Trouble with X-axis

Here it goes. My X is behaving odd. I calibrated the steps per mm and got it spot on going from 0 to 200 and back to 0. Working great. Then from 0 I say go to 100 and it goes to 99.5, then on to 200 and its on, then 300 and it goes to 300.5, on to 400 and it goes to 401, then 500 and its about 501.5.

I have swapped motors and it has continued. I swapped where the cables plug into the. Shield from X to y and even plugged into y axis and using those controls it persists.

as a note I’m working with the inventables team to try and figure this out but thought I would post on here.

I checked a couple more times and it still the same issue. Now coming back after the 100 increments up to 500 and it being at 501.5 on each 100mm increment its ~1mm off on the + side at of each Mark. But arrives back to 0 perfectly

Consider me confused

You should do the calibration using the largest movement for your machine. Once you get that spot on then check the shorter distances and see if you have better results.

Have done that as well.

The y axis is not exhibiting this behavior. Calibrated for 200 and on moving 100 it moves spot on to each 100mm Mark. And back to zero.

Oh yea. The X stepper motor is significantly hotter quicker than and of the other motors whether it’s wired to X or y port of shield.

Since you have two motors in parallel on the y axis each motor is getting half the current that the X axis motor gets if the current limit potentiometers for those axes are set to the same value.

Try putting the X motor on the Z driver and the Z motor on the X driver and see if the Z motor then gets hotter than the X motor.

What is your drag chain situation? How many and what size cables are in the drag chain? What size motors do you have? I was losing steps because I added some cables to my setup and the motor couldn’t fight the bend resistance of all the cables.

I had reduced the potentiometer on the y axis during the switch. It not only gets hot while moving it gets hot while holding. I can try switching to z axis today.

All cables in the tray are the standard ones from inventables. 2 shielded and 2 limit switches.

I though it was losing steps, but during a cut it follows the same path every time. And during the calibration I noted about it would also be gaining steps.

Is possible your belt is stretched out irregularly?
Maybe after a few hours of operations, any anomalies in belt spacing will be spread out?

Are your Y axis V rail/ V wheels clean? The only thing I can think of that’d cause intermittent mm / step is location specific mechanical interference. But even that wouldn’t make sense for gaining steps. What in the world.

Yes. Belt is good. This happened on gt2 and on the newer gt3 belting I have put on. It’s very strange indeed

All 4 on the X are brand new. I agree with you i can’t see it gaining steps.

What isn’t making sense is the motor is on average 20 degrees hotter than all other motors.

You wouldn’t happen to own an oscilloscope, would you? I’d be interested in seeing the stepping pattern of the three wires to the X axis motor. Did you say you were using shielded stepper motor cable?

No can’t say I own one. Would like to get one.

But yes the wire is the shielded one from inventables.

The behavior has been the same between two different motors.

Both motors have gotten hot during use? If that’s the case I’d think your belt might actually be a little tight.

I will try loosening it today. I didn’t think it was too tight. But will give it a go.

Something else I’d be curious of is the potentiometer position to the X Axis motor. Does it get hot while it sits still and the machine turned on?

Yes. It gets hot while in hold awaiting command.

Oh. Well then I mostly take back my suggestion about the belt, that sounds like a potentiometer setting issue. It definitely shouldn’t be getting very hot doing nothing. Try bringing that down a little and seeing if it cools off.