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Video Man
01-29-2010, 01:25 PM
Having to bore out a bunch of steel wheels for a kiddie train at the local railroad museum where I volunteer...installing 2.250 diameter tapered roller bearings...can anyone help me with the proper bore diameter for this? There has to be some clearance so you can get the bearing race back out if you had to...but I don't know where to find out how much clearance to allow. Appreciate any help! :) / video_man

Limy Sami
01-29-2010, 01:47 PM
Any help?


http://www.maintenanceresources.com/referencelibrary/bearings/rbshf.htm

Video Man
01-29-2010, 01:56 PM
Any help?


http://www.maintenanceresources.com/referencelibrary/bearings/rbshf.htm
Thanks, the info there serves to show that "nothing is ever easy"! But I didn't find any data or formula to say how big a bore to make..thanks for pointing out the site, it does have a lot of other info..../video_man

MarshSt
01-29-2010, 03:32 PM
I don't have an easy answer but I remember finding fit sizes in the mfg catalogs based on bearing size and type. Maybe the Timken catalog on line..............

Steve

wierdscience
01-29-2010, 03:42 PM
Cups in that OD range +.000/-.0015"Even if you bore them in .002" oversize it's nothing a dab of loctite won't fix.

If they ever need to be removed for replacement a quick pass around the race with a MIG gun will shrink them out.

motorworks
01-29-2010, 03:48 PM
Bore so that it is just a light push with your thumbs at room temp and as good old WS said, loctite :)
eddie

Dr Stan
01-29-2010, 03:50 PM
Have you checked "Machinery's" or Audel's Millwright's book?

.RC.
01-29-2010, 04:14 PM
There has to be some clearance so you can get the bearing race back out if you had to...but I don't know where to find out how much clearance to allow. Appreciate any help! :) / video_man

Nope... With bearings the rotating part is always a interference fit..

The specs for a rotating outer housing 50-80mm in size with an N7 fit (normal loads) is -9 to -39 microns

Carld
01-29-2010, 08:39 PM
Video Man, if you will give the bearing # and race # I will look them up in my bearing catalogs and give you the specs.

oldtiffie
01-29-2010, 08:49 PM
Having to bore out a bunch of steel wheels for a kiddie train at the local railroad museum where I volunteer...installing 2.250 diameter tapered roller bearings...can anyone help me with the proper bore diameter for this? There has to be some clearance so you can get the bearing race back out if you had to...but I don't know where to find out how much clearance to allow. Appreciate any help! :) / video_man

The OP had pretty well specified a light clearance fit - "some clearance" just about says it all.

Seems to be a "Loctite" job as said, so I'd suggest the required bore size = bearing size +0.0005/+0.002".

I am surprised that he didn't specify the inner race "fit" as well as removal of one race pretty well suggests the other is a similar fit.

Video Man
01-29-2010, 09:15 PM
Video Man, if you will give the bearing # and race # I will look them up in my bearing catalogs and give you the specs.
Thank you, they are 15578 cone, 15520 cup. And a big thanks to you and everyone who replied, really appreciate your interest, guys!

Video Man
01-29-2010, 09:20 PM
The OP had pretty well specified a light clearance fit - "some clearance" just about says it all.
I am surprised that he didn't specify the inner race "fit" as well as removal of one race pretty well suggests the other is a similar fit.

Using the same bearing on both side, this will be like a trailer axle, sort of. I remember doing wheel bearing replacements on my Ford in the 70's, a drift punch would knock out the inner races if you took your time, so am figuring there's a light fit there... thanks for your reply! /video_man

wierdscience
01-29-2010, 11:02 PM
When I remove roller bearing cups assuming replacement the easiest method is to run a bead of weld around the bearing face.The heat expands the housing bore slightly and the contraction stress of the weld shrinks the race to a point they nearly fall out.

This method also works on ball bearing races stuck in blind bores.

Carld
01-30-2010, 12:17 AM
15520 cup 2.2500" OD--.5313" wide--bore size -.0010" to .0000" that means you want the bore no more than .001" undersize.

15578 cone 1.0000" ID--cone length .6875"--fit on shaft +.0005" to .0000" that means the shaft can be .0000" to .0005" oversize.

Overall width of cone/bearing assembly--.6875

Video Man
01-30-2010, 04:23 PM
15520 cup 2.2500" OD--.5313" wide--bore size -.0010" to .0000" that means you want the bore no more than .001" undersize.

15578 cone 1.0000" ID--cone length .6875"--fit on shaft +.0005" to .0000" that means the shaft can be .0000" to .0005" oversize.

Overall width of cone/bearing assembly--.6875
Thanks a million,Carld, much appreciated! :o /video_man

Machinist-Guide
01-30-2010, 07:18 PM
A little tip for installing your bearings.
Put the race in the freezer and freeze it. This will cause it to shrink and make it slide into the bore much easier.
Assuming you don't have a bearing heater. Heat the bearing with a hair dryer this will cause it to expand and slide on the shaft easier. You can heat them in your kitchen oven but don't get them too hot. 100-150F should do it. I think the bearing heaters at work are factory preset at 150F

Video Man
01-31-2010, 03:46 PM
A little tip for installing your bearings.
Put the race in the freezer and freeze it. This will cause it to shrink and make it slide into the bore much easier.
Assuming you don't have a bearing heater. Heat the bearing with a hair dryer this will cause it to expand and slide on the shaft easier. You can heat them in your kitchen oven but don't get them too hot. 100-150F should do it. I think the bearing heaters at work are factory preset at 150F

Aha! That's assuming I can bore to that kind of tolarance in the first place, 40 wheels at 2 bores each, ahh, probably some will drop in and some will need a jackhammer...! Thanks for the info! /video_man

EVguru
01-31-2010, 05:30 PM
Put a couple of notches in the housing so you can get a drift to the back of the race.

Carld
01-31-2010, 07:56 PM
Locktite is your friend.