[FlyingThinkTank]

I've had a CNCRP standard 24x48 machine with NEMA 23 electronics and linuxcnc for a few months now, and I use it primarily to cut wood 1/4" deep at a time with a 1/4" endmill. I'm going at 40 in/min cutting speed, and seemingly randomly the X axis will jump violently out of alignment and ruin my cut. I've tightened the pulley set screws, so I'm not sure what to look at next. I have the motor tensioners as tight as they will go. Does anybody have ideas?


Thanks!

[nlancaster]

To much tension could be causing lost steps on the motors. Do the Pulley screws have locktite on them?

[FlyingThinkTank]

Too much tension where, exactly?

Yes, I put Loctite on the pulley screws.

[nlancaster]

To much tensions in the motor tensioners.

[FlyingThinkTank]

To much tensions in the motor tensioners.

Why would that cause the machine to seem like it's hopping over a tooth on the gear rack? Tightening the tensioner helped to reduce the problem previously, but it didn't quite get rid of it.

[nlancaster]

It is sounding like it is hopping a tooth? or just losing place? Because to much tension can cause to much drag on the motor resulting in lost steps.

[jueston]

when you loosen the spring that holds the rack against the pinion with the power off, can you easily spin the stepper and rack gear? when i built my PRO4848 i over tightened several parts, and this was one of them. if you can't easily turn the stepper and rack gear reduce the tension a little and reinstall.

i also over tightened the eccentric bearings on the risers, and all of these things being to tight each added friction to the movements which caused my X-axis to loose steps.

[FlyingThinkTank]

It is sounding like it is hopping a tooth? or just losing place? Because to much tension can cause to much drag on the motor resulting in lost steps.

Would losing a step cause it to jolt violently? This is my first gantry machine, so I wouldn't know the difference.

After it does it, if I jog the gantry back to home, it's clear that the gantry is no longer perpendicular to the table, if that helps.

[FlyingThinkTank]

when you loosen the spring that holds the rack against the pinion with the power off, can you easily spin the stepper and rack gear? when i built my PRO4848 i over tightened several parts, and this was one of them. if you can't easily turn the stepper and rack gear reduce the tension a little and reinstall.

i also over tightened the eccentric bearings on the risers, and all of these things being to tight each added friction to the movements which caused my X-axis to loose steps.

I can spin the gears/steppers pretty easily. I haven't looked at the bearings, though. I do know that my rails aren't 100% straight, so maybe I need to accommodate for that...

- - - Updated - - -

I also looked at my acceleration, and it was set to a default of 30 in/s/s. I changed it to 5 and will post the results of that.

[LeeWay]

I have the older style CRP drives on my plasma. I only hand tighten the turn buckles and it works great. Too tight is just as bad as too loose, but for different reasons.



Also double check the the slave axis is identical to the master. What drives are you using?