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.