Lapping holes?

[Guy Thomas]

I just finished reading Tim Zowada's article in "Knives Illustrated" on the details that make a fine custom knife. In it he mentions drilling, reaming and lapping the pivot hole on a folder blade. Drilling and using a straight reamer to get a precision sized hole I understand, but what is lapping?-Guy T.

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I have gotten a lot of results.
I know several thousand
things that won't work.

Thomas A. Edison

 

[Darrel Ralph]

Lapping can be done with a hole lap . They can be bought at J and l Industrial supply for under 10.00 for the lap you want for your hole size. Sewveral differnt compounds are available for the type of material you are lapping.



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[Guy Thomas]

Thanks for the info Darrell, so lapping is a type of polishing of the interior of the hole?-Guy T.

 

[Sumo]

Lapping typically is done by taking a mandrel made of metal softer then the one you want to lap (ie. brass/cast iron/copper) and embedding the grit into it, basically the mandrel acts like a hone once you've done that, and takes very tiny amounts of material if a fine grit is used(1200 grit or so).
Another thing I've done a few times (havent tried it on a folder though) is when you're polishing the 'male' part, you take it so it barely will slide into the female part, and rub some of the abrasive from a piece of wet crocus cloth onto it. Not quite as nice as lapping but in the end both surfaces and up being mated together rather nicely.