Bearings and shaft

[dnp101677]

I am bulding my first stirling engine and I am wondering how the shaft is supposed to fit into the bearings. The plans call for a .250 diameter drive shaft (the .250 is an open dimension - it actually says .250 Stock). So, I bought a piece of .250 dia. stainless that actually measures .249 dia. The ID of the bearing is .2475 dia. Will this be alright or will I need to turn another shaft that I can press fit the bearings onto? I am thinkning that maybe the weight of the flywheel is enough to allow the bearings to turn with the shaft instead of the shaft turning inside the bearing (I think I said that right). Any thoughts on this would greatly appreciated.

 

[ttrikalin]

Not sure I understand... a schematic or a drawing would go a long way towards that...

best
tom

 

[doc1955]

Not sure what your drawing are saying but .0015 press on that size bearing is to much. If you are looking for a press fit a .0003 - .0007 press would be more appropriate for that size.

 

[Powder keg]

You could just emery it down to a slip fit then use a dab of Locktite to hold it?

 

[Jasonb]

Is that the actual spec size of the bearing or are you measuring with digital callipers as these will under read at that sort of size?

Jason

 

[jonesie]

you need to ck the bearing id real close ,with small hole gage , gage pins or bore mikes, if you have a light press of .0003 and some green locktite will be all you will need if you make the press to tight you could ruin the bearing ,you could also heat the bearing in your oven at 300 degs then press on shaft, good luck

 

[kustomkb]

I would press the bearing into the housing with a half thou' interferance.

And polish the shaft for a snug sliding fit like powder keg said.

Assembly is difficult with press fits on both components.

Also the bearing races will swell and collapse the same amount of press fit so it could seize up a little.

jm2c

 

[dnp101677]

Thanks for the feedback guys. I'm glad I asked! By the way, we have a runner ;D. Just ran for the first time this afternoon after tracking down some air leaks and fixing them with o-rings. Now I have some questions on a heat source, but I think I will start a new topic for that one. Thanks again.

Dan

 

[Powder keg]

Somethings wrong with my monitor. I didn't see any pictures?

 

[dnp101677]

Here's a picture. Although it is not quite finished. I am making a new flywheel and polishing everything. Thanks again for the ideas.

Dan