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Prusa i3 MK2: V2 holder clips for Y-axis' bearings (LM8UU and igus drylin RJ4JP-01-08)

by MartinMajewski, published

Prusa i3 MK2: V2 holder clips for Y-axis' bearings (LM8UU and igus drylin RJ4JP-01-08) by MartinMajewski Oct 25, 2016

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Autodesk Fusion 360

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Summary

ATTENTION: Please read the project's update notes at the bottom of this page!

I add to my effort to make the linear system of the Prusa i3 MK2 more stable, reliable and easier to adjust these clips for the ordinary LM8UU ball bearings, which come with the machine. As with Thing 1837936 (http://www.thingiverse.com/thing:1837936) you don't need the flimsy zip ties any longer. Instead, you can mount your bearings "pre-aligned" to the Y-carriage by using two M3 screws per bearing.

A further advantage is that the bearings are now aligned in the center of the Y-carriage's notch. So there is no longer the risk of misaligning the bearings vertically. Nevertheless, the Y-carriage has still the full range of operation, because the clips for the side of the carriage with the two bearings are designed to slide into the gab of the frames corner pieces.

There are still two things to consider:

  1. Though I had the LM8UU bearings and tested the fit of the clips on them, I have not tested them mounted directly on my machine. The reason is that both of my machines are equipped with the igus RJZM-01-8 bushings and in heavy use.
    So I ask the Thingiverse community to give me feedback on how the clips perform and what I should improve.

  2. According to nillabean (YouTube Video: VYW1p3T9tKo) the drylin igus RJ4JP-01-08 are very good, stiff and yet affordable linear bearings (not to confuse with the omnipresent RJMP versions). I have tested it myself and also got positive feedback from the community. They fit, and therefore the RJ4JP-01-08 are now "officially supported" by these clips! :-D

Thank you!


Please also take a look at my other designs, printer parts, and tools.

If you like to support me and my work, please consider to follow me

Sending a tip over Thingiverse will buy me some coffee to stay productive. :-)
Thank you very much.

Print Settings

Printer:

Original Prusa i3 MK2

Rafts:

No

Supports:

No

Resolution:

0.2 mm

Infill:

Not important


Notes:

Use as many perimeters (shells) as needed to fill up the gaps. I used six on my 0.4 mm nozzle.
I wouldn't recommend a brim because it makes the cleanup more difficult.

You need

2x DoubleBushingSideClip
1x SingleBushingSideClip

Orient the DoubleBushingSideClips correctly, so that the carriage can move along the entire length of the shafts.

Post-Printing

Clean your print from any unintended filament remains, like a brim. It is crucial that the bearings do not get misaligned by any derbies.

The bolts that showed to have a perfect fit are M3x16 - I use stainless steel 2.5 mm hexagon socket screws with a cylindric head like also found inside the Prusa i3 MK2 kit.

Project Updates

No. 3

Besides the positive feedback that the clips also work with the igus drylin RJ4JP-01-08, I have also tested it myself now. They fit!

Many thanks to igus for sending me the test samples! :-)

So this is no "work in progress" anymore.

No. 2:

Version 2 (V2) of the clips is now online.

You'll find the clips as single objects or as a complete set to download and print.

Changelog:

  1. The clips now hold the LM8UU bearings more tightly
  2. The bearings are pressed against the Y frame to stop them from spinning.
  3. The M3 screw holes are narrower now to provide better grip for their thread.

No. 1:

So, I made the changes suggested by bret4 and tried different approaches of how to reverse the screw direction.

The good...

1) I lowered the clearance of both, the bearing hole and the screw holes. Right, this was a good point. Both are now much tighter in fit, and should not wiggle or get loose anymore.

2) I lowered the surface that faces the Y-carriage frame by 0.2 mm (one layer's height), which again tightens the bearing much more by pressing it against the carriage frame.

The bad...

As shown on the following pictures reversing the screw direction results in a big problem: The screw-heads are crashing against the X-Y-metal-frame. My frame is already lower than Prusa Research suggests in its assembly manual, because my frame also rests on the table where the printer stands. Every other user that has assembled the frame as suggested by Prusa will obviously have the same trouble.

