.5 bore signal cannon questions

[burnsb]

I finally got an old atlas 6" mini lathe.  I've about finished tearing her down and setting everything back right.  Her name is Greta, and I explained to my wife that she is going to have to accept this other woman in my life.  She took it pretty well, my wife that is.  (Greta knew about this going in and doesn't say alot anyways).
 
My sons and I are pyros, my wife has learned to accept this also, and this 4th of July is going to be awesome since we now live in the county. 
 
Anyhow, on to cannons.  I want to build a small signal cannon.  My rough plans are a 2" barrel tapering to 1.5-1.75 at the end of the bore.  Material will be 1018 CRS.  The bore will be a nominal .5 but will actually be .513.  Even though I don't plan to fire any projectiles, some idiot might one day and I wouldn't want it to jam.  Length of 6"-10".  Lanyard actuated primer firing mechanism.  Smooth bore without a smaller id powder chamber.  I have not decided if I want a wheeled carriage or a mortar style base.
 
I'm not a history buff and know little about cannons other than the research I've done in this forum and on other sites.  I do wish to avoid maiming/killing family, innocent bystanders or myself.  But I really want a small black powder cannon for the backyard to fire loud blanks with.  This forum seems to be very knowledgeable and I would appreciate any advice.
 
My main questions are:
1. 1018 CRS ok for barrel?
2. Bore to OD ratios ok?
3. Primer mechanism is commonly accepted as legit on signal cannons?
4. FFg powder? Charge size?
5. Powder chamber- if this is smaller than rest of bore id does it make it the cannon louder?  Why are they smaller?

[GGaskill]

1. 1018 CRS ok for barrel?  1018 is fine.
2. Bore to OD ratios ok?  Our recommendation is OD over powder chamber should be 3 times chamber diameter.  1/2" in 2" is 4 times so you are OK there also or you could go to 21/32" diameter and still be 3 to 1.
3. Primer mechanism is commonly accepted as legit on signal cannons?  We need more detail here.  Lanyard firing for small guns is not usual because the small guns get moved around by pulling the lanyard unless you are using friction primers.
4. FFg powder? Charge size?  I would go with 90-100 grains for a blank charge.  Adjust as needed for desired results but stay as low as possible.  Makes your powder last longer too.
5. Powder chamber- if this is smaller than rest of bore id does it make it the cannon louder?  Why are they smaller?  A reduced diameter chamber does not make a gun louder.  It is done when the gun is designed primarily for shells, which are 2/3 to 3/4 the weight of same size solid shot.  It allows the outside diameter to be smaller which reduces the weight of the barrel, which reduces cost and makes for easier handling in the field.

Take a look at the gun below and in this thread for something that looks like a cannon but has simple lines that are easy to make.

[burnsb]

For the firing mechanism I'm thinking about something along the lines of a pinball plunger. Main spring is either a compression or tension coil spring that the firing pin/plunger runs inside of.  At cocked position the plunger has a groove in it that a small spring loaded pin slides into.  Pull the small pin back and the plunger/firing pin is rammed forward.  Pretty simple but if my explanation is unclear I can draw something up tonight at work and post it tomorrow morning (May 2).  If you don't mind napkin 'prints. 

Shouldn't take much force to trigger that.

Thank you for the link, that is very close to what I want to do.

Is it acceptable to thread the trunnion and the barrel and join them that way?  Possibly using JB weld as a thread locker.

[Victor3]

 You could make something like you're describing, to fire #11 caps. Be advised though, that your striker (plunger) might need a bit more of a run at the cap, and/or a stronger compression spring than you might assume. The stronger the spring, the more force required to pull the pin holding the striker. Might require a fairly heavy base to keep the cannon from jerking around when the lanyard's pulled.
 
 For 4th of July, I like good ol' fuse. Or, if you enjoy the fun of making the gun go off immediately via your action (like with a lanyard pull) you could always use electric ignition. 

[jamesfrom180]

Many possible forms of ignition.  I personally want to try a cannon lock.  Forms of it are available for under $25  See here http://www.dixiegunworks.com/product_info.php?products_id=1642
I also like the broom straw quills.  They are described in a thread here posted by Seacoast Artillery. For small cannon they are great because you can use a push button ignited map gas torch, or linstock. People have also recomended 22 cal. blanks as good hot primers.  Benefits are they do not required much of a nipple and are relatively cheap.

