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Manouchehr M.
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Eric Hejdström
Location: Visby, Sweden Joined: 13 Mar 2007
Posts: 184
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Manouchehr M.
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Sean Manning
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 Posted: Sun 11 Oct, 2009 10:28 am Post subject: |
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I know a bit about that but I'm having trouble coming up with references. There might be some bibliographic notes in Bert Hall's Weapons and Warfare in Renaissance Europe which is about the technology of gunpowder weapons. Gabor Agoston's Guns for the Sultan discusses the Ottoman cannon and gunpowder industry. Colin Martin's and Geoffrey Parker's The Spanish Armada has lots of information on guns in late 16th century Europe.
What periods are you interested in?
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Jean Thibodeau
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| Posted: Sun 11 Oct, 2009 10:56 am Post subject: |
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I remember reading " somewhere " that canons or at least bronze canons where cast vertically with the chamber end down as the weight of the liquid bronze increased density or at least reduce any porosity in the breach end.
This was to make the powder chamber as strong as possible and any weakness would be at the muzzle end i.e. the bronze as strong as possible where pressure is strongest at ignition of the powder charge.
You can easily give up your freedom. You have to fight hard to get it back!
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Addison C. de Lisle
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| Posted: Sun 11 Oct, 2009 11:26 am Post subject: |
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| Jean Thibodeau wrote: | I remember reading " somewhere " that canons or at least bronze canons where cast vertically with the chamber end down as the weight of the liquid bronze increased density or at least reduce any porosity in the breach end.
This was to make the powder chamber as strong as possible and any weakness would be at the muzzle end i.e. the bronze as strong as possible where pressure is strongest at ignition of the powder charge. |
I don't know about historical cannon-casting, but from the standpoint of having done larger scale bronze casting, as well as small scale casting of silver, casing them vertically would make the most sense, and they would probably have to be cast with the hole facing up, as you say (shaped like a "U"), in order to prevent air bubbles from being trapped in the barrel. Air bubbles stop the investment from pressing against your form in that area, which leads to a blob of metal in the shape of the air bubble sticking off your casting.
As I typed this it occurred to me that investment casting isn't be the most efficient way to mass produce something like a cannon, and it would probably have some kind of re-usable mold. However, I think the problem of air pockets being trapped in a barrel cast in an upside-down "U" shape would still distort the metal and result in an incomplete cast.
These are just my speculative thoughts on the subject and not researched historical fact, so view them as such.
www.addisondelisle.com
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Jeroen Zuiderwijk
Industry Professional
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| Posted: Tue 13 Oct, 2009 3:11 pm Post subject: |
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The art of cannon casting is described in "De la Pirotechnia" by Vannoccio Biringuccio, dating to 1540 (amongst many other highly interesting descriptions of metalworking techniques at the time). I had a translation of it on loan some time ago. If you can track it down (Amazon has copies of it), it's definately a worthy read, if alone for the highly poetic way the technology is written down making it a very interesting read. They surely don't write technical documents like they did back then anymore.
Jeroen Zuiderwijk
- Bronze age living history in the Netherlands
- Barbarian metalworking
- Museum photos
- Zip-file with information about saxes
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Elling Polden
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| Posted: Tue 13 Oct, 2009 4:01 pm Post subject: |
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Here's a extensive description of the process;
http://www.melfisher.org/cannonsurvey/castguns.htm
"this [fight] looks curious, almost like a game. See, they are looking around them before they fall, to find a dry spot to fall on, or they are falling on their shields. Can you see blood on their cloths and weapons? No. This must be trickery."
-Reidar Sendeman, from King Sverre's Saga, 1201
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Matthew Fedele
Location: Auburn, NY USA Joined: 21 Jul 2005
Posts: 64
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| Posted: Tue 13 Oct, 2009 6:28 pm Post subject: |
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Mel Fisher is a little off, the first artillery was forged out of iron, then cast in bronze, then eventually cast in iron.
It can be cheaper to buy an original than have one cast these days. It seems that if they are damaged at all the value of an old cannon is greatly diminished.
Cheers!
Matthias
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Elling Polden
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| Posted: Wed 14 Oct, 2009 7:33 am Post subject: |
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The very fist, smaller ones, waaay back in the 14th century, where cast.