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ZylindricButtonHeadComparison.jpg

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ButtonHeadScrew.jpg

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ZylindricScrew.jpg

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/CrashAgainstTheFrame.jpg

The ugly...

Trying to move the screws more towards the Y-carriage frame to hide the heads inside the clips and preventing them from crashing against the X-Y-frame results in an ugly geometry (with a big hole). This would affect the stability of the clips, and the screw heads would press against the bearings, which could misalign them again.

Anyway, I will publish the tighter fitting version later today. The screw-reversal will be held back until I find something that works better.

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I don't understand why this clip allows the bearings to sit proud of the mounting surface, meaning that the bearing sticks out of the top of the clip. This is unlike the other design with the other drylin bearings where the bearing and clip top appear to be flush, allowing the clip to contact the carriage plate. I'm sure this oofset contributes to deformation of the bearing if overtightened.

Was there a reason to do it this way instead of extending to contact the plate more solidly? Perhaps I'm missing something....

I don't exactly get it to which offset you relate with your post.

The bearings have contact to the bed's mounting plate as if you were using zip ties. This design choice has been made to prevent the mounting bed from raising in the vertical direction. Lifting the bed by providing clips which enclose the bearings completely would mean to have to change dimensional settings within the firmware because you loose some of the build volume's height. This loss could lead to trouble on Z calibration like a crashing nozzle because the settings within the firmware are set for the particular dimensions of the original Prusa design.

But if you mean the offset which lets the bearings stick out at the front and the back of the clips: this is because the bearings overlap the cornerstones on the maximum and minimum position of the Y-axis travel (see the pictures).
For the single bearing side, however, this design choice saves you dozens of layers to be printed.

Hope that helps to clarify my design choices!

Happy printing!
Martin

My mistake! I did not remember that the bearings sit in a slot on the mounting plate. This makes the clips fit perfectly as you describe. I'll install as soon as I can.

Sorry probably a dumb question, but I assume these should be printed in ABS? or would PLA be ok?

Thanks

PLA is perfect. I don't print in ABS (hate the smell), therefore, all my designs are made out of PLA or PETG.

Is it possible that you can make a 30mm between holes version?
I would like to use it in my non-MK2 prusa

Will this fit the MK1? Don't think they changed the bed mount dimensions...
Just ordered a pack of these bearings and didn't know they need to be secured with clip in order to work properly.

You can mount your new bearings just as you had your old ones installed. There is no need to use my clips to get any printer going in the first place!

It will work, but these bearings are meant to be press fitted to get the most out of them. Otherwise it will be a bit loose fit.

https://www.youtube.com/watch?v=ZGBipbgwgME

I know that video, but Thomas is referring to RMJP bearings, and not the RJ4JP that I recommend my clips for here.

The RJ4JPs are designed in a way that consumer 3D printers can utilize them without an enclosure.
Nevertheless, my clips (made out of 3D printed plastic, are also not designed to "press fit" a bushing, as the material, and the production tolerances are too weak. My clips shall prevent the bearings from wiggling.

Ah ok. I got the bearings mixed up. Good to know I can mount these just with zip ties, but I might have a go with you clips.
There seems to be so much play in my y and x axis that I'm wondering how can anyone get good prints with LM8UU's.

Comments deleted.

Great model! Works great with IGUS bearings.

One note to future printers: upon first install, my bearings would bind quite badly when the bed was all the way to the front or back. (It never did that with the original bearings.) Turns out my frame was very slightly too narrow. After slightly widening the threaded rods, it's smoother than a baby's butt.

Thanks for the model! Installed this morning. Perfect print, and fit. Bearings are held in very solid. I screwed in from the top with these screws, worked great. http://e3d-online.com/Screws-for-Plastic-3mm

You're welcome! Glad to hear that you like it.

Thank you for providing information about the screws you are using. Very useful.

Please share your made parts as "I made one" to help to promote this project to other users.

