[Barefootboy4]

My DIY CNC machine has been working just fine for a couple of years now but one strange thing keeps happening. I'm hoping someone can tell me what's causing it
.
1-When the machine is plugged in and powered up but just sitting there with the router turned off and not running a cut file every once in a while I will here a stepper make a bump noise. Like when you first plug in the machine and you hear the steppers lock up. When this BUMP noise happens one of the axis direction will reverse itself. Most of the time it's the Z or Y axis and very rarely it will be the X axis.

2- If I unplug the machine and plug it right back in everything goes back to normal.

3- It never does this when running a actual cut file (Which is good)!

4- The limits all work fine. All wiring to motors are done using shielded cable with the standard star wiring to ground.

5- I'm thinking its some issue with the drivers getting a false signal but do not understand where it's coming from.

6- Running Mach 3 and a standard Keling kit with Keling drivers and C10 breakout board.

Any ideas of where to look for solving this issue.
Thanks
Stephen Everett in Maine

[OCNC]

1-When the machine is plugged in and powered up but just sitting there with the router turned off and not running a cut file every once in a while I will here a stepper make a bump noise. Like when you first plug in the machine and you hear the steppers lock up. When this BUMP noise happens one of the axis direction will reverse itself. Most of the time it's the Z or Y axis and very rarely it will be the X axis.

So if the machine is just sitting there powered up but parked how do you know that the axis has reversed itself? Also how often does this happen? Is it every time the machine is on?

Chris

[adprinter]

My DIY CNC machine has been working just fine for a couple of years now but one strange thing keeps happening. I'm hoping someone can tell me what's causing it
.
1-When the machine is plugged in and powered up but just sitting there with the router turned off and not running a cut file every once in a while I will here a stepper make a bump noise. Like when you first plug in the machine and you hear the steppers lock up. When this BUMP noise happens one of the axis direction will reverse itself. Most of the time it's the Z or Y axis and very rarely it will be the X axis.

2- If I unplug the machine and plug it right back in everything goes back to normal.

3- It never does this when running a actual cut file (Which is good)!

4- The limits all work fine. All wiring to motors are done using shielded cable with the standard star wiring to ground.

5- I'm thinking its some issue with the drivers getting a false signal but do not understand where it's coming from.

6- Running Mach 3 and a standard Keling kit with Keling drivers and C10 breakout board.

Any ideas of where to look for solving this issue.
Thanks
Stephen Everett in Maine

Go to the diagnostics screen in Mach, and just leave this screen up when sitting idle (and watch for any of the limit LED's to light up). Sounds like since it mainly affects your Z and Y axis, that you may have a limit switch cable about to flex in two (maybe inside the energy chain somewhere). If so, watching the diagnostics screen may help you to run down which wire is giving you problems.
Other things to check: the limit switches themselves could be sticking, or even carbon build-up on their contacts could be causing an arc. Try cleaning them all, and see if the problem goes away.

[Fastest1]

Steppers? I would suspect a loose wire between the driver and stepper.

[ger21]

Could be a weak parallel port.
Jog back and forth, and measure the voltage on the direction pin.
It should be 5V in one direction, and 0V in the other.

[Barefootboy4]

Guys,
Thanks for the ideas. Turned out to be a crack case of the X axis Limit Switch. Changed it out and all is good! Thank you for the guidance
Steve

[Claude Boudreau]

Guys,
Thanks for the ideas. Turned out to be a crack case of the X axis Limit Switch. Changed it out and all is good! Thank you for the guidance
Steve

I fail to understand why a bad limit switch would reverse an axis ...
should it not give you a limit switch triggered alarm.
Even more strange is that the X axis was rarely involved , the Z and Y had the problem more often...

[Fastest1]

Claude, maybe he shares 1 pin for all of his limit switches and or he is using a homing routine when this happens. Otherwise I am with you. A faulty switch shouldn't cause reversal in any other duty.?

[louieatienza]

I just had a similar problem with my machine, where I'd here the stepper "click" then it would stall. Ended being bad Molex connectors. I guess reconnecting them a couple times made them get loose? Ended up hard-wiring everything, and no problems now....

[Claude Boudreau]

I have to agree with ger21 suggestion.
Seem to me the only way to reverse an axis. ( without configuration changes.)

I'm affraid you might not be out of the wood just yet.
and you are barefootboy4!

[Barefootboy4]

You guys are correct. My problem still persits. I've checked all connectors and can find no problem. I'll keep looking.

[Fastest1]

Electrical gremlins can be a ***** at times. Been there and still doing that!

[Claude Boudreau]

You guys are correct. My problem still persits. I've checked all connectors and can find no problem. I'll keep looking.

Althought your problem never arose here, I had a similar experience where, due to ground loop interference,I would loose control of my motor , It would start making increasingly louder noise in one stepper, to the point of burning my xylotex board.(twice)
I almost had enough and was ready to trow everything in the garbage...
Until I isolated my computer ground,from my machine control box,with a piece of plexiglass to mount my db25 connector. I also, to my dismay,and contrary to common practice, had to disconnect both end of my shielded wires ground in order to completely stop the noise in my stepper.
There is a simple parallel capacitor that cant prevent this, that was suggested on later post.
Good luck , I hope this will steer you in the right direction, since you are barefootboy. (Sorry I cant hold myself)LOL

P.S listen very closely to your stepper when its idling, if one motor is making,for lack of a better term, a gurgling sound, try the capacitor on that line, or disconnect your shield from ground to see if the noise is altered.

[Claude Boudreau]

Althought your problem never arose here, I had a similar experience where, due to ground loop interference,I would loose control of my motor , It would start making increasingly louder noise in one stepper, to the point of burning my xylotex board.(twice)
I almost had enough and was ready to trow everything in the garbage...
Until I isolated my computer ground,from my machine control box,with a piece of plexiglass to mount my db25 connector. I also, to my dismay,and contrary to common practice, had to disconnect both end of my shielded wires ground in order to completely stop the noise in my stepper.
There is a simple parallel capacitor that cant prevent this, that was suggested on later post.
Good luck , I hope this will steer you in the right direction, since you are barefootboy. (Sorry I cant hold myself)LOL

P.S listen very closely to your stepper when its idling, if one motor is making,for lack of a better term, a gurgling sound, try the capacitor on that line, or disconnect your shield from ground to see if the noise is altered.

Anything new barefootboy4?

[kmin]

Happend to me this morning: I switched on my machine and found that z-axis direction is reversed by itself. Everything is working normally, no noise, heat or lost steps. I'm jogging z up and it's going down, jogging down and it's going up. Smoothly and precisely.
I was thinking that I have messed up something in mach3 settings, so loaded an old profile but didn't change anything. I restarted the machine several times but z keeps on moving reversed dir. It looks almost paranormal to me, is it even technically possible?
Guys, please help me to understand what's going on...