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Y-Axis Shift when not on High Power  

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lee.r3
(@lee-r3)
Active Member
Y-Axis Shift when not on High Power

Context - machine runs fine when on high power, 0 issues. Belt has been tightened, rods and bearings well lubricated. Printing in PLA at 20-25% infill. 

Any print at auto power results in a shift on the y-axis (and only y) at random intervals. 

Trying to eliminate possible issues here, what should I look at next? (Obviously I can run it in high power constantly but would prefer not to have to). 

Posted : 29/09/2019 11:35 am
Bunny Science
(@bunny-science)
Noble Member
RE: Y-Axis Shift when not on High Power

Hate to say it, but this is almost certainly a mechanical resistance issue. I know you went through it already, but being able to print only in high power, but not stealth means the Y-axis has resistance greater than the available torque in stealth - something which should not occur if your axis is mechanically correct.

1. Look for anything that is obstructing your Y-axis motion. Cables under print bed, heater cable assembly hitting something during rearward motion, etc. If nothing is found, go to step 2.

2. DISCONNECT the Y-belt. Yes, completely remove it. You probably hesitate about doing this, but belt-free gives your maximal sensitivity looking for points of friction. A flick of a finger should send the y-carriage all the way from one end stop to the other. If it doesn't move that freely, your bearings and rods are suspect. Fix things until the y-carriage moves without resistance.

3. Check the idler for free rotation.

4. Connect your belt and set tension to about 6 lbs. At that tension, pushing down the middle of bottom belt should reach an increase in palpable tension at 2-3 mm deflection. If it is tighter than that, you're probably increasing motor or idler friction

You will find the mechanical problem.

 

Posted : 29/09/2019 12:20 pm
lee.r3
(@lee-r3)
Active Member
Topic starter answered:
RE: Y-Axis Shift when not on High Power

@guy-k2

Thanks, will work through that. Machines about 2 years old so could be some wear I can't see.

Posted : 29/09/2019 12:25 pm
lee.r3
(@lee-r3)
Active Member
Topic starter answered:
RE: Y-Axis Shift when not on High Power

@guy-k2

Completely dismantled and rebuilt. Increased z-height on retraction / hop to 0.8mm in case it was snagging on the model. 

Benchy ran perfectly after, but now printing a larger print I'm getting a slight shift again. Going to replace the bearings and idler next to see if that helps, then the rods if still an issue. 

Posted : 01/10/2019 8:46 am
Bunny Science
(@bunny-science)
Noble Member
RE: Y-Axis Shift when not on High Power

printing a larger print I'm getting a slight shift

Any chance the heat bed cable is hitting an enclosure wall?

Posted : 01/10/2019 3:27 pm
lee.r3
(@lee-r3)
Active Member
Topic starter answered:
RE: Y-Axis Shift when not on High Power

@guy-k2

I’ve checked the movement on the cables from the bed and there’s nothing to snag on - switched the fabric cable wrap to the old plastic wrap as well just in case.

Posted : 01/10/2019 3:49 pm
lee.r3
(@lee-r3)
Active Member
Topic starter answered:
RE: Y-Axis Shift when not on High Power

Bearings replaced and still an issue on auto-power, going to try rods next

Posted : 16/10/2019 1:53 pm
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