Author Topic: Wrinkle free balls (Read 1619 times)

tkthorn · « **on:** April 29, 2011, 05:02:13 AM »

My Field Cannon has an 1 1/2" bore and I made a Ball mold out of Aluminum, after the mold heated up I could cast perfect Balls. My problem is the new mold that I made for my 2" bore Naval Cannon refuses to give me wrinkle free Balls. Both of my molds are made the same just one is 1 1/2" and the new is 2". My molds are vented to allow air to escape. I'm thinking it may be an issue with getting the molten lead into the mold quick enough? Anyone have any suggestions?

Terry T.
tkthorn

rampa room artillery · « **Reply #1 on:** April 29, 2011, 06:09:58 AM »

pour faster??? heat your lead up hotter, heat your mold up. but mostly pour as fast as you can.

seacoastartillery · « **Reply #2 on:** April 29, 2011, 06:13:22 AM »

In my experience, it's the diameter of the sprue hole that is the spoiler. If you calculate a normal progression and then add 50% to 75% more to the size, things should work out wrinkle free. The metal partially 'freezes' prematurely unless it has quite a bit more volume to keep it hot. This presupposes that you have the entire mold brought up close to 425-450 degrees F.

Hope this works for you,

Tracy

Cat Whisperer · « **Reply #3 on:** April 29, 2011, 06:15:36 AM »

I'm assuming the mould was hot (440df or so).

I'm assuming a lead-tin-antimony alloy or two of them

Then the two things that will cause wrinkles are:
a) pouring too slowly (get a larger ladle) or
b) alloy temperature too cold.

A little tin in the alloy will help the alloy flow into corners - not many of those in a sphere.

Max Caliber · « **Reply #4 on:** April 29, 2011, 06:38:55 AM »

tkthorn, how large is the sprue hole in your 2 inch mold? It should be at least 1/4 inch for a ball that size, 3/8 would be better. In casting almost any metal the faster the mold is filled the better will be the casting. but, if you can't get the metal into the sprue hole fast enough it doesn't matter how big the hole is. If possible, make the entrance to the sprue into a funnel shape large enough to pour the metal fast without spilling it. Usually, with a small sprue, a lot of metal misses the hole and winds up on the ground or on the outside of the mold and this causes wrinkles in the balls because the stream of molten metal is being broken. You want to cast the ball in one continuous pour. l cast balls into the cold mold until I start getting good ones without wrinkles, returning the bad ones back to the melting pot.

tkthorn · « **Reply #5 on:** April 29, 2011, 06:59:30 AM »

It is 1/4" with a large beveled opening, I think I will try 3/8" like you said and seacoastartillery mention that too .I have been looking for a larger Ladle without any luck, the one that I am using is just big enough to fill the mold and sprue with nothing left over. That could be some of my problem also, that would help in filling the mold quicker. I am going to give that a try, Thanks. If you know where I can get a larger Ladle please let me know.

Terry T.
tkthorn

Double D · « **Reply #6 on:** April 29, 2011, 08:35:05 AM »

You might want to consider getting at a steel mould and cast some zinc. The zinc balls are recoverable and thus reusable and generally as is, no recasting.

Zinc is close to the weight of a iron cannon ball for the bore diameter, The lighter weight translate to lower pressures when fired and lighter recoil and less strain on barrels and carriages. Zinc is more durable then lead and is less likely to be deformed in handling. Projectile this large in lead are extremeley sensitive to deformation....ask me about deformna tionin one inch RB.

Double D · « **Reply #7 on:** April 29, 2011, 12:31:55 PM »

Sorry some clean up of our family oriented board was necessary...I didn't want to explain it to my 16 year old Granddaughter...

dan610324 · « **Reply #8 on:** April 29, 2011, 01:02:13 PM »

sorry

armorer77 · « **Reply #9 on:** April 29, 2011, 01:25:01 PM »

If you can weld , take 4" of 2" square tube weld on a handle and a base plate . Crude , but it works .