Good shooting, but good building first, I know I like to see build pictures and lots of them. 

[GGaskill]

Is it acceptable to thread the trunnion and the barrel and join them that way?  Possibly using JB weld as a thread locker.

The problem with threading is that the holes are not going to be very deep and even using fine threads and a bottoming tap, you will not get many threads in the holes.  Welding is by far the best solution.

[burnsb]

You could make something like you're describing, to fire #11 caps. Be advised though, that your striker (plunger) might need a bit more of a run at the cap, and/or a stronger compression spring than you might assume. The stronger the spring, the more force required to pull the pin holding the striker. Might require a fairly heavy base to keep the cannon from jerking around when the lanyard's pulled.
 
 For 4th of July, I like good ol' fuse. Or, if you enjoy the fun of making the gun go off immediately via your action (like with a lanyard pull) you could always use electric ignition. 

I see what you're saying about the force required to release the spring, I'll have to think on this.  I really want it to have a mechanical action so I guess I'm going to have to do some tinkering and see if I can get the force down.  Otherwise I'll use one of the other options.
 

Many possible forms of ignition.  I personally want to try a cannon lock.  Forms of it are available for under $25  See here http://www.dixiegunworks.com/product_info.php?products_id=1642
I also like the broom straw quills.  They are described in a thread here posted by Seacoast Artillery. For small cannon they are great because you can use a push button ignited map gas torch, or linstock. People have also recomended 22 cal. blanks as good hot primers.  Benefits are they do not required much of a nipple and are relatively cheap.

Good shooting, but good building first, I know I like to see build pictures and lots of them. 

I like the idea of .22 blanks, that should be pretty easy.
 
I plan on posting pictures of the build, my lathe parts came in today (spindle bearings and split nut fingers).  So this weekend I hope to reassemble the old girl.  If I have time I'll start on the steady rest (hardware for that should arrive this week as well).  I always feel like I'm making tools to make tools. 
 
If the board would be interested I can post pics of the steady rest build as it should have a lot of applications in cannon making as they are expensive to buy but pretty easy to build.
 

The problem with threading is that the holes are not going to be very deep and even using fine threads and a bottoming tap, you will not get many threads in the holes.  Welding is by far the best solution.

Ok, sounds like I need to suck up to one of the welders at work then.  I don't know how to weld but some of these guys turn out a weld that looks like it was stitched with a sewing machine.
 
Also managed to get ahold of the 1018 CRS, it is 2.25" x 10" although that length is going to be a little much for my lathe and I'll probably decide to trim it some more.
 
Thank you all for the great responses.

[GGaskill]

I learned to weld at a community college.  Courses were cheap, instruction well done and they allowed us to bring in our own projects.  Take a TIG class or three.

[Double D]

Small guns just don't have the mass to use a mechanical ignition system.  No big deal for a noise maker but hazardous for a ball shooter.

Fuse or quill fire.

[Victor3]

 If you want to go totally nuts (as I've been accused of at times), you could do something like this setup I made for one of my cannons. Only requires a light tug on the lanyard to release the hammer and pop a 209 primer...
 

 

 

 
 The blued steel thingy at the rear is just a quick-release sling swivel I added to make it easy to attach the lanyard.

[flagman1776]

Delete
 

[burnsb]

I learned to weld at a community college.  Courses were cheap, instruction well done and they allowed us to bring in our own projects.  Take a TIG class or three.

Currently pecking away at a mechanical engineering degree, work load is heavy now but I hope to go back in the fall.  I'm a machinist by trade and really don't want to weld professionally but maybe one day I'll learn how for hobby use.  I think I can get my lead man's brother to weld the trunnion for a case of beer.   
 

Small guns just don't have the mass to use a mechanical ignition system.  No big deal for a noise maker but hazardous for a ball shooter.

Fuse or quill fire.

I don't plan to ever shoot anything other than blanks, but I definitely see how it could be dangerous if someone knocked over the gun by tripping over the lanyard.  So, if I were ever to fire a projectile I will remove any trigger system that I have installed and go with a quill.  Also see how the low mass of the gun could lead to innacurate targeting if the gun were nudged as a result of the lanyard pull.
 