Thanks Martin,
really nice design. The y-carriage is not moving anywhere anymore behalve on the y-axis. With the zip-ties i could move it a bit in x and z directions.
Printed it in PLA and used the 9. Spare M3 screws/bolts. 2x M3x10 and 1x M3x12 on the left and right side (closest to Z-Frame V slot) and the 1x M3x12 and 2x M3x18 inner side (here is more space for bit longer screws/bolts). As soon i get some M3x16 screws/bolts i will change it.
BTW: I didn't tight them up until i moved the y-carriage few times up and down so the LM8UU with YOUR holders could align with the rods.
To get it bit less noisy i bought some PTFE spray and applied it in the LM8UUs and on the rods.

Hi,

"The y-carriage is not moving anywhere anymore behalve on the y-axis"

I hope this is a good thing because it reads as my clips prevent your y-carriage from moving! :-D

Have a nice day and please report back, if any problems occur.

Mar 5, 2017 - Modified Mar 5, 2017
Gussner - in reply to MartinMajewski

Hi,

It is a good thing. The y-carriage is NOW only moving in Y direction as it is supposed to do.

Thanks, you also have a nice Sunday

Whats the OD of the bearings this is designed for?

I have FM08 and it has O.D. 15.982 - 16mm

thanks

I looked up "OD" and what you mean is the outer diameter, right?

The lm8uu and the RJ4JP-01-08 have both an outer diameter of about 15 mm. So these clips are for bearings with an "OD" of 15 mm.

The other clips (where you have also asked the question) are for bearings with an outer diameter of about 16 mm. You should definitely try out the other clips.

Happy printing.

thank you! And thanks for checking out the other bearings for me too.

Feb 5, 2017 - Modified Feb 5, 2017

I just got my MK2 kit and I'm planning on installing the Drylin bearings right from the beginning. I already have 6 Drylin bearings and I have a MonoPrice Mini Select that I can print them on. Since I don't have the MK2 built though I don't have a real good reference for what parts are needed. If I am going to replace the X and Y axis bearings, which parts should I print? The choice from the "files" are:

DoubleBushingSideClip.stl
LM8UU_Clip_V2_CompleteSet_ScrewFromTopOnly.stl
LM8UU_Clip_V2_DoubleBearingSide_ScrewFromTopOnly.stl
LM8UU_Clip_V2_SingleBearingSide_ScrewFromTopOnly.stl
SingleBushingSideClip.stl

Thanks

Hi there,

if you have the RJ4JP-01-08 bearings, you need two Clips with the cutout and one without it.

So

LM8UU_Clip_V2_CompleteSet_ScrewFromTopOnly.stl

or

2x LM8UU_Clip_V2_DoubleBearingSide_ScrewFromTopOnly.stl
1x LM8UU_Clip_V2_SingleBearingSide_ScrewFromTopOnly.stl

Using the RJ4JP-01-08 bearings, you don't need anything special for the X axis, as they only replace the original lm8uu ball bearings.

See here: https://instagram.com/p/BQIfjZQDDGN/

You don't even need my clips for the Y axis, to be honest, but from my experience and the positive reactions from all the users here at Thingiverse, you will get a better experience with them (once you carefully read the instructions and adjust them accordingly).

You can take the very first picture of this project with three clips depicted there as a reference for what you need.

Martin,

A big thank you for this great design! After my Prusa MK2 lost it's calibration due to loosened tywraps I switched to these clips. they really helped to improve the stability of the heatbed.

You're welcome! Happy printing! :-)

Many thanks for your sharing. I am having an issue with igus bearings. When I first installed your holders and igus it was too tight so I couldnt completely tighten the screws. Left a little looseness to make it work. After couple of prints I figured out the Y axis bed is wobbling when I check with hand. I dissassambled the bed and tighten the screws to max. And I had the best print of all times. It was perfect then I understand that Y axis stabilty is everthing for print quality.

But now it started to wobble again, not as much as the first one but I see that bearings are being worn in time and it starts to wobble.

What do you suggest? Should I remove your holders and tighten them with zip ties? Because the screws are at their max. If I force more they are going to slip.

