Prusa Z Screw Isolator

by DaleDunn, published

Prusa Z Screw Isolator by DaleDunn Mar 27, 2012


This little bracket allows the Z axis screw to wobble without influencing the position of the nozzle. The Z axis nut iss captured in a bracket that is not rigidly coupled to the X end brackets as with the regular Prusa.

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I don't think it's bandy. The piece fit rather snugly on the smooth rod. The wobble is in the same pattern with or without your mod. It's just that with your mod it isn't as pronounced. This makes me think there is something else wrong with my printer. (it an i2 btw)

You probably have some slop on your smooth rods, or you may be seeing some of the banding I linked to in a G+ discussion in another comment.

I gave this a shot. It helped my wobble some but didn't get rid of it.

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If you built your Prusa without the upper Z axis nuts and springs, you can lift the X axis off of the lower Z nuts to install these. If you have the springs, you'll have to back the Z axis screws out of the X axis. If you want to keep the springs, you can install a second pair of these above the X axis.

As pointed out by Buserror in the comments, you will need to make sure you have enough room in your X ends for the movements of the screws. I found when assembling my Prusa that the threaded rods themselves are abrasive enough to widen a hole in ABS parts, if used as a file. So, if you don't have enough room for your Z wobbling screws, you can use them to open up the hole. Or you could possibly straighten them enough by hand to avoid interference. Either way, make sure you have enough clearance.


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jaeg on Apr 8, 2014 said:

I gave this a shot. It helped my wobble some but didn't get rid of it.

DaleDunn on Apr 8, 2014 said:

You probably have some slop on your smooth rods, or you may be seeing some of the banding I linked to in a G+ discussion in another comment.

DaleDunn on Mar 22, 2014 said:

A note on long-term usage: Have some spares on hand. I had a set of these split, apparently from exposure to the oil I used on the threaded rod. Material was Protoparadigm ABS.

i-make-robots on Feb 11, 2014 said:

Model has holes, doesn't slice without massaging.

newboldstone on May 2, 2013 said:

Made a huge difference in print quality. Thanks!!

DaleDunn on Mar 19, 2013 said:

As pointed out by Whosa whatsis on a G+ thread, this will eliminate Z wobble but introduce a small error in layer height. See here: https://plus.google.com/u/0/10...

TheHawk on Mar 18, 2013 said:

Printing one now, had to use netfabb to repair the part though. Love the simplicity and effectivity of this design! Good job! :)

RegionX on Jul 14, 2012 said:

this wont slice not sure what to do?

DaleDunn on Jul 16, 2012 said:

Not sure. Try a different slicer, maybe different settings. IIRC, I used SFACT when I printed these. So, that or Skeinforge should slice it. For a less-forgiving slicer you may need to shove it through one of the on-line .stl repair services whose names escape me at the moment.

mattproc on Apr 1, 2012 said:

I just printed a pair of these and the M8 nut fits perfectly, but the other end seems a bit small for the smooth rod. It seems to me that it should barely touch (just enough to keep the nut holder from rotating).

Anyone running these yet? Do yours grip the smooth rods at all?

DaleDunn on Apr 1, 2012 said:

As the software support people say, it's working as designed. Mine do grip the smooth rods a bit, but not enough to cause any problems with the Z axis movement. My thinking is that this is a better option than designing for a little slop, because, well, slop is slop, but you can always sand off a little material if it grips the smooth rods a little too tightly.

BusError on Mar 28, 2012 said:

This solves potentially /two/problems. On my printer the X sometime get caught on the threaded rod when going down, and if the nut escapes, the leveling is totally BEEEPed. This little piece keep the nut in place, so it won't happend again!

And if it removes a bit of wobble. all the better :-)

scm77 on Mar 28, 2012 said:

You got it! =-O

I searched very long about a way to decouple the X-carriage from the Z-axis screw to eliminate wobble.

This is so simple but should work reliable, I love it.