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Stan Thomas

Hi Dave,

Reaming is not the problem – its the steps before!!!

If you try to ream out any material from a small end bush, invariably you will end up with a bell-shaped hole, with no guarantee the gudgeon pin will be parallel to the big end eye.

So start by reaming the bushes in a lathe to size. Better still, turn both the O/D and I/D to size from stock material so the bush is parallel, allowing about 4 thou for interference fit.

What I’m going to say now will cause Roger Moss to have an epelictic (or is that epicyclic) fit.

Once the bush is in place, a small amount will need to be cleaned out due to shrinkage. Do this by tapping the reamer into the hole with a light blow with a mallet. Turn the reamer half a turn, and repeat the process. Aim to get the reamer through as quickly as possible.

DONT do the obvious trick if spinning the reamer round like a propeller – you will just get a tapered hole.

Dont worry about scratch marks from the reamer, and dont make the bush too tight otherwise it will pick up.

No need for lubricant – the object is to remove material.

Good luck.

Stan Thomas.