Or should I put a piece of paper between the holder and the bearing (don't know if it is possible) I need some advice.

Many thanks in advance

Hi,

I use the igus bearings for over four months now on a 24/7 rate. My printers are printing constantly, because I have commissional work to do. I have not noticed any wear off by now.

My bed wobbles a little bit too, but it did also with the standard lm8uu bearings and even more with zip ties. If solid clips can not stiffen the bearings, how can zip ties strip do? But it is a minor wobble... I need quite a lot of force to provoke it.
Nevertheless, I haven't noticed any print quality hits, because the wobble appears only as rotation around the up axis (so horizontally twist if you will). The Y motor should not cause this wobble during linear motion.

I think the problem is, that you have overtighten the screws in the first run. As I described it in the project's description, you may not tighten the screws all the way. The torque has to be used to adjust a smooth run, so less is sometimes more..
It is also not necessary to have the bearings squeezed hard against the metal frame, because the clips has little lips for the bearings' notches, which will secure the bearings in place.

Even worse: if you squeeze the RJ4JP-01-08 bearings, which have no metal casing protecting them (unlike the RJZM-01-08 - http://www.thingiverse.com/thing:1837936), you bend them and cause them to generate a lot of uneven friction against the shaft. This might have caused the fast wear off of your bearings.

If I were in your spot, I would replace the RJ4JP with new ones and give it another try. The second time around I would carefully tighten the screws until my bed runs smoothly (without the heated print bed part at first). Then I would print a few things observing the quality. If the bed wobbles a little bit horizontally (twisting), but the prints are perfect, than this is how your machine behaves. I have two MK2s and each one of them has other characteristics, even though they are equally equipped. If it wobbles vertically you have other serious problems like bended shafts, or a twisted Y frame.

Then again, if your prints are bad, you have these options in my opinion: Try zip ties (maybe this is the best solution for you - but I doubt that it will last for the long run. Zip ties wear off, too), or try the metal case protected RJZM bearings. In the last resort you can still use the standard lm8uu and zip ties again to get the behavior Prusa intended in the first place.

3D-printing is still a "work in progress" with a lot of trial and error. :-)

Hope I could give you some ideas how to solve your problem.

Happy printing my friend!

Prusa i3 MK2: V2 holder clips for Y-axis' igus drylin RJZM-01-08 bushings

Many thanks for your ideas. I did not tighten them in the first installation.

Let me see what will show up. My prints are fine now but maybe it is a placebo. Lets see what will happen. I will update here

Does it wobble left/right or up/down? Or both?

LEft and right, I can see the rod moving inside the bearing. I can see the gaps I mean. But as Martin mentioned it was a bit wobbling with stock bearings too.

As I mentioned in another comment, Prusa does not use the most precise shafts anyway. If you want to have a more snuggly fitting linear motion system, you will have to buy more professional and expensive parts. The MK2 is perfect for its 650 Euros as a kit, but it is still a "you've got what you've paid for" thing.

Martin could you please share the links for that black high quality rods? Many thanks...

Jan 28, 2017 - Modified Jan 28, 2017
patrizio - in reply to murathanaraz

You can use the aluminium IGUS AWMP-08 rods if you use IGUS RJ4JP-01-08 bearings; but they will give even more wobbling as those rods have slightly different tolerance (thinner at most) - and even more wobbling if you use RJZM-01-08, has they have still different tolerances (larger at most than RJ4JP-01-08). I've AWMP-08 + RJZM-01-08on Y and AWMP-08 + RJ4JP-01-08 on X, and i'm not really satisfied by the Y. Also those rods bend more easily (may be an issue for very heavy prints), and you CAN'T use them with normal metal ball bearings.
If you want the maximum quality, i suggest using Misumi rods and bearings, they'll have no wobbling at all as they have an interference fit rather than a clearance fit (but they are noisier).

Can you post a picture of what screws you use to make this work please? I have just printed but I cant see how this would work as the screw heads don't have anything to press down on as it's screwing into a slope.

