Author Topic: A new cannoner (Read 8507 times)

GGaskill · « **Reply #30 on:** September 28, 2007, 04:12:21 PM »

I would like to put the mold in the oven but I think my mom would not be very happy about that.

Don't assume she would not allow it (although I don't know her.) Ask; tell her it is a slow process that should evolve only water vapor and cause no harm to the oven.

I have never done lost foam so I can't help with that. Try it and see what happens. Just from the procedure, you will have to deal with noxious smoke and bubbling plastic.

See if you can find a foundry somewhere nearby and talk with the people there. I imagine they would be happy to share with the next generation.

Cannon caster · « **Reply #31 on:** October 01, 2007, 11:31:23 AM »

Yesterday I cast a small pocket mortar. It is made from brass and is 6-7 cm long. I haven't drilled the bore (it will be 13 mm) yet and the hole for the fuse but will probably tomorrow. The mold was a steel pipe closed with pressed plaster at one end. The brass was homemade 80:20.

cannonmn · « **Reply #32 on:** October 02, 2007, 07:28:52 AM »

>What is better for cannons brass or bronze?

Gunmetal bronze, 90% copper and 10% tin (the alloy percentages can vary somewhat, and sometimes other metals make up a small part) is the one generally-agreed-upon nonferrous alloy for casting cannons. A lot of the historical literature particularly from England refers to "brass" cannons, but that was merely another term for bronze when referring to cannons.

Brass is an alloy of primarily copper and zinc. It does not normally attain the same tensile strength nor hardness as bronze, and is not used for casting "serious" cannons. By "serious" cannons I mean military weapons, line throwing cannons, and high quality salute cannons.

From reading these boards I think I'm going to get a lot of people saying I'm wrong, but that's what I believe and what I've read in many reliable sources.

The current metals market makes things very confusing due to the large number of nonferrous copper-based alloys available. Some alloys labeled bronze of one kind or another have the same constituents as some brass alloys, and vice-versa. So when I say bronze, I mean an alloy containing roughly 90% copper and 10% tin.

The question "Can I cast a brass cannon that will fire blanks safely?" is another matter. A small muzzle-loading salute cannon would probably work fine for some number of shots, provided it was well -made with thick enough barrel, and not overloaded nor wadded. A big mistake a lot of BP shooters seem to make is wadding or over-wadding their cannons. However, I would personally not recommend making a cannon out of brass if your main purpose is to shoot projectiles out of it.

Let me add a disclaimer that I'm not by any means the most experienced cannon shooter nor manufacturer there is, the information I'm putting in this post is largely academic and not gained by actual experience. I've made a couple of small cannons out of 1018 steel but all rhe rest were bought. I've shot a lot of cannons but only one brass one. It was small and the barrel ruptured about the tenth time I put a small firecracker in it to make noise. I had one small bronze cannon fail also but that was due to a gross overload. I have not had any problems with ferrous metal cannons.

Cannon caster · « **Reply #33 on:** October 02, 2007, 10:32:25 AM »

How about cast iron? Is it a good cannon material? Or is it too brittle?

I have seen your videos Cannonmn. Very nice! I can't wait to see your new large mortar!!

cannonmn · « **Reply #34 on:** October 02, 2007, 11:23:25 AM »

>How about cast iron? Is it a good cannon material? Or is it too brittle?

Hi, glad you like the videos.

Again, I'm coming from more of a "what I've read for a long time and what people tell me" since I seldom shoot unlined cast iron cannons except for occasional blank loads.

The general consensus is that replica cast iron cannons should have a properly-installed seamless steel tube, closed at the breech end by acceptable methods. Organized groups such as the NSSA do not permit anyone to fire an unlined cast-iron cannon at their events.

Cast iron is kind of a fickle material, and it seems like getting iron castings without blowholes, stress areas, etc. is nearly a lost art. Due to all the uncertainties of cast iron, the liner is required.

We have mid-19th C. cast iron original guns that were cast by founders who had many years experience casting good cannons. I would fire them with reduced loads if they were in excellent condition, but I'd still fire with a fuse and retire a safe distance.

