inserting M206 (THC Off)

+M11 (provided you fired the plasma with M3 M10)
beefy wrote:just before the torch is turned off. Then any THC Up/Down signals are ignored and loss of Arc OK will not stop motion.


...no I am not getting it either .... The Proma will work with that combination above too (although the proma is very slow!!! .... I need to sell my old one...!)

I only know of sheetcam for plasma, I don't know if / how well cambam does plasma or any other small user plasma software (read: not expensive).
Rob
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Re: Remember Arc Lost position

Postby beefy » Sat Oct 22, 2016 2:30 am

Robertspark wrote:
beefy wrote:
Example for divot prevention you turn off the torch (deliberately) a short distance during before the cut path ends. Therefore you are turning off the torch DURING motion and you do not want the loss of Arc OK to stop motion. That is completely achievable with cam by inserting M206 (THC Off)

+M11 (provided you fired the plasma with M3 M10)


Cheers Rob,

I'm actually very aware of that but I do have a question for you regarding it so I've started a new thread in the plasma section. Don't want to "contaminate" this one with an off-topic subject.

Keith
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Re: Remember Arc Lost position

Postby shad » Sat Oct 22, 2016 6:50 am

beefy wrote:Example for divot prevention you turn off the torch (deliberately) a short distance during before the cut path ends. Therefore you are turning off the torch DURING motion and you do not want the loss of Arc OK to stop motion. That is completely achievable with cam by inserting M206 (THC Off) just before the torch is turned off. Then any THC Up/Down signals are ignored and loss of Arc OK will not stop motion.

Hello Keith. You right. I forgot about the M206 command for disable the THC and think about how to solve this problem :oops:
I can not get used to the fact that the M205/206 disable THC (wait arc for move and AVC) globally :o
Maybe it's the legacy of the Mach CNC, but all my controllers has adjustable ArcLost timer. It's allow to delay turn off the ArkOK signal to the CNC for prevent stop of the motion. "M5" command also finish this timer.
Just I did some tests too and found that if you turn off the torch for a few milliseconds before the end of the cut and did not stop the motion, the isotherm process is sufficient to finish cutting and reduce divot.
Of course in previous post I said about the deliberately arc lost event and we don't need to store arc lost position.
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Re: Remember Arc Lost position

Postby cncdrive » Sun Oct 23, 2016 9:00 pm

Guys, I have just talked to my API developer collegue about the Arc lost position and he said that this is already implemented.
He said (which I also knew about as we discussed about this earlier, but I totally forgot it) that if the ArcOK signal gets lost then the target position for the motion controller will be that exact point,
so what will then happen is that the motion controller will stop the motion with decceleration and then will move back to the position automatically where the Arc was lost.
So, this is already implemented in the current official release also. :)
So, you can just wait for the Idle state of the controller when the Arc goes off and then you can read the coordinates from the DROs, because the machine will be standing on the exact coordinates where the ArcOK signal got lost.
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Re: Remember Arc Lost position

Postby Robertspark » Sun Oct 23, 2016 9:02 pm

Wow! Thanks.... one for the website advertising features there plus users manual. Thank your api developer. Don't think there's no one else offering that built into the motion controller plus control software
Rob
Einstein ― “If you can't explain it to a six year old, you don't understand it yourself”
...working my way through the 1000+ ways things don't work to find the one that does
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