Replacement bearings recommendation  

Re: Replacement bearings recommendation

sorry
read LBBR 8 2LS

reférence :

regards

Re: Replacement bearings recommendation

sorry
read LBBR 8 2LS
they will fit. but i don't know if you'll notice a noise reduction to the standard ones.
a good idea will be mounting them with fitting bearing holders, that you can find at thingiverse, instead of zip-ties (JP's genuine fixing method).

Re: Replacement bearings recommendation

got a link for it? All I found was this and its been taken down:

http://www.thingiverse.com/thing:14814

Re: Replacement bearings recommendation

got a link for it? All I found was this and its been taken down:

http://www.thingiverse.com/thing:14814

yes, just look here:
http://www.thingiverse.com/thing:1848700/#files

[update] or here:
http://www.thingiverse.com/thing:710913
[/update]

by the way, the ones you've found won't fit for the MK2 y-axis bearings, they will collide with the frame.

Re: Replacement bearings recommendation

sorry, but don't use the thingiverse 710913 part. i can't recommend it.
😳
it "looks" as it would fit for the MK2, but it will lift up the whole print bed approx. 5mm !
so you might run into several problems (maybe prabu.a's problem is related to it too.... i'm gonna ask him).

just printed them and wanted to prepare everything for the replacement bearings (they still are in shipping status) and noticed it.

Re: Replacement bearings recommendation

I have just ordered from Misumi PSFU8- rods in the specific lengths and for bearings I went with the LMU-N8 no seal. These were the recommendations from them. I went no seal since it is a dust free environment and I can oil the bearings. I found out that the bearings with seals will add drag (whether it affects it who knows) but the bearings have to be oiled before installation.

I will try to report back once installed and working. Probably a couple weeks.

Re: Replacement bearings recommendation

just a litte experience to share:
💡

my DryLin RJ4JP-01-08 arrived here last week (together with DriveLin high precision aluminium rods) and i spend the whole afternoon 'til now to replace them at my MK2.
unfortunately it was not successful over all. 🙁

at the y-axis i got into severe problems, because the axial clearance of the bearings is higher than the axial clearance of the standard ones. i tried to tighten them a little bit with the holders (thingiverse 1848700) to increase the friction but this didn't help very much, even so that i managed to get the friction at both sides pretty level and the carriage moved harder than usual.

➡ the clearance of the bearings always induced a little (but visible) skew of the whole printbed when the y-axis moved forwards or backwards.

and if we think about it for a moment, it's pretty obvious that this is causative to the 3-point design of the y-carriage.
if we had a 4 point carriage (would say: 4 bearings, two at each y-rod), i think the DryLin bearings will do a great job at the y-carriage because they reduce the noise level siginificant.

in the meantime i went back to the genuine bearings that came with the kit. now the axial clearance has vanished and there's no more skew when the y-axis movement changes its direction.

i'd rather have a precise printer than a silent one.

💡
update:
i'm back to the standard ball bearings and steel rods at all axis.
the igus DryLin's may reduce the noise, but the higher friction caused several problems. one of them is the slight skew of the heatbed (described above) another one is the effect that at the x-axis some fast movements of the x-stepper are not successful... due to the required additional force.
you can see the effect on the printing (layer shift in x-direction) at the attached picture.

so at least in "silent mode" (my default setting) the RJ4JP-01-08 are not suitable for me.

Re: Replacement bearings recommendation

If the X is too stiff with igus bearings, then you have probably tightened too much the 2 screws on the right side of the right rods holder.

For Y, you don't have to tighten the RJ4JP at all; if the bed rotates when changing direction, that's because one of the two left bearings is too much tightened; that could also be caused by the fact that your Y is not a square but a parallelogram (all measurements right but angles aren't 90°).

Btw, you have to use zip-ties for rj4jp.

