Reaming a mold

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  • Last Post 23 December 2008
CB posted this 10 December 2008

I have a couple of these molds for my Marlin 336 in 35 Remy and for use in my Contender 357 Max pistol.

I need to make this mold close to 359 or exactly .359, I have reamers and a milling machine and a lathe.

I figure just line bore this slightly and then maybe recreate the lube rings if they get too thin diuring this process.

Any suggestions or Any one have a better idea?

 

Thanks,

Jerry

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jimkim posted this 10 December 2008

If you bore the hole you will cut the rings out. It may be better to use lapping compound to open it up.  You could put a bullet from your mould in a lathe(soft jaws) then drill and tap the bullet so you could put it on a mandrill. Put it in a hand drill. Apply lapping compound to the bullet. Put it in the mould close it and go for it. Use a fine grit compound so you wont take off too much. The members at the Cast Boolit forum would be more help than I.

http://castboolits.gunloads.comdisplay.php?f=9

If you really want to use the lathe you could probably grind one of your reamers to match the bullet profile or make some boring tools to match the grooves and bore them out, but your touch off and measurments would have to be just about deadnuts perfect.

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JetMech posted this 10 December 2008

Jerry, How much do you need to open them up? I have a Lyman 410459 that I need to open up .002, so I've been reading about “beagling", which entails applying a strip of aluminum tape to one mold face. People who have done it claim the bullet is still round and is .001-.003 larger. The lapping method might work also, but I worry about making the mould out-of-round. I like Jim's idea of using a boring bar, but, you'll be using a 4 jaw chuck on the mill so it has to be centered perfectly.

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CB posted this 10 December 2008

I think your chances of success are going to be pretty slim. A better idea might be to sell the moulds you have and just buy a custom cut to your specs.

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CB posted this 10 December 2008

I have used the beagling thing to make enough bullets to test out and see if the basic design and weight will do the job.

If that proved successful I would have a mold made to the specs I needed.

Finding the absolute center of an already bored mold is going to be a tall order of business. A couple of tenths off and you will have a ruined mold that you cant sell and the need to buy a need one, not to mention the huge amount of time you will have invested tinkering around trying to find the center of the cavity. If the mold has more than one cavity then you can spend more time than its worth.

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CB posted this 10 December 2008

Jeff and all,

Finding the center of the mold is not a problem and beagling the mold with two cavities is challenging, but not impossible. I am looking at maybe an increase of .0015.

This is the mold that I want to enlarge: http://www.lymanproducts.com/lyman/bullet-casting/mould-details-rifles.php?entryID=58>http://www.lymanproducts.com/lyman/bullet-casting/mould-details-rifles.php?entryID=58

I have a RD class=Tahoma-16pxbTLC359-190-RF mold that works extremely well, plus I have a Lyman 214 gr 358 SWC mold that works surprisingly well in the Marlin 336 in 35 Remy.

I may try to make a “cherry” for this mold, that will cut the bands properly. I have some reamers that may fit the job to do this with. I bought a grab box of reamers a few years ago and there are a few that maybe useful for this project.

But an expanding lap maybe the best choice. I want to plan this out, so ooops don't happen.

Again Thanks,

Jerry

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CB posted this 10 December 2008

Jerry,

You might have good chances by making a cherry. I know of a couple of guys who tried making cb molds by making just a single cut cherry. That type seems to me would work for opening up certain places in cb cavities?  I never done it, but figure a good jig to hold the blocks solid would be the most important. Lapping with compound is just the pits.  :#:   ...............Dan

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billwnr posted this 10 December 2008

why not make a “bump die” and bump the bullet up to the size you want.

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CB posted this 10 December 2008

I don't understand how you're going to use a reamer on the mould? Even lathe boring it would be pert near impossible since all you're talking about is taking out a thoudandths and a half or .00075 per side. Why not just lap it a bit or use a different alloy.

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CB posted this 10 December 2008

I am asking questions to figure this out.

 

Jerry

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cityboy posted this 10 December 2008

Jerry

If you need to enlarge the mold only about 0.0015” why don't you just lap it out? I have lapped a couple of Lee moulds with good results?

Put a bullet into the cavity and locate the center of the base. Then drill a hole large enough to take a self-tapping or sheet metal screw with a hex head.

Then coat the bullet with an abrasive and put the bullet into the cavity. A cordless screw driver with a hex socket can be used to drive the lap.

You will then have to clean out the mold and make trial casts to see how much the cavity is opened up.

Jim

 

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singleshot posted this 10 December 2008

Jerry- If you do not care about the gas check you can ream (or bore) the base band out to whatever diameter you want- and you may be surprised at how well it will shoot! Charlie Dell often did this. Trying to open the other bands is a crap shoot, IMHO.

Willis Gregory

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303PV posted this 12 December 2008

There was a sample Fouling shot article on the CBA website.

Home-shop Mould Making by Tom Slater ,Adamsville, Ohio. That covers lathe boring a mold very well. It was from March 1998.

Piet

 

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CB posted this 12 December 2008

I called Lyman today and they said they would do this to both molds for me, but it may take a few months to get them back.

Jerry

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R D posted this 23 December 2008

Jerry;     I heard of a guy turning a disc the same width and diameter as the drive bands on his bullets and then using that as the lap for enlarging his mold. I believe he used his drill press or mill to drive it so everything stayed plumb. He said that he got true enlargement of the bands without rounding all of the other parts of the mold. I intend to try this method on my next one as it sounds good to me. The lube groves being a little larger should be no problem . He said that if he needed the nose larger to fit the lands he turned the bands and grease grove bottoms down a bit on a bullet and used it. If it don't touch it don't cut.

    A good machinist should be able to center that on a lathe or mill and bore it a little with out any trouble if you decide to go that way. It's not that hard just tedious careful work.

R D

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