Author Topic: 4" diameter projectile? (Read 2079 times)

nematode · « **Reply #30 on:** July 20, 2009, 06:38:30 AM »

This response to the original question may be late but the problem got my juices flowing again so here's another answer - I really don't have time to do this but what I would or could do for all of you guys that are looking for projectiles to fit your cannons would be to take an impression of the cannon bore. Then I would fashion a mold from the impression and depending upon what type of projectile you want, plastic or metal etc, I would cast the projectile. There is some very good quality, low shrink urethane resin on the market, available online, that is two parts. You can add glass or metal fillers if you wish, to change the properties of the finished product. Adding filler helps minimize volume shrinkage even further. As mentioned in another string about casting projectiles, I have not worked at the larger scale most of you are in with your cannons but I'm sure that up to a certain size bore, casting would be a feasible way to get your projectiles. Just a thought. If I had time I could make a video to show the steps for taking the original bore impression, making the negative mold from that impression, mixing the resin with filler(s) and casting, finishing a projectile. I have no cannons, however, and so I'd have to collaborate with someone here via mail. I am willing to do this at no cost for someone with a cannon bore of 1 inch or something like that as a first experiment. PM me and I will make arrangements to ship materials to you so that you can take the impression of the cannon bore. I will ask you to ship the impression back to me. I will make the mold and cast the projectile, making video as I go. I will return the projectile via snail mail and ask the collaborator to test it in the cannon, with video. Altogether we could put together a nice instructional video from start to finish, if it works!

Cat Whisperer · « **Reply #31 on:** July 20, 2009, 06:57:52 AM »

COOL!

I wish I had something worthy of going through this (I shoot nothing for serious target work as many of the folks here do).

BUT, I want to see the video, or at least a series of pix!

Double D · « **Reply #32 on:** July 20, 2009, 08:24:56 AM »

What kind of tolerance can you work to? How would build in windage?

nematode · « **Reply #33 on:** July 20, 2009, 12:37:16 PM »

Double D - not sure your questions are for me but I'll comment on tolerance for casting pewter. Basically, the alloy I use has special properties. Amazingly, the alloy I work with cools from the inside out. As it cools it shrinks but here's the interesting part - it does not shrink on the outside surfaces. I mean, if a mold is not made properly and the piece is too thick, it can shrink on the outer surfaces which is a casting defect called draw. Generally, larger pieces push the limits and if the casting is not allowed to cool quickly enough, draw will happen - this would never work for cannon balls or cylinder projectiles. Experts will insert teflon pellets into their molds when casting thick or massive pewter pieces, thus, achieving a hollow casting, less mass and less or no draw, etc. This is why I suggest a small bore experiment first - eliminate issues with too thick a casting and draw. In that scenario I should be able to get a right cylinder projectile, for example, that fits the bore perfectly and is uniformly concentric and smooth.

I do not know what windage means.
Here is a question - how should an ideal projectile fit in the bore of a cannon?
Should it fit the bore so snugly that it must be pushed down the barrel?
Or, should it have ever so slight a clearance so the projectile will slide down all the way, unaided?

dan610324 · « **Reply #34 on:** July 20, 2009, 02:05:02 PM »

the widage is the clearance between the projectile and the bore
for smootbores and ball it should be approximately 1/40th of the caliber

but I guess that you mean rifled barrels and cylindrical projectiles when you talk about to make an impression of the bore and make the projectiles from that

sorry but I must ask , pewter is that the same as tin ??
or is it some alloy ??
if so what mix ??
pity that you dont live in sweden, I got 660 lbs of soldering tin that I have no use for (60/40 tin/lead)

nematode · « **Reply #35 on:** July 20, 2009, 02:23:16 PM »

thanks dan - appreciate the information on windage. yes actually the term pewter means an alloy of tin. there are an infinate number of alloys of course. most casting pewter is an alloy predominantly of tin and secondarily, lead. the lead-free pewters are eutectic alloys having the same crystal structure repeating throughout. the better casting pewters are usually around 90% tin, 4 or 5% lead with the balance in trace metals like berillium, cadmium etc that impart subtle qualities. the lead is in these formulations because it helps the molten alloy flow and by the way these alloys cast much more detail than pure lead would cast and also at lower melting points than lead. sorry none of this has anything to do with cannons or projectiles. since lead was used for musketballs in the old days I'm thinking pewter alloys would work in place of pure lead today, for the same and for small cannon projectiles.

