How do you make your reamers and laps?

[customcutter]

I've said it before and I'll say it again. I think the key to consistency with the laps and or the reamers is being able to make a consistent size and ogive.

I was thinking today about Cane Mans using a factory bullet to make laps with and it finally dawned on me. After he did this he has to "size" his bullets. Don't get me wrong there is nothing wrong with that process just an extra step. Then I wondered why does he have to size them. He's lapping with a .224 bullet with a lapping compound between the lap and the die. That extra few thousandths doesn't vanish, it causes the die to be just slightly over size.

Then I remembered the article about the dentist who would make as many as 30 laps for his dies, each one .0005" larger than the last. He was able to do it because of the "hydraulic" fluid in his lathe heating up until it stabilized.

I just received my 12 tubes of diamond lapping compound the other day. My D-reamer is .218 and a 6s ogive. I'm going to try and make at least 4 laps with the largest being .223, all with the same 6s ogive. I'm trying to figure out how to mount a grinding wheel on a arbor like Teddyblu did. My air pencil grinder just doesn't have the torque needed for the job.

[R.Ph. 380]

Why can't you "turn" on your lathe, the perfect 6s ogive at 0.220". Put 2 diametrically opposed grooves in opposite sides to serve as a repository for the lapping compound and start lapping? What have I missed in the whole process? I am a complete "non-machinist but it seems elementary.

Bill

[customcutter]

Bill, I'm not a machinist either. I wish it was that simple. Lathe's cut in a straight line, most people have made their reamers by making 3 straight cut's at varying angles and then blended them together with a file. In order to make an ogive you have to make a radius. The idea of opposed groves sounds good, but the grinding compound will not stay in the grove, therefore the ID will increase by at least 2X the diameter of the grinding compound + lap diameter.

thanks,
CC

[Cane_man]

cc i made my pointing die slightly oversized because i wanted to size them at the end as a 'safety measure' to give me peace of mind that the bullets were sized properly... i was turning the shanks down on the bullets and was able to hit 0.224 without any difficulty... but you are right though, in that the ogive portion of the bullet would be slightly oversized because that part of the lap was not reduced... didn't seem to matter when shooting the bullets, i think what i want to do next is make a meplat trimmer and that would help a little as well...

did you make your core seating die? you need to do this so you can have some seated cores ready to check and see where you pointing die is at while lapping...

[customcutter]

Cane, no I haven't made the core seating die yet. I did do a lot of reading over the past few weeks trying to figure out ID's, though. I've got a basic design drawn out on paper now with lots of notes, for all the dies except for the point forming die. Just need to get some time in the shop. Holidays, and researching/ordering parts for the 6.5Grendel AR have kept me out of the shop.

The first thing I want to do is modify my radius turner to hold the HF cutout tool. I also have to slow it down from 10,000 to 3,000 RPM (don't want the wheel coming apart in my face). Oh, and did I mention I'll have to make a mandrel to hold a grinding wheel???? But then I'll be ready to roll. I was trying to figure some way to grind the ogive's on my surface grinder using the cutout tool to turn the lap, but out of my grasp for now. I'll have to cover the ways, etc on the lathe to protect everything from the grinding dust.