so i drew up these plans right... what do you all think?

[fallout360]

Hey guys, just signed up a few min ago but ive been trolling through these forums for about a week now. So ive been interested with building a cannon for a awhile now and after reading a lot of different design theories, plans, loads, etc. i think i might have something i could build and feel safe about.

The plan:
               - so i was thinking about using 1080 steel and acquiring a piece with a 4" dia and 16" long
               - the bore would be 1.5" x 11.75"
               - the powder chamber is 1" x 1.375" (though if u look at the drawing theres a second lone hash mark, my thought is i might be able to move either the chamber back that far giving me more bore length OR elongating the powder chamber. if thats a safe possibility.)
               - the trunnion design is not completely thought out yet, i want to bore shallow holes in the side of the cannon to countersink the trunnions (is that the best route) and as far as attaching it to a carrage im thinking a metal sled is the best idea welded up out of 1/4" plate.

the notes on the bottom are more likely wishfull thinking about energy and velocity but none the less if like to be able to hit a moderate velocity with lead balls. i used http://jefenry.com/main/Firearms.php as a calculator.

id appreciate all the input i can get, im not an engineer but a designer so my math could be off 
thanks guys!
 

[armorer77]

The first thing you should look at is the powder chamber , make the final cut with a 1" ball end mill . Lose all the sharp corners , as much as possible . Also you will want at least a 2" long powder chamber for this bore size . Armorer77

[seacoastartillery]

     We always consider material first.  The answer can actually be the same for either low pressure application or moderate as yours will be.  1018, 1020 or 1026 steel are all excellent choices.  High carbon steel like 1080 is fine for springs with proper heat treatment, but for cannons no.  Reason being that if some future owner of your piece overloads it greatly, the quality of resiliancy and non-fragmentation should be paramount.

     WELD those trunnions for all cannon which will have REAL RECOIL such as yours will have!  Threads are a bad choice anyway, because they tend to loosen up when you least expect it.  A c'sink with flat bottom .50" deep max should work fine.  LC steel is far more tolerant of too much weld heat, but weld carefully anyhow.  It will look better.

Sounds like you have an excellent attitude about this project.  Best wishes!


Tracy and Mike

[Double D]

A cannon is much more than a piece of shafting with a hole down the middle.  I can tell by looking at your drawing that this is your first venture intro cannon making.  We can help you come up with something that is more than shafting with a hole.

What profile  are you going to make. The profile is what everyone sees when they look at your cannon.   That profile will tell people that you took the time to learn something about about cannons and how they should look.  That profile also will dictate dimensions and proportions, and in particular things like trunnions size and location.

I think your barrel length is a bit short- 4 to 1 (barrel length to  Barrel diameter) for most standard cannons profiles.  Even the stubby little Mt.  Howizter is right around 5 to 1.  A 4 inch x 16 inch piece of 1018 would work pretty good to make a Golf ball bore size model of an 8 inch Siege howitzer which is closer to 3.5 to 1 or 4" x 14" barrel.   

If you you had a longer piece of 4 inch than 16 inch, say 20 inch or more, you would have more options.   

Trunnions should be the same length and diameter as the bore and slightly forward of the Center of gravity, giving a breech heavy  preponderance.



 

[dominick]

Ditto on the steel choice.  For a cannon barrel, you would want to make it from a low carbon steel such as 1018.  1018 has .18 percent of carbon compared to .80 percent in 1080.  The last two digits of the four digit designation is the point percentage of carbon.  1080 is good for making knives, it is also the high carbon element of Damascus steel where the process uses alternating layers of high carbon and low carbon sheets.  1018 will also cost less and be easy to weld.  Good luck on your project and welcome to the forum.  Dom

[fallout360]

wow thanks guys! this is the most helpful forum ive ever been to!

Armorer77 - good point on the rounded chamber that was definitely an oversight on my part. though im still not sure on how one determines the size of a powder chamber.

seacoastartillery - yeah the last thing i want to do is make another pipe bomb (bad idea long ago :p) now as far as metal selection goes do i want to stay with hot or cold rolled? when i was trying to decide which metal to go with i was looking for the highest yield and tensile straights yet still being affordable. as far as the trunnions go (sorry didnt really explain what i had there) i was going to weld them to the barrel but i wasn't sure if i could sink them into the barrel or flush/butt weld them. but sinking them in then welding is what im going to do now for sure. the bolt on the end was just a way of securing the trunnions to the mount, but yet still allowing the cannon to traverse up and down .... kinda like a bushing (still not very well explained lol)

double d - i agree about the profile i just haven't gotten that far in the design process. one question which i was wanting to ask is how much meat do i have to leave on this for it to be safe. i know more is needed around the powder chamber, but as far as the barrel is concerned i think ive seen it written that a .5" wall is safe while leaving more around the breach. but because im not sure i left it straight. so now if i lengthen the barrel (20"-24") does the powder chamber change as well?

