Limit/Home bounce

[swissi]

If you have exchanged physical switches and input ports on the Acorn and the problems follows the X-Axis, my guess would be that something happened to your X-Axis when you crashed your machine. It looks to me that the machine table moves backwards just enough to trip the switch again after CNC12 has cleared the switch and stopped the motor.

Did you check the X-Axis if anything supporting the lead screw and motor came lose? Any bindings in the area where the home switch is?

Have you checked the backlash on the X-Axis after the crash? Set the X-Axis backlash to 0 and home the axis and check if the problem persists.

Good luck with your troubleshooting.

-swissi

[Dan M]

Can you post a picture of the machine with the sensors installed as well as a picture of the wiring?

Everyone is just guessing since we can’t see what you see. I know you said you changed inputs but have you hooked up the x switch to a different axis input? That way you can eliminate the switch being bad or a problem with wiring.

If you swap x and y and y trips you know it’s a problem with the switch or wiring or the machine is hitting the switch like the other poster said.

If x still trips than I have no idea what would cause it since it would have to be something with the the software like a bad wizard setting.

Just try hooking up a sensor that is working to the x axis input and go from there. Maybe you’re wiring got crushed or something, I haven’t seen the machine or know what stage you’re at. Is it finished?

What kind of machine are you building/retrofitting?

[mick41zxr]

Thanks Marty,
When I ordered the Metrol switches I thought I was ordering NC, however when they arrived they were NO.
Not ideal but I now have a bunch of them so might as well use them. I crashed while jogging over before homing. I was cleaning the machine & not watching carefully enough.

I have tested with a regular micro switch & problem repeats.

Below are some photo's of the machine & control board.

[martyscncgarage]

Move the X axis limit switch to an unused input. Use the wizard to set the current input to unused and assign the new input.

Is that a VFD in the upper right of your cabinet.
You have a lot of "spaghetti" in there. I can't help but wonder if noise is being induced into that line.

[cnckeith]

if it only occurs on reset/estop cycle then i suspect noise is the cause. when a relay or contractor coil cycles it makes a voltage spike which can get into the limit wires and fool cnc12 into thinking a limit was tripped. there are several remedies one of them is to put a "snubber" also called a quench arc across the coil. here is a tech bulletin covering this subject.

http://www.centroidcnc.com/dealersuppor ... ds/206.pdf

[mick41zxr]

Thanks Marty & Kieth,
I will do some more testing over the weekend & report back.
The reset was from the on screen control pan & not by E-stop. I have the VFD turned off while testing so no contactors are being operated.
Is a snubber for the contactors to the power supplies for the drives and Acorn?
Regards,
Michael

[martyscncgarage]

Look for Tech bulletin #206 on snubbers
http://www.centroidcnc.com/centroid_diy ... browse.php#

[cnckeith]

a typical debug technique for a repeatable problem is to start disconnecting things one at a time. or more radical.. go back to bench test and see if problem exists and start adding items one at a time and then determine where the problem is introduced.

[mick41zxr]

Ok disconnected everything bar E-Stop & X-Limit switch.
48V power supply disconnected. Check 24V power was a true 24v.
Connected General NC Micro switch to DB25 board to move it as far away from everything else.
Move limit to Input 1 (10) in DB25, use short 5' wire on micro switch.
Problem still exists. Only way to to eliminate issue is to remove the 24v supply to the input circuit in Acorn.
Is it possible the Meanwell 24v/5v power supply is inducing noise as only PS & Acorn now running.
I will try a different supply & maybe an EMF filter before the supply.
Regards,
Michael

[mick41zxr]

Ok I have taken apart, stripped down & swapped everything. I even swapped out to another Acorn I had for router conversion pending.
Replace power supply, Installed EMI filter I had, reset wizard to just E-Stop & single Home/Limit.
The problem persists.
Uninstalled CNC12, reboot & fresh install, problem still there.

The only way I can make the problem go away is change the input to 'SecondAxisHomeLimitOK'.
It is completely repeatable as soon as I change input back to 'FirstAxisHomeLimitOK' the problem re-appears.
The odd thing was system was working perfectly before crash, homing & everything.

This is driving me nuts...
Regards,
Michael