Re: Replacement bearings recommendation

hi patrizio,
i would have assumed the same, but with the igus i had the x-axis screws very loose, just to make sure that the x-axis belt didn't hang through.
for the extruder carriage i used zip-ties to fix them (only to keep them in place... no real squeezing).
🙄

at the y-carriage i used the thingiverse 1848700 holders, they have a smal brim that fit's into the two furrows of the bearings.
during the first attempts they were not very much tightened... but the axial clearance still was too big, so every change in the y-direction movement let the whole printbed rotated a little bit. when moving in +y direction, the left corner of the printbed was slightly ahead of the right corner, when moving in -y direction it was vice versa.

as i tried to explain above, i even tightened the right (the single one) bearing a little more, so friction was quite the same at both sides.... but i still had the skew.

btw. x and y are perfect perpendicular with the original bearings. no complaint of a "slight misalignment" when running the xyz calibration.
😀
with the igus installed, the xyz calibration nearly failed (said something about a misalignment that will be corrected by the firmware, but suggests to consult the assembly manual).
🙁

Re: Replacement bearings recommendation

I've tried something different in quieting the bearings and wanted to air it out here. I read on a few higher-end bearing manufacturer's sites that they recommend using o-rings in the bearing grooves for quieting the ball movement noises as well as allowing for some misalignment. As I don't have a sound meter at home, I couldn't quantify the difference but prior to installing the o-rings on the X & Y axis, I had to run in silent mode to avoid disturbing the household. Now I can run in powerful mode when everyone is sleeping without being able to hear it on the next floor up. The bed still rattles on fast movements (mesh bed calibration) but is otherwise quieter.

Note that I tried to install on the Z axis but the mounting is too tight to allow for the o-ring thickness, a modified bracket would have to be printed to allow for these to accept O-rings. As it is the other axes that are usually having the most movement I've left those off for now.

Re: Replacement bearings recommendation

➡ the clearance of the bearings always induced a little (but visible) skew of the whole printbed when the y-axis moved forwards or backwards.

and if we think about it for a moment, it's pretty obvious that this is causative to the 3-point design of the y-carriage.
if we had a 4 point carriage (would say: 4 bearings, two at each y-rod), i think the DryLin bearings will do a great job at the y-carriage because they reduce the noise level siginificant.

well, the RJ4JP need a press fit, without it they have too much play by design. that is why you get a skew and worst case binding.

and concerning people replacing their cable ties with clips like those http://www.thingiverse.com/thing:1848700/#files
...there is a good reason for the cable ties. it allows the bearings to compensate for parallelism errors

Re: Replacement bearings recommendation

As I mentioned in the improvements section, I came across: http://www.igus.com/wpck/3661/drylin_r_rjum_02?C=US&L=en RJZM-02-08's and they look like they can be a drop in replacement, unless I'm missing something. They have a 15mm OD.

Re: Replacement bearings recommendation

well, the RJ4JP need a press fit, without it they have too much play by design. that is why you get a skew and worst case binding.

Wonder why the Igus sales rep then told me, quoted freely: "due to the stiffer nature nature RJ4JP can be used with zip ties" and does not require a press fit. Even the spec sheet here does not mention the requirement of a press fit: http://www.igus.com/wpck/17748/Motek14_N14_6_3_Vollkunststofflager

Are you sure you're not confusing RJ4JP with the tan RJM-01, which clearly state that a press fit is required?

Re: Replacement bearings recommendation

...there is a good reason for the cable ties. it allows the bearings to compensate for parallelism errors

i would agree if the bearings would only be fixed by the zip ties to a plain surface, but the zip ties press the bearings into the reliefs (or pockets) at the y-carriage.... so no more chance to selfaligning.
i'll give the RJ4JP another try as soon as my new y-carriage, with mounts for 4 bearings, will arrive here from the netherlands.

Re: Replacement bearings recommendation

➡ the clearance of the bearings always induced a little (but visible) skew of the whole printbed when the y-axis moved forwards or backwards.

and if we think about it for a moment, it's pretty obvious that this is causative to the 3-point design of the y-carriage.
if we had a 4 point carriage (would say: 4 bearings, two at each y-rod), i think the DryLin bearings will do a great job at the y-carriage because they reduce the noise level siginificant.

well, the RJ4JP need a press fit, without it they have too much play by design. that is why you get a skew and worst case binding.

and concerning people replacing their cable ties with clips like those http://www.thingiverse.com/thing:1848700/#files
...there is a good reason for the cable ties. it allows the bearings to compensate for parallelism errors

Not really accurate on the press fit.
"Igus themselves told us with RJ4JP the zip tie is sufficient. People keep confusing the grey RJ4JP with the brownish RJMP. RJMP require a press fit. RJ4JP don't."

