Replacement bearings recommendation  

Re: Replacement bearings recommendation

Since LM8UU is sealed, I went with Misumi LMU-8, Misumi LMU-N8 are unsealed.

But to be honest, i don't have the first clue if we actually need sealed or not.

Re: Replacement bearings recommendation

I went with the LMU-N8 as I don't want a seal causing drag. But they are open cage. Who knows what is better. At the end of the day these printers are not in high-dust situations and or being exposed to rough elements.

Re: Replacement bearings recommendation

Funny question... did you have issues ordering from Misumi. They are refusing to deal with anyone who is not a business, even got a call from their English rep asking for Trade Documents. They don't have a retailer you can buy from so a bit of a weird impass...

Re: Replacement bearings recommendation

I guess i was lucky in that respect that i actually do run a small business. But yes, Misumi here in Germany is refusing to deal with private endusers. I do not know of any UK sources, but in Germany you could order from a shop called

https://youprintin3d.de/schraubenmutternlager/lager/linearlager/322/markenlager-lmu8-linearlager-4-reihig.html

I've never dealt with them, so I got no idea if they're reliable or not. Since nobody actually brexited as of today (afaik), that might be an option for you.

Re: Replacement bearings recommendation

Cheers for that, managed to 'Create' a sole trading self employed company and created an account with them. They asked for my Trading licence so pointed out that in the UK you only need that for international trading and that as we were unlikely to Brexit within the span of my lifetime they went away and got the UK sales manager to call me. She was really good and I explained that being self employed I don't even need to register as a company, but would still class as a business customer. She advised that as a Business to Business transaction you cannot return goods. End result I spent 26 Euros and have so new bearings coming... I am worn out now, never known a company who doesn't want to sell its products, the next step was USA as their business over there has different trading rules...Life in the UK!!!!!

Nick

Re: Replacement bearings recommendation

I think this "no returns" is at the heart of the issue with Misumi's odd sales policies here in the EU. That, combined with their rather "unique" online shopping experience and I can see how they would get swamped with refund requests from private endusers.

Anyway, glad you got it sorted.

Re: Replacement bearings recommendation

I ordered them in the US and it was super easy?! All I did was put the name of my employer in the box and bang, I bought them. Maybe the EU branch of Misumi is completely different.

Re: Replacement bearings recommendation

Thanks everyone for a really useful thread. My prebuilt mk2 has begun to make some horrid rattling sounds when moving in Y and from descriptions here and elsewhere I'm pretty sure it's the bearings. I'm looking at the IGUS RJZM-01-08 as replacements.

However, should I be replacing these? The machine is only 2 months old, and was a pre-build. It seems pretty clear to me that these bearings are a known point of failure and if this were any other product I'd be looking for a free repair or replacement. I appreciate that with machines like this, upgrades and replacements are expected (that's why we love open source and designs like this), but that doesn't mean we should ignore the usual rules governing mechanical failures in purchased goods, does it? Especially when it appears that the failure is well known.

If I buy new bearings and replace them, would that weaken any claim against Prusa (c.f. most warranties become invalid as soon as you open the case of a bit of machinery)?

Anyone have any opinions on this?

Re: Replacement bearings recommendation

Honestly? If you ordered a prebuilt machine you also paid extra for better support, service & warranty as clearly stated on the product page. I therefore would demand a free replacement under said warranty.

Re: Replacement bearings recommendation

Hi Stefan, well, that's really my thinking as well, but how would that work? Since it's a prebuild, presumably the "appropriate" action is to replace the entire machine (if I bought a washing machine and one of the bearings failed, I'm pretty sure the manufacturers wouldn't expect me to replace the bearing myself). However, unless Prusa have a special "line" for replacements, I could be looking at 6 weeks for a new machine and, of course, it'll come with the same bearings so unless the problem itself is solved, which appears to be poor quality bearings, I'll be in exactly the same position in another 2 months time.

I could replace the bearings myself if Prusa sent me new ones. But what if I screw up the replacement, will that invalidate further warranty work? What if it's not the bearings but something else?

Obviously I'm trying to get a response from Prusa directly - and I know it's the Holiday season so I'm allowing some delay - but I'm not getting much luck so far. I've been asked to check the belt tightness and how well the bed is secured. Nothing seems out of place, but I didn't build the machine, haven't gone through the build process, so I really can't be certain. More importantly, the whole point of paying for a pre-build was to avoid this sort of mucking around. I paid the extra so I could print from day one, hopefully avoiding problems.

Feeling very disappointed at the moment.

Re: Replacement bearings recommendation

I personally would be content if they'd send me a bunch of replacement bearings and swap them myself. Warranty is kinda hard to enforce in the first place, so I guess it is kinda moot to think how this would affect future warranty claims. The argument could be construed by sending you whatever replacement parts you end up getting, they also authorized you to swap them without violating the warranty in the process. At least that would be my stance if it comes to it.

And yes, i am a bit irked as well about some of these quality issues that I've run into with my kit. I'd be even more disappointed if i had bought pre-built.

But hang in there: once I swapped my bearings for Igus / Misumi (or even some decent Prusa ones - there must be some good ones out there, right?), replaced a broken fan, resoldered some wires, swapped the chewed up PTFE tube in the hotend and kept fiddling with bed leveling despite the miraculous auto leveling: in the end you will be rewarded with extremely well looking prints. It just takes way more tinkering than i expected / was lead to believe by the glowing reviews out there. It is still a bargain of a printer that rivals way more expensive printers in print quality, just a little less so in (some few) parts quality..

