Author Topic: Cannon Wall Thickness? (Read 2033 times)

long colt lawrence · « **on:** September 11, 2003, 02:58:44 AM »

Howdy Ladies and Gents,

Has anyone ever seen a table or guide discussing wall thickness vs. bore diameter or pressures involved? Assuming you shoot sensibly with a roundball or blanks, the pressures developed should be relatively constant and therefore calculatable (calcuable?) and sometime in the past somebody must've done it. Are steel liners necessary? I'd like to make a scale model with a brass barrel around 16"-24" and the mental wheels are just starting to turn regarding how to go about it.

Calamity Jane · « **Reply #1 on:** September 11, 2003, 05:17:33 AM »

If'n yer gonna FIRE it, always, ALWAYS, ALWAYS use a steel liner.

Thar's two problems with brass and the minor one is its strength. The major problem, since brass is NOT used as a "structural material", its composition and "integrity" are always open to question.

Use a steel of a known grade 'cause if it's "graded" than it's consistent and ya kin calculate its strength.

JMHO

CJ

long colt lawrence · « **Reply #2 on:** September 11, 2003, 06:34:08 AM »

Thanks Calamity! I've been visiting your website for a while now watching the cannon updates. Great stuff! Whatever I make will be smaller 'cause my lathe is smaller. I couldn't open your proofing clips 'cause the site said somethng about too much space being taken, but I'll try agian in a bit. OK OK no shortcuts, but it sure would've been easier if I didn't have to work with steel. :wink:

Calamity Jane · « **Reply #3 on:** September 11, 2003, 07:49:56 AM »

Try http://home.inreach.com/mohave.gambler/ Mohave Gambler put a copy up on a site that allows greater MB/hour than my Geocities site.

Ya kin go all-bronze, jist don't shoot it!

If yer buildin 16 to 22" barrel length, yer 'bout the same size as mine; mine's only about 26" long.

Don't get discouraged - steel is yer friend! (In this case.)

CJ

Double D · « **Reply #4 on:** September 11, 2003, 12:35:38 PM »

LCL,

Go to the top of the Forum and look at our Black powder mortar and Cannon firing safety rules. In the safety rules is the guidline for making liners.

I also have just came across an old copy of The muzzleloading Artilleryman and an article on lining a cast iron gun. Let me know if you want that article.

Cat Whisperer · « **Reply #5 on:** September 11, 2003, 03:12:31 PM »

LCL -

Have never seen a table for pressure vs. material strength. But the approach that I've taken is simple. Look at what ever others are doing successfully and make it stronger. That way they'll never read about your failure in design on the national news.

Go for strength. CJ's recommendation is good. I'll go one further, skip the wimpy steels that will work and over build by using 4130 or 4140. I go so far as to avoid all welding as well (although rational people use it & it's ok if done right (preheat etc)).

My fear driven design style comes from having seen a bronze cannon explode (5 of us standing 10-15 feet behind it) and when I graduated from field artillary OCS I saw a LTC hold a party celebrating his last payment for a 105mm howitzer he blew up as a Lieutennant.

So, press on, make it happen. Having a big bore mortar or cannon is like nothing else. When I fire mine, the people with their class III stuff stop firing and come and see what I'VE got!

long colt lawrence · « **Reply #6 on:** September 12, 2003, 01:44:40 AM »

Wadda'ya mean make it outa bronze as long as I don't fire it? Thats kinda like havin' one of those plastic half profile pistols in a frame with the sprayed velvet background. I just can't do it.

Thanks again, Y'know Calamity if yours is 26", I definitely have to scale mine down some more. A mortar would work, I could get a decent bore diameter without the length. But I prefer a cannon. Decisions, decisions...