Bind-Reducing X Ends for MendelMax & Prusa and MendelMax.com precision leadscrews

by kludgineer, published

Bind-Reducing X Ends for MendelMax & Prusa and MendelMax.com precision leadscrews by kludgineer Apr 20, 2012


These x ends are designed to minimize Z axis binding. They do that by adding a second set of bushings into the X axis idler. These bushings allow the X shafts to move a small amount in the X direction while remaining rigid in the Y & Z directions. This allows the distance between the two x-ends to increase and decrease as the height changes, helping to minimize Z axis binding.

Note: The leadscrews these weere designed to be compatible with are no longer available. You can still use these with a printable nut adapter such as these: thingiverse.com/thing:23326

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Oops, that is a bug, I will try to get that corrected.

I took some pictures to illustrate the issue. See this link: http://imgur.com/a/JxyUZ

You *can* use the same clamp on both ends, but you need to secure the MTW Leadscrew with screws of an exacting length that must not touch the clamp below (not so secure). The heart of the issue is with the stl of the idler itself, and could be corrected if the 3 holes securing the MTW leadscrew were reversed. In case there is an issue linking to an imgur album, here is a direct link to a pic that summarizes the issue:


The same clamp works on either side. You just need to print two copies of it.

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Update: Added a variant to use with select 3-hole lead screws such as the new ones sold by Maker's Tool Works ( store.makerstoolworks.com/motion/z-axis-lead-screw-and-nut-set-of-2/ ) and the PBC leadscrews sold by Trinity Labs. These files are names X End [part] for MTW Leadscrew. Source file is also updated to the latest versions.

Uses eight SDP self aligning bushings, available from Stock Drive Products ( sdp-si.com/eStore/Direct.asp?GroupID=469, also available from store.makerstoolworks.com). Four in the idler end for the anti-binding feature, and four for the Z axis bushings. It is compatible with either 8 or 10mm bushings in either bronze or PTFE-filled acetal. Use bronze with precision shafting or PTFE with drill rod for best results.

The motor end clamp and the delrin nuts all attach with M5-20mm screws and nuts.

Update: Added an alternate version that clamps on both ends. This eliminates the anti-binding benefits, but is easier to print reliably. With the easily adjustable Z axis shaft spacing of the MM 1.5, the non binding features are less important than they were on earlier versions. This version uses the same clamp as the motor end.

Update: Added an optional lead nut adapter to use with select 3-hole leadscrews such as the new ones sold by Maker's Tool Works ( store.makerstoolworks.com/motion/z-axis-lead-screw-and-nut-set-of-2/ ) and the PBC leadscrews sold by Trinity Labs.


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slauziere on Feb 1, 2013 said:

Unless I'm missing it, could you post the alibre file for the clamping idler? I see in the zip file is the bushing version of the idler. Thanks, much appreciated!

kludgineer on Feb 5, 2013 said:

The source file has been updated to include that part. Thanks for letting me know!

kludgineer on Dec 6, 2012 said:

I usually use 35%.

Chelmite on Dec 5, 2012 said:

What's the recommended density for printing this part in ABS?


wilson on Sep 1, 2012 said:

any chance you could post the solid file for the clamping version of the idler? the zip file only contains bushing version. Thanks!

opnotic on Jun 20, 2013 said:

In case of others looking for a clamp that fits the idler side: http://www.thingiverse.com/thi...

wHack23 on Jun 22, 2012 said:

Hwy could you post the alibre files for these I particularly want the non binding version. I printed it fine but my slicer made the holes too large, so the bearings just fall out. Thanks

kludgineer on Jun 26, 2012 said:


librav on May 24, 2012 said:

Would you consider a second idle version comprised of a body and clamp similar to the motor end? I seem to be having problems printing circular bearing holes with my Prusa. They print out slightly flat on the lower outside corners.

kludgineer on May 30, 2012 said:

Sorry it took so long, but yes, I have added a version like that.

Anonymous on May 3, 2012 said:

Great work. I printed the parts and bought the bronze bushings (10mm) you recommended for the Z rods. It seems that the outer diameter of the bushing is slightly too large to fit in the ends of the X-end parts. What technique would you recommend to get them to fit? I suppose I can sand the interior of the PLA tube with my dremel. I might also heat up the piece in an oven set for 210C and insert the bushing when the plastic is soft. What do you think?

kludgineer on May 30, 2012 said:

I recommend 8mm linear shafting for the X
amp; Y and 10mm for the Z. The loads on the X
amp; Y axis are purely in line with the shafts, so making them thicker would have a negligible benefit. The Z axis also carries the X axis, so it has side loads, so increasing the thickness of those shafts is more beneficial.

jimjimma on Apr 22, 2012 said:

Thanks for adding some description around these, I'm in the process of building a 1.5 and was wondering what the deal was with the larger diameter holes on the Idler. Makes sense now, I better buy some more bearings then :).

bsg on Apr 21, 2012 said:

So would this be a bug correction for MM v1.5 (like v1.5.1)?

kludgineer on Apr 21, 2012 said:

No, These were designed for MM 1.5, but are not specific to it. They ccan be used for any printer that uses the same shaft
amp; threaded rod spacing as the MendelMax (for example the Prusa).

Because of that, and because these rely on parts that you can only buy from me (the leadscrews), I am posting these as a separate item instead of as part of the MM 1.5 thing.

Chucktastic on Apr 21, 2012 said:

Are you able to get the X-axis belt tight enough without significantly deflecting the Z-rods with this design?

kludgineer on Apr 21, 2012 said:

I have only tested it with the 10mm Z shafts that are included with my kits, but it is plenty rigid with those. I would expect that it would be fine with 8mm shafts also, but I cannot say for certain.