Newb question: Cheap DIY home-brew mold- will this work?

[Oreo]

I'm interested in a truncated cone .40s&w mold. Sure I could buy one but I've been thinking of trying to make one just to see if and how well this idea would work. So I'm seeking your input 'cause y'all know about these things. ;)

I've been doing some figuring... A standard 13/32" drill bit is .40625" if they measure exactly as they're advertised. No idea what size they'd actually drill a hole to but maybe a tad larger. Anyway, considering typical shrinkage percentage for wheel weight alloy (.85%) that puts you at .4028" which sounds shootable and definitely sizeable.

I've got a theory on how to use a drill bit and a cheap drill press to cut something that resembles a mold by stacking & clamping flat stock of either aluminum or steel.

OK, flame on. Let me have it. :)

[Willbird]

If you use a new quality twist drill and it is running exactly true it will often drill right on size. There are other factors in play however than the shrinkage of the bullet alloy, namely the expansion of the mold itself. A few group buy molds I honchoed the cavity measured darn close to what dia the bullet dropped, those were of course aluminum.

If your mold is going to be split like a typical bullet mold your challenge is going to be drilling right on the parting line within .001".

A man always learns SOMETHING by doing a project like you describe :-).

There is a youtube video of a guy making 12 gauge shotgun slugs by drilling holes in fuzz board and pouring lead in them. It is posted in the shotgun section here.

Bill

[44man]

What will you do for lube?

[Hurricane]

He could use Lee Liquid Alox or Johnson's Paste Wax to lube the bullets.

[Oreo]

I plan on having a single lube groove. I want to duplicate the Lee TC bullet shape - more or less.

By using layers of flat stock I can drill a few layers with a smaller hole & insert them into the stack where I want the groove. Same goes for the truncated cone nose profile. I'm figuring on using something like a countersink bit to drill a cone hole & then remove the layers of the point & replace with solid layers.

Now, I'm hoping that the surface finish of the holes will be satisfactory as drilled 'cause I won't be able to hone them. I can use just about any material though. I have a great metal shop close by. I could use aluminum, steel, brass, whatever really.

[IcerUSA]

Sounds like a Master Lock mould idea .

Keith

[Wayne Smith]

Once you have it all drilled and stacked up how are you gonna hold it together? I can think of a couple of ways.

[Oreo]

Actually, a Master lock was my inspiration. Has anyone done this before?

What I was thinking was making two stacks for the mold halves. Drill some holes for bolts or rivets to keep the stacks together but use a solid top & bottom plate to keep the two stacks bound together solid for the drilling operations. Then remove the solid top & bottom plates.

[beanflip]

For about $24 you can buy a lee 2 cavity mold with handles

[Willbird]

Hmm why not use a master lock, and make a 2 cavity :-) ??

Bill

[Oreo]

Why make a 2 cavity when I could buy some flat stock & make a 200 cavity? :bigsmyl2:

OK, seriously... I was thinking a 6 cavity. I could do a lot of things- buy molds & such. I'm more just curious how well this idea would work.

[Bent Ramrod]

I read somewhere that clamping a thin piece of cardboard, like a postcard, between the blocks will help keep the drill centered between the halves.

That's an intriguing idea. Conceivably, you could make any length, and any number of lube grooves to whatever depth you wanted, just by switching out sections.

[Buckshot]

..............I think if you enjoy using your hands and making things you'll have a ball. I also believe it will be educational. I really cannot see why it wouldn't work. Be sure to taper your lube groove piece. And since you have a drill press you CAN hone the cavity walls.

.................Buckshot

[Oreo]

I can hone the cavity walls but I'm starting with a .406" cavity. Don't you think opening it up any further would be a bad idea?


I read somewhere that clamping a thin piece of cardboard, like a postcard, between the blocks will help keep the drill centered between the halves.

That's an intriguing idea. Conceivably, you could make any length, and any number of lube grooves to whatever depth you wanted, just by switching out sections.That's the idea. If this simple bullet design comes out OK then I'll know I'm on to something. All sorts of design variations could be conceived pretty easily at that point.

The postcard idea sounds interesting but wouldn't that cast a slightly flattened bullet?

And what's this about tapering the lube groves? I can't taper the thickness of a piece of flat stock.

[Bret4207]

If you don't have some taper to the lube groves you have the devils own time trying to get the boolit to drop out of the cavity. You might better find a drill around .395 or so and finish the cavities with a chucking reamer. They only run $12.-15.00 through MSC and then you'd have an accurate hole in the exact size you want. The "slices" making up the lube grooves could have a simple counter sink used to add the taper I suppose.

I would start on the small size with a single cavity until I figured out what the expanded size ends up being.

[Oreo]

Ah, I see what you're saying about the lube groove. That sounds easy enough to do.

Agreed that I'll do a few single cavity test blocks till I've got decent results casting.

I'll have to look into the company you mentioned. I didn't know where to go for non-common sized bits. I figured they'd be super expensive which is why I was thinking a 13/32" common bit was awfully convenient.

[Willbird]

Well if you look up drill sizes there are 4 options.

Fractional
Number
Letter
Metric

Many times one of the 4 in a standard size is very close to what you desire.

Bill

[Wayne Smith]

I don't know the technical language, so I'll try to say this non-technically. I'd be concerned that when you pinch the layers together the pinching process itself would separate the layers at the cavity enough to create flash. I'm thinking you will also need some sort of high temp bond between the layers.

[leftiye]

Actually, make your bearing band sections thicker and taper their sides for tapered sides on your lube grooves. Before you start drilling cavity holes, make your plates, and drill and pin them to keep them aligned. Then drill the cavities all at once to grease groove diameter with the plates fastened together. Use a drill with your final nose shape. Then all that is left is to open up the bearing band plates to finish diameter, taper their sides, and finish the nose pate just in front of your front band. Your plates will need to fit perfectly flat, and if they warp, ye're scrooged.

[bpfh]

The postcard idea sounds interesting but wouldn't that cast a slightly flattened bullet?


Drill a couple of bolt holes through the mold, insert card, bolt together.

Drill a pilot hole in whatever smaller drill size you want (like a 4 or 6 mm HSS drill bit) down the card between the bolted parts... but after removal of the card, your hole will be *very* slightly oval...

Remove from jig, unbolt, remove card, rebolt, reinsert into jig, drill out with your favorite drill bit, finish if needed with reamer, then yonder hole will be as round as you like :)

Now, where can I get that .224 sized drill bit :?:

Cheers,
bpfh

[Bret4207]

www.mscdirect.com BIG, BIG,BIG!!! industrial supply place. Get the catalog if you can. It's like 10" thick! You can get any size drill made from them and reamers in .001 increments IIRC.

[bpfh]

www.mscdirect.com BIG, BIG,BIG!!! industrial supply place. Get the catalog if you can. It's like 10" thick! You can get any size drill made from them and reamers in .001 increments IIRC.

OMG I've died and gone to heaven! :-D

Cheers,
bpfh

[revolver junkie]

hmm it sound like a very interesting idea but i agree that you would almost need either a mill or surface grinder to face the sections but then again if you could find stock that would be close enough it may work i am concerend about that warpage factor then again im not a machinist

[Buckshot]

.............. MSC sells reamers in fractions of a thousandth (.3002", .3005", .3010", etc). For your plates I doubt you planned on using sheared merchant stock, picked up at the local Lowes or Home Depot? While MSC isn't the only source for it you could use blanchard ground plate for the "leaves" of your mould. However I imagine regular ground finish flat stock should work as for width and thickness it's usually held to about .005" per 6".

..................Buckshot

[HeavyMetal]

I got to tell ya this is an"inventive" concept!

I'll go with buckshot on this one, you'll need to have the plates stack like they were polished.

My only thouht here is that after you do all this work you'l have lead get between the plate "seams" and then won't be able to get the mold open or the boolits out.

Having had a mold hot enough that every vent line had a 1/8 inch whisker on it I can see this happening. But it might not.

Am curious to see how it turns out. Please post pic's, if you can, as this porject progress. We may have some flash's of inspiration for you. As such you might consider one of those Texas plater kits to plate the mold cavities to prevent to the whisker issue.

[longbow]

If you want cheap and easy that makes perfectly cylindrical booits that shoot well, make a push out mould which makes smooth sided boolits (like for paper patching) then knurl them.

They can be made using a drill press and hand tools though a lathe or milling machine makes it faster and easier.

A basic description is given here:

http://www.lasc.us/Brennan_4-4_PaperPatchedBullets.htm

I've made quite a number over the years with good success. Mine are a little different but same idea. Ideal used to market these for PP boolits.

Longbow

[RayinNH]

Please also post a picture of yourself, before and after this exercise in frustration. We want to see the difference in hair loss...Ray

[leftiye]

You'd almost have to use annealed flat stock, and through bolts from the bottom that screw into the top plate, and ground plates as mentioned.