prusayo
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Replacement bearings recommendation

Thu Oct 20, 2016 11:21 pm

When it comes to replacement nozzles it's a simple decision. But when it comes to LM8UU replacement bearings I've seen dozens and dozens of recommendations. If I'm looking for bearings replacement instead of IGUS what would the best choice be?
http://www.mcmaster.com/#61205K75 - $20
https://us.misumi-ec.com/vona2/detail/1 ... ode=LMU-N8 - $5
https://folgertech.com/products/12-x-lm ... 3d-printer - $10 for 12
http://www.vxb.com/SM8sG-P-8mm-Slide-Bu ... t19753.htm - $20
Something else?

My bed has always rattled on fast movement so I would like to replace the x/y bearings.

What about the rods, should I replace those as well?
http://www.mcmaster.com/#6112k45/=14m108h
https://us.misumi-ec.com/vona2/detail/1 ... 718%3A%3Aa
Something else?

jonathan.b4
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 1:56 am

I used the Misumi bearings in my initial build based on the reports of rattling, defective and unsmooth bearings I encountered in my research. So I don't personaly have any basis to compare them to the stock bearings. But I am very happy with the Misumi. From time to time there is a resonance that will get a rattle out of them. But it is extremetly rare and very brief.

They slide with much less resistence than the stock bearings because they to not have a seal. The stock bearings have a platic seal that causes friction on the rods and they do not move freely. For instance, gravity is not enough to pull a smoth rolling(non defective) stock bearings off the rod with the rod held vertically. But the Misumi bearings slide off with seemingly no resistence. I speculate that this decreased ressitence may allow for higher travel speeds before the steppers miss a step.

I would have also upgraded the rods at the same time but there was a 4 day lead time and I didn't want to delay my build. I don't have any reason to complain about stock rods. But I still may eventually try the Misumi rods in the interest of experimentation.

Omikron
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 3:37 am

Click the P/N for the OEM site, click the price to go somewhere and spend too much on them.

1. SKF LBBR8-2LS/HV6 : 19.52USD

2. KH08-PP : 15.77USD

3. VXB LM8UU : 10.37USD

4. igus drylin RJ4JP-01-08 : 1.99

I prefer the SKF ones myself. IMHO they are some of the best available.

prusayo
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:30 am

jonathan.b4 wrote:I would have also upgraded the rods at the same time but there was a 4 day lead time and I didn't want to delay my build. I don't have any reason to complain about stock rods. But I still may eventually try the Misumi rods in the interest of experimentation.
So for the Misumi rods: https://us.misumi-ec.com/vona2/detail/1 ... 685%3A%3Aa

What options would be optimal:
Material: bearing steel or 440C stainless steel
Heat Treated: Induction Hardened (or not hardened)
Surface finish: None, hard chrome, low temp black chrome
Shaft Fits Tolerance: g6 or h5
Type: PSFJ or PSFU

I can't believe how choices there are!

prusayo
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:31 am

Omikron wrote:Click the P/N for the OEM site, click the price to go somewhere and spend too much on them.

1. SKF LBBR8-2LS/HV6 : 19.52USD

I prefer the SKF ones myself. IMHO they are some of the best available.
Interesting, I wonder how much better the $20 skf ones are compared to the $5 Misumi ones. For x/y that's $120 vs. $30.

Omikron
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:35 am

prusayo wrote:
Omikron wrote:Click the P/N for the OEM site, click the price to go somewhere and spend too much on them.

1. SKF LBBR8-2LS/HV6 : 19.52USD

I prefer the SKF ones myself. IMHO they are some of the best available.
Interesting, I wonder how much better the $20 skf ones are compared to the $5 Misumi ones. For x/y that's $120 vs. $30.
I'm not sure myself, but I am willing to bet the jump from the standard chinese LM8UU bearings to the $5 Misumi bearings are a huge jump, while going from $5 to $20 is a much smaller jump. For me it was just a matter of not wanting to worry about it any more, and I was (perhaps some would say foolishly) willing to throw money at the problem and make it go away.

jonathan.b4
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:37 am

prusayo wrote:What options would be optimal:
Material: bearing steel or 440C stainless steel
Heat Treated: Induction Hardened (or not hardened)
Surface finish: None, hard chrome, low temp black chrome
Shaft Fits Tolerance: g6 or h5
Type: PSFJ or PSFU

I can't believe how choices there are!
Definitely G6, bearing steel with induction hardening. I am undecided on the hard chrome. It does make it a harder surface then hardened steel alone. But I understand it is already plenty hard as standard. So it may be more about aesthetics. Unless I can find a reason not to I would go with hard chrome because I tend to over do things.

jonathan.b4
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:54 am

Omikron wrote:I'm not sure myself, but I am willing to bet the jump from the standard chinese LM8UU bearings to the $5 Misumi bearings are a huge jump, while going from $5 to $20 is a much smaller jump. For me it was just a matter of not wanting to worry about it any more, and I was (perhaps some would say foolishly) willing to throw money at the problem and make it go away.
How many rows of balls do the SKF bearings have? The picture shows what looks like 8 but that may just be a stock picture.
Image
Last edited by jonathan.b4 on Fri Oct 21, 2016 4:56 am, edited 1 time in total.

Omikron
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:55 am

jonathan.b4 wrote:
Omikron wrote:I'm not sure myself, but I am willing to bet the jump from the standard chinese LM8UU bearings to the $5 Misumi bearings are a huge jump, while going from $5 to $20 is a much smaller jump. For me it was just a matter of not wanting to worry about it any more, and I was (perhaps some would say foolishly) willing to throw money at the problem and make it go away.
How many rows of balls do the SKF bearings have? The picture shows what looks like 8 but that may just be a stock picture.
They definitely have 8 glorious rows. The application note document from SKF for it's bearings refer to it as a "precision instrument" and they certainly feel that way.

prusayo
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Re: Replacement bearings recommendation

Fri Oct 21, 2016 4:57 am

jonathan.b4 wrote: Definitely G6, bearing steel with induction hardening. I am undecided on the hard chrome. It does make it a harder surface then hardened steel alone. But I understand it is already plenty hard as standard. So it may be more about aesthetics. Unless I can find a reason not to I would go with hard chrome because I tend to over do things.
Here is a ton of info on rods from Misumi, I may try the LTBC coating:
https://ultimaker.com/en/community/5103 ... ion?page=3

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