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Author Topic: probe problems, mach 3 is acting wierd  (Read 3939 times)

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probe problems, mach 3 is acting wierd
« on: January 07, 2010, 05:16:25 PM »
 ??? I have been experimenting with building my own touch probe, the first one was contact type, the second was the break contact type.  when running the first one the pin 15 was set to active high, and all worked well except the accuracy was awful.  the new one  i set the pin 15 to active low and while the led is off when not in contact, the mach 3 standard bed of nails routine behaves freaky.  it seems to choose its own feed rate, it's own z depth, it stops when making contact but who knows when that will be? i uninstalled and reinstalled mach i fiddled with everything that i could think of, but it still acts up.  so just for grins and giggles i reset the active high setting and ran the routine in the air,moved the contact with my hand and the routine runs along just as normal as ever until of course i release the probe.  so why in the world would the active high, active low setting have any thing to do with the way that mach executes g-gode???

The 3d scan plug-in has never behaved rationally, so i can't just switch to another routine.  My auto zero z plate also behaves stupidly in this state.  I have perused the forum, but haven't had any luck seeing anyone with this problem.

Any help here guys would be greatly appreciated
Re: probe problems, mach 3 is acting wierd
« Reply #1 on: January 07, 2010, 05:46:16 PM »
 ;D Correction i got my highs and lows backwards, the original touch probe was set to active low, the new break contact is set to active high.
Re: probe problems, mach 3 is acting wierd
« Reply #2 on: January 07, 2010, 06:06:10 PM »
;D Correction i got my highs and lows backwards, the original touch probe was set to active low, the new break contact is set to active high.

Sounds like noise.  You probably need a stiff pullup (100-200 ohms) on the probe input.

Regards,
Ray L.
Regards,
Ray L.
Re: probe problems, mach 3 is acting wierd
« Reply #3 on: January 07, 2010, 08:20:05 PM »
Yeah; if you had asked me "where are you grounding this"homemade" probe?" and i would have said "to the router", and you most likely would have replied, " Are you nuts! You can't make a break contact probe work like that".

Yeah, I always have to learn the hard way.  Your comment confirmed what i was thinking.  Thank you for the quick response too.

BTW as you no doubt have surmised by now i ain't the sharpest knife in the drawer.  If i were going to add a resistor to a now properly grounded probe, Where should i connect it??

Thanks again.
Re: probe problems, mach 3 is acting wierd
« Reply #4 on: January 07, 2010, 09:19:18 PM »
Yeah; if you had asked me "where are you grounding this"homemade" probe?" and i would have said "to the router", and you most likely would have replied, " Are you nuts! You can't make a break contact probe work like that".

Yeah, I always have to learn the hard way.  Your comment confirmed what i was thinking.  Thank you for the quick response too.

BTW as you no doubt have surmised by now i ain't the sharpest knife in the drawer.  If i were going to add a resistor to a now properly grounded probe, Where should i connect it??

Thanks again.

Put the pullup on the BOB, between the PROBE input pin and +5V.

Regards,
Ray L.
Regards,
Ray L.
Re: probe problems, mach 3 is acting wierd
« Reply #5 on: January 07, 2010, 11:10:50 PM »
I don't know, that gets a little weird.  I have a capacitor on that input per the mach blue zero plate instructions, maybe i should put this probe on it's own input, maybe steal it from z home then install the resistor.  oh well who needs a home on z anyway, or will the resistor hooked to 5 volts in be a good substitute for the capacitor that is currently there?


Thanks you have been a big help ;D