Hi,

please take a look on my other clips that are related to this ones here: http://www.thingiverse.com/thing:1837936

As you can see from this picture (http://thingiverse-production-new.s3.amazonaws.com/renders/59/13/85/92/d7/80b4af92e77010cc997a4d7cba69de13_preview_featured.jpg) you simply put your M3 screws from the top through the metal frame and screw them into the holes of the clips. The clip's holes are tighter than the M3 screws, so that their threading cuts into the plastic.

Please read also through the other comments, as I already gave a lot of assistance and explanation on similar questions.

Happy new year,
Martin

Prusa i3 MK2: V2 holder clips for Y-axis' igus drylin RJZM-01-08 bushings

Ahh. I didn't spot the screws came through from the top side! Problem solved. thanks for the quick reply!

Comments deleted.

In case anyone is wondering: M3x16 ;-)

Right!

I will add this information to the project's description page.

Have a nice weekend!

I just reassembled my Y-Carriage and ran the XYZ Calibration again, which complains that it's compromised because it can reach the front calibration points. Y0 seems to stop ~1mm before the clips hit the block, and the clips are of course oriented like in your photo (the cutout sliding over the block).
Any idea what could be wrong?

"... because it can reach the front calibration point." should be "can't reach", right?

But as you describe it there is no crash, neither of the clips, nor of the bearings against the printed corner blocks of the Y-frame, right? Have you touched the M10 rods and changed your metal Z-frame's position (unintentionally) in any case? Setting the metal Z-frame to a position too far to the back of the M10 rods will cause the PINDA probe to not reach the frontmost point of the bed, because the Y-carriage triggers the endstop to early.

oops, typo, yes i meant "can't" =)

That does sound logical! I did realign everything because i replaced the bearings in all three axis with RJ4JPs (which are a really great upgrade), and while doing that i realign the whole frame and made sure that i get exactly 100.0mm distance from the back to the Z frame.
I used this chart: https://raw.githubusercontent.com/PrusaMK2Users/MK2_Tips_and_Tricks/master/Prusa%20i3-MK2%20Dimensions.png

Before that i had a distance of ~110mm, i guess i'll move my frame a bit further to the front again...

Thanks again, i really like all your upgrade parts!

Cool, haven't seen that drawing before. Thank you for showing me.

I have a rule of thumb: As long as there are 3D-printed plastic parts involved, I use quantitative measurements solely as a guidance.
And especially the Prusa i3 MK2's Y-frame assembly is a guessing game, because it is relies on rods that are prone to twisting and corner elements that are 3D-printed of soft plastic. :-D

True, and the (allowed) torque is also difficult to guess, which is probably why my Z axis is now way over 100mm, and each side at a different distance - but the calibration says my axis are perpendicular! :'D

Thanks again!

Is it possible to get the source for the thing? I would like to alter the mounting option.

Hi, sorry for the late response, but I missed your comment somehow.

I decided to not give away my "source files", or in case of Fusion 360 the step files.
The STL models are pretty detailed in terms of polygon count and surface approximation of the parametric t-spline surfaces. So anyone who wants to make a remix can modify or recreate the models according to the associated license.

I made this decision because I am using my designs also in commercial projects for my clients and want stay safe in terms of agreements.

Have a nice weekend.

Hey Martin!

All of your bearing clips appear to have a "ridge" to lock into the circular cutout on the LM8UU and igus bearings. Unfortunately, some higher end bearings such as those from SKF do not have these clips, and it's a completely smooth surface.

Can you make a version that captures the edges of the bearings? Hopefully the extra .2mm that you dropped to make the bearings tighter will also help hold them in lieu of the ridges.

Hi,

I will and the clips are already in the making. Unfortunately I don't have too much time this week for this.Moreover, as I don't have the SKF bearings laying around and I am low on budget for buying stuff that I just need for design reasons, it is a little bit more complicated to achieve good results. You see, having these things physically available gives me an intuitive feeling of how a design has to evolve during the actual CAD process. Doing the same thing just from schematics and pictures is prone to misconception and therefore needs more time for me to evaluate a correct design. I don't like to publish things that do not have a certain level of quality - at least not one on which I can build upon from the feedback of others.

