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Z-axis Issue?

Posted by Zimtower

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Zimtower

Z-axis Issue?
June 26, 2012 07:49AM

Registered: 13 years ago
Posts: 44

pyuNK.jpg

Is this what I think it is? This is my 5th attempt at printing btw.

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Nudel

Re: Z-axis Issue?
June 26, 2012 09:42AM

Registered: 16 years ago
Posts: 689

If the ridges match the threads on the threaded rod on z, it could be the rod is not straight and is pulling the entire x gantry out of position.

Lube.

Check/adjust z couplings and trapped nuts.

Exchange bent z rod for a higher quality (=probably straigher) stainless steel rod.

Cool print though, my nieces would love that! smiling smiley

Edited 1 time(s). Last edit at 06/26/2012 09:44AM by Nudel.

--
-Nudel
Blog with RepRap Comic

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jcabrer

Re: Z-axis Issue?
June 27, 2012 09:15PM

Registered: 19 years ago
Posts: 824

This is likely Z_Axis wobble.

Show a picture of your printer, and it will help identify the culprit.

Usual suspects are captive z-motors (screwed down), captive lead screws (either by using two sets of nuts in the x-motor/idler ends, or using the printed 608 bearing holders at the top or bottom of the rods, or bent rods.

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Zimtower

Re: Z-axis Issue?
June 28, 2012 06:39AM

Registered: 13 years ago
Posts: 44

My z-axis threaded rods were slightly bent. I got some silver coated rods in the mail, gonna install tommorow and see what I have.

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Zimtower

Re: Z-axis Issue?
June 29, 2012 06:47AM

Registered: 13 years ago
Posts: 44

2bKiO.jpg

I just installed these very straight threaded rods and there is a tiny amount of improvement. I am also using the spiral couplers which I hear can be self-defeating.

[www.thingiverse.com]

I am guessing I should print these out?

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zipfactor

Re: Z-axis Issue?
June 29, 2012 10:10AM

"....or using the printed 608 bearing holders at the top or bottom of the rods, or bent rods"

So the bottom of the threaded rod on a standard prusa should not go through this bearing holder attached to the base, but rather just float in the air?

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nophead

Re: Z-axis Issue?
June 29, 2012 10:15AM

Admin
Registered: 19 years ago
Posts: 7,883

There is no base on a standard Prusa. Yes the rods dangle from the motor.

[www.hydraraptor.blogspot.com]

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jcabrer

Re: Z-axis Issue?
June 29, 2012 12:17PM

Registered: 19 years ago
Posts: 824

Helical flex coupling are meant to be used in situations where you have a captive rod and captive motor. The coupling then allows there to be misalignment without placing stress on the bearings.

In the case of repraps, the ideal solution would be a motor with a threaded shaft, but these are expensive.

Almost any solution will produce good results IF the mating of the rod to the motor is concentric, and the rod is straight.