BoomLover · « **Reply #10 on:** April 29, 2011, 03:00:12 PM »

4" of 2"', welded on at an angle? Pour out of one of the corners, right? I mean, weld your handle on to one of the corners, makes sense to me....BoomLover

Cat Whisperer · « **Reply #11 on:** April 29, 2011, 03:20:43 PM »

Quote from: tkthorn on April 29, 2011, 06:59:30 AM

...
If you know where I can get a larger Ladle please let me know.

Terry T.
tkthorn

If it holds enough it's ok - if it pours it in fast (same idea on sprue cutter hole size).

Winger Ed. · « **Reply #12 on:** April 29, 2011, 07:41:53 PM »

Hi heat & fast pouring speed/mold fill is the deal.
I had a extreme version of the same problem years ago casting 8lb. Lead downrigger/trolling weights for fishing.

I'd pour through the little sprue hole, as fast as my RCBS bullet casting Lead pot would flow:
Then hold a torch on the mold to get everything hot enough for the wrinkles to finish flowing out.

Cat Whisperer · « **Reply #13 on:** April 30, 2011, 01:33:35 AM »

That reminds me of the Lyman 12ga slug mould - kept a tourch on the cavity plug between pours to keep it hot enough.

You can put a metal plate (1/4" aluminum or iron) on top of a hot plate and pre-heat the mould between pours.

tkthorn · « **Reply #14 on:** May 01, 2011, 04:37:08 AM »

Would a outdoor propane burner produce enough heat to melt Zinc?

little seacoast · « **Reply #15 on:** May 01, 2011, 04:51:12 AM »

easily

Zulu · « **Reply #16 on:** May 01, 2011, 05:01:07 AM »

Quote from: tkthorn on May 01, 2011, 04:37:08 AM

Would a outdoor propane burner produce enough heat to melt Zinc?

Yes it will. I melted a pot full and moulded 3" balls with my crawfish burner. I used a heavy wall piece of 10" pipe with a 3/8" plate welded on the bottom. Also welded some handles on it. If you need a picture, I'll take one. I put a 1/8" plate on top as a lid. My ladle was a 3" piece of pipe with a bottom welded on and a 2' long handle. The pipe was heated and formed into a small spout. It worked great!
Like others here, I had to feed the deformed balls back into the pot until my mould got hot enough.
After about 6 or 7 balls, my mould would be too hot and the balls would sag when I tipped them out.
I either had to let them sit a while after that in the mould or just shut down until the mould cooled down. Shutting down was better because I didn't waste propane keeping the pot hot.
Zulu

keith44 · « **Reply #17 on:** May 03, 2011, 08:13:26 PM »

Zinc eh, interesting. At what point (ball diameter) does it make more sense to switch from lead to zinc or whatever other metal??

I'm asking this from a muzzle loaders point of view. "Ball rifles" need the softer lead to obturate to help the patch take the rifling and impart spin to the ball. but with smooth bore cannons there is no need for such soft alloys.

Cannoneer · « **Reply #18 on:** May 03, 2011, 10:38:45 PM »

Keith,
The real reason for not using lead projectiles in larger caliber cannon is because of its weight; the greater the weight the harder it is to move, and because its harder to move, greater pressure builds up inside the barrel (possibly making it unsafe). I know people's opinions are going to differ on what size should signal a move to a lighter metal, but I've got an 1-inch bore gun that I'm going to use lead ball in; for bores bigger than that I'd switch to zinc, aluminum, or steel.

tkthorn · « **Reply #19 on:** May 06, 2011, 11:57:28 AM »

I'm guessing that I can't cast zinc cannon balls in my aluminum mold. Will this metal stick to the aluminum?

