Bearing Brand Advice

[Bill Adamsen]

Picked up a bit of a whine on my slider a few months back, holidays came and went. Finally getting around to buying the bearings - 2 required 6206zzc3. I did get some great advice from fellow SMC members (thanks Dave and Dennis) but now that I'm trying to buy the bearings I'm finding a bewildering array of suppliers and manufacturers ... and an unexpected variation in price. Are all the souces of equal quality or is there one source you have found of particularly high quality?

[Jerry Bruette]

Just get the best price you can for SKF bearings and you'll be fine. Not sure what brand you have now, if they're SKF the zz suffix means they have metal shields on both sides, the C3 suffix is the class of fit.

If your bearings have rubber seals then the SKF suffix would be 2RS.

[Joe Kaufman]

Are you sure about the size? That's a fairly big bearing for a slider, 62mm od, 30mm bore.

NSK (Japan) is another good quality bearing.

[Mike Goetzke]

From recommendation at OWWM I have bought several bearings from Accurate Bearing. Excellent products and service.

Mike

[David Kumm]

6200 series is about right for a newer slider. 6300 for older ones. ( Machine bearings have gotten smaller and cheaper ) My first choice would be SKF explorer as they are a little higher precision for not much more $$. If you will run the machine for hours at a time in a commercial environment, C3 is the way to go but as a hobby guy I stay with standard clearance. Fag, Fafnir, and then NSF or NTN are next in line. Motor bearings run hotter so the C3 clearance is normal for those. Dave

[Bill Adamsen]

Motor bearings run hotter so the C3 clearance is normal for those. Dave

Caused me to lookup SKF's "trouble conditions and their solutions" (page 106 (http://www.skf.com/binary/tcm:12-114679/140-710%20BIMG%2011_2012_tcm_12-114679.pdf)) and indeed for motor bearings they recommend C3 ... I'm assuming that relates to ABEC-3? But the bearings that I'm replacing are in a arbor assembly (the 6206 in the drawing) so I'm wondering if I could use bearings with tighter tolerances such as an ABEC-5. The bearings quoted by qualitybearingsonline were SKF Metal Shielded C3. Less than $10 each. The cheapest ABEC-5 bearing I can find is in the $50 range, with $140+/- more common.

The other question is about lubrication for the shielded bearings. Some of what I'm reading indicates that shielded bearings require and leverage lubrication. As shown in the attached drawing, there is a reservoir in between the bearings so I guess they are in fact lubricated and not "lifetime lubricated and sealed (http://www.machinerylubrication.com/Read/575/electric-motor-bearings)."

Lot to learn obviously.

[David Kumm]

Bill, the picture you show is not a reservoir but just a place for any grease to go that escapes the bearing. You want shielded or sealed. You are mixing clearance with precision. Two different things. Clearance relates to the extra distance between the balls and the inner and outer races so as the bearing heats up the balls don't start to get tight as the bearing expands. Ig both the inner and outer races are confined by a shaft or castings, the expansion will be against the balls. Normal clearance is CN which usually isn't stated on the bearing. C3 is a little looser and used when then outerbearing is captured in a casting like on your machine AND the bearing will be run for long enough periods to get warm or in hot condition, like in a motor. Precision relates to how perfectly round the inner and outer races are. The more round, the higher the precision and the less need for additional clearance as the balls don't have tight or loose spots to spin in. SKF explorer are ABEC 3 which is generally as high a precision as you will get with a sealed or shielded bearing. You can find higher but you don't gain much as precision bearings are often open and have brass or phenolic machined cages to reduce friction. First choice are Explorer or FAG, Fafnir etc. If all you find are C3, don't sweat it. not a deal breaker, I just prefer tighter clearance on a spindle bearing if not run hard. Dave

[Rich Riddle]

From recommendation at OWWM I have bought several bearings from Accurate Bearing. Excellent products and service.

Mike
If you call Accurate Bearing, ask for Lynn. She helps us hobbyist and is used to us. Just ensure you have all the measurements required when you call her. She's very knowledgeable and will help you get a good bearing at a reasonable price.

[David Kumm]

Accurate Bearing has very good prices and service. You won't get SKF, most likely NTN, or Nachi. If you need standard bearings they are a go to place. If looking for a specific cage, precision, or clearance you have to remember it makes no sense for them to spend much time sourcing even one $100 bearing so best to do your own research. Dave

[Bruce Wrenn]

To help you get an understanding of bearings, go to "The Big Bearing Store," and look up how bearings are made. Maybe someone could post the link to make it easier.