Weird issues with random axis

[keithmcelhinney]

Last week I had my mill stop responding properly. It was doing a helixcut down a pocket and the z and the y axis stopped moving. So I tried to get the Z up and it wouldn't move. Restarted and the z would come up but the y moved with it! Acted crazy after that so I got a new bob from John and got it wired up. Now I had an issue with y moving in one direction and not the other. Went to the back and low and behold one of the cables from the bob to the stepper driver was not clicked completely. So I did a dry run and everything seemed ok. Did the cut and the z stops moving while doing a peck drill. Didn't realize it until it broke the bit. Then I tried to move the y and it studdered really bad and made a racket and wouldn't move. So I restart everything and make sure all the cables are clicked in and everything seems to work. So I do another dry run and this time let it do the full cycle. I first rezeroed everything so it would be easy to tell if it messed up and right when it was finished and it was going to home it made a quick noise like it was slipping. The x and y at that point were off by 100-125 thousandths. Now I am assuming it was at the end of the cycle when I heard the noise, but can't say it for sure. I took the y axis covers off an found chips in there (bad!) so I cleaned it all out and re-lubed everything and both axis seem to move nicely. Actually seemed smoother than before.

Since I have replaced the bob, I can only assume that the issues have to do with the computer or the drives/steppers. Since it is happening on a random axis, I am thinking it is the computer. Right now I am running through the parallel port to the bob. I have a smoothstepper I can install. I am thinking if there is something wrong with the parallel port, moving over to the smoothstepper could cure it. Long shot I know, but I don't have another computer I can hook up to test it that has a parallel port.

To recap:
Random axis will stop working and then work fine (with no noise)
Makes "I'm stuck" noises when it shouldn't be stuck
Mach always thought the axis were moving
Before even this happened sometimes moves were not fluid. Seemed like there was a very slight pause in between g-code commands. Very noticeable when doing helix cuts. Restart of mach fixes this.

I assume the "I'm stuck" noise is some sort of slipper. Can I adjust this?

Any help would be greatly appreciated. I have so much work to do and am getting backed up by the day...

Thanks - Keith

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[keithmcelhinney]

Well I can't put the smooth stepper in. Missing the green connector for it! Damn it!

[UniqueMachining]

Keith

Quite the collection of issues. A few observations.

1. About a year ago I updated to a SSD (Solid State Disk) and noticed that all machine operations appeared smoother.
Conclusion: Mach instructions were sent to the machine quicker and eliminated some issues.

2. Some months ago I updated to the smooth stepper and noticed a further improvement. All remaining sporadic gremlins disappeared.
Conclusion: The smooth stepper has eliminated all remaining periodic parallel port hiccups.

Beyond that I would:

1. Verify that the gibbs are properly adjusted.
2. Verify that the ways are receiving sufficient oil. (Move the table fully to the right. This will expose approx. 8" of the X way. Check for lubrication.)
3. Checking the Y axis requires removing the accordion cover and is a bit of a PITA.
4. Check the tightness of the ball screw to motor coupler.

Hope this helps.
John

[keithmcelhinney]

Thanks John! I did do all those steps already except number 4. I am not going to lie, the y ball screw had chips around it. Cleaned it all up and everything is smooth. Proper lubrication on all axis. I thought I found an issue with the wires going into the stepper driver. The cord was hanging a bit and pulling on the plug going into the driver. So I did a dry run and everything worked. So I did a short job that was basically peck drilling 4 holes (finished the one from above). Worked great and everything was still zero'd. Decided to try a cut and got a minute into it and it messed up again. This time the y moved negative for both negative and positive moves. x and z worked fine. So I shut down mach, brought it back up and tried y again. It stuttered for a second and then worked fine. I ordered a new motherboard that should be here by the end of the week (I hope). Hopefully John or Ray will be able to get me the connector for the smooth stepper but I am not entirely sure that is going to fix it.

-Keith

[keithmcelhinney]

And I have an SSD already.

[bhurts]

Could be the cable to your y axis motor. Check the connection at the drive and the motor. Also check continuity.

Ben

[cteufert]

The shuddering sound and slipping of position points to the stepper motor not over coming the torque needed to move the table / head. I have seen this when I programmed the axis acceleration in Mach3 to be too fast but it will also happen in an otherwise functional machine is the power feeding the stepper driver is too low. I would check the raw stepper power supply voltage both when the machine is idle and when the table is moving.

[SCzEngrgGroup]

The shuddering sound and slipping of position points to the stepper motor not over coming the torque needed to move the table / head. I have seen this when I programmed the axis acceleration in Mach3 to be too fast but it will also happen in an otherwise functional machine is the power feeding the stepper driver is too low. I would check the raw stepper power supply voltage both when the machine is idle and when the table is moving.

There is no "stepper power supply". The stepper drives run directly off a 50V AC input.

Regards,
Ray L.

[keithmcelhinney]

Since it runs off 50v is that what the transformer is for? Could that be bad? Could it be that the wiring I have in the house is actually at fault?

Thanks guys I appreciate all the input...

-Keith

[SCzEngrgGroup]

Since it runs off 50v is that what the transformer is for? Could that be bad? Could it be that the wiring I have in the house is actually at fault?

Thanks guys I appreciate all the input...

-Keith

No. The transformer feeds all three drives. If it was bad, ALL three axes would be misbehaving. The odds of that big, beefy transformer failing are close to zero.

Regards,
Ray L.

[CROSSHATCH]

I would manually check each axis with your hand and feel the resistance it takes to turn the end of the ballscrew by hand. Perhaps your Gibs are too tight or too loose and causing the table or the Z-axis to shift and bind.

Regards,

-Jason