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
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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: http://www.thingiverse.com/thing:23326


Update: Added a variant to use with select 3-hole lead screws such as the new ones sold by Maker's Tool Works ( http://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 (For example http://shop.sdp-si.com/catalog/product/?id=A_7Z41MPSB10M, also available from http://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 ( http://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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Sep 8, 2016 - Modified Sep 8, 2016

I dont get how the bearings could fit for anyone, the diamater of a lm10uu is 19mm, and the holes of this are 16.5mm.

These were not designed for LM10UU's, they were designed for the self-aligning bushings mentioned in the instructions. SDP has redesigned their site, so the old link is bad, but this is the part they were designed to use: http://shop.sdp-si.com/catalog/product/?id=A_7Z41MPSB10M

Sep 9, 2016 - Modified Sep 13, 2016
DeanR - in reply to kludgineer

I see!
thanks for the response. I am placing one long lm10uu for each rod now, i shortened the model a bit since they are 55mm long.
Do you think this is a good idea?

Props for your all your work.

What do you think of my mendelmax? don't pay attention to the x belt on the picture, i had it twisted at the time.


Bulldog extruder assembly - X carriage + mount
by DeanR

Have you found that this change has made a significant difference in your print quality?

I can't seem to get the size right even though the Printer is Calibrated. All tests come out good the only difference is that the L and R on the Y axis are Revered.

Try printing something with a word, and check if the is reversed

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!

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

I usually use 35%.

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


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

In case of others looking for a clamp that fits the idler side: http://www.thingiverse.com/thing:49464http://www.thingiverse.com/thi...

X Ends & Endstops - For 3 Hole Leadscrew Nuts

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

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


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

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

Awesome thanks. But I did notice that this does not include the same non-binding idler that is posted on this page. It doesn't have the slits or the shorter tower for the smooth rod. I guess it should be easier to print though.

Oops, sorry that was an older version. I have reuploaded the file with the correct version.

Awesome thanks.

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.

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

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?

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.

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 :).

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

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.

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

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.

What about twisting? The tension on the x belt should cause twisting force on the xends (twisting about the z rod). How do you solve this?

The parts are quite rigid, I doubt you could make the parts twist. If so, you probably printed the parts with too sparse of infill.