Boring Or Reaming A Mould Out

[jimkim]

I was wondering if any of you have ever bored or reamed a mold to a larger diameter? I have a 36 cap and ball revolver, and was thinking of opening a HBWC mould up to the 0.366" groove diameter.

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[vernm]

Search the web for instructions on how to do this. I tried it and it worked well. Work on an aluminum mould goes pretty quickly. An iron mould takes a lot longer.

I honed out an aluminum mould about .002". I'm thinking if you lapped a mould .008 or more, it might be difficult to keep the cavity round. I held the mould in my hand and let it wobble as I lapped. The cavities came out very round. But that was expanding the cavities just .002".

Give it a try. You can always lap a little extra and push the bullet through a sizer die to round it out.

Keep in mind, cast bullets almost always work better 1 to 2 thousands over groove diameter.

I used a timer to document how long it took to achieve the desired diameter. Then use that time on the remaining cavities. You can always tweak the cavity with a little extra lapping, but it's hard to put metal back on. Go slow and check often.

[GregLaROCHE]

If you have an aluminum mold, chances are you can open it up with grinding/lapping compound. I tried to remove some imperfections from a steel mold once and didn’t get anywhere. Only a very shiny boolit that I was spinning in the mold with the compounds.

[country gent]

Youre taking opening up.009 or .0045 on a side touchy any way you go. It can be bored but set up and actual machining you dont have any room for error. in set up or catching the original bore. Lapping is going to be a long slow process removing that much.

If you have access to a lathe with a 4 jaw chuck it can be bored but set up is critical as is the premeasuring and tooling since you wont be able to see where the bar is when its in the cavity. Your going to have to work to the numbers both x and Y axis. A good sharp boring bar is going to be needed. I would recommend a light skim cut on the minor dia to find the edge then the bands. A light cutting oil will help with finish.

Lapping is going to require several grits.
I would cast up a dozen or so good bullets then drill a hole in the base and glue in a pin 1/8" key stock works well.
I would start with 120 to 180 grit compound working to 600. 120/180, 240, 320 and last 600.
Hand lapping is very precise. Work slow and careful
You will want a small t type tap handle. 2 flat steel plates light oil or water ( depending on compound) and a good vise.
Impregnate the first lap with the coarse grit. lightly coat the bullet with the coarse compound and then roll between the 2 plates with a medium pressure. this presses the grit into the lapps surface . making it the cutter.

insert into blocks and clamp in vise.
With a tapping motion ( back and forth rotation) work thru 3-4 full rotations.
1/4 turn and back 2-3 times then another 1/4 to 1/2 turn back and forth to full circle this is one rotation.
Clean and measure the easiest way is to heat and cast a few bullets.
repeat this with each finer grit unto you are to size

As this is a much longer bullet than the normal round ball or conical I would check to see if there will be enough room for powder. I am assuming this is a cap and ball revolver. THe other issue will be the added length is going to add a lot of force to loading.

[Mal Paso]

I lapped a Lyman iron mold with 320 diamond from Arrowhead Lapidary. I mention the source because there is some real garbage diamond out there. I sprinkled it on a steel plate and rolled it onto the bullet lands with a file. Spun them in the cavities with a hex screw with the tip cut off to keep it from penetrating the bullet more.

[MT Gianni]

A decent HBWC mold is worth far more than a custom BP mold. I don't think you will ever gain back what you are out. Add to that the average accuracy and it would take an amazing mold to improve it.

[Pressman]

I cringe every time I read of someone wanting to ream out a mould. I keep seeing this disaster.

291540

[358429]

Is that a joke pressman?

[MT Gianni]

Is that a joke pressman?

If you have been doing this for a while it is what you often see, a ruined mold. The victim of someones better idea.

[Oyeboten]

I was wondering if any of you have ever bored or reamed a mold to a larger diameter? I have a 36 cap and ball revolver, and was thinking of opening a HBWC mould up to the 0.366" groove diameter.

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What Cap & Ball Revolver has a Groove to Groove diameter of .366?

Also, why would you want a Hollow Base Wadcutter for a Cap & Ball Revolver?

[jimkim]

What Cap & Ball Revolver has a Groove to Groove diameter of .366?

Also, why would you want a Hollow Base Wadcutter for a Cap & Ball Revolver?My Pietta police revolver. I slugged the bore and the major diameter measures 0.366".

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[Good Cheer]

Oh wow. That's only a tiny bit smaller than what I'm used to seeing in their chambers.

[Traffer]

I use reamers to expand the size of molds and dies.

[358429]

That mold is making fishing weights.

We dont need no stinking eye hand coordination.

[Traffer]

I cringe every time I read of someone wanting to ream out a mould. I keep seeing this disaster.

291540

She's a bit crooked but otherwise PERFECT.

[jmorris]

I was wondering if any of you have ever bored or reamed a mold to a larger diameter?

Sure, even bored cylinders for liners/larger pistons, made molds from scratch, indicated in more parts that I could count over many years.

What material are you working with?

How much material are you wanting to move?

What equipment do you have access to?

If you haven’t ever used a hand drill but can order a Chinese one off Amazon tomorrow, expect results like the photo posted above.

[jimkim]

Sure, even bored cylinders for liners/larger pistons, made molds from scratch, indicated in more parts that I could count over many years.

What material are you working with?

How much material are you wanting to move?

What equipment do you have access to?

If you haven’t ever used a hand drill but can order a Chinese one off Amazon tomorrow, expect results like the photo posted above.I was thinking of getting a single cavity Lee WC mould and machining it to take the base pin, and reaming or boring it from the top to open it. The machine is a Wells index mill. He also has a Chinese lathe, but I am not sure if he has a four jaw chuck. I don't believe he has a boring head for the mill. It's been ten years since I've done any real machining.

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[Good Cheer]

My first altered mold was a Lee 9mm 111 grain RN upgraded to 3/8" for a Navy Arms 1861.
Worked great. Made the revolver an awesome gong ringer. 43 years later I still have both.

[Castloader]

I’m thinking of modding a brand new brass MP mold to convert GC to PB for one or two cavities(out of 4) and perhaps remove lube grooves at the same time. I have a littlemachineshop 7x12 mini lathe that I’ve used for about 6 years.
1) Is this a stupid idea? MP doesn’t sell this mold without lube grooves or in a PB. It’s for a 45-70.
2) boring bar or custom made “D” drill? Drilling guarantees the finished cavity ID is correct.
3) Best way to hold the work? Planning to use a faceplace b/c my 4-jaw doesn’t have the capacity. Obviously need to keep the mold closed and keep it from moving.

[farmbif]

all ive ever used in the two 1851 navy's that ive had were round balls I cast out of pure lead in a .375 mold. the lead weighs right about 90 grains, with a full load of fffg the ballistics are nearly identical to a .380 acp.

[Castloader]

all ive ever used in the two 1851 navy's that ive had were round balls I cast out of pure lead in a .375 mold. the lead weighs right about 90 grains, with a full load of fffg the ballistics are nearly identical to a .380 acp.

This response - in no way - answers my questions

[Rapier]

Your mold, but were it my mold it would be recut on a mill with a new cherry. If a nose pour. If I did not have a way to hold both sides, stable and adjust the sides for depth of cut, so I could open the bottom, I would call the original mold maker.
I have a suspicion it wold be way cheaper to just find a new mold that fits your needs/wishes.
If a bottom pour, your option, but I would still see about using the mill.

[Good Cheer]

Pietta's can be a problem or an opportunity depending upon which side of the bed I got out of.
This was my solution to how they machine their chambers smaller than groove diameter.
http://i.imgur.com/YPlCXD3.jpg (https://imgur.com/YPlCXD3)