Fabrication and inspection of tight tolerance bushing

[fastline12]

Need to make some tight tolerance bushings with a .120" ID +/- .00015. The question is we do not have an ID grinder and even if we did, not real sure how you grind such a small ID.

I am not sure if we can hold that tolerance with the drill/ream method but just maybe. In addition, the spec calls for an HRC 58-62. I am concerned of my tolerances going all funky with HT so considering hard turning that but never turned something that hard before. Even if we could get the work done, I am not real sure how to inspect something like that.

We could of course send these out but we have more coming and would be nice to keep the business in house.

 

[MintJulep]

How long is it?

 

[fastline12]

Some at .250", some at .500"

 

[dgallup]

For something like that you need to make a rough machining, heat treat it & then grind it.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[MikeHalloran]

Lathe +
toolpost grinder +
Borazon grinding pins +
patience.





Mike Halloran
Pembroke Pines, FL, USA

 

[fastline12]

Any thoughts on inspection of this bore? Finish is not on the drawing yet. My first reach is an air mic but they typically have an extremely small measuring range and we have several sizes to do. Can a comparator do this?

 

[IpsumSD]

You could inspect it with .0001 increment gage pins, but it won't be easy. If you can fit a .0001 undersize pin in but not a nominal, the hole is probably good. It's tricky with increments that small.

Otherwise an air micrometer will probably do the trick.

Matt Coughlin
Ipsum Engineering

http://www.IpsumSD.com

 

[dgallup]

If your diameter tolerance is that small you probably need to measure roundness too.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[ornerynorsk]

Honing or lapping may be the most cost effective and practical. You cannot ream material of that hardness and maintain any kind of accuracy or finish. ID grinding is tedious at best, though there are firms that do it well. An air gage should do the trick nicely.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.