how would you make a sabot for my cannon?


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CANNONMAN
July 29, 2014, 07:36 PM
A while back I was given a collective thumbs down for wanting to cast copper cannon balls. As I have given up trying to get the copper out of the numerous motors, I've decided to agree. Anyway, a small juice can fits, sort of. The juice can is about a 1/2" shy or lacks about 1/4" on all sides. I have seen success with filling soda cans with concrete and desire to do so with these readily available juice cans. So, would you: 1. Heavily patch the can or 2. create a sabot of sorts? Next for increased accuracy what are your collective thoughts about pouring an inch, or so, of lead first then fill with concrete in order to front weight the ordnance. It's a smooth bore cannon but I would like to create spin. Can this be done with a sabot this narrow? Ideas? "Success is more attitude than aptitude." Some one smarter than me

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dprice3844444
July 29, 2014, 08:31 PM
pvc pipe?

WestKentucky
July 29, 2014, 08:35 PM
A block of plastic and a lathe would be a good start. A good endpoint would be an injection mold recreating what you made on the lathe.

Pete D.
July 29, 2014, 08:39 PM
No patch. Cannons and mortars are loaded so that there is a tiny bit of space between the projectile and the wall of the bore.....this space is called windage and it is necessary. However you put together your sabot, size it to allow for windage.
Windage is computed multiplying the round ball diameter by 25/24ths.
A two inch projectile would thus need a bore that is 2.083 inches in diameter - say 2.1".
Pete

MErl
July 29, 2014, 08:47 PM
As a way to see if it'll work, wrap the can in cheap masking tape.

Curator
July 29, 2014, 08:57 PM
Original cannon sabots were made of wood but some undersized-projectiles were centered in the bore with a ring of heavy rope. While "windage" was allowed for, it was only required when shooting fused shells. The fuses were loaded facing out and relied on the wash of hot gas around them to ignite it. Loading with fuse toward the powder charge almost always caused the shell to burst in the gun or immediately after leaving the muzzle. No fun there!

Why not try a few wraps with 1/4 inch rope at each end of your juice can? Glue them on with "white-glue" so they don't unravel when your are loading them. A smooth-sliding fit will give the best accuracy. If your juice can projectile is going to be longer than it is wide, some lead poured into the forward end will help in the accuracy department. Think of the old Breneke shot gun slugs that shoot great in smooth bore shotguns.

4v50 Gary
July 29, 2014, 10:51 PM
Cylindrical piece of wood. They did that in the old days.

BTW, by the time of Gustavus Adolphus and the Thirty Years War, there were leather wrapped cannons too.

witchhunter
July 29, 2014, 11:58 PM
Way back before electricity we used Snap-E-Tom cans filled with concrete. they were a slip fit. Not much clearance, but they worked.....kinda.

kBob
July 30, 2014, 09:01 AM
There were several designs leather guns and folks do get excited about them from time to time.

They were thin walled bronze guns that were wrapped in rope (or some models wire) for reinforcement. The leather was to protect the rope and possibly contain fragments when the guns failed. They were very low round count to failure guns. Their purpose was to be light and transportable. They certainly could not compete with solid field guns for round counts even on a one day basis.

On the other hand one might take them where they were needed but no cannons expected. To paraphrase a famous ACW maxim "Get there furstust with ......something."

A great deal of effort and money seems to have been put into them though few were ever fielded and used. Much of the work came to a stop when the King tried leading from the front one too many times down in the Germanies.

I am not really a military historian , but I play one on TV :)

-kBob

zimmerstutzen
July 30, 2014, 11:23 AM
The Dryese needle gun fired a football shaped bullet contained in a dense fibre sabot. Sort of like a very dense paper mache' Of course a simple homosote wad under a "wrapped" underside can should probably work fine. The wrapping may affect the projectile's flight negatively however. I suppose paper patching as done with BPCR bullets may help take up the space, but why not just search for a better fitting projectile.

Jim Watson
July 30, 2014, 11:33 AM
The only cannon I ever shot, a little "grasshopper gun" was being loaded with a round zinc ball taped to a wood disc. Accuracy was pretty sad, but the gunner said it was lots better than with a naked ball.

The battery members mined the berms for their zinc shot to recycle; a 20 lb Parrott rifle was launching 17 lbs of zinc per round.

If I were the OP, I would be grocery shopping with calipers to see if there was a different can of correct caliber.

There was an old gunzine article describing a gun being shot with concrete filled cans with a lot of windage. One day they loaded a can not knowing there was a void in the concrete. The unsupported end of the can expanded like a Minie, sealed the bore, and went a LONG way off their range.

Willie Sutton
July 30, 2014, 11:54 AM
The unsupported end of the can expanded like a Minie, sealed the bore, and went a LONG way off their range.

