Lapping wrist pins

[Humph7ey]

I have to make my own pins. They are 9/16" x 2. 3/8 long which will be case hardened.
Any ideas for lapping to the high finish required? I have some cast iron bar that I can use to make laps and some coarse carborundum but how will I get the fine finish?

 

[Blogwitch]

If you are trying to get down to size, then exterior hones might be what you require. If you are just trying to get a nice polished surface finish, then very fine wire wool should obtain that.

I bought my set of hones from Polly engineering, but I still need to make them (one of my first jobs when shop gets up and running). Download the catalogue from here. Well worth having just to see what is available.

http://www.pollymodelengineering.co.uk/sections/bruce-engineering/tools.asp

John

 

[Humph7ey]

They look posh, but I think I could get by with some bent metal and a hinge with some iron and lapping compound. That is an amazing catalogue by the way.

 

[rlukens]

You might give burnishing tools a look. A single point burnisher in tool holder will give great results.

Edit: I assumed your talking the pin OD and not the rod bore.

 

[Humph7ey]

They are going to be case hardened but thanks for your interest.
The cast iron lap seems to work well on an old pin. lost a couple of tenths in 5 minutes.