esab ultrarex retro fit plasma / flame cutter

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24 May 2012 14:11 #20333 by jd896
i have found the correct one in pnc must have tired eyes

still canot get the open loop tests tho

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29 May 2012 10:34 #20479 by jd896
pnc all sorted now turns out i'm stupid

any way things left making me think are the pid tuning but trial and error i know however i can only get my p value up to around 1.4 the rest of the settings are in the zero point range with the p any higher i get loads of oscillation anybody else only have low figures

next what do people think would be the best way of doing the hight control i.e. turn the output of of it then pause say 3.1 seconds (how long it take torch to go all the way down) then turn the output on for power source wait for the ok signal back then start motion, and on finish cutting command turn tourch up output on for say 3 seconds to clear plate and start move to next cut

would this be in some classic lader or gcode sub routine?

thanks john

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29 May 2012 12:05 #20480 by BigJohnT
jd896 wrote:

next what do people think would be the best way of doing the hight control i.e. turn the output of of it then pause say 3.1 seconds (how long it take torch to go all the way down) then turn the output on for power source wait for the ok signal back then start motion, and on finish cutting command turn tourch up output on for say 3 seconds to clear plate and start move to next cut

would this be in some classic lader or gcode sub routine?

thanks john


That can all be done in G code with G4Pn for the pause and M66ish (iirc, check manual) for the digital input and a similar one for digital output.

John

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29 May 2012 15:19 #20482 by jd896
that would mean coding in the post file of the cam software would it not

would it be just as hard/easy to code in ladder is it possible to be done it ladder i suspect quite easy from the reading ive done but how would you call the ladder or could it even be an m code ?

i just want to get away from changing the post processor in the cam software i have less of a clue about that then this my perhaps backward view is it may be easier to make linuxcnc interpret the code of the cam in the right way rather than make the cam produce it right if it were

also as far as connecting contactors and relays to the 7i37ta ive read about this r/c snubber circuit or free-wheeling diode to suppress back emf from the relay coil what kind if any are we talking about here is there different voltage/current ranges ?

thanks john

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29 May 2012 16:37 #20486 by BigJohnT
Any way you look at it your going to have to change your post processor to add your needs. It could be as simple as calling a named subroutine (that's what I do) with the G code in it. Ladder is not really the place to execute G code.

John

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29 May 2012 19:21 - 29 May 2012 19:22 #20490 by PCW
Almost any diode will work as a free wheeling diode as long as its voltage and current ratings are adequate
a 1N4001 is a good choice for a 7I37. The important thing is to get the polarity correct. The diode cathode (stripe end) should go to the positive side of the coil. For small relays (say 100 mA max) the 7I37 will work without a free wheeling diode
but will generate more noise as it switches off.
Last edit: 29 May 2012 19:22 by PCW.

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29 May 2012 21:02 - 30 May 2012 13:44 #20496 by jd896
Probably not the right thing to do but as a temp fix I have powered the relay off the computers psu and upon a following error erlia (estop relay) the keyboard lights flashed and no longer responded until I unplugged and reinserted it so I was wanting to choke the relay more than just the card

Having looked at the specs that would be ok for most would it not

sorry for the above wasn't thinking straight must have been tired
Last edit: 30 May 2012 13:44 by jd896. Reason: noticed what id written

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30 May 2012 13:46 #20506 by jd896
hi guys im trying to tune my axis only the x for now as the drives not come back from repair yet

but can anybody give me some clues as to how accurate the scale in the hal scope is ie what the u's and such relate too i want to know how close my error is

also what would people say it acceptable for a plasma gantry ?

thanks

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30 May 2012 14:44 #20508 by BigJohnT
I guess that depends on if your torch is high-dev or just an air torch. I'm happy if my position is <0.010 from commanded and in my case that would be due to belt stretch and other items as mine is stepper driven.

axis.N.f-error OUT FLOAT The actual following error

Not much to go on in the manual for that pin, I assume your watching that pin and iirc it is in machine units. When I tuned my CHNC I triggered on velocity and watched commaned vs actual and or following error as I adjusted the PID.

John

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30 May 2012 14:59 - 30 May 2012 15:01 #20509 by jd896
the commanded vs actual velocity are exact up to around 400mm/s but for small high speed jogs it shakes the gantry so ive taken it down to 250mm/s i think

so in the image the text at the side of F(0.02400) = 0.26509 does this after the = sign mean 0.26509mm?

and for now the power sources a powermax 85 till we get it burning most of the day and can warrant a fancy new hydef one

also what needs a fine tune to get that spike out is it d or ff2?
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Last edit: 30 May 2012 15:01 by jd896. Reason: no photo

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