Leave a half inch of can unfilled with concrete and exploit this idea to obturate the bore on firing?



Willie

.

25cschaefer
July 30, 2014, 05:44 PM
How about a disk of thick leather/rubber/sumthin glued to the bottom of the can?

bigfatdave
July 30, 2014, 05:58 PM
Why NOT Papier-mâché?

It has been done
http://en.wikipedia.org/wiki/Papier-m%C3%A2ch%C3%A9#Paper_sabots
http://upload.wikimedia.org/wikipedia/en/8/88/Schenkl_projectile.jpg
The Schenkl projectile, used in the American Civil War, used a papier-mâché sabot

CANNONMAN
July 30, 2014, 07:55 PM
Great ideas from a great group of guys! Love the plastic coating concept. What are the odds of finding the right ID's and OD's of readily available pipe? PVC melts around 120f. I might try a dip approach. I like the idea of leading the front of this thing. Ball mill is almost complete and ingredients are at the ready. Results coming, hopefully soon. Oh, forgot, the tolerance is way off to consider the amount windage. However, I will take your comment to heart when deciding the thickness of the coating.

CANNONMAN
July 30, 2014, 08:24 PM
I couldn't get the idea of Willie Sutton's out of my head. At first I thought, "No way! the rate and degree of the pressure would obliterate the thin aluminum before any obturation." So keep the baby and toss the bathwater! I think it looks kinda like a gas checked wad cutting cannon thing! Ideas?

Willie Sutton
July 31, 2014, 12:58 AM
^^

Methinks you would want a bearing band on the front as well. Masking tape should work.


Willie

.

4v50 Gary
July 31, 2014, 01:15 AM
Duct tape > masking tape.

RetiredUSNChief
July 31, 2014, 08:10 AM
If you don't want to make this a pain in the keister, then you need to think about how to set up to make sabots easily...meaning with as little time consuming labor as possible.

A sabot is nothing more than a device used which will enable your cannon to fire a projectile with a smaller diameter than the bore. Making something that will enable you to create sabots for a variety of different diameter core projectiles with little effort should be your goal. Once you have that, you'll be good to go to create sabots for whatever you want to fire.

I have a carbide cannon with a three inch PVC bore, so I've given some thought to this. At least, I did before finding oversized tennnis balls that perfectly fit the bore. Here's how I would have gone about it:

First thing you need to do is make a mold with an inside diameter that matches that of your bore. Actually, you may need to make the mold with an inside diameter that is slightly smaller than your bore. This doesn't have to be anything too fancy, but it should be durable because you don't want it falling apart after making only one or two sabots.

The mold should have a hole in the bottom. The purpose of the hole is, at the minimum, to allow you to push your completed sabot out of the mold. An additional function of the hole would be to allow you to properly center and support the core of your sabot inside the mold without any extra support required. This would be accomplished by sizing one end of the core of your sabot to fit the hole enough to allow the core to stand on it's own, properly centered in the mold.

Once you've created your mold, spray the inside with something like a silicone lubricant. Place the mold on a level surface and insert the core of your sabot. Now pour a "potting compound" of your choice into the mold. This can be a plastidip, plastisol, epoxy compound, fiberglass, or any other substance which you can mix and pour around the core. The key is that it will bond to the core and set up/harden while sitting in the mold.

Once the potting compound has set, pop your completed sabot out of the mold. (This is where the hole in the bottom comes in handy.)

After some experimentation on what works best for you in terms of the mold and potting compound, you can now make several more molds so you can make more than one sabot at a time. If it takes a couple hours for the chosen potting compound to set up, it would take quite a bit of time to churn out a dozen sabots. Make a dozen molds and you can then make several dozen sabots on a lazy day.


There is a large variety of materials you can make a mold from, and even more materials you can use for the cores and potting compounds. For example, plaster of paris might make an interesting sabot because it may hold together just long enough to perform it's primary function, yet essentially be pulverized to give a more dramatic "smoke" cloud as the round exits the barrel.

If you make your mold out of a fairly rigid, but slightly flexible, material (like some plastics), then the slight flexibility may make it easier to pop your completed sabot out. Likewise, making the mold out of metal might give you the ability to heat the mold with a hair dryer to cause it to expand slightly, making it easier to pop the sabot out.

SEE IT LIKE A NATIVE
July 31, 2014, 12:40 PM
Try using Durhams Rock hard water putty ! It is great for moldmaking and should make an excellent sabot when hard ! Kevin

Willie Sutton
July 31, 2014, 12:49 PM
Or you could line your barrel and then enjoy shooting cans without further hassle.

Willie

.

