View Full Version : Lathemeisters: How to Hollowpoint?
09-08-2005, 12:18 PM
Title says it all - almost. I have an RCBS 350 grain, .40 caliber, single cavity mould that I would like to make into a hollowpoint mould. I have a pretty good lathe with a 4-jaw chuck. I also have a chinese mill/drill machine. What would be the best way to approach this project?
09-08-2005, 08:36 PM
Which can you center the easiest accurately. I only have a lathe to do my HP'ing and I'm sure a milling machine might make it easier. I sometimes spend 30-45 minutes getting a mould centered. On some moulds I have found it is easier to make a hardened drill guide and use my drill press. I tend to use the largest bit I can and then make a stepped pin if possible. I would play around with a mould that has been misused to see what works the best. I practiced on some really cheap common moulds I had. Good luck, Mark
09-09-2005, 11:07 AM
I would go through the front side of the block. That is the side where the base of the bullet is and the sprue cutter rests on. Take the sprue cutter off.
Center up your blocks in the 4 jaw. Use the tailstock center and place it into the hole to help guide you. This will ensure that you are concentric to the bullet bore.
Once it is centered, you've got the big hole of the base of the bullet to go though. Drill your hole and then ream it for a finer finish. Make it a standard size. After you have the hole to your satisifaction, you must make the hollowpointer which is basically a rod with a handle on it. The end of the rod that goes in the mold has whatever configuration point that you put on it.
Thats it. Not much to it really other than taking the time to ensure that you have zero runout. After you get it close with the tailstock center, make sure that you "dial" it in with an indicater on both planes. Make sure that the faces are square and that the hole runs true.
The rest is the easy part.
09-09-2005, 01:13 PM
Pardon my stupidity if it shows. If it doesn't, I'll show it some other time.
How about casting some bullets with the mold, finding the center of the bullet and drilling it.
Then use the drilled bullet as a guide by putiing it back in the mold with lube and drilling it through the blocks on a drill press. I could ruin a bunch of remeltable bullets before I would dare drill a mold.
09-11-2005, 04:41 AM
...........Cabezaverde, this is the way I hollowpoint a mould:
Set it up in a 4 jaw chuck and eyeball the cavity in as close as you can. Before doing so, make sure the blocks are stationary to each other. IE: the alignment pins are doing their job. Similar to HotGuns suggestion I just have a 3/8" piece of rod I turned a 30* angle on to form a point. Chuck it in the tailstock drillchuck and run it up close to the cavity.
It needs to be running pretty close since most TI's are only good for .030" movement. Then the TI is put in a tool holder and moved in so it rides on a lube groove. Finish dialing in the 4 jaw. I use a TI indicating to .0005" and you sure don't need more. You might be amazed at how whacked out some cavities are. I used a .0001" reading TI once and that was nuts. You'll just make yourself crazy chasing tenths all over for no good reason.
You'll find the TI will bounce over the parting line, sometimes .002". Get the cavity sides perpendicular to the parting line to read within .0005". Then go after the parting line sides. Sometimes .0015" is as good as you can get, side to side, but try, HA!
On the left is a Lyman 311410. On the right is a mould with a pin and the pin spindle and handle. Before you chuck up your mould blocks you need to check to see which number centerdrill or spotter you can use. If you don't, you can go a bit too deep and cut a nice shoulder where you REALLY didn't want one. Been there, done that and lesson learned.
So anyway you're all chucked and indicated and you mash the green button and run in the centerdrill to start the hole. Back it out and replace it with the bit you intend to use to make the hole. I use drill blanks for the hollowpointing pin for a few reasons. One is that it's almost an exact fit for the hole you will drill. Where do I get them? Well off the shank of the drill I just drilled the hole with, of course [smilie=s:
On E-Bay there are several places that sell surplus aerospace stuff and amongst it all are longshank aircraft extension bits. Most are like brand new, high quality, come in a wide assortment of sizes and they're cheap. Usually you can get 5 lbs of'em for maybe $10. Most are smaller sizes just perfect for hollowpointing. A 1/4" one is a big honker. Many are letter or number sizes. Even better, lots of them are drill reamers. On the flutes will be 2 lands for super guidance and clean holes. Also many will be piloted with std diameter pilots.
Normally drill shanks are not hardened to the same degree the actual fluted part is, so the chuckjaws can get ahold of it. Any unhardened ones are the ones I use if possible, to make the pins from. However, many of these are hardened their entire length. Why these are avoided to cut for the pins is that they are all M2, M7, or M42 and colbalt HSS and make superb cutting tools for the lathe and for use as inserts in boring bars. Why buy more expensive HSS cutting bits when you have them right there on the end of your drill bits?
This is a captive pin setup where you have no corepin to remove and replace each time. The sequence is the same except when you're done you reverse the mould and re-indicate off the hole. Then I used a 5/16" centercutting endmill to plung in to create a larger diameter hole for a sholder, to help guide the pin back into position when the blocks are closed. I used a rotary table to mill the slots in the guide arms, but you could chain drill and then file.
Here I'm making corepin spindles. I used to keep 4-5 of'em on hand as you need one for each mould you HP and I was doing maybe 3-5 a month. Then I had a member here send me 10 single cavity pistol bullet moulds to hollowpoint! Gadzooks, I was immediately behind. I used to just casually make'm one at a time.
Down there at the end of the lathe bed you can see a 6 position turret and this was the first opportunity to use it. I put a #4 centerdrill in one spot, then a .125", .161" and a .185" drill bits. With a 3' long piece of 1/2" OD HRS in the collet I zeroed a parting tool and a form tool to cut the spindles.
First you'd centerdrill, then advance a drill bit and drill to depth. The spindles are 1/2" OD for .125" then go to .375" for a half inch and then to 1/4" for 1.25". That last 1.25" inch run in powerfeed was peeling off a full 1/8" at 800 rpm and .0028 IPR. They'd get HOT! After the 3rd or 4th they were parting off blue. I was using a TNMG carbide insert and if you look close in the photo you can see a big wad of little '6' and '9' chips on top of the bit. They were silver coming off but they hit the chip pan blue.
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