Simply follow me here on Thingiverse and you will be informed as soon as I release the clips.

omnikron - Since Martin said he doesn't have a lot of time to make his bearings for full-length right now, you can see if mine will work for you, since they have a Customizer option for full-length capture: http://www.thingiverse.com/thing:1819779

Of course, you may have to tweak for the size of your bearings, since the left side can't be captured on both ends (the Y corners have only enough cutout for the bearing alone). But I don't see why it wouldn't work if you get the strap size tight around the bearing body. Mine don't look near as cool as Martin's but hopefully they'll get the job done for you.

Good luck !

-=dave

Prusa i3 MK2 Y Chassis Bearing Straps

Are there ways I can help you get the the information you need?

I just removed your old bearing designed parts from the bed and installed the RJ4JP bearings on the bed with zip ties. It moves much smoother now. Wonder if zip ties are needed to let them float a little.

I also found that rotating the bearings when mounted and siding a rod through them that there is a spot that the rod slides better. Mostly this seems to happen when the lettering on the bearings line up the same way.

I found this out on the bearings in the z axis rods. Pressed them in and rotated them until the rods moved smoothly through them. Did the head bearings and bed bearings the same way and they work nicely.

Not sure I want to change anything more right now. My machine is super quiet with just installing the plastic igus bearings.

It is great that you've found a setup that works for you as you like it. Congratulations and have fun with your MK2. :-)

I am not doing this to "force" something on the community, nor am I saying that this is the ultimate solution. Even if I don't like some design choices of the Prusa Research team, I think that they did a wonderful overall job creating the MK2. So I just publish the things that I do for myself and use myself - or in case of the LM8UU clips was asked to do by the community (the clips for the igus bushings were the ones I created for my personal use case).

Just one more word to the smoothness and the orientation of the bearings: The functionality of ball bearings is sensitive to the orientation. The balls apply force on the shafts. With two ball bearings on one shaft mounted to the same frame, unaligned ball rows can distort the shaft, so that it adds unwanted friction to e.g. the bearings plastic parts.
But if you encounter a sluggish behaviour despite having the balls aligned correctly, this might be a strong signal towards having the frame not perfectly square. Either your shafts are not perfectly (within tolerances) at a 17 cm distance, or not perfectly parallel. The usage of zipties allows the bearings to compensate for this, because the rigid frame of the Y-axis does not allow for any adjustment. This is however a desired feature that should be backed by the clips, but it requires the frame to match the narrow bounds.

Nonetheless I like to thank you for your feedback and hope to see you at another project of mine! :-)

Your 100% correct. The bearings shipped with my printer have a lot of play in them. Other ones that I have around have a lot less play on the original shafts. The igus bearings need the machine adjusted so they slide smoother. The original bearings have enough play in them to get away with a machine that isn't built as accurately.

The notch ridge on yours seems too deep ? I designed a similar set in OpenSCAD that is Customizable to your bearings, in case they may be of use for these specialized bearings others need straps for (http://www.thingiverse.com/thing:1819779). I see now that my Customizer script sets the strap length at specific sizes (with +/- for "Loose" to "Tight) but if others need custom lengths beyond the stock MK2 bearings, I can make that paraemter user-settable instead.

I'm trying to reduce the noise of the Y axis, so I will let you know on the RJ4JP-01-08 size comapred to stock bearings, if I get them. Thanks to you and nillabean for the tip !

Prusa i3 MK2 Y Chassis Bearing Straps

What do you mean exactly with too deep? The ball bearings snaps in just fine, at least with the eight lm8uu bearings I have tested. I am also using my clips now for an other project. Therefore if something does not fit, I expecting it to be related directly with the Y-carriage mounting that I had not tested. So please explain in more detail what is not correct, so that I can fix it for all users to enjoy.

I like your customizable approach, but your design is a little bit week in terms of mechanical strenght. I printed it and broke already two pieces while screwing M3 screws in. That's why I made the triangular shape with much more material to withstand the stress. Maybe you can use this also as feedback for improvements?

