NEED folks smarter than I

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skizzums

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okay, I am going to mill out my .22 bator mold tomorrow to between 70-80gr from 55gr. at first I thought this would be super easy, my wife being a hygienist can "borrow" really nice specific shanks for me from work, and I found a great one, with the size and perfect shape I would like. and being medical devices, they are about as true as you can get



so, I assumd I would just get the mold clamped in correctly on the mill and set up the stops to go to the desired length and use this shank to drill out the grease ring and crimp ring and lengthen the nose. and then polish the internals to a fine shine. BUT.....this ain't gonna work, I need that gas-check shank. so how on earth do I expand the internal size of the mold w/o cutting through the check shank? any ideas? has anyone done something similar?

after running the new .227 sizethough the .225 sizing die, I should have a great bore riding surface left-over

my only idea, is to chuck up the end-mill shank and take a file and grind down the fat body of the die to a point on the nose that is the .208-.210 I need for the check and just lengthen the nose. I don't know of a way to do just one side at a time and kep it true enough, how does lee do it?
 
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Can't help ya there. Sometimes when I build a doghouse, the dog has trouble figgering out how to get into it. I ain't much on engineering. :cool:
 
how does lee do it?
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Lee lathe turns their cavities. A spud is inserted in a hole that's undersized, then moved off center to cut the lube grooves and form the nose.The entire mold is held in the chuck and turned against the spud/cherry.

The way Lyman did it was a special vise held both mold halves apart, the cherry was centered on where the mold would close, then the mold halves came from both sides at once. Chips were blown out often until the mold closed completely on the cherry.

These days molds are made on CNC mils that do each side of a mold at a time. They are so precise that the cavities line up on the center line of the mold. All the alignment pins, screw holes and vent lines are done the same way, the milling machine chooses the correct tool from a conveyor that has all the cutters/drills/mills ready to work.

Your problem is to try to advance the mold half against the cutter without the cutter grabbing it or the mold half trying to move away from the cutter. Also, that looks to be a pencil grinder cutter. The flutes aren't deep enough to hold much/many chips. AND aluminum tends to ball up on cutters, you'll need a lot of fluid to keep the chips from galling the mold.

The way you have it pictured there should work IF you can hold the mold half securely and advance it exactly the right amount so as to not cut too far in, creating an oval bullet.
 
Lee lathe turns their cavities. A spud is inserted in a hole that's undersized, then moved off center to cut the lube grooves and form the nose.The entire mold is held in the chuck and turned against the spud/cherry.
Click to expand...

I think I can actually do tht. thank you. I don't have a lot of experience with the mill but it can do some amazing things if you can just figure it out.

as for cutting into just half at a time, I don't feel comfortable with that. hopefully my dad can school me on something, but he has very little experience too. his dad was a machinist and left him a massive lathe and the mill when he passed

someday I need to figure out the lathe too, but it's about as big as a car and gotta be 60 yrs old.
 
well I went today fully ready to get my mold kicking. we found out a way to do it half and half and keep it round, with a large bullet and keep the gas-check shank. we also found out that we can ust make new molds from scratch pretty easily. but the first thing on my list was a quick cope mount on my old mosin. quick turned into five hours, and my seven year old couldn't take it anymore. so the mold gets put off again till next weekend or the next or the next or whenever I find the time...

but I got a nice solid mount on my Finn
http://thefiringline.com/forums/showthread.php?p=5950893#post5950893
 
Good mold making takes some specialized skill. In your shoes, I would practice on scrap and then maybe on an inexpensive Lee mold before going after a good pair of blocks. You may run into issues with everything from chatter to tool marks that you need to work out.

You may want to reconsider your whole approach, as well. Veral Smith uses a tracer lathe for his designs. This lathe has a boring bar that follows the outline of the half profile of the bullet design cut into a flat pattern. With some ingenuity and the mill, you could probably work out a tool holder that does something similar so you aren't stuck with whatever shape the burrs come in. Using the slowest power feed on the lathe would tend to keep the surface finish better, too. Just be sure, if that lathe has been sitting unused for a long time, that you look at changing the spindle oil and filling any other reservoirs there may be in the saddle gearbox, as well as shooting way oil into the lube points (or if it has an oiler, change that oil out for the appropriate way oil and inject that) before you first crank it up. I have had good luck with Mobil lubricants for that. I use their DTE Light spindle oil, and their Vactra #2 way oil. I don't know the size of your lathe (mine's a 13"×40"), so I don't know if those are appropriate, but a recommendation will be in the manual.

One thing that struck me is that eliminating the lube grooves might be due some reconsideration. You have powder coating and you have a gas check. Once you find the maximum velocity for that combination, might it turn out that also filling the lube grooves could get you to a still higher velocity? I don't know, but it might make for some interesting experimentation.
 
No, I want the lube grooves gone. For weight reason and the fact that I can always tumble lube before or after powder coating(which I likely will), I have no lube sizer and have no patience to pan lube a thousand rounds of plunking ammo

Luckily I have tonnes of AL stock to play first and get it right. I may just make new molds from scratch rather than even mess with the bator mold. Or after I get it right, I may just add a third or even forth cavity to the bator
 
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