Ideas on making a core die

[wywindsor]

I have a blank 7/8'' die. A mill and lathe. I need a core die for a .22 spent case setup I bought. So I'm thinking .1875 roughly maybe somewhat larger as the derimmed cases are .203. So where to start. Drill hole size followed by a reamer of which size. And how many steps to the final reamer size. Next I assume is to polish it. How and with what. Any help on the how's and what greatly appreciated. I have a Corbins S press.


Thanks

[contendernut]

.190 and .191 are my sizes of squirt dies for 224

[deltaenterprizes]

I use .187” wire for cores so a little bit bigger and still a readily available
reamer size.
The die may grow slightly when you polish the inside.
The punch should be .0005-.001 smaller than the inside diameter of the die.
You can polish the inside with wet or dry sand paper and oil going progressively finer all the way up to 2000 grit.

[midnight]

I would drill and ream my hole about .001 too small, say .189 and then using an expandable brass barrel lap, lap it up to .190 using progressively finer clover lapping compound, 400 to at least 1200 the finer the better.

Bob

[dimaprok]

I would drill and ream my hole about .001 too small, say .189 and then using an expandable brass barrel lap, lap it up to .190 using progressively finer clover lapping compound, 400 to at least 1200 the finer the better.

Bob

Where is a good source to buy in smaller quantity? Looking at McMaster a 1lb can for $45 in 400 grit and $99 for 1200. Just trying to figure out a more budget friendly solution rather then spending $500 on lapping compounds in order to make couple die for myself.

[Reload3006]

As a retired tool n die maker I would suggest you ream the hole close +\- .005” mine is .191 then hire a job shop to hone the final dimension I can’t see that costing you as much as the lapping compound and it would stay truer IMO you know what they say about opinions

[dimaprok]

As a retired tool n die maker I would suggest you ream the hole close +\- .005” mine is .191 then hire a job shop to hone the final dimension I can’t see that costing you as much as the lapping compound and it would stay truer IMO you know what they say about opinions

Nah... I've made a bunch of Lee style push through sizing dies for lead and Zinc bullets and copper jackets too. They work well for me. After I bore it, I wrap M3 nylon back sandpaper on the split wood dowel, put some light stone oil and lap it. I didn't even use multiple grit, the worn out pieces end up with finer grit. Its not ideal but that I knew how to use it and as long as my sized item comes out scratch free, that's all that matters.

When I saw some youtube videos of guy using American Laps, I was like - wow... this is next level... that and Sunon honing machine. I got multiple dies I want to make and there is a reason I bought lathe and milling machine, I want to learn, I just need to find smaller more affordable supply of this stuff, I think I'll stick to one grit and see how it goes... if I can only find smaller quantity.