I like designs that enclose the nipple with a hammer cup at the moment of firing which gives some protection from cap debris. 

That sounds like a good point.  Never realized a cannon/small gun threw so much out the back end.
 

If you want to go totally nuts (as I've been accused of at times), you could do something like this setup I made for one of my cannons. Only requires a light tug on the lanyard to release the hammer and pop a 209 primer...

 
 
Spring is inside the center cylinder that looks like a dowel pin?  Clean looking work.  Thanks for posting the pics.
 
This morning I got the lathe's compound oiled, greased and reassembled.   

[GGaskill]

I think I can get my lead man's brother to weld the trunnion for a case of beer.   

I did that a couple of times before learning to weld.   

[Victor3]

Spring is inside the center cylinder that looks like a dowel pin?   

 Spring is under the pin in a hole in the bbl. Pin has a step in it (under the brass housing) to retain it.

[burnsb]

I have changed my mind about how I want to build this cannon.  No lanyard firing.  Since I'm going to put this much effort in it I might as well make it historically accurate.  Been looking at the Napoleon M1857. 
 
Hopefully I'm not violating etiquette here, can someone please email me plans?  Or do I need to purchase these?  Saw the plans at Dixie Gun Works, Maryland Silver and Antique Ordnance, but they look like overkill for my needs. 
 
Just looking for dimensions, or something that I can accurately scale off of.  (Probably going to have to stretch/squeeze it a little for lathe capacity and the size of the piece of stock I have, but it will be reasonably faithful.)
 
Currently have the lathe back together, lot quieter spindle/gears and much smoother carriage now.  Armstrong milled the corners off the chunk of steel I'm making my steady ring out of.  Will be turning it this weekend.
 
Thanks.
 
 

[Double D]

Antique Ordnance Publishers is the place to go for  Cannon plans.  The first time you order you will  flinch at the price, $25 plus  postage for 120  11" x 17" pages.  You won't bat an eye the next time.  The plans from AOP are a bargain.

The plans are in most case from original drawings and are full scale. They also contain a page on how to convert the drawings to various scales.


You won't regret getting your plans from them.

What is you lathe capacity and what size stock are you going to use?

[Microboomer]

If you know what you want to build, you can't beat the AOP plans for detail.  If you want to look at a variety of Civil War field cannons for inspiration for your next project, you can't beat the Hazlett book described below.  It does contain dimensioned drawings for the Napoleon, but probably not as much detail as the AOP plans that DD mentioned (I don't have that particular set).  I'm in the middle of writing up a set of mini-reviews for the cannon books in my small collection, which I'll post all together when I finish in a couple of days - here's my review for Hazlett:

 Field Artillery Weapons of the Civil War (revised edition), by James C. Hazlett, Edwin Olmstead, and M. Hume Parks, 2004, University of Illinois Press, 324 pages, $25.39 (amazon.com)  This is a very well organized book covering the smaller artillery of the Civil War, primarily covering weapons up to 12 pounder size, but also covering Coehorn mortars and a few larger weapons.  Each chapter focuses on a specific type of cannon and has good descriptions of their design, construction, and use.  There are many photographs of cannons in their current state in various parks.  There are quite a few fully dimensioned drawings of barrels.  Mountings are not covered well, but chapter 17 “Carriages” has some nice photos of a reproduction Napoleon carriage and its parts, as well as basic dimensions for some common field carriages.  The appendixes contain locations for existing field weapons, which is a great way to find the nearest location for your favorite gun.   You get a lot of bang for your buck with this book!  There is a preview of this book at google books, so you can take a look and see what you will [size=0pt]g[/size]et before you buy.
andy

[burnsb]

Next paycheck I will order the plans from AOP.
 
Lathe capacity is 6.25" swing with 18" between centers.  The stock is 3.25"x12."  I may have to trim the length some.  However given some dimensions on wikipedia, that ratio stock should be ok for a mini-Napoleon. However I plan to make the bore around .625, the scale length may be short for that, but that will be ok.  Haven't done much math on it yet, just bore to length ratio, which was pretty close to what I've got.