dan610324 · « **Reply #36 on:** July 20, 2009, 02:56:32 PM »

yes it would do , but its probably way to expensive
I would guess that 99.9% of the fired balls is never recovered

wheel balancing weights , either zink or lead is probably the most commonly used material for round balls
lead for the smaller and zink from 1" and up

lead weights with a few % added tin (4-6%) is very good for modern rifled firearms, so I would guess that it would be a very good alloy also for rifled cannons
maybe a little to hard alloy to use in hollow based bullets, Im not sure about that
but for breach loaders, and muzzle loaded cannons who use a piece of barrel as the bullet mold I guess its perfect

KABAR2 · « **Reply #37 on:** July 20, 2009, 03:08:49 PM »

Quote from: skip77 on July 20, 2009, 02:23:16 PM

thanks dan - appreciate the information on windage. yes actually the term pewter means an alloy of tin. there are an infinate number of alloys of course. most casting pewter is an alloy predominantly of tin and secondarily, lead. the lead-free pewters are eutectic alloys having the same crystal structure repeating throughout. the better casting pewters are usually around 90% tin, 4 or 5% lead with the balance in trace metals like berillium, cadmium etc that impart subtle qualities. the lead is in these formulations because it helps the molten alloy flow and by the way these alloys cast much more detail than pure lead would cast and also at lower melting points than lead. sorry none of this has anything to do with cannons or projectiles. since lead was used for musketballs in the old days I'm thinking pewter alloys would work in place of pure lead today, for the same and for small cannon projectiles.

Pewter I believe will be too soft for certain forms of projectiles being a soft metal it will deform too easily, we already have a thread on what would you do if

you had a ball stuck down the barrel, this was with lead, if the barrel is fouled and someone starts to hammer to get a pewter ball down the barrel it will create

a nice plug. In a breech loader there would be less issue but I wonder about metal being left behind in the rifling.

nematode · « **Reply #38 on:** July 20, 2009, 03:22:27 PM »

Dan - hadn't thought about cost but you are right. Pewter is not cheap and therefore probably not a viable candidate here.

Karbar - another good point I hadn't thought of, softness and affects from that aspect. Since most pewters melt below pure lead, they could even melt before leaving the barrel... not familiar with cannon facts but certainly pewter could crud up the rifled works. Again, I think it eliminates pewter from the mix.

Thanks for comments guys.

Cat Whisperer · « **Reply #39 on:** July 20, 2009, 03:27:17 PM »

Pewter is largely tin. Cheaper mixes have larger portions of lead.
(Used in the 1700's for things like pitchers, glasses and plates. Too much lead had predictable results.)

I have cast 96.5% tin 3.0 % Silver and 0.5% copper.

It measures about 42 on the Rockwell "B" scale - equivalent hardness to copper jacketed bullets.

When casting zinc in sand moulds, the cannon ball cools and shrinks - leaving the surface seriously non-spherical.

When casting with the tin-silver-copper into COLD moulds the result is the most perfect bullets and spheres I've ever cast.

dan610324 · « **Reply #40 on:** July 20, 2009, 03:38:21 PM »

the tin will NOT foul the bore,
you add it in lead alloys just to minimize the lead fouling of the bore

KABAR2 · « **Reply #41 on:** July 21, 2009, 02:55:35 AM »

Quote from: dan610324 on July 20, 2009, 03:38:21 PM

the tin will NOT foul the bore,
you add it in lead alloys just to minimize the lead fouling of the bore

Ahhh but if when fired some of the pewter melts and spalls off into the barrel the result could get messy.

NitroSteel · « **Reply #42 on:** July 21, 2009, 05:48:01 AM »

Last night we finished up the mortar barrel and made a makeshift carriage to try it out. My cohort is going to make the carriage out of oak, so that it will look authentic.

The dimensions of the mortar is 6" outer, 4" inner, with 1.5" deep, 1.5" diameter powder chamber. This makes the wall thickness 2.25" all the way around.

We filled a propane cylinder with quickcrete (lubed the exterior also) and fired the mortar using a sizeable charge of 2fg. It was a very impressive boom and even more impressive to hear the round when it landed, I believe it was the longest airtime we have achieved yet...

Double D · « **Reply #43 on:** July 21, 2009, 05:55:14 AM »

Cool!!!

Airtime! Yeah!!!

Cat Whisperer · « **Reply #44 on:** July 21, 2009, 06:49:00 AM »

TOF!

Time of flight is the Army term.

I usually get 6 to 10 seconds out of my 4.55" 7.5lb projos.

There is nothing like hearing the round rip/snap off branches and then go THUD on the ground!

NitroSteel · « **Reply #45 on:** July 21, 2009, 06:55:06 AM »

CW, we looked at each other after what seemed to be 15 seconds and said, maybe we just didn't hear it... About that time, it came down in the hardwoods and just crushed a tree and then hit the ground (400-500 yards away). It's all private property, so no worries on hitting anything/anyone. It is the same place we send bowling balls. Hopefully I can find the "bullet" on Saturday.

