# PC guide bushings



## TWheels (May 26, 2006)

Why do the PC guide bushing sets always have a 51/64 OD bushing., and not, for example a 7/8 inch OD bushing?


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## tomp913 (Mar 7, 2014)

I believe that the 51/64" guide is used for the P-C Hinge Mortising Jig.


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## Cherryville Chuck (Sep 28, 2010)

Thanks. I've always wondered that too.


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## TWheels (May 26, 2006)

tomp913 said:


> I believe that the 51/64" guide is used for the P-C Hinge Mortising Jig.



Thanks very much @tomp913. That makes sense for why there is a 51/64 but does not explain the absence of a 7/8 in OD. I looked up PC hinge mortising jigs and saw mention of the need for such a guide bushing however.
It is 20.24 mm, a little to far from 20 mm for tight fitting joints, etc,


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