Author Topic: Really BIG bullet moulds (molds) - need help! (Read 1364 times)

Cat Whisperer · « **on:** August 31, 2003, 03:12:14 AM »

Several folks have asked about getting/making moulds in larger sizes, like from 1-1/2 to 2-1/2 inches in diameter.

I have a lathe and a milling machine & am in the process of building a radius cutter to make these moulds.

What have y'all seen that works? What problems have you encountered?

Thanks,

Double D · « **Reply #1 on:** August 31, 2003, 03:19:56 AM »

Okay great you are going to do the varmint calibers, how about somethng straigh one inch. Then in mid size say. 2.75, diet coke can size roundball?

Cat Whisperer · « **Reply #2 on:** August 31, 2003, 07:24:57 AM »

DD -
When the tooling's finished I'll do whatever diameters are needed.

My experience in casting only goes to 12ga slugs personally - seemed to work well with linotype, tougher with the softer lead alloys.

I had some 4-1/2" cannon balls made from zinc - irregular shrinkage and cavities were problematic.

The question therefore is that of how large a sphere can be successfully cast?

For the 1-1/2 to 2-1/2 (or so) I'll do both the spherical and hollowbase wadcutters. Anything bigger and my wallet would hyperventilate on each round fired.

John Traveler · « **Reply #3 on:** August 31, 2003, 07:46:44 AM »

For the size projectiles you are describing, golf-ball size, medium cannon, etc., I don't think you can count on simple gravity casting such as is used for normal-zied cast bullets to get good results.

Objects that large and require great uniformity are die-cast (ram-pressurized melt) or are done on a centrifuge device.

Investment cast gun receivers mold cavities, for example, because of the intricate voids and details, are frequently subjected to low-pressure vacuum as well as centrifuge to get complete fillout.

HTH
John.

Cat Whisperer · « **Reply #4 on:** August 31, 2003, 04:32:07 PM »

It seems to me that there's another attempt to solve the problem of shrinkage or incomplete filling. Namely the use of a sprue and one or more risers. That would go from almost no pressure to several inches or so of pressure at the time of pouring.

The 2-1/2" cast lead wadcutter with a hollow base did look good (from what I remember); but I did not see the mould.

DD - what are the bore diameters for which you need moulds?

kciH · « **Reply #5 on:** September 01, 2003, 10:22:50 PM »

I think you could get them to work OK, but you'd want to pre-heat the mould to near your alloy temp. Pouring the lead from a height above the sprue would help you to get get good mould fill, just like it does with bullet moulds. I'm somewhat skeptical of vent lines, but in a situation like this, they would probably be required also.

flintman · « **Reply #6 on:** September 02, 2003, 04:17:28 AM »

Where in good ole VirginnyIA are you?I'm in Marion,Jeff,276-783-9746.

Cat Whisperer · « **Reply #7 on:** September 02, 2003, 04:03:15 PM »

kcih -
Pre-heating makes a lot of sense, another good comment! I agree on the vent lines - not for me, rather I'll go with one or more risers for better flow of metal and more pressure.

flintman -
Just up the hill from beautiful downtown Pulaski. Used to do the physical security inspections and terrorism counteraction briefings for the reserve unit there in Marion.

Kenneth L. Walters · « **Reply #8 on:** September 03, 2003, 11:53:34 AM »

Are you aware that sinker moulds do this job fairly well and are readily available and inexpensive?

Leftoverdj · « **Reply #9 on:** September 03, 2003, 12:37:36 PM »

I've got a sorta super minie ball I pulled out of a range backstop. Think it was fired from an 8 pound cannon. It's about soup can size with side walls about 3/8" thick.

Lemme know if anyone wants the exact measurements. Seems to be pure lead and very well cast.

Cat Whisperer · « **Reply #10 on:** September 03, 2003, 02:53:46 PM »

Kenneth L.
Good to hear from you - you've always added much to the discussion on the various boards.

I'm looking for something just a little more precise (for target work). I have observed that cannons are somewhat forgiving for variation in shape and diameter.