I've read that in the US, the average tensile strength of cannon cast iron improved from about 10,000 psi to over 30,000 psi due to improved techniques, from about the 1820's to the 1850's. Even so, I dont think the NSSA allows original cast iron cannons in its matches unless the guns are lined, but someone check that issue, I'm not in the NSSA.

I hope that info helps somewhat, wish I had more personal experience with it.

Cannon caster · « **Reply #35 on:** October 02, 2007, 11:49:01 AM »

Well it looks like bronze is the best. I have to find tin somewhere. Also I have heard that it is a good thing to add a small amount of lead to the bronze or brass to make it harder. Is that true?

cannonmn · « **Reply #36 on:** October 02, 2007, 12:51:12 PM »

>Well it looks like bronze is the best. I have to find tin somewhere. Also I have heard that it is a good thing to add a small amount of lead to the bronze or brass to make it harder. Is that true?

I've never heard that but I've never tried to make bronze. I doubt it has anything to do with hardness. You might want to check around before you try to create castable bronze from the raw materials because I'm pretty sure there is some kind of technique required, and possibly other materials that act as flux.

The particular type of base metals you use might make some difference also, as in the case of trying to cast aluminum. You can't just take any old scrap aluminum and get a good casting I'm told, since some aluminum alloys are only intended for extrusion etc. Casting aluminums have additives that help it pour.

I'm not a metallurgist or founder but I know there are a lot of tricks to doing that stuff successfully that only come with experience or training. I'd talk to someone who has successfully cast bronze before.

Artilleryman · « **Reply #37 on:** October 02, 2007, 12:55:09 PM »

Cannonmn, The N-SSA has the following rule that applies to original barrels.

"Actual or exact scale replicas of Civil War artillery pieces may be fired. The term “Civil War” applies to any artillery piece whose model antedates April 26, 1865. Replicas of artillery pieces must duplicate original pieces. All reproduction barrels must be made of iron, steel or bronze. All reproduction barrels and those original barrels failing inspection must be lined with a bore liner of extruded seamless steel tubing of a minimum ANSI standard and of a minimum 3/8-inch wall thickness."

You can use an original unlined barrel if it passes inspection. Generally speaking original iron barrels have bores that are not well suited of competition and liners are installed. There are a few original barrels that have been on the line. Reproduction cast iron barrels have liners. Barrels made of solid steel do not have to have liners. Bronze guns that pass inspection do not have to have liners. There are some rifled bronze reproductions that have rifled liners simply because bronze rifling does not last long. Hope this helps.

cannonmn · « **Reply #38 on:** October 02, 2007, 01:29:50 PM »

Thanks, good info on the NSSA rules there!

One other piece of info about casting bronze cannons: I was looking though some old documents in the National Archives. One letter I found was a report to the Chief of Ordnance from William Wade, dated in the early 1850's as I recall. He was visiting Ames foundry in Chicopee or Springfield MA. Ames had a contract to cast bronze M1841 6-pounders for the US but they were having trouble. The tin was separating out from the bronze as soon as the bronze got in the mold. leaving big splotches of tin on the gun's surface, and of course a weaker alloy. Wade worked with them until they improved the process so the tin did not separate out.

I seem to recall some kind of flux was requried. Wade kept in the background but he was a relatively high-paid Civil Servant who traveled around from one foundry to the next, helping them adopt the latest methods, and developing some of them himself. He was also Thomas J. Rodman's mentor. He preferred to work through Rodman to get his methods adopted. Wade reported directly to the Chief of Ordnance.

Don Krag · « **Reply #39 on:** October 02, 2007, 03:02:10 PM »

Lead increases flow-ability when casting which increases the ability to fill you mold and to fill any fine details. It also improves machinability on most metals. I've cast leaded red brass and it flows much better than regular 360 brass. Lead is usually in very small percentages.

Cannon caster · « **Reply #40 on:** October 02, 2007, 09:42:08 PM »

Quote from: Don Krag on October 02, 2007, 03:02:10 PM

Lead is usually in very small percentages.

