1st attempt casting a lap

[Mike W1]

Want to lightly lap a couple Lyman DC .45 moulds so did some experiments today. Set the hotplate for 349°F and the pot at 709° F and heated things up. Used a brass 3/8" compression nut as well as 3/8" steel nuts with cardboard separators. The ones made of the thin cardboard from flat rate boxes seemed to work better than the other stuff from an office type folder. Kind of like the gap idea and steel nuts are cheaper than brass so I may end up going that way.

Hottest mould temperature I ever got was 304° F and fumbling around by the time I got ready to pour it'd usually dropped 18-36° F. Laps weren't perfect but not real bad either. Punched the pour holes in the cardboard with a 1/4 paper punch. Next go round I'm gonna punch the pour hole 3/8" , make the pattern slightly larger and put a 1/8" punched hole to go over the sprue cutter stop pin. Should get a little less temperature loss that way as it'll be quicker to do.

Also think I'll jack up the temperature on the hot plate and pot both by about 50° F which will probably help.

Any suggestions to what else I might try to cast a better lap? I've pretty well gone through all the notes I've accumulated over the years and some newer ones recently passed to me.

Thanks.

[dragonrider]

I like your idea using the cardboard for a spacer but I don't see the need for a perfect lap.

[country gent]

Should work okay you dont need perfect bullets to lap, a few light wrinkles will help carry compound. I ussually just drill a blind hole in the base of the bullet and glue a stem in them. a piece of 1/9" key stock drilled hole dia across corners and epoxied into hole does a great job. I would go with thicker card board or a couple layers glued together. A square with hole punched for stop pin and tucked under sprue plate on other side and holes punched on location would help hold it in place a little clay around the outside would help hold nuts while filling.