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Phantom Limit and Estop triggering
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Author:  Mike Kroening [ Wed Mar 10, 2010 4:01 pm ]
Post subject:  Phantom Limit and Estop triggering
Hi All,

Some info for any of you using limit switches and Estop switches with Mach3.

After I added the switches I started experiencing problems with them triggering out of the blue while cutting. Setting the debounce in M3 did not help. I am using well shielded cables also.

I put a scope on it and found intermittent spikes.

Solution is to add an individual 0.1 Uf / mfd film type capacitor to each set of wires bridging as close to the breakout board as possible. This acts as an Rf filter and the problem should be resolved. I have since run a few million lines of code and have had no problems at all.

Note: DO NOT USE AN ELECTROLYTIC Cap for this



Happy CNC bliss
Mike
Author:  Mike Kroening [ Thu Mar 18, 2010 1:59 pm ]
Post subject:  Re: Phantom Limit and Estop triggering
AH HA! I found my Phantom RF spike. I was getting a static discharge from the vacuum hose when it touched the frame usually somewhere in mid table area. The hose may touch the upper gantry at various stages of XYZ location. The ground wire was broken for this hose.

I'll leave the caps on though. :)

Mike
Author:  cyborgcnc [ Thu Mar 18, 2010 8:19 pm ]
Post subject:  Re: Phantom Limit and Estop triggering
AWESOME!

Not having a properly grounded hose, can at times cause havoc. A lot of people underestimate the static that can build up when you are sucking chips through a rubber hose at high speed!

In addition, depending on the drivers you are using, a touch of this charged hose against one of the stepper wires, can sometimes cause enough back voltage to fry a stepper driver (especially the cheaper ones, like xylotex...). Others like Geckos are tough to kill! :-)

Lots of folks over at CNC zone have had this problem, and in almost all cases, it was attributed to an improperly grounded vac hose!

Moral of the story: GROUND DEM HOSES! :mrgreen:
Author:  npalen [ Fri Mar 19, 2010 8:23 am ]
Post subject:  Re: Phantom Limit and Estop triggering
Good info to know, guys.
Thanks
Nelson
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