Centering up a shaft in a much larger bore

[R.G.]

I had a friend ask me how to center up a cylindrical shaft inside a larger bore, and leave room for pouring the gap full of catalyzed urethane rubber. He was dreaming up external fixtures to hold the shaft and bore, with release layers and so on.

I had this idea that if one took fine music wire, and wound a spring on a triangle-shaped core, similar to winding a spring, that when the tension was removed, it would semi-unwind into a series of almost-triangular sections in a spiral. If one inserted the shaft into the spring-of-triangles, then inserted this mess into the bore, the triangle sections would on average center up the shaft in the bore, by all being symmetrically bent by the shaft and bore. The bore could then be poured full of ****.

Will this work?

 

[Tom Griffin]

R.G.

I supposed it depends on how concentric the bore and shaft need to be. The spring thing would probably get you close but if you are looking for concentricity within a few thousandths, an external fixture will be required.

Tom

 

[Tony Wells]

Without knowing the particulars of size, what about positioning the housing on the mill table on X-Y zero, and putting the shaft in a collet or chuck also on center, then fill with goo?

 

[R.G.]

Oh, sure. Do it the simple, direct, smart way!



Probably something like acetal or nylon donuts with wax on them would even release from the **** as well as holding a tolerance.

 

[jonathan01]

I sketched this real quick. The sketch is not really fully designed, you have to add nuts on each side of the blocks and on the outside of the fixture and such. You should be able to figure out the idea i am trying to show. As far as release layers I don't know that.

It is basically threaded rod and blocks to center the pipes.