It was awesome. We'll time the next round.

NitroSteel

dan610324 · « **Reply #46 on:** July 21, 2009, 07:03:06 AM »

the few thousands of a second that the flame from the burning powder is in contact with the backside of the projectile is to short to heat it to melting temperature

or else you couldnt have lead core in modern rifle and pistol ammo

RocklockI · « **Reply #47 on:** July 21, 2009, 08:07:43 AM »

so mary rose had some square bored cannon . i was under the impression that square bullets were illeagl to shoot at christians.....

i read about that in a book somewhere . something about the horrable wounds ......of course i heard the same thing about crossbows .....and that didnt last long if at all .

i think the church was making these rules up . one mans infidel must be whoever he's facing ...and so on .

gary

Double D · « **Reply #48 on:** July 21, 2009, 08:39:12 AM »

Quote from: NitroSteel on July 21, 2009, 06:55:06 AM

It's all private property, so no worries on hitting anything/anyone. It is the same place we send bowling balls. Hopefully I can find the "bullet" on Saturday.

NitroSteel

Two things wrong here.

If you can not see impact, you are missing half the fun.

If you can not see the impact zone, you can see those 12 year old kids who haven't learned or haven't been taught to respect private property.

You wouldn't fire your 30-06 off in the air like this, why would you think it any safer with your cannon.

NitroSteel · « **Reply #49 on:** July 21, 2009, 08:52:54 AM »

Area is inaccessable to anyone else. And, yes, I do shoot my 30-06 into the same area (not straight up into the air because it WOULD likely travel out of the safe zone), but into the same area. My understanding is that a 30-06 might travel as far as five miles. As long as my mortar won't travel over about 1.5 miles - - I'm good.

Sighted in the new Swarovski on my 30-06 yesterday in the same exact place

. Don't take it as me being smug, but I am safe. I wouldn't think of shooting this far on someone elses place, not knowing what is behind it. On the other hand I do like hearing it crash into the trees more than seeing it crash into the hay field. On the other hand, if I had a place where I could safely land it in the water without worrying about it crashing into something expensive of mine or someone elses, I'd have it always land in the water. Can't beat those huge columns of water for effect...

NitroSteel

NitroSteel · « **Reply #50 on:** July 21, 2009, 08:58:14 AM »

Oh yeah, there are no neighborhood kids, for that matter, there are no neighborhoods.

brokenpole · « **Reply #51 on:** July 21, 2009, 12:32:22 PM »

Personally speaking...the heck with time of flight...I want to see smoke and flame!!!!

Double D · « **Reply #52 on:** July 21, 2009, 02:47:13 PM »

Quote from: brokenpole on July 21, 2009, 12:32:22 PM

Personally speaking...the heck with time of flight...I want to see smoke and flame!!!!

Smoke and fire are half of it. Smoke, fire, flight and impact that's where it's at...and as a bonus visiting the impact zone to see what a zinc round ball or bowling ball does when it hits.

I am going to have a wooden fort on the range for a target at the Montana shoot, that should be fun to see the balls hit.

Mike and Tracy are coming up a couple of days early. I have heard through the grapevine, second hand that Tracy and Mike enjoy the wood working and are very creative. So I think I will just take them up to the range and drop them off with a stack of wooden pallets and some baling wire and let them create, while the rest of us go sight seeing.

A side note on shooting into the trees. I have shot into the trees where Tim shoots. Even though the impact zone is in the trees the impact zone is still visable.

NitroSteel · « **Reply #53 on:** July 21, 2009, 02:57:15 PM »

I usually shoot the balls into our hayfield, however the hay is in serious need of being cut right now and I don't want to ride out into it to find my "bullets" and beat the grass down, probably couldn't find them anyway at this point. I've already got a few good scaldings for leaving the "bullets" IN the hayfield in years past to get into the haycutters... Much easier to put them into the trees right now and it is awesome to hear the limbs crack.

KABAR2 · « **Reply #54 on:** July 21, 2009, 03:13:28 PM »

I'm guessing there are very few tree huggers in your parts of the country.............

if they ever get wind of impact zones .........

NitroSteel · « **Reply #55 on:** July 21, 2009, 03:28:07 PM »

You're not suggesting that I put spotted owl decoys in the tops of the oak trees to attract them to the area are you

?

Double D · « **Reply #56 on:** July 21, 2009, 03:44:22 PM »

I know about shooting out into a hay field. I hate loosing my cannon balls in the hay field, and the cutters are so unapologetic when they hit one of my balls and put a ding in them...then they don't even bring them in when they see them. But boy they sure wanna stand around a shoot them!!