Replacement bearings recommendation - Hardware, firmware and software help

RE: Replacement bearings recommendation

cooldude — Fri, 08 May 2020 20:14:11 +0000

I think these are same as LUM8 but without the seal

RE: Replacement bearings recommendation

cooldude — Fri, 08 May 2020 20:13:35 +0000

https://us.misumi-ec.com/vona2/detail/110300026540/?HissuCode=LMU-N8

RE: Replacement bearings recommendation

karl-herbert — Fri, 08 May 2020 20:09:50 +0000

@amodak2014

I do not know the type "LUMN-8". Would you put a link to these linear bearings?

The correct dimensions to the bearings would be:
Outer diameter 15mm
Inside diameter 8mm
length 24mm

RE: Replacement bearings recommendation

cooldude — Fri, 08 May 2020 18:28:47 +0000

I am looking to replace bearings and rods on my new MK3s kit..Can i use LUMN-8?

RE: Replacement bearings recommendation

karl-herbert — Tue, 31 Dec 2019 16:38:08 +0000

@omikron

I agree. Rather work with good quality than trouble with cheap goods. I only use SKF bearings on all my machines.
I am glad that there are still quality products to buy. You won't notice the difference until you try it.

Happy new year!

RE: Replacement bearings recommendation

yang — Tue, 31 Dec 2019 03:05:43 +0000

I have a Chinese bearing supplier whose bearings are very good. http://www.deep-grooveballbearing.com/

Re: Replacement bearings recommendation

Spacemarine — Sat, 12 Jan 2019 01:07:55 +0000

Sintered Bronze Bearings (h7) with silver steel rods (h9):

Shell: Can be compressed as it is a soft metal (bronze, sintered) but is definately harder than RJ4JP-01-08. Compression needed to reduce slop.

Housing: Definately needed to get the best out of them, can be used without but will have slop then

Fit: Available in different lengths and thickness, e.g. 8 ID, 12 OD, 20 lenght (mm). A housing can be made to make them fit like the LMUU8, with no housing custom printed parts are required.

Noise: 2 dB above ambient

Motion: Consistent friction in direction change, friction comparable to LMUU8 or even less, extremely smooth motion IF aligned properly and with the right rods.

Slop: No slop if using a housing for press fit, else slop is like RJZM-01-08, -0.1mm

Costs: Comparable cheap, between 1 and 3 $ depending on the length.

Misc: Don't need lubrication under normal circumstances as the are self-lubricant, allow high speed motion up to 5 m/s and withstand temperatures up to 100 °C.

Cons:

- Build: High precision needed aligning the rods and the bearings themselves, if two on one rod. In the latter I suggest using one housing for both then (2x Z, 1x Y, 1x X). Equipment needed for the press fit into the housing (or higher budget by let someone else do it).

- Load: Not suitable for high loads.

- Environment: Need clean environment -> clean rods if using in open space or use an enclosing.

- Rods: Need hard rods made from cold work steel, e.g. silver steel.

Conclusion: If you have the right equipment or you can find a skilled person to do the press fit and building the housings and your rods are precisely aligned, these bearings are the best of both worlds: High precision and silent operation.

Has anyone here sintered bronze bearings? This sounds interesting. Did you try this out?

Re: Replacement bearings recommendation

spark — Sun, 22 Jul 2018 01:32:49 +0000

@giovanni
Yes, black residue and scoring is a bad sign. Do you have a magnet? MK3 are supposed to come with hardened steel but I've heard the first batch was "accidentally" shipped with MK2S's stainless steel rods, some issue with miscommunication, etc. Hardened steel are ferromagnetic meaning magnets will stick to them, stainless steel is not and won't. Also, during assembly it is possible that printed parts are misaligned or have bad prints. Result, the rods are not perfectly spaced or splay apart. This is bad as the rods must be perfectly parallel and perfectly spaced for best glide. If not, much more stiction (grabbing by bearings when changing direction) and friction. You can find out by disconnecting the x-belt so the X-carriage moves freely, then slide left and right several times. If there is any increase of friction, you have splay, if the X-carriage doesn't slide on it's own after giving it a good shove, the spacing is wrong. Those are the three things to check prior to calling support.

Hope this helps.

Re: Replacement bearings recommendation

Pinaux — Sat, 21 Jul 2018 21:17:55 +0000

Hi to all... Ho have the mk3.. I bought it 3 weeks ago. 100 hour of printing... And the stock bearing completly ruined the rods.. Lines engraved in the rods.. Only the x and y axis are ruined... The lubrificant on the rods are black... For the metal... I have contacted the custumer service by chat... And i wait for an answer... I want to change rods and all bearings. You agree?

Re: Replacement bearings recommendation

3D Printing Pro — Thu, 26 Apr 2018 16:51:36 +0000

What about cutting the IGUS bearing (more or less like the attached image, neglect the helix shape) and using a tunable (with screws or whatever) collar to compress it to the right size, eliminating any slop (by tightening the collar)?