However, the first LARGE ones where wrought iron, so you are both right 
"this [fight] looks curious, almost like a game. See, they are looking around them before they fall, to find a dry spot to fall on, or they are falling on their shields. Can you see blood on their cloths and weapons? No. This must be trickery."
-Reidar Sendeman, from King Sverre's Saga, 1201
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Jean Thibodeau
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| Posted: Wed 14 Oct, 2009 7:54 am Post subject: |
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| Elling Polden wrote: | The very fist, smaller ones, waaay back in the 14th century, where cast.
However, the first LARGE ones where wrought iron, so you are both right |
And the wrought iron ones built like a barrel with metal bars welded to each other and reinforced with iron hoops.
Mostly these being breach loading with the breach being secured by using wooden or iron wedges.
Bronze cast canon being stronger and less prone to catastrophic failure but expensive due to the cost of bronze.
Cast iron I think is weaker but this was compensated for my making them heavier with thicker chamber and barrel walls.
I think bronze made a superior canon but you could probably build 2 or 3 cast iron canons for the cost of a single bronze canon.
( Note: Some of this may need to be fact checked as I'm going from general memory and not based on a specific reference I can quote ).
You can easily give up your freedom. You have to fight hard to get it back!
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Eric Hejdström
Location: Visby, Sweden Joined: 13 Mar 2007
Posts: 184
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| Posted: Wed 14 Oct, 2009 8:37 am Post subject: |
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| Quote: | | And the wrought iron ones built like a barrel with metal bars welded to each other and reinforced with iron hoops. |
Hence the word gunbarrel!
Here's an quite good page about cannons: http://riv.co.nz/rnza/hist/gun/firstgun.htm
In general, the first reason to discard the wrought cannons in favour of cast bronze is the loss of gaspressure when fired. Me and a friend have built a breechloaded mid 15th century cannon and even if we used a steel pipe for the barrel (for safety reasons since this was a first try) we noticed a quite large loss of pressure, especially when firing solid shots. Grapeshots with about 2lbd of lead bullets gave about the same reult as a loosely fitting solid ball.
Here's a still from when we testfired it in January this year. Notice the massive gasflame around the back of the barrel where the chamber is. And it was very securely wedged in place I tell you. The fit has to be incredible well made if this should be prevented. A fit that's not possible to attain with blacksmithingtools...
So I can definately see the reason to move onwards to casting cannons. However, the firing rate with a breechloader is much much faster then a muzzleloader but you loose effective range and accuracy.
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Jean Thibodeau
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| Posted: Wed 14 Oct, 2009 10:12 am Post subject: |
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| Eric Hejdström wrote: | | However, the firing rate with a breechloader is much much faster then a muzzleloader but you loose effective range and accuracy. |
With at least one spare chamber or preferably 2 or 3 I would guess one could maintain a high rate of fire by reloading chambers while one was being used ! This probably limited by the dangers of overheating or stressing the barrel and having it blow up, so I imagine that after a dozen shots at most one would have to let things cool down a bit. 
But I would guess that if one had 5 or 6 preloaded chambers the rate of fire could be higher than with a muzzle loader but there would still be a need to wet the inside of the barrel between shots to avoid accidental ignition due to burning embers inside the barrel: This would slow down the maximum rate of fire for the sake of safety in normal use but in an emergency I guess the rate of fire would depend on how fast one could unwedge the spent chamber, load in a new chamber and wedge it in.
Oh, and with all that flash at the breach I guess one would want to use a very long linstock and look away from the canon.
But this is drifting a bit from the original question of how canon was cast and more into period use. 
Casting techniques in the 15th, 16th, 17th, 18th and 18th century also developed and evolved I imagine.
In the 19th century chilling and shrink casting steel bands around the barrel was also used so that the inner casting would be surrounded by bands of steel that at room temperature would put compression on the inner tube.
( The link explains better and with less chance of mistakes in technical details or terminology ).
http://en.wikipedia.org/wiki/Dahlgren_gun
Also the Odman gun:
http://en.wikipedia.org/wiki/Rodman_gun
You can easily give up your freedom. You have to fight hard to get it back!
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Elling Polden
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| Posted: Wed 14 Oct, 2009 3:52 pm Post subject: |
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Over all, manefacturing techniques where innsuficient to make reliable breechloaders of any size (handgun to cannon) before ca 1840, though many diferent designs where tried.
For instance, the Revolver consept was tried as soon as a ignition mechanism that did not need to be wound was available.
