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Martin Majewski
(@martin-majewski)
Trusted Member
LM8UU ball bearing Y-carriage clips

Hi all,

adding to the other topic of mine regarding the additions and enhancements for the Original Prusa i3 MK2 I wanted to announce, that you can now try out clips for the LM8UU ball bearings (the ones that comes with the printer) for the Y-carriage.

http://www.thingiverse.com/thing:1848700

Please read the instructions and be aware, that this are parts that I couldn't test completely myself.

This is a work in progress!

Please report back any issues or improvement suggestions.

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
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Posted : 25/10/2016 12:48 pm
Omikron
(@omikron)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips

Hey Martin!

Fantastic work! These clips seem to work fine for the igus bearings and the standard LM8UU bearings, but the SKF bearings don't have the "rings" for the circlips. I sent you a link to the SKF CAD datasheet via PM a couple days ago.

Do you think you can make a version that tries to align or capture the edges of the bearings instead of using the rings that may or may not be there?

Posted : 26/10/2016 10:15 pm
Martin Majewski
(@martin-majewski)
Trusted Member
Topic starter answered:
Re: LM8UU ball bearing Y-carriage clips

Hi,

as I replied to you at Thingiverse the SKF version is on its way.

Because I am writing my Master's thesis (has to do with 3D printing - still waiting for Josef to answer my PM), working and have my family back from vacation (two small daughters can be demanding) my time is limited. I will try to get my hands on the SKF bearings asap and you will be the first one to get your hands on the SLT file!

Bye
Martin

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
Instagram: www.instagram.com/martinjmajewski
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Posted : 31/10/2016 8:32 am
Omikron
(@omikron)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips

Hi,

as I replied to you at Thingiverse the SKF version is on its way.

Because I am writing my Master's thesis (has to do with 3D printing - still waiting for Josef to answer my PM), working and have my family back from vacation (two small daughters can be demanding) my time is limited. I will try to get my hands on the SKF bearings asap and you will be the first one to get your hands on the SLT file!

Bye
Martin

Oh gosh, I certainly didn't mean to barrage you with silly requests! I simply didn't know what the best place was to leave feedback. My apologies for doubling up.

There is certainly no rush or emergency on my end. Please deal with your important stuff first and maybe if you get bored you can take a look at the bearing clips. You've already contributed so much. 🙂

Posted : 31/10/2016 1:50 pm
Martin Majewski
(@martin-majewski)
Trusted Member
Topic starter answered:
Re: LM8UU ball bearing Y-carriage clips

No worries!

I ordered four SKF LBBR 08-2LS bearings yesterday from ebay for 4 Euros each. The seller said, that he ordered the wrong ones and has no need for them anymore, but the small price point makes me wonder anyway 😀
Lets wait and see what I will receive in the next couple of days.

Btw.: I updated my Thingiverse account, so anyone who wants to support such investigative purchases of mine for other design projects and requests is sincerely welcome to leave me a small tip. At least it will fund me some coffee... *yawn

I will get back to you guys...

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
Instagram: www.instagram.com/martinjmajewski
Twitter: www.twitter.com/MMajewskiNet
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Posted : 01/11/2016 12:08 pm
JoanTabb
(@joantabb)
Moderator
Re: LM8UU ball bearing Y-carriage clips

I hope you get what you expect...

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 02/11/2016 2:24 am
Martin Majewski
(@martin-majewski)
Trusted Member
Topic starter answered:
Re: LM8UU ball bearing Y-carriage clips

So I got the SKF LBBR 8-2ls and they seem to be genuine and brand-new. So I think I made a pretty good deal.

I will create a clip design for them, but I think I have to start over with it for these bearings, as they need a different approach to stay in place.

However I have to admit that the first trial on a shaft was not that impressive. They run much stiffer than the igus or even the lm8uu bearings. Maybe I have to use them a little longer. Moreover I have the impression, that the rectangular parts right in the middle of the bushing have to be pressed in order to make the bearing run easier. I have to read the specifications more thoroughly to get a better understanding of what the clips have to have for best performance.

I will receive another sample shipment from igus in the next couple of days with the RJ4JP-01-08 bearings. This means that I can then verify the fitting of my lm8uu clips against the igus bearings and get this Thingiverse project out of the "work in progress" status i.e. add official compatibility for these bearings.

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
Instagram: www.instagram.com/martinjmajewski
Twitter: www.twitter.com/MMajewskiNet
YouTube: www.goo.gl/QJTQKv

Posted : 08/11/2016 11:20 pm
Omikron
(@omikron)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips

So I got the SKF LBBR 8-2ls and they seem to be genuine and brand-new. So I think I made a pretty good deal.