Please report back.

I think I'm going to try your mounts with the drylin bearings on my prusa. Also going to look at up grading the shafts to full 8mm. The ones on my machine are only .312 of an inch in diameter. Ordered my RJ4JP-01-08 bearings.

Cool! Please report how the clips fit.

If there is too much of a difference ragarding the LM8UU I will upload a completely new Thing that is designed solely for the RJ4JP bearings.

I printed the single bearing side and RJ4JP-01-08 fit prefect. I still have to bolt it to the printer but the bearing snaps in just right.

Very nice! Thank you for your feedback.

Please pay attention, if the bearings are loosely twistable when attached inside the clips to the Y-carriage. If so, I have to adjust the clips slightly, so that they get locked by the pressure of the carriage-frame. Otherwise they will start wiggling during operation. I have observed this behaviour with this clips and the lm8uu bearings on an another project (not the Prusa i3 MK2!!!). It would be nice to know if this comes from the clips, or the new project's frame.
I already made an adjustment so that it fits the new project perfectly, but I don't want to publish the modified versions as long as there is no problem with the current ones (never change a running system, right?).

Installed your bearing mounts. They are to loose on the bearing. I sanded them down a little to pull the bearing into the slot in the bottom of the bed plate but they really need a little removed from the part where they touch the bottom of the aluminum bed mount. Also the holes are way to big for the screws. They should be around 2.5mm for a m3x.5 screw. They look like they are closer to 2.8mm. This will let the threads strip out in the plastic. I would rather see the screws turned around the other way and use locking nuts on the aluminum side of the bed plate. This way you will not have to remove all the bed mount screws to install the bearing mounts. You could put small pockets in the plastic part for the cap head screws to fit into.

If you have cad files for these parts I could make these changes.

So, I made the changes and tried different approaches of how to reverse the screw placing direction.

The good...

1) I lowered the clearance of both, the bearing hole and the screw holes. Right, this was a good point. Both are now much tighter in fit, and should not wiggle or get loose anymore.

2) I lowered the surface that faces the Y-carriage frame by 0.2 mm (one layer's height), which again tightens the bearing much more by pressing it against the carriage frame.

The bad...

As shown on the following pictures reversing the screw direction results in a big problem: The screw-heads are crashing against the X-Y-metal-frame. My frame is already lower than Prusa Research suggests in its assembly manual, because my frame rests also on the table where the printer stands. Every other user that has assembled the frame as suggested by Prusa will obviously have the same trouble.

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ZylindricButtonHeadComparison.jpg

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ButtonHeadScrew.jpg

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ZylindricScrew.jpg

https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/CrashAgainstTheFrame.jpg

The ugly...

Trying to move the screws more towards the Y-carriage frame to hide the heads inside the clips and preventing them from crashing against the X-Y-frame results in an ugly geometry (with a big hole). This would affect the stability of the clips and the screw heads would press against the bearings, which could misalign them again.

Anyway, I will publish the tighter fitting version later today. The screw-reversal will be hold back until I find something that works better.

Thank you for your feedback.

I will make the suggested changes and post a V2 version here for you to try out.

I installed your v2 version with the igus bearings and they are working. I found that I have to adjust how tight I make the screws. They just need to be snugged up or the bearings become tight on the shafts. Once everything is adjusted they seem to be working great. The screw holes in the mounts fit the M3 x 2.5 screws really nice. The bearings do not spin or move around at all. Now my printer is so quiet I can run it all I want and not be bothered by the sound.

Thanks for all your work on these parts.

Great to here that you like it.

I added the advice to be sensitive on the screws in order to adjust the clips and compensate for any imperfections a few days ago. From my experience it differs from machine to machine. On my second printer, that received the V2 first, I could tighten up all screws and it works great. On my first machine I had to loosen one screw of one clip on the double bearing side by a half turn to make it work. FDM printed parts are still and will remain stacked plastic spaghetti: no two objects are completely identical.

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