Here's a 1600 German one from the Danish Royal Armouries;
http://www.thm-online.dk/genstande/6-SB296/
"this [fight] looks curious, almost like a game. See, they are looking around them before they fall, to find a dry spot to fall on, or they are falling on their shields. Can you see blood on their cloths and weapons? No. This must be trickery."
-Reidar Sendeman, from King Sverre's Saga, 1201
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Manouchehr M.
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Eric Hejdström
Location: Visby, Sweden Joined: 13 Mar 2007
Posts: 184
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| Posted: Fri 23 Oct, 2009 4:09 am Post subject: |
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| Quote: | | With at least one spare chamber or preferably 2 or 3 I would guess one could maintain a high rate of fire by reloading chambers while one was being used ! This probably limited by the dangers of overheating or stressing the barrel and having it blow up, so I imagine that after a dozen shots at most one would have to let things cool down a bit. Wink Question |
We are using three chambers and when doing our drill safely and in a very orderly manner we fire three shots a minute. We could easily ruch it to five shots a minute and that includes a swabbing between every shot. We are wetswabbing the barrel with a mix of water and vinegar to cool it. We have such a hefty barrel so I guess we would have to fire a whole lot of shots before it gets a least bit warm. The chamber is not even hot to the touch after firing but maybe we oversized the dimensions a bit but hey, saftey first!
| Quote: | | Oh, and with all that flash at the breach I guess one would want to use a very long linstock and look away from the canon. |
Heh, our linstock is just around 30" long but you should stand a bit behind to the side anyways!
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Jean Thibodeau
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| Posted: Fri 23 Oct, 2009 8:02 pm Post subject: |
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| Eric Hejdström wrote: | | Quote: | | With at least one spare chamber or preferably 2 or 3 I would guess one could maintain a high rate of fire by reloading chambers while one was being used ! This probably limited by the dangers of overheating or stressing the barrel and having it blow up, so I imagine that after a dozen shots at most one would have to let things cool down a bit. Wink Question |
We are using three chambers and when doing our drill safely and in a very orderly manner we fire three shots a minute. We could easily ruch it to five shots a minute and that includes a swabbing between every shot. We are wetswabbing the barrel with a mix of water and vinegar to cool it. We have such a hefty barrel so I guess we would have to fire a whole lot of shots before it gets a least bit warm. The chamber is not even hot to the touch after firing but maybe we oversized the dimensions a bit but hey, saftey first!
| Quote: | | Oh, and with all that flash at the breach I guess one would want to use a very long linstock and look away from the canon. |
Heh, our linstock is just around 30" long but you should stand a bit behind to the side anyways! |
Nice to know the details from someone with first hand experience firing these.  
So I guess with enough preloaded chambers a fairly high rate of fire could be maintained for quite a bit of time.
Just a question about trying to limit the gas leakage: I think that a reduced diameter part of the chamber enters the " breach " end of the barrel ? I wonder if a thick leather washer compressed by the wedge used to secure the chamber would be effective at least for one use ? Might be soaked in water or greased ?
Such a washer could compensate for the poor fit/tolerances in period of the chambers in the barrel ? No idea if this is a functional idea or a historically valid and known idea, so I'm curious about your opinion/knowledge about this.
You can easily give up your freedom. You have to fight hard to get it back!
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Eric Hejdström
Location: Visby, Sweden Joined: 13 Mar 2007
Posts: 184
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| Posted: Sat 24 Oct, 2009 7:31 am Post subject: |
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We actually have a narrow part of the chamber that fits snugly into the back of the barrel but the reason it doesn't fit as good anymore is that recoil and the hammering down of the wedge behind have driven the barrel about 1mm forward. This is more than enough for the gaspressure to escape. Especially when firing a solid shot. We have also discussed the idea to use a leather washer. Unfortunately we haven't "aired" the cannon since august so I guess it's time soon... We're probably go for a thick, but soft, leather washer drowned in tallow. Hopefully we will get better results.
Well, even if we're getting further from the original subject I just thought that I'd post a link to the very first time we used the cannon. Hope you enjoy it even if the quality is quite bad...
Premiere! January 2009
http://www.youtube.com/watch?v=R6ZdLfBqmas
March 2009
http://www.youtube.com/watch?v=CVbecIWvmYE&feature=related
(shooting blanks with different types of wadding)
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