5/8 keyed shaft trouble

[dddriveman]

Our keyted shaft this year is exactly the right size but it will not fit into our bearings very easily w\o geting stuck. Any advice PLEASE HELP ME!!!!!!!!!!!!

bty: the size of the bearing opening is .623
and the shaft is .625

[DaBruteForceGuy]

two things you could do... first is get yourself a 5/8 drill bit and bore out the bearing (fancy vice work if you are using a roller bearing)... also, the other side is to take some very fine grit sand paper and sand your shaft... be careful to do the whole shaft though so you may fit something the whole length up... grease her up and good luck to ya!

[ShadowKnight]

Aye, sandpaper most likely would most likely be your best bet. Hint on using it, roll the sandpapaer around the shaft so that you sand evenly the whole circumference of the shaft. It may take a while but it's easier than having to go out and shell out the bucks to purchase 5/8" shaft and have it machined and wait, or wait for keyed 5/8" shaft to come via mail. I hope that helps...God bless

[sanddrag]

Liquid wrench makes things fit that seem like they won't. Give it a good soaking. Also, make sure that there aren't any burs on the shaft. I would not go boring your bearing.

[DaBruteForceGuy]

... yea come to think of it you're probabaly using a ball bearing and those really aren't the greatest things to be boring out. Brass bearing on the other hand are ok...

[Ed Sparks]

We gave up long ago trying to force fit those nice precision bearings on non-precision shafting. We now bite the bullet and order precision shafting (slightly undersized) from McMaster-Carr (see "Keyed Shafting"). The more force you apply in assembling these two parts, the greater the odds that you will have to dis-assemble these two parts at the worst possible time.

-or-

A lathe, some emery cloth, and time ................

[Alex Cormier]

there was a post earlier stating that the 5/8 keyed shafts do not fit again this year that comes in the kit with the bearings.....

[Andy Brockway]

We have had good success chucking the shafts in a lathe, running at medium high speed and using a file. This will take off material faster than emery so check often with verniers or calipers. Stop when the bearings slide freely. This takes two passes as you swap ends of the shaft in the chuck.

Keep the file moving just like you were filing a stationary piece and clean the file frequently.

[Adam Y.]

The edges of the shaft could have be knurled. This usually happens when you drop the shaft on its end. When this happens the end actually mushrooms and becomes bigger. This results in a shaft that does not fit. Also, since your bearings are getting stuck on the shaft at certain areas that means the shaft has burs on it. Take a piece of emery cloth to it. Do not use sandpaper. That will make the problem worst. Also since emery cloth is designed to take material away from the shaft do not do it too much.

[Tytus Gerrish]

we had a similar problem with an OD ont firring into an ID we had 4 rookies with sandpaper for 3 hours to solve that problem,

[Dick Linn]

Our shaft was precisely at .6250 while the bearing holes are about .002 under. We're ordering another shaft from MSC (page 1802), which should be anywhere from -0.0005 to -0.0015 under. Hopefully we'll get one that's on the small side and won't have to sand much. I didn't check the McMaster-Carr equivalent to see what it's tolerances were.

BTW, a .002 press-fit isn't unusual but makes it a pain to get things in and out. In normal service, you wouldn't want the inner bearing race to start spinning on the shaft, or it could end up welded to the shaft.

[Mr. Ivey]

They were made like that for a reason. Look at the shaft from last year, and look at this year's shaft. This year's shaft is a lot nicer, it's set like a gear shaft in a car or something to that extent. The reason it's so hard to get a bearing on there is because they need to be pressed on there by a bearing press, and pulled off by a bearing puller. You can get the puller at a NAPA or another auto shop. To press them, get a piece of soft wood and a big hammer. Find a work bench with a hole drilled in it that's bigger than the shaft, but smaller than the bearing, or something of the liking. Tap the shaft into the bearing using a rubber hammer until it's just fitted inside of the bearing. Then center the shaft and the bearing over the hole in the bench. Place the soft wood over the other end of the shaft (the one that's pointing up), then slowly drive the shaft through the bearing to a spot that you have marked. Be sure to hit the piece of wood exactly where the shaft is on the other side. Go very slow and be very exact. This is what I have done to get the bearings on, to get them off, I just get my puller out of my mechanics tools at home.
Hope that helps.
ivey