GGaskill · « **Reply #20 on:** May 06, 2011, 12:02:02 PM »

You have a good chance of melting or at least distorting aluminum moulds if you cast zinc in them; the temperature is too high.

gunsonwheels · « **Reply #21 on:** May 08, 2011, 07:27:56 PM »

The variables are mold mass, mold temp, metal temp, metal pour speed (governed by the ladle and the sprue size), solidifying time (sufficient to solidify the pour but not so long as to cool the mold temp). These days a good quality IR temp gun (not the cheapo's they are too inaccurate) would be very valuable to a successful pouring session (I used to use Tempil temp stix). Outdoor high output propane burners are great with a large iron frypan for a vat and a ladle made of 3" dia exhaust tube with a welded bottom and a welded slag scraper (I use these for slugs of .75# to 1.25#). The vat and ladle need to be large enough to enable pouring as many projectiles as you desire but more importantly the ladle needs to allow a smooth, uninterupted flow into mold from start to sprue filled. When you get the variables where they belong and get into a casting rythym you'll get about nine out of ten good projectiles (no wrinkles or cold setting lines or internal voids). It's harder to do well with mini-ball slugs of 40mm dia (1.6") but with perserverance it all works. Remember to keep at it until you get it working for you. When I sold my first gun the buyer called and cried about every week after a casting session. We kept at it until he came up to the technique I had learned through trial and error and he went from one good out of about 25 pours to 18 or 19 out of 20.
Good Luck!!!

SAFETY NOTE:
IF POURING LEAD MAKE SURE YOU ARE OUTDOORS AND USE A FAN ON LOW SPEED TO KEEP FUMES FLOWING AWAY FROM YOU... I KNOW... ANOTHER DARN VARIABLE

Double D · « **Reply #22 on:** May 10, 2011, 09:24:56 AM »

GoW,

How does that mould work wiht zinc?

gunsonwheels · « **Reply #23 on:** May 10, 2011, 11:25:53 AM »

Never been tried with anything but lead. The whole idea of the plug in the bottom and the softness of lead is to enable "upsetting" the pour-formed skirt into the rifling at the beginning of ignition and at/near the bottom of the gun bore ...sealing escaping powder gas and enabling the rifling to spin/rotate the slug before it exits the bore. I've spent hours in front of a sand pile in a gravel pit shooting and digging out the slugs to be sure the charge, design(s) and metallurgy were all working to provide that function.
However, most riflemen (persons?) I know today are casting or swaging the rifling grooves into the slug when makiing it and before shooting to enable getting the spin. When they do that, they are able to use harder metals like zinc and wheelweight metal... some continue to use a plug-formed hollow cavity design and some have eliminated the cavity altogether.

GGaskill · « **Reply #24 on:** May 10, 2011, 12:34:34 PM »

The traditional Minie cavity shape is difficult to produce so one might consider making the skirt much shorter in length so it stays closer to the bulk of the casting. On a 1" bore or greater projectile, you probably don't need more than 3/16" to 1/4" of skirt length to engage the rifling and seal the bore.

But I have yet to try this in lead or zinc projectiles.

gunsonwheels · « **Reply #25 on:** May 10, 2011, 02:00:11 PM »

One of my early aquaintances shooting a 40mm had a very deep cavity formed by the plug... he was always having problems keeping gas pressure, combined with poorly controlled casting variables, from blowing a hole out the nose on firing... and when he did get a good slug/seal, the cavity pressure increased the skirt diameter to about 1.3 times its as-cast diameter as it cleared the end of the muzzle. I copied my cavity shape and depth from a fellow I used to shoot against who always beat me... (shallower and as pictured) and then did the sand pile tests to make sure the upset was consistent but not inordinately deforming the in-flight characteristics of the overall shape. Had one thin skirt design and shallow which when it did seal curled the skirt clear around forward.
There's a fellow from Nebraska that shows to the Casper shoot every year with a 40mm tube in a 2/3 scale '61 parrot. He placed 2nd in '09 and 1st in '10... he casts a slug about two times longer than mine, has a smaller cavity (though not as shallow as you suggest) and uses wheelweight metal instead of lead. With Wyoming winds he is at a decided disadvantage shooting against the 3" bore F/S guns but he is always right up there near the top... and our max target is 800 yards!