How much?

cannonmn · « **Reply #41 on:** October 02, 2007, 11:46:24 PM »

Here's a site for do-it-yourself casting. He uses an oil burner he made, and regular commercial crucibles he bought. He tried out a mix of purchased silicon-bronze and scrap bronze. He does not like lead or zinc in his bronze due to the fumes. He offers booklets on casting that I'd probably buy if I were going to try it.

http://www.backyardmetalcasting.com/brasscasting02.html

cannonmn · « **Reply #42 on:** October 03, 2007, 12:23:09 AM »

Here's a video showing the casting of some small bronze items. The narrator took a 1-week course in it that showed him how to make an efficient furnace out of a metal bucket. It looks like everyone who casts bronze uses ceramic crucibles since bronze is cast at 2000 degrees F. I guess that's too hot for your usual iron and steel pots used with lead and zinc casting, therefore they use crucibles. It looks like this caster uses scrap bronze and gets decent results, although he doesn't talk about the metal.

http://www.youtube.com/watch?v=jFOo5EWNl8M

Cannon caster · « **Reply #43 on:** October 03, 2007, 08:24:57 AM »

Thank you for the links Cannonmn.

I have seen the backyard metal casting site. Very interesting. The video is also very interesting. About the crucibles iron or steel pots can be used to melt brass, bronze or copper. I melted around 2 kg of brass in a coffee cooking pot with very thin walls. The pot lasted around 10 melts. You can see the pot at: http://www.metacafe.com/watch/744893/how_to_making_and_casting_brass/ This time we melted much less than 2 kg.

Perhaps the best thing to do would be that I buy a round bronze stock and drill the bore and the vent. But then it is not the complete do it yourself . I am also very interested in casting so I would like to cast the cannon. Me and my friend did cast one cannon and one pocket mortar. The mortar isnt finished yet (the bore is only partially drilled), Both made from brass. If you are interested you can see the cannon at: http://www.metacafe.com/watch/794729/firing_a_homemade_cannon_using_whistle_mix/

Cannon caster · « **Reply #44 on:** October 05, 2007, 09:35:55 AM »

Me and my friend made several cannons from inox pipe by crimping the pipe at one end, heating it and hitting it with hammer to seal it better, putting a piece of lead in the pipe ad melt it and let it solidify in the pipe. We putt the lead there to seal the pipe better (less gas escapes). Does the lead add to the strenght of the seal or is it better not to add it?

GGaskill · « **Reply #45 on:** October 05, 2007, 11:54:33 AM »

Does the lead add to the strength of the seal or is it better not to add it?

It depends if the lead actually "wets" the surface (the way solder does) or if it just sits on top.

The real question is the use of pipe. Inox means nothing to me so maybe you can explain the term. Ordinary pipe should not be used for cannon barrels to be fired.

While the general design recommendation of this board is that the chamber walls be as thick as the chamber diameter, if you are going to deviate from this recommendation, you should at least have some idea of the stress in the wall before firing the barrel. You can go to this web page for a stress calculator that will give you some useful numbers (in English units.) The web page is NOT a total cannon design page so don't attribute too much to it but if the calculations say the stress is greater than half the strength of your material, you should try another design.

Cannon caster · « **Reply #46 on:** October 05, 2007, 12:17:46 PM »

Quote from: GGaskill on October 05, 2007, 11:54:33 AM

Does the lead add to the strength of the seal or is it better not to add it?
You can go to this web page for a stress calculator that will give you some useful numbers (in English units.)

So the wall thickness and inside diameter should be in inches? In what unit should the chamber pressure be (where I live atmospheres are used)? And in what unit is the hoop stress written? I am not used to english units so this is a problem for me.

Inox is a high strength stainless steel. The pipe I use is not a ordinary one. It is a very good pipe (also very expensive, one foot costs around 7-8 dollars while ordinary costs much, much less).

I think that the lead wets the surface (it doesn't move when I shake the pipe and after 4 shots it is still there).