Officers'Wife
July 31, 2014, 01:17 PM
A while back I was given a collective thumbs down for wanting to cast copper cannon balls. As I have given up trying to get the copper out of the numerous motors, I've decided to agree. Anyway, a small juice can fits, sort of. The juice can is about a 1/2" shy or lacks about 1/4" on all sides. I have seen success with filling soda cans with concrete and desire to do so with these readily available juice cans. So, would you: 1. Heavily patch the can or 2. create a sabot of sorts? Next for increased accuracy what are your collective thoughts about pouring an inch, or so, of lead first then fill with concrete in order to front weight the ordnance. It's a smooth bore cannon but I would like to create spin. Can this be done with a sabot this narrow? Ideas? "Success is more attitude than aptitude." Some one smarter than me
Roll the can in Kraft paper until it's the right diameter.

CANNONMAN
July 31, 2014, 01:31 PM
RetiredUSNChief, How about a simple drawing for a simple cannonman kind of guy? Also, what do you think about "fluting" the tail of the sabot? I am thinking that if I were to drill a few holes from the back to the front at say 15 Degrees off axis that the expanding gases would force the projectile into rotation. All thoughts and ideas, as always, are welcomed. "A single effort is worth a thousand dreams!"

RetiredUSNChief
July 31, 2014, 10:06 PM
RetiredUSNChief, How about a simple drawing for a simple cannonman kind of guy? Also, what do you think about "fluting" the tail of the sabot? I am thinking that if I were to drill a few holes from the back to the front at say 15 Degrees off axis that the expanding gases would force the projectile into rotation. All thoughts and ideas, as always, are welcomed. "A single effort is worth a thousand dreams!"

Hmmm...you're asking quite a lot! I do better making examples than sketching.

But imagine a drinking glass with straight sides sitting on the counter. If the inside of the drinking glass is the same diameter of your cannon bore, then that would look like the mold I'm talking about. If you were to drill a hole through the center of the bottom of that glass, that's the hole I'm talking about which you could use to help push your finished sabot out.

Stand the core of your sabot upright in the center of the glass, then pour the potting compound around the sides and let it set up.


That's all there is to it. With that image in your mind now, you can go about making a custom mold or finding something that is the correct diameter.

You might start out looking at some concrete cylinder molds. Also, look into some round stainless steel round forms.

What you're looking for is a cylinder which is already the right size to use as a mold. Try googling these things and searching "images" to see what I mean.


If I were to make a mold, I'd first make myself a cylinder of the exact diameter that I would want the outside of the sabot to be. Ideally, this cylinder should just fit the bore of your cannon.

Then I'd make a mold around the cylinder. Depending on how you want to do this, you could create reusable molds or you could create plaster molds that you would break apart once the potting compound sets up. Making a mold out of fiber glass should be fairly easily done. Just remember to coat the cylinder with something to make it removable when you're done so you can pull it out of your newly formed mold.

Pancho
July 31, 2014, 11:20 PM
Have you considered using aluminum foil? Cheap, easy to form.
I'd be cautious about using plastics because of the fouling possibilities.

CANNONMAN
August 1, 2014, 08:27 PM
I kinda like the plastic idea. Has anyone tried melting a pot of PVC? I think the idea of making a mold, filling with re-enforced concrete and coating with PVC sounds quick, inexpensive and gives a lot of room to experiment with design.

zimmerstutzen
August 1, 2014, 09:52 PM
When I was about ten years old, I got a Plastic toy army molding set for my Birthday. When I ran out of plastic pellets we just melted down bleach and detergent bottles that we cleaned well and cut up. There was a heated cylinder with a funnel bottom smaller than a Lee lead melting pot. There was a piston attached to an arbor press arrangement for forcing the melted plastic through the base. We could mold anything available as a metal mold for molding lead soldiers, etc. We had a lot of burned fingers, but it was fun. Similar industrial units are now available for sale on-line, but the cheapest are about $800.

It is far easier to melt detergent bottles than pvc.

Officers'Wife
August 2, 2014, 04:28 PM
Hmm, low ignition temp plastic + the heat of a powder charge? It would be good for setting fire to brush piles as well. It would be an interesting effect after dark though.

RetiredUSNChief
August 2, 2014, 05:13 PM
Hmmm...

I forgot to address the issue with respect to imparting a spin on the projectile.

A stabilizing spin on a projectile, not having studied this, is likely a function related to length, diameter, shape, and RPM. A little spin might not be stabilizing at all. In fact, it may destablize somewhat.

If you're shooting round shot, I wouldn't worry about it. If you're shooting round shot in a sabot, I still wouldn't worry about it. If you're shooting elongate sabots, then it would be something you'll just have to experiment with and see what you can do to make it spin and how effective it is.

You can impart spin by altering the aerodynamic shape of the sabot. You can probably impart spin by the shape of the bottom of the sabot. How much and how effective, I don't know how you could gauge. Well, how much I don't know...but how effective could be gauged by studying the impact marks in a target object to look for keyholing.

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