A great tool for lapping sizing dies

[Michael J. Spangler]

http://www.mcmaster.com/#expandable-laps/=l82y9e

So I just used one of these for lapping out my .401 die to .403.
It worked awesome. I started with a 3/8" through hole expandable lap. It expands to 15% over its original size.

My machinist buddy helped me with it so it was a pretty solid set up. He put the die in a collet on a fixture on the table of his Bridgeport then he chucked the lap in the mill, lied it up and went to town. We started with too fine of a grit compound and worked our way up to 45 micron which pretty fast.
I believe it was a diamond compound.

Definitely worth the $ if you want super precise control and a concentric sizing die.

I spent about $3 on a wooden dowel and probably as much on some cheap sandpaper to try to lap it with a hand drill. I could have spent the $7 on this lap in the first place. Definitely worth it.

[Char-Gar]

Way to complex and way to much money for a simple operation. But some 320 grit Clover emery paste and that is all you need to buy. Coat some cast bullet with these and push them through the die. Add more paste when they start to get easy and measure often. It doesn't take long to open up a sizing die .001 - .003. Clean the dies well with some kind of solvent to get rid of any grit. I use plain rubbing alchol. The Clover paste will have all kinds of uses around the shop. I bought a small can in 1968 and it is just about gone. Time to buy some more.

[mdi]

Thanks for posting that tool. One can never have too many tools or too big of a toolbox!:mrgreen:

[leadman]

Those might also be a great way to open up a mold as less chance of getting it out of round than with a boolit and lapping compound. Price is very reasonable also.

[rbertalotto]

I love tools! Can never have enough!

Thanks!

[alfloyd]

Take a look at these:
http://www.kbctools.com/usa/Navigation/NavPDF.cfm?PDFPage=608

That is what I use, with diamond lapping compound.

Lafaun