GGaskill · « **Reply #47 on:** October 05, 2007, 03:38:36 PM »

1 atmosphere is about 14.7 lbs per sq in. I tend to use 20,000 lbs/sq in as the chamber pressure since we don't have a practical way of measuring it and that has been reported by Switlik. The diameter and thickness should be in inches (25.4 mm per inch.)

However the equations are not based on any particular measuring system so as long as consistent units are used, the results should be correct. (In fact, I tested the page using millimeters and atmospheres and the results seem correct compared to using English units for the same values.) Material stress is normally not expressed in atmospheres (pascals is used, I think) but I expect the metric system has simple relationships between the two.

Rickk · « **Reply #48 on:** October 06, 2007, 10:59:38 AM »

Without proper flux it is very difficult to get lead to wet to stainless. Plain 'ole carbon steel is hard enough to solder to, stainless has an oxide coating on it that must be removed by the flux to get the lead to stick to it.

It might be sort of "stuck" in there, but it is most likely not soldered.

Victor3 · « **Reply #49 on:** October 07, 2007, 03:42:21 AM »

"Inox", far as I gather is just another word for "Stainless" (In+ox = Does not oxidize).

Trivia - "inox" in Victorinox knives means they are stainless steel. IIRC, the founder's wife's name was Victoria.

Cannon caster · « **Reply #50 on:** October 07, 2007, 07:16:55 AM »

Yes Inox is stainless steel but as you know there are many Inoxes. Some stronger, some not.

Double D · « **Reply #51 on:** October 07, 2007, 08:23:04 AM »

Isn't Inox a stainless steel distributor in Europe?

Cannon caster · « **Reply #52 on:** October 07, 2007, 11:13:53 AM »

I don't know about that. Where I live everybody calls stainless steel inox. There are many kinds of stainless steel or inox.

Yesterday we drilled the bore of the pocket mortar (13 mm). Then we wanted to drill the vent an we broke two drill bits.

Victor3 · « **Reply #53 on:** October 08, 2007, 12:02:42 AM »

Quote from: Rickk on October 06, 2007, 10:59:38 AM

Without proper flux it is very difficult to get lead to wet to stainless. Plain 'ole carbon steel is hard enough to solder to, stainless has an oxide coating on it that must be removed by the flux to get the lead to stick to it.

It might be sort of "stuck" in there, but it is most likely not soldered.

Very true. Even with the correct flux it's often difficult. Even if you use abrasives to prepare it right before soldering, as soon as SS is heated up to soldering temp it again forms a chromium oxide coating that solder or braze just doesn't like to adhere to at all.

Cannon caster · « **Reply #54 on:** October 08, 2007, 12:24:46 AM »

So adding lead doesn't help (except for making it more gas tight)?

GGaskill · « **Reply #55 on:** October 08, 2007, 03:36:10 PM »

... (except for making it more gas tight)?

That's really all it can do. Lead is a relatively weak metal.

Artilleryman · « **Reply #56 on:** October 08, 2007, 04:39:58 PM »

Quote from: Cannon caster on October 05, 2007, 09:35:55 AM

Me and my friend made several cannons from inox pipe by crimping the pipe at one end, heating it and hitting it with hammer to seal it better, putting a piece of lead in the pipe ad melt it and let it solidify in the pipe. We putt the lead there to seal the pipe better (less gas escapes). Does the lead add to the strenght of the seal or is it better not to add it?

Crimping the end of a tube to make a cannon in my opinion is not a good idea. Giving enough time sooner or later the crimp will open up with who knows what kind of results. It would be much better to make your cannon by methods described in numerous posts on this board rather than taking shortcuts.

Cannon caster · « **Reply #57 on:** October 09, 2007, 09:53:43 PM »

Would welding over the end of the crimp help?

Double D · « **Reply #58 on:** October 09, 2007, 10:04:49 PM »

No absolutley not. Crimping is a bad idea all together. Have you ever seen any firearm with a crimped breech? No? Must be a reason.

Make a proper breechplug and weld it in place.

Artilleryman · « **Reply #59 on:** October 10, 2007, 02:56:12 AM »

Another problem with crimping. How do you clean the "breech face"? This would be a good place for an ember that could ignite the next charge.