CNC Mill Tool arm

[Duesentrieb66]

Hello All!

The toolarm of my cnc mill is not always coming out. To be precise: 9 out of 10 it doesn't. I didn't figure out any pattern: Temperature, time of running etc.

while try to find the error I measured if there is enough voltage on the motor and accidently figured out a workaround:

When the Fluke is in AC mode and I measure between pin 29 and 32 it ALWAYS works!

While this hack gets me going during the week, when people are around to hold the fluke to the contacts, I can not work on the weekends when I am alone. I tried to add wires to the contacts JP11 2A and JP11 3A and the fluke. That DOESN't work - I littarly have to hold the pins from the Fluke to the contacts like in the picture shown. Strange...

Does anyone has an idea how to fix this? Any suggestions are much appreciated!!

Thanks, Duesentrieb

[Grandchuck]

Printed circuit board/solder pad issue?  The physical pressure makes it work?

[Duesentrieb66]

good idea - thanks!

I just made a small gcode what makes a slow move in X followed by a tool change. That gives me time to walk back to hook up the Fluke. i will try again and will not put any pressure on it.

cheers!

[KrudyZ]

good idea - thanks!

I just made a small gcode what makes a slow move in X followed by a tool change. That gives me time to walk back to hook up the Fluke. i will try again and will not put any pressure on it.

cheers!

Or just do what you did before, but not have the Fluke on the other side of the probe cables.
In other words, it's very likely that you pushing in that location is closing a poor contact, either in the plug, the connector, the solder of the connector or a trace on the PCB.

[Duesentrieb66]

I just tried that. Same probes, same pressure but no fluke attached.

Doesn't work

[KrudyZ]

Your 3rd picture shows two wires going into JP10 3A, but the schematics only shows one...
Or is the extra wire going to the cap?

[Duesentrieb66]

Right? I was asking this my self.

Also, my gut feeling tels me that the cap 101 is the problem. But I can't find it anywhere, I would replace it.

To me it ilso not 100% clear why there is a cap. Can someone please explain me why?

Thanks!

[KrudyZ]

My guess would be the cap is introducing phase shift between the phases to change direction.
One phase is driven directly and the other through the cap.

[duak]

That motor & the carousel motor are both reversible AC induction motors and the cap provides the phase shift.  The cap is about 10 - 20 uF at a few hundred volts and is in a metal can or plastic cuboid screwed to the inside of the electrical enclosure.  It could also be closer to the motor in a junction box.  It could indeed be bad or at least lowered in value.  HVAC suppliers or motor rewind shops should have something similar.

Are the Grayhill 70M-0AC5A solid state relays socketed?  One might be getting blinky and as a last resort I'd consider replacing or swapping the ones controlling the arm.

Is this a Tormach or Fadal or ?

BTW, I'm in Vancouver, BC and have fiddle farted around with various CNC machines since retiring.

Cheers,

[Duesentrieb66]

Thank you all for your time to help me!

Grandchuck was actually right - when I press the board with pure hands it works as well. It was just bad luck when I tried first time or I didn't press enough/too much.

My next step is now to take the board out and check all the connection and re solder what looks bad. I keep posting the results.

Thank you duak for the explanation!!

Have a great weekend

[Duesentrieb66]

to duak: it is a Bridgeport TorqueCut22. love this little machine