Installing bearings; heating vs. cooling

mmorris · Post by **mmorris** » Sat May 08, 2010 12:33 am

I installed quill bearings and drive sleave bearings today; one drive sleave bearing was very tight.
I've investigated several websites and they all say to cool your bearings and heat the shaft before installing. It seems that heating the shaft would cause it to expand and cooling the bearing would cause it's opening to contract, just the opposite of what is needed. What am I missing here? Does this really work?

JPG · Post by **JPG** » Sat May 08, 2010 1:48 am

[quote="mmorris"]I installed quill bearings and drive sleave bearings today]

What you have described is basackwards.

The 'male' part gets cooled, the 'female' part gets heated.

Thus the drive sleeve gets cooled and the bearings heated prior to putting bearings on the shaft. However, when putting the sleeve with bearings into the headstock bore, cool the sleeve/bearings and heat the headstock.

It must be done quickly before the heat transfers and the dimensions return to 'normal'.

A bearing puller/installer is necessary for tight fits.

mmorris · Post by **mmorris** » Sun May 09, 2010 8:13 pm

That makes sense; I don't know what the other sites were discussing. How much heat can the bearings take before installing; 200, 400 degrees F?

JPG · Post by **JPG** » Sun May 09, 2010 8:27 pm

[quote="mmorris"]That makes sense]

I would not go over 200. Ya do not want to break the grease down. I really really recommend the bearing puller for this!!!!!!!

SDSSmith · Post by **SDSSmith** » Sun May 09, 2010 8:44 pm

JPG40504 wrote:I would not go over 200. Ya do not want to break the grease down. I really really recommend the bearing puller for this!!!!!!!

I prefer using a press for installing the bearings and the puller for removing them.

mmorris · Post by **mmorris** » Sun May 09, 2010 8:54 pm

I used the puller to try to press one bearing in the drive sleave (the other went on easily), but couldn't get it to push it in (the screw part kept slipping off the top of the drive sleave) and had to resort to a pipe that fit on the inner race and a hammer. It went on fairly hard, so I hope I didn't damage the bearing. I'll try putting the motor in the freezer before I do those bearings.

JPG · Post by **JPG** » Sun May 09, 2010 11:23 pm

SDSSmith wrote:I prefer using a press for installing the bearings and the puller for removing them.

Since we are discussing the 'drive shaft', they can be 'pulled on'.

The press works good only if you have one!

The pipe method works if the end of the pipe is square. The secret is tap gently from multiple directions to prevent binding.

mmorris · Post by **mmorris** » Sun May 09, 2010 11:30 pm

JPG40504 wrote:Since we are discussing the 'drive shaft', they can be 'pulled on'.

The press works good only if you have one!

The pipe method works if the end of the pipe is square. The secret is tap gently from multiple directions to prevent binding.

Gently? Woops.

SDSSmith · Post by **SDSSmith** » Sun May 09, 2010 11:41 pm

JPG40504 wrote:Since we are discussing the 'drive shaft', they can be 'pulled on'.

The press works good only if you have one!

The pipe method works if the end of the pipe is square. The secret is tap gently from multiple directions to prevent binding.

You are right jpg, the press works good if you have one. I didn't so I use a hydraulic jack, a frame made of two by fours and hardwood pieces with holes sized to whatever I am pressing on.

JPG · Post by **JPG** » Mon May 10, 2010 1:55 am

SDSSmith wrote:You are right jpg, the press works good if you have one. I didn't so I use a hydraulic jack, a frame made of two by fours and hardwood pieces with holes sized to whatever I am pressing on.

Interesting!!!!!