[Double D]

May I suggest you get a copy of Round Shot and Rammers and look the cannons in there.  Find a design there and work from there.

The area over the breech needs to be three times the bore diameter.  If you use and established design and adhere to the basic configuration you should be just fine.

If you really want to learn the design, get your self a copy toe Paul Muller's Treatise on Artillery.  Very old text and a bit hard to tread, but the basics are there and you will learn how a cannon is designed.  Make a first cannon following the concepts in Muller and then go free hand.

I don't know where you saw  .5 but it is not a one size fits all number. It might be good for .50 cal, but probably way to thing  for a 4 inch bore.

[fallout360]

so which book would you suggest over then other?

just to be clear your saying for example if the bore is 1" the over all dia at the breech needs to be 3" at least, correct?

you know i may have seen the .5" in a post about mortars. i kinda remember something about seamless tubing... and something going boom

[fallout360]

hey what about using 4140 for the barrel steel?

[GGaskill]

4140 has welding problems unless you are a really experienced welder with the right gear.  1018 is strong enough and welds easily.

If you taper the tube from chamber area to muzzle for a 1" bore gun, a wall thickness at the muzzle of 1/2" should be fine.

Take a look at the Robinson's Battery web site, particularly at the "Guns - Page 1" through page 3 entries in the table of contents at the left, for examples of dozens of mid-19th Century guns and mortars.

[seacoastartillery]

seacoastartillery - yeah the last thing i want to do is make another pipe bomb (bad idea long ago :p) now as far as metal selection goes do i want to stay with hot or cold rolled? when i was trying to decide which metal to go with i was looking for the highest yield and tensile straights yet still being affordable. as far as the trunnions go (sorry didnt really explain what i had there) i was going to weld them to the barrel but i wasn't sure if i could sink them into the barrel or flush/butt weld them. but sinking them in then welding is what im going to do now for sure. the bolt on the end was just a way of securing the trunnions to the mount, but yet still allowing the cannon to traverse up and down .... kinda like a bushing (still not very well explained lol) 

     Fallout360,    Cold rolled steel is slightly stronger.  You may get ratings of 65,000 instead of 60,000 with hot rolled.  Who cares?  60,000 is more than enough.  Negatives outweigh positives with cold rolled.  In many common sizes used by cannon builders it is unavailable.  Also it is significantly more expensive.   Hot rolled can be lumpy and bumpy on the outside and loaded with scale, but a simple skim cut on the lathe takes care of that!  We have made plenty of cannons with hot rolled rounds and have never had a problem.  Internal material integrity is just as good as cold rolled in our experience.

Remember this:  the closer your cannon's shape is to a historical piece, the more atta-boys you will get!  Get a book; you'll be glad you did.  Take your time.

Tracy

[Double D]

so which book would you suggest over then other?

just to be clear your saying for example if the bore is 1" the over all dia at the breech needs to be 3" at least, correct?

you know i may have seen the .5" in a post about mortars. i kinda remember something about seamless tubing... and something going boom

Got WWW.ABEbooks.com and look for both books.  You shouldn't have much problem finding Roundshot and Rammers.
http://www.abebooks.com/servlet/SearchResults?sts=t&tn=round+shots+and+rammers&x=37&y=11

.  Muller's might be tougher.   Well I just check and the print on demand community now are offering Muller for $20 plus postage
http://www.abebooks.com/servlet/BookDetailsPL?bi=4196595302&searchurl=an%3Dmuller%26sts%3Dt%26tn%3Dtreatise%2Bon%2Bartillery%26x%3D26%26y%3D5

[Doc Brown.]

Hi fallout. I don't know if this is common practice but its how we press in are trunnions. Heres a link to a little bit of it. http://www.youtube.com/watch?v=kJ4TVb94A-s

[Double D]

Just make sure after shrinking and pressing those trunnions in, that you weld them so they stay securely in place.

They are load bearing and can come loose.

[Doc Brown.]

Is there any where i can find a chart that would show the amount of interference needed for different amounts of loads or force or something. I know they put train wheels on with a sweat fit. Thanks

[GGaskill]

I think you need minimal interference.  As long as the trunnions are tight, the weld will only have to resist the trunnions pulling out.

[Double D]

Train wheels are not subject to shear force.

[GGaskill]

Train wheels are not subject to shear force.

Generally not, but they could be with uneven braking forces.

[Cat Whisperer]

...
  Hot rolled can be lumpy and bumpy on the outside and loaded with scale, but a simple skim cut on the lathe takes care of that! 
...

Tracy

The scale can/may be right-much hard too.  I wore out a cutter bit (didn't have carbide) cleaning the scale off my first mortar back in '74.