Re: Replacement bearings recommendation

...there is a good reason for the cable ties. it allows the bearings to compensate for parallelism errors

i would agree if the bearings would only be fixed by the zip ties to a plain surface, but the zip ties press the bearings into the reliefs (or pockets) at the y-carriage.... so no more chance to selfaligning.
i'll give the RJ4JP another try as soon as my new y-carriage, with mounts for 4 bearings, will arrive here from the netherlands.

4 igus-like bearings will most probably bind on this Y setup. The point of having 3 is to have two aligned bearings to align against X/Z rotations, and the one alone to align against Y rotation - with assembly and tolerances homogeneity against skew. If you add one bearing, you'll fight against the entire Y assembly instead of adapting to it. That would not be an issue if the Y assembly was not assembled by humans and printed parts.

As I previously said, the zip-ties shall not press the RJ4JP bearings, or they'll eventually bind (even with 3) or cause skew on direction changes (if one is tightened more than the others). In fact, you may have to glue the zip-ties to the bearings to both keep them in place (avoid sliding/rotating) and get them to align (by their inducted misalignment thanks to the zip-tie almost-looseness).

Given this theory, the only way to reliably use RJ4JP on the Y is then to use zip-ties. Some use them with success with fixed mounts, but that's because they have (by either luck or time spent on calibration) a perfect Y assembly.

If someone has time/money, i suggest to spend them on the fixed mount + RJZM-03-08 + eventual collateral modifications caused by them. It seems to me that is the correct way to solve all the various problems at once. That's an hypothesis - for now I've only experienced stock, RJ4JP, RJZM-01-08, zip-ties and fixed mounts.

Re: Replacement bearings recommendation

Hi all,

I had replace my bearing because a lot play with the left bearing.
I I have installed brackets for fixing. Because very important. The bearings must be in a cage.

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

Install SKF LBBR-8 2LS ( 9 € ) . It's very good no play and no vibration.
I am very happy. I highly recommend.

Attention to tighten the brackets not too much.

sorry for my english " google""

Regard from FRANCE.

TV you tube :

Re: Replacement bearings recommendation

As I mentioned in the improvements section, I came across: http://www.igus.com/wpck/3661/drylin_r_rjum_02?C=US&L=en RJZM-02-08's and they look like they can be a drop in replacement, unless I'm missing something. They have a 15mm OD.

I own RJZM-02-08 bearings. In my experience, the tolerances are still not good enough despite coming with aluminum housing to constrain the IGUS plastic. If you look at the specifications, the RJZM-02-08 bearings can have up to 70 microns of slop, which is actually quite a lot for bearings.

I've installed RJZM-02-08 bearings on two separate printers now and they've always had more slop afterward in comparison to normal linear bearings. I literally just switched my Prusa i3 MK2 away from the RJZM-02-08 bearings back to the stock bearings because the stock bearings have less slop.

Again, this is just my experience. Many others seem to have success with the RJZM-02-08 bearings, so either I'm doing something wrong or others just aren't noticing the additional slop.

I'm not completely inexperienced though, I own a bunch of Misumi rods and bearings, and the difference is night and day. Misumi LMU-N8 bearings are super strict and require rods to have less than 18 microns of slop. That's much better than the 70 microns allowed by the RJZM-02-08 bearings.

EDIT: Sorry, I actually own RJZM-01-08 bearings, which are the same thing as the RJZM-02-08 bearings, but in a 16mm OD package rather than a 15mm OD package. The tolerances for the RJZM-01-08 bearings are the same as the tolerances for the RJZM-02-08 bearings.

EDIT2: I note that the RJ4JP-01-08 bearings might actually have a tighter tolerance than the RJZM-02-08 bearings according to the specs. The RJ4JP-01-08 bearings supposedly allow up to 40 microns of slop, while RJZM-02-08 bearings allow up to 70 microns of slop.

Re: Replacement bearings recommendation

I was mailing with a rep from igus. He confirmed that RJ4JP-01-08 would be the ones to pick over RJZM-02-08 (because of the tighter tolerance). And the RJ4JP-01-08 do *not* need a press fit. There really is no good reason to use the RJZM-02-08 in this context.

From what I know it might be a good idea to have the two bearings on the one side mounted and the single bearing on the other side just attached with a zip tie.

Re: Replacement bearings recommendation

I must have got lucky- I picked up both the RJZM-02-08 and the companion rods IGUS carries for them and cannot detect any slop at all. Perhaps thats the key. Dont do it half way.