5/8 keyed shaft trouble

[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

[magnetnerd]

Our shaft seems to be a little bit on the small side...the bearings, gears, etc. slide on and off with ease. Last year our shaft was aluminum and we had steel gears, this year we're using steel shaft and steel gears. Any ideas on how to keep the bearings where they are?

[Dick Linn]

Originally Posted by magnetnerd

.... Any ideas on how to keep the bearings where they are?

We use shaft collars, which are readily available from MSC. Price is typically in the $1.50 - $4. range.

[Ali Ahmed]

If you have accsess to a lathe, put the shaft in there and take some fine sandpaper to it. We find that this works really well and it is better then having someone just sit there and sand becuase this will keep it nice and circular.