Bearing Issue...Never Seen This Before...

[Rob F.]

P.S. You are spot on with poor engineering practices and incompetent installers all around, hence I am leaving at the end of June. Long story, but I find it hard to work at a place where torque wrenches are never used, micrometers for bearing replacement gather dust, and the answer to something failing is to just swap in a completely different piece of gear.

Sounds like a good move to keep your sanity

 

[mottrhed]

I would appreciate the second check on both the housing and shaft. I did the math for the fitment when I started noticing that we were replacing these bearings every four weeks and no-one here could give me a good answer on if it was a K5, K6, H6, H7, etc. type fit. The part number for the bearing we are using is SKF BS2-2206-2RS/VT143.

P.S. You are spot on with poor engineering practices and incompetent installers all around, hence I am leaving at the end of June. Long story, but I find it hard to work at a place where torque wrenches are never used, micrometers for bearing replacement gather dust, and the answer to something failing is to just swap in a completely different piece of gear.

Sorry to everyone for posting, I should have caught that chatter mark going all the way to the bottom of the bore and the chatter on the outer edge of the c-clip groove. I brain-farted. LOL. There is an old dude rolling in his grave right now, because he would have slapped me upside the head saying "I taught you better than that."

Ya, unfortunately some people just don't have the desire to learn and do things right. Good luck with your next endeavor!

Anyway, thats a spherical roller, you can pull up all the tolerances on skf's website, quick glance I saw k6 shaft fit and n7 housing fit, but without knowing the application and forces Im kinda in the dark and thats just a starting point. But that housing wall is so thin that any significant interference will just stretch it. If it was going through my shop and I didnt know anything else about it, Id make the shaft fit +7/+10 microns interference, and the housing -10/-15 interference. Note, Im not saying make the housing -10/-15 below nominal, as the outer race will likely be -5/-7 out of the box, so take that into account to hit the "mounted interference". That being said, with a straight bore roller you are setting the mounted negative clearance (aka preload and/or clearance) in that bearing by the shaft and housing fits... Hopefully its spinning slow and you can get away with some sloppy tolerancing.

 

[ezduzit]

My first thought was tool chatter. However it is possible the marks came from the bore first having been knurled (to eliminate a loose fit) prior to machining.

 

[RC Mech]

Chatter

In this thread or on the part?

 

[michael.kitko]

Id make the shaft fit +7/+10 microns interference, and the housing -10/-15 interference. Note, Im not saying make the housing -10/-15 below nominal, as the outer race will likely be -5/-7 out of the box, so take that into account to hit the "mounted interference". That being said, with a straight bore roller you are setting the mounted negative clearance (aka preload and/or clearance) in that bearing by the shaft and housing fits... Hopefully its spinning slow and you can get away with some sloppy tolerancing.

Thank you for the quick double check. That's almost what I had. I had the +7/+10. I went a bit small on the housing coming in at -5/-10 due to what you said with wall thickness. It spins at about 800 RPM max. Again, thank you for the quick double check.