Safety question....

[tombstone270]

Again I am a newbie....just found this forum a few days ago....I thank you for all your help so far...info here is great....

I have a golf ball cannon ....1018 steel  16" long 1.75" bore 13" deep last 1.75" of the 13" is 1" powder camber .... 2 15/16" OD....That gives me just a hair over .5 inch walls...

Maximum Grains      
Ball charge                :  200 Fg/FFg
Salute charge            :  500 Fg/FFg


Is this safe....



thanks

tomb

[Double D]

Safety guidelines we reference here on GBOCannons call for one caliber wall thickness over and around the chamber area of the the bore.  Chamber diameter = 1inch, wall thickness = 1 inch minumum. 

Are the loads referenced manufacturers suggested loads?  If so I would treat them as maximum loads.  Reduce ridiculously and work up.

[dan610324]

technically its a howitzer and not a cannon as it got a reduced powder chamber
to such an large caliber I would recomend fg instead of ffg

impossible to say if its safe to use or not as you dont tell anything about the technical design of the cannon

[RocklockI]

200 grains is not much of a load . Be sure and check the distance from the rear of the bore to the touchhole . There 'may be too much distance from the rear of the bore to the touchhole.

200 grains in a GB dia. foil packet is going to be like a thick silver dollar and may fit in the bore and after being rammed in ,and be too short to pierce with a pick !!!!!  

For a