bearing press fit question

bhigdog · Sep 21, 2020

I need to press a 1.375" ID ball bearing the length of a 7.5" long 1.378" shaft to a shoulder. A .003" interference fit. I only have a 10 ton hyd press. I figure heating the bearing is a waste of time as is chilling the shaft. Your thoughts? Doable or should I just farm it out. I'd use a moly anti sieze. Thanks...Bob

Limy Sami · Sep 21, 2020

IMO 0.003'' is a very tight press fit??? ...........I'm not saying its wrong, just check on bearing fits required by the manufacturers

Can you reduce the diameter of the shaft where the bearing doesn't seat - ''only'' 0.001 - .0002'' is enough

Bobw · Sep 21, 2020

I'd guess that the 1.378 shaft isn't going to be 1.378 after the bearing gets pushed over it.
And its not going to look very good either.

Gordon Heaton · Sep 21, 2020

A fit like that for 7+ inches is nuts. Its too tight even for a bearing length fit. If this is a new build and you can't relieve the shaft, maybe you should build up the bearing seat and pick a different bearing. A 35mm bore bearing would give you a good fit with either minor shaft build-up or chemical bearing mount, and might be available with the required OD. If not, perhaps the OD bore could be adjusted?

bhigdog · Sep 21, 2020

It,s the crank bearings for an IR compressor. The fit is what it is. I measured quick and dirty so maybe it,s a bit less but still pretty heavy. The oem replacement crank comes as an assembly with bearings attached. I,m guessing i,ll need a heavier press.......bob

atomarc · Sep 21, 2020

Why the shaft isn't reduced where there is no bearing or seal fit is pretty strange, but I think if you did heat the bearing to the max safe limit allowable, and did chill the shaft a tad if possible, that the bearing would slide right down the shaft and you'd be in like Flynn.

7.5 inches isn't that long...just ask my wife!

Stuart

Phil in Montana · Sep 21, 2020

Fit is to tight even for a C-3 bearing, and heating and cooling are NOT a waste, they are the only way to do it. your fit should be .0003-.0005 tight and relieved up to the fit...Phil

13engines · Sep 21, 2020

I'm sorry Bob, but I'm having a hard time believing that's an inch series bearing. The 1.378 is pretty much dead on a 35mm (6XX7 series) bearing. 0.003" is too much fit for a bearing that size. Where's the need?

If your bearing doesn't have R22 on it and have a 2 1/2" OD, I bet you'll see 6007 on there. (35X62mm) Honestly, I've replaced a a lot of bearings in my life and it's hard to recall handling an inch series bearing across any type of equipment or vehicle. Maybe there are some common types of equipment that tend to use inch series bearings. All I know is I've not run across it. At least that I can remember. Maybe some wheel bearings?

You said down and dirty measured. If you got one, flip that caliper over to metric and see what it tells you.

Ha... or maybe I just have mush for memory. But seriously... 3 thou fit? Yeoch! Wonder what IR could tell you?

Did that bearing come as part of a kit? Or did you source it yourself using down and dirty measurements?

bhigdog · Sep 21, 2020

Yup, could be metric. I'll have to dig it out of the shit can. Measurements are of the shaft and the OEM bearing I pressed off (with difficulty and lots of heat). I'm beginning to think I was bit hasty/sloppy in my measuring. I agree .003 can't be right. ...Bob

mattthemuppet · Sep 21, 2020

Can you still read the bearing code of one of the shields on the original bearing? Assuming it had shields that is...

MattiJ · Sep 22, 2020

mattthemuppet said:
Can you still read the bearing code of one of the shields on the original bearing? Assuming it had shields that is...

Sometimes manufacturers use oddball bearings with outer diameter in mm and inner in inches or vice versa. These are not necessarily marked in any obvious way.
I stumbled once to 608 bearing with 5/16" bore. Took for a while to fiqure out what the f*** is going on and another collection of swear words to find out that replacements are not available easily from anywhere.

Mike1974 · Sep 22, 2020

I've used dry ice in the past for heavy press fits. IIRC, something like a 4" OD bronze tube pressed into a steel cylinder...

bhigdog · Sep 22, 2020

No shields. Ball bearing with open retainer.........Bob

Richard Friedman · Sep 22, 2020

.003 press fit

bhigdog said:
No shields. Ball bearing with open retainer.........Bob

.003 press fit on a solid steel shaft will cause your inner bearing race to grow almost that much. You balls will be cramped and the bearing will not last.

bhigdog · Sep 22, 2020

Understood. I'm going to do a better job of measuring this am. The shaft does measure 1.378 with no relief in the center section. .....Bob

bhigdog · Sep 22, 2020

My face is red. After measuring the way I should have: The bearing is a MRC 207, 35MM ID. The shaft is 1.3785 so it looks like about a .0005 interference fit. Way more doable.
A trial heating of the old bearing to 300F grew it about .002. I'm thinking it should not be a problem. (famous last words). Hey, thanks for the input guys........Bob

BoxcarPete · Sep 22, 2020

Best to keep the bearing below 225F, but a short trip to 300 isn't likely to do too much harm. Sounds like 225 should give you enough growth as it is though.

Mike C. · Sep 22, 2020

Shaft diam 1.3781-1.3785 for that fit.

Mcgyver · Sep 22, 2020

bhigdog said:
My face is red. After measuring the way I should have: The bearing is a MRC 207, 35MM ID. The shaft is 1.3785 so it looks like about a .0005 interference fit. Way more doable.
A trial heating of the old bearing to 300F grew it about .002. I'm thinking it should not be a problem. (famous last words). Hey, thanks for the input guys........Bob

I was paging through thinking 3 thou, man those bearing catalogues are way off

. Not having fancy bearing heating equipment, I use a 11g sq bit of steel on a cheap hot plate place he bearing on top of it then watch it with one of cheapo infrared thermometer guns. irrc 250 is the safe limit. Every time I've done it, 250 F gives lots of clearance and it just drops right on. I wouldn't think the the 7" would be an issue.

BT Fabrication · Sep 24, 2020

Mcgyver said:
I was paging through thinking 3 thou, man those bearing catalogues are way off . Not having fancy bearing heating equipment, I use a 11g sq bit of steel on a cheap hot plate place he bearing on top of it then watch it with one of cheapo infrared thermometer guns. irrc 250 is the safe limit. Every time I've done it, 250 F gives lots of clearance and it just drops right on. I wouldn't think the the 7" would be an issue.

250F will be plenty, it could grow about 0.0025" id.

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