Made a few mold laps

[Mike W1]

Have been fiddlin' around trying to come up with a method to make a lap and here's what I came up with. I liked the idea of a nut cast in place with a cardboard separator to clear the top of the mold. Tried several materials and finally came to using a piece of Pepsi carton. After making the pattern and punching the holes a couple small drops of Elmer's glue kept the nut in place and dried it overnight. Pattern was sized to the mold top (sprue plate removed) and made it simpler to center the holes fairly well. Right side was left longer and longnose pliers were used to mount on the hot mold. Seems to work.

To get decent fillout I found it necessary to preheat on the hot plate which in this case was set to 380° F. By the time the Lee 10 lb pot was up to 374° C (about 706° F) the plate was staying at set temperature and the mold was about 306° F. Mold temperature would drop about 20° F in the process of fitting the pattern and nut and pouring it. Smaller mold than this would likely be easily done with this method and a reduction in both nut size and punched holes. Also tried a 1/4" hole instead of the 3/8" but couldn't see any improvement in things. Cast 6 on this attempt and they pretty well centered the nut on the bullet. Used a Lyman DC 452374 mold. FWIW

http://i.imgur.com/nrR52Lp.jpg
http://i.imgur.com/4PUFIB4.jpg

[Yodogsandman]

Thanks, I was thinking of using tape for a spacer. What's your goal here, from what diameter to what diameter? What will you use for a lapping compound on a steel mold?

[jsizemore]

I drill a 1/8" hole in the base of the boolit and then use this polishing mandrel from my Dremel kit:

https://www.dremel.com/en-us/Accessories/Pages/ProductDetail.aspx?pid=401

Chucked in my battery drill at slow speed with a little Flitz or Maas metal polishing crème makes short work of sticky cavities.

[Mike W1]

Thanks, I was thinking of using tape for a spacer. What's your goal here, from what diameter to what diameter? What will you use for a lapping compound on a steel mold?

I have a different mold that sticks sometimes and figured I'll just "polish" it with a mild abrasive sometime. Not looking to change any diameters. Whatever to use, it'll be as fine an abrasive as possible to find.

[OS OK]

My first thoughts were to use a 'centering transfer punch' (upside down, point up so it doesn't mar the boolit nose in mold) that's a smooth fit so you can just slide the nut and spacer over the punch down onto the top of the mold, or 'pre-thread' it onto the punch first, then hold the nut down with needle nose and gingerly slide the transfer punch up and out.
Waaalaah! Seems as though it could be done quickly and without loosing too much heat…preheat the punch? I dunnoh? Then you'd be handling all the parts with pliers that add some difficulty to working fast and accurate.
I like the hex nut idea as I would like to have more positive control of that boolit without putting undo torque in some off angle axis direction causing a wallough. Is that a word? You get the meaning though…I have this to do on a 6 ganger and hesitate to jump in right away without lots of input just like yours here…thanks!

OS OK

[MT Gianni]

I have a different mold that sticks sometimes and figured I'll just "polish" it with a mild abrasive sometime. Not looking to change any diameters. Whatever to use, it'll be as fine an abrasive as possible to find.
Try comet cleanser and toothpaste. Mix 50-50 and then cut the head of a self drilling deck screw about 1 1/2" long. pack the bullet with the abrasive, chuck the screw up in a cordless drill and turn it until the bullet starts to rotate. If you get nervous that you are going to drill out the bottom mark the screw at the bullets length with tape and stop before you get there.

[44man]

Polish is one thing but I have had to enlarge many molds and I needed to cast at each stage to get larger boolits as I went. The boolits wear fast. I needed to enlarge only drive bands or a GC portion a few times and made rings of brass that fit, had to make many because you would be surprised how fast they wear down. This because I had a good bore fit and did not want to enlarge the nose. Then to solve the loose GC fits.
Worst were Minie' ball molds from Lyman when friends could not hit a 4'X4' board at 50 yards. After lapping, they could hit the gong at 200 meters. That was fun, I dropped the hammer on the gong once, thought I missed and turned to load another when the DING came back.