Re: Replacement bearings recommendation

I have just bought 12 IGUS Drylin bearings,
I plan to put Drylin into the X and Y axis of my new printer, and see how much difference it makes to the noise!
then I will have spares for the old printer once I get bored with the noise...
Joan

Re: Replacement bearings recommendation

Hi everyone, been reading through this tread and not having received my kit yet some will say what do I know. This machine has been pitched at a low prise point for its capabilities. There have been glowing reports, almost to good to be true but these are still early days for the home market in 3d printing and I am grateful for the opportunity to get into this technology now. I don't see any comparison with a washing machine and consumer rights ! We buy into the opportunity to the research and development of this machine and have the abilities to upgrade and improve on its design which to me is part off the experience of buying this machine. Expect problems and solve them, if you don't want this then wait 10 years. All the best to everyone and happy new year. Jez

Re: Replacement bearings recommendation

Thanks everyone for a really useful thread. My prebuilt mk2 has begun to make some horrid rattling sounds when moving in Y and from descriptions here and elsewhere I'm pretty sure it's the bearings. I'm looking at the IGUS RJZM-01-08 as replacements.

However, should I be replacing these? The machine is only 2 months old, and was a pre-build. It seems pretty clear to me that these bearings are a known point of failure and if this were any other product I'd be looking for a free repair or replacement. I appreciate that with machines like this, upgrades and replacements are expected (that's why we love open source and designs like this), but that doesn't mean we should ignore the usual rules governing mechanical failures in purchased goods, does it? Especially when it appears that the failure is well known.

If I buy new bearings and replace them, would that weaken any claim against Prusa (c.f. most warranties become invalid as soon as you open the case of a bit of machinery)?

Anyone have any opinions on this?

Assuming they are using the same bearings in their printer farm they have extensive empirical experience. Why is this a known point point of failure? I read many complaints about the noise they Y axis produces but haven't seen explicit failures in any numbers. A rattling bearing is still very distinct from a failed bearing.

Re: Replacement bearings recommendation

Yes, PR did have a bad batch of bearings which were shipped out at one time; they have now upgraded their bearing stocks.

I asked the question when the bearing problems were first advised on here by users. This is the spec of the bearings which I believe are currently in use:

Category: Precision Bearings
Material of Outer Ring GCr15（AISI52100)
Material of Steel Ball GCr15（AISI52100)
Ball Rows 4 rows
Ourter Diameter - 15mm(-0~0.01)
Bore Diameter - 8mm(-0~0.007)
Width - 24mm(+0~0.05)
Loading - 78.4N

dynamic load is 0.265kn, and static load is 0.402kn

There was no mention of the rods in that communication however...

Peter

Re: Replacement bearings recommendation

Hi @jeremy.s trust me, I understand what you're saying; but there's an important difference between a kit and a pre-build and a difference between personal development of a product and sub-standard parts being included in the initial shipment. I have no problem with the idea that over time I'll update my i3, one of the attractions for me was that very concept, but I don't expect vital components to fail within a couple of months of delivery. It doesn't matter if it's a washing machine or a printer or anything else, I shouldn't have encountered problems so soon.

@simon.p As to whether rattling is a failure or not, I'd argue that's really just semantics. For me, a bearing that rattles and has obvious play is not fit for purpose as used in a 3D printer where vibration and XYZ tolerances are key to the performance of that machine. Whether they have truly "failed" from an engineering definition is irrelevant, they should not be loose and the bed should not wobble.

Re: Replacement bearings recommendation

I personally would like to have seen more about linear bearing preparation in the manual. I was instructed my a friend who had worked with them before in other areas that when shipped they have anti rust oil rather than a proper lubricant. This oil is meant to be purged on installation and your lubricant applied before installation. These little things may seem an insignificant part, but without there continual smooth operation, everything can go downhill very quickly. I am sure they could work for many hours on the oil supplied, but will likely last a lot longer with a decent quality oil.
It wouldn't take much to add this to manual.

Re: Replacement bearings recommendation

@simon.p As to whether rattling is a failure or not, I'd argue that's really just semantics. For me, a bearing that rattles and has obvious play is not fit for purpose as used in a 3D printer where vibration and XYZ tolerances are key to the performance of that machine. Whether they have truly "failed" from an engineering definition is irrelevant, they should not be loose and the bed should not wobble.

This is most certainly an enginnering question. Do you observe a decline in print quality/performance?

Re: Replacement bearings recommendation

This is most certainly an enginnering question. Do you observe a decline in print quality/performance?

It can be answered from a completely different approach:

My wife told me at the dinner table:

"Either you turn off this noisy marvell of engineering or you be cuking yourself next time."
And guess what my choices were in the bedroom during an overnite print 😀

In short, failed or not, in order to maintain peace in the family home, these bearings had to go. They were not fit for my purpose: printing when somebody else was in the house. Now, with Igus i am again well fed and.. erm.. that too 😉

Re: Replacement bearings recommendation

Hi all,

My name is pascal, i live in France and I recieve my prusa I3 last week.
Il have a problem with the bed axe Y and the bearing. I am not happy because there a play with one bearing and the bed vibrate on small displacement with a speed 50 mm/s or more.
I think Prusa should give me a guarantee So I had replace the bearing with a beter solution and I change bearing with a SKF LBBR 20-2LS d: 20 mm and D : ext 28 mm.

it's a good solution and validate by prusa ?
sorry for my english langage.
TV You tube in France : Pascal ktm

regards