I will create a clip design for them, but I think I have to start over with it for these bearings, as they need a different approach to stay in place.

However I have to admit that the first trial on a shaft was not that impressive. They run much stiffer than the igus or even the lm8uu bearings. Maybe I have to use them a little longer. Moreover I have the impression, that the rectangular parts right in the middle of the bushing have to be pressed in order to make the bearing run easier. I have to read the specifications more thoroughly to get a better understanding of what the clips have to have for best performance.

I will receive another sample shipment from igus in the next couple of days with the RJ4JP-01-08 bearings. This means that I can then verify the fitting of my lm8uu clips against the igus bearings and get this Thingiverse project out of the "work in progress" status i.e. add official compatibility for these bearings.

Thanks for the update, Martin! I agree that initially the bearings did feel stiffer but they felt much better for me after they broke-in a little bit. I also am not sure about the metal plates either. When I installed mine (using zip ties) i made sure that at least two of the metal plates were pressing directly into the print bed.

Posted : 11/11/2016 9:21 pm
Lee
 Lee
(@lee-2)
Re: LM8UU ball bearing Y-carriage clips

How is it that the screws from the top does not interfere with the plate? Doesn't the plate fit flush against the Y carriage? (Just purchased my printer, don't have it yet so I'm still absorbing this).

Bad decisions make good stories

Posted : 17/11/2016 8:50 pm
Martin Majewski
(@martin-majewski)
Trusted Member
Topic starter answered:
Re: LM8UU ball bearing Y-carriage clips

How is it that the screws from the top does not interfere with the plate? Doesn't the plate fit flush against the Y carriage? (Just purchased my printer, don't have it yet so I'm still absorbing this).

The heated bed rests on spacers, as shown in e.g. in a picture found inside the assembly guide:

So there is plenty of space between Y-carriage frame and the bed plate.

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
Instagram: www.instagram.com/martinjmajewski
Twitter: www.twitter.com/MMajewskiNet
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Posted : 17/11/2016 9:05 pm
Lee
 Lee
(@lee-2)
Re: LM8UU ball bearing Y-carriage clips

The heated bed rests on spacers, as shown in e.g. in a picture found inside the assembly guide:

So there is plenty of space between Y-carriage frame and the bed plate.
I see, thank you for explaining!

I'm still soaking it all in. Even though I've gone through the whole manual once, some of these things make more sense in the context of other subjects like your modifications.

Bad decisions make good stories

Posted : 18/11/2016 4:12 pm
Martin Majewski
(@martin-majewski)
Trusted Member
Topic starter answered:
Re: LM8UU ball bearing Y-carriage clips

Just a quick update on the LBBR SKF bearings:

I made a clip design from the ground up for the bearings, but it is not satisfactory enough for my inner perfectionism. :ugeek: The only real spot to secure the bearings from sliding are the metal plates and their framing respectively. Or they have to be pressed against the Y-carriage's frame, which can cause trouble regarding the movement smoothness, as soon as the bearings are stopped from wiggling by the clips (lessons learned from the other clip projects). I have to rethink this a little longer and maybe I can come up with something completely different.

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
Instagram: www.instagram.com/martinjmajewski
Twitter: www.twitter.com/MMajewskiNet
YouTube: www.goo.gl/QJTQKv

Posted : 19/11/2016 10:44 am
Martin Majewski
(@martin-majewski)
Trusted Member
Topic starter answered:
Re: LM8UU ball bearing Y-carriage clips

A final though on the LBBR SKF bearings:

I have given up designing clips for them, as I had no time for this lately to get a quality standard I am happy with - besides this I really don't like the bearings at all.
Currently I am using the LBBRs as "stoppers" to store my other igus bearings slid on a shaft. 😀 🙄 😆

-- www.martinmajewski.net --
Thingiverse: www.thingiverse.com/MartinMajewski
Instagram: www.instagram.com/martinjmajewski
Twitter: www.twitter.com/MMajewskiNet
YouTube: www.goo.gl/QJTQKv

Posted : 18/12/2016 1:26 pm
ayourk
(@ayourk)
Reputable Member
Re: LM8UU ball bearing Y-carriage clips

I do use SKF LBBR bearings. The dimensions are 15mm diameter with a 25mm length. I've tried other ones on Thingiverse and found clearance issues, so I designed my own. They are available in my TinkerCAD profile. Be sure to read the comments in the model about anything special.

Dimensions PNG

and an 8 inch (200mm) or greater caliper is recommended.

Posted : 19/12/2016 9:10 pm
gz1
 gz1
(@gz1)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips

My printed bearing holders are wearing out (from all the wrenching of prints off the print bed; also turns out printing them in PLA is not a good long-term solution), so I'm giving these a try. They look like a pretty decent design.

Could I request:

1. Put a 0.2mm chamfer on the bottoms to counteract first layer squish
2. Slot for an actual nut instead of just burying a screw in plastic

?

Posted : 28/12/2016 10:20 pm
ayourk
(@ayourk)
Reputable Member
Re: LM8UU ball bearing Y-carriage clips

My printed bearing holders are wearing out (from all the wrenching of prints off the print bed; also turns out printing them in PLA is not a good long-term solution), so I'm giving these a try. They look like a pretty decent design.

Could I request:

1. Put a 0.2mm chamfer on the bottoms to counteract first layer squish
2. Slot for an actual nut instead of just burying a screw in plastic

?

I know that for my design at least, there isn't enough clearance for using nuts. The First Layer squish mates up against the metal, so I don't see a problem there.

Dimensions PNG

and an 8 inch (200mm) or greater caliper is recommended.

Posted : 28/12/2016 11:53 pm
gz1
 gz1
(@gz1)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips


I know that for my design at least, there isn't enough clearance for using nuts. The First Layer squish mates up against the metal, so I don't see a problem there.

I *think* there should be enough space for nuts. You should be able to tuck them up into the dead space between the bearing and the carriage. Use square nuts or something if you have to.

I did it with my design; granted mine is a little extended so there's a little extra room:

The first layer squish mating up against metal is exactly why you need the counter-chamfer. The part where it meets the *bearing* might tuck up against the groove in the bearing, but the side that meets the *metal carriage* will be skewed by the deformation. It's really a no brainer.

And speaking of all this, there's a 3rd request:

3. Extend the mounts so the bearings don't actually touch the carriage.

If there is *any* error in the oval cuts in the carriage -- whether the cuts are inaccurate, or the spraypaint is non-uniform, or any combination of the sort, the bearings will be seated inconsistently. You can probably expect better consistency through the printed parts (as long as your first layer squish isn't distorting the mating surface). So I would extend the mount by maybe 1mm to make sure the bearings never touch the carriage. You might lose about 1mm of Z height... but I think there's already an extra 10 built in anyways.

Posted : 29/12/2016 12:44 am
gz1
 gz1
(@gz1)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips

Kind of figured nobody would agree so I just sat down and redid the part myself.

It's tight, but there is just enough clearance for the nut + clearance against the bearing (+ clearance) as long as you implement my 3rd suggestion to get the bearing off the carriage. If you draw it up yourself you will see.

Worst case -- you grind a little bit off of a square nut to get it to fit.

Also added the anti-squish chamfer. Dunno why anyone would ever argue against such a chamfer on such an obvious part with mating surfaces, unless you're using a tool where adding chamfers is painful.

Printer is currently busy doing other stuff so I'll have to test it afterwards.

Posted : 29/12/2016 4:02 am
richard.l
(@richard-l)
Moderator
Re: LM8UU ball bearing Y-carriage clips

gz1,

When your design is complete would you mind sharing? I am going to tear down my second MK2 to add igus bearings and would like to try your holders.

Posted : 29/12/2016 3:26 pm
gz1
 gz1
(@gz1)
Estimable Member
Re: LM8UU ball bearing Y-carriage clips

My design is in Onshape here:

https://cad.onshape.com/documents/414d936e6b9ffbe0cf57032f/w/2454aa6716236949206c287e/e/cf7e6d811179c9fe670a01a3

You might need to adjust the radius of the LM8UU cutout depending on how your printer performs -- I'm currently setting a +0.2mm radius on both the major radius and the lock radius -- if you look for the 0.2's you'll find those. If they're too loose, reduce it (or alternatively, wrap the bearings with kapton tape to snug them up). If they're too tight, increase it. You want it to be just about just right. Probably want to print at .2mm height.

There's an unfortunate side effect to this mod. Since I raised the aluminum frame up by 1mm, that means you need to lower the Y axis cable mount by 1mm. So you have to print a shim.

But it gets worse. When you put that 1mm shim in there, the Y carriage screws, which were barely long enough to engage the heated bed standoffs, are now too short. So you'll need to replace the caphead screws. I have to go cut some down; you'll want to prepare about 12-13mm thread length caphead screws. Why things are designed so close that 1mm can cause problems, I have no idea.

As you assemble the y belt holder, make sure the endstop is also reliably triggered. Had a few issues with this; the design should account for this now, but be aware that the way you bias the y belt holder adjusts how it hits the switch.

Posted : 29/12/2016 9:28 pm
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