Leftoverdj -
I'd love to know the dimensions and shape!

Double D · « **Reply #11 on:** September 03, 2003, 03:27:20 PM »

Sinker Mould do in fact do a good job, but none come in the right calibers for CW and my project.

Now a word of warning. I built a two pieces mould for my 2.75 inch Coehorn mortar. I design the slug to look like 2.75 inch airgun pellet, with a not quite so hollow base. the cast slug weighed 7 1/2 pounds. Fired with 5 1/2 oz of Cannon grade 1F. The shoot broke the sides of my base. We are talking about 2 x 6 oak here. I learned later that the 2 oz per inch of bore rule of thumb doesn't apply to mortars with a smaller powder chamber. I also think it had something to do with the weight of the slug.

I think what is need is cast solid zinc ball.

Leftoverdj · « **Reply #12 on:** September 03, 2003, 03:38:22 PM »

3 3/4" long
3 1/8" diameter
Sidewalls 1/4" thick
Cavity 3 1/4" deep

Nose seems to have had a cone 2" wide by maybe 3/8" high. Hard to tell because the nose may have been pushed in a bit on impact. Can't find any parting lines. They may have been wiped off or it may have been cast in a cylindrical mould.

Dimensions approx since it is somewhat battered. Shows odd clockwise three groove rifling. No real lands and grooves. Sorta like three touching inclined planes.

Leftoverdj · « **Reply #13 on:** September 03, 2003, 03:47:25 PM »

I'm assuming you folks know the old standby for cannon shooting was the appropriate size of can full of concrete?

I'd be real leary of cast lead RBs since they are so much heavier than the original cast iron balls.

Cat Whisperer · « **Reply #14 on:** September 03, 2003, 05:07:40 PM »

Leftoverdj -

Thanx for the dimensions! It's a great place to start, assuming it's an accurate design.

Yes, I've used much concrete. That's why my mortars are in beer-can caliber (the old type), beer-can caliber (the new type), soda-pop bottle (16/20/24 oz) and 4" pvc pipe calibers. The smallest is golf-ball caliber which are readily available.

I've found that the heavier the round the longer the range. Hence the desire to use metal. A 4.5" zinc ball is just at 10 lbs (a little lighter than cast iron), where the longest length of 4"pvc pipe (4.5" OD) weighs 7.5 lbs. Lead would way too heavy (my wallet would hyperventilate at each round fired).

But since most of my mortars are cut from one piece of 4140 steel and very much oversized I am seriously considering lead for the smaller ones.

http://img.villagephotos.com/p/2003-1/82347/BTRPK[CORUINEKJDKTLN-Can Coehorn Mortar 2.jpg

http://img.villagephotos.com/p/2003-1/82347/SBCGPDVLJGVWCGJMNJCK-4pvc01.jpg

Leftoverdj · « **Reply #15 on:** September 03, 2003, 05:26:01 PM »

I don't see how it could not have been accurate. It's your basic HBWC scaled up. Rifling marks are sharp the length of the projectile. Oughta shoot decent even in a smoothbore since the weight is well forward. My guess is that it was loaded directly onto the charge since the bottom edges of the skirt are not upset.

It's pure luck it did not go into the casting pot years ago. It's just eight pounds of found lead to me.

HHI 812 · « **Reply #16 on:** October 05, 2003, 09:03:53 PM »

I think he uses a small tomatoe can, and he made this big mold to make a lead collar on the bottom of the can, which he puts the can in the mold, and casts a collar around the bottom of the can. I guess the collar will fill up with the pressure? He then puts concrete in the can, and he has another mold like for that, because the tip of the concrete is rounded! Buddy even rifled the barrel! Couldn't believe he even made nuts and bolts, to duplicate the type of nuts and bolts they made in the old days! He also made a sight in the back, which looks like some rectangular brass set up, with a sliding sight for elevation. He has this thing so in detail, with the chains, pins, and made the spokes, along with a bent steel strip around the wooden wheel. Got several poles with some kind of tips on them, to load the cannon. They are hanging under the cannon with some hooks, that he also duplicated. He had a whole set of plans of what the real ones were built in the old days. I'm trying to get a photo of it, but nobody seems to have a digital camera. I suggested that he get a video camera, to document everything when they go and test fire this thing. I guess they wanted to figure out the trajectory of the sights or something. Nice set up, but figured a retired engineer would be as precise as this, to even the nuts and bolts, which he said he had to make since they don't make them like that any more? Figure if he waited till it got cold, he could probably try it out in the open somewhere, and have the holes in the ice to mark where the bullet falls? :grin:

Double D · « **Reply #17 on:** October 06, 2003, 12:34:52 AM »

The problems we have found with concrete filled cans is kinda like cast bullte with voids. They don't fly very true. If we could find a casting material with a consistant density and the weight of concrete that would work.

I am toying with idea of ball bearings, but have always been told that they were rough on bores.

Cat Whisperer · « **Reply #18 on:** October 06, 2003, 12:37:59 PM »

I actually priced a 4.5" ball bearing - US$105.00 or so for ONE.

So much for that idea.

Cat Whisperer · « **Reply #19 on:** October 06, 2003, 12:45:29 PM »

HHI 812 -

If I read you right, he's putting in the can to make a hollow base into the projectile. That's an interesting concept. Even filling it with concrete (mortar would fill more evenly - and the standard techniques for vibrating out the air pockets should be used as well) is a cool approach.

With artillary rounds there is a brass or copper ring at the base called something like a bourlett (French, pronounced bour - lay) don't have a clue to the real spelling. (We got most of our artillary terms from the French in the frenzy to catch up during WWI. French 75 and so forth.)

The ring will engage the rifling and seal as well as spinning the bullet via the rifling.

olduvai george · « **Reply #20 on:** October 07, 2003, 02:04:10 AM »

Mr Cat Whisperer: may i reccommend you contact the cannon/mortar shooters at the www.n-ssa.org , north-south skirmish association. we shoot lots of big cannons amd mortars in competition. the can probably offer something positive to help. george

Lead pot · « **Reply #21 on:** October 07, 2003, 02:46:08 AM »

Cat Whisperer.

Ever think of swaging the ball?You can cast a core in a can close to the size and weight.build a hydrolic press on the order of a log splitter with a double I beam instead of one rail to keep the flexing down.
You have the knowledge of tooling so building the die would not be a problem.It would be even easyer to make a hollow base mould like a air gun pellet.
Just a thought Cat Whisperer.

Kurt

Leftoverdj · « **Reply #22 on:** October 07, 2003, 05:45:54 AM »

Quote from: Double D

The problems we have found with concrete filled cans is kinda like cast bullte with voids. They don't fly very true. If we could find a casting material with a consistant density and the weight of concrete that would work.

Tried vibrating the concrete? That's how they get the voids out in construction.

Double D · « **Reply #23 on:** October 07, 2003, 12:19:22 PM »

Old George.

If the N-SSA guys would just divulge where they are getting their ammo we would be very happy. I would love to find a source for 1 inch and 2.5 zinc balls

I just picked up copies of the South Bend Replica Catalog and the Complete Cannoneer. Why I didn't do this years ago, I don't know.

Leftoverdj,

It's the gravel in the cement, that makes for the void effect...at least thats my theory.

The South Bend Catalog says use Bondo for projectiles. How about filling my beer can with bondo. Any thoughts on that?

talon · « **Reply #24 on:** October 08, 2003, 06:04:12 AM »

Take a look at eBay # 3630852885, ending in about 6 days. It's a multi-cell 1" canon shot mold.

Double D · « **Reply #25 on:** October 08, 2003, 12:24:09 PM »

Hey not bad! I'm going to watch that one! not a bad looking shape either. there are two guy bidding on it alread. I'll bet it goes for a good chunk of change!

Does anyone know where I can find aluminum or zinc balls 2.5 inch? The complete cannoneer says steel balls should not be used because of the ricochets. they say nothing about barrel damage. They do say ring guage them first. I am going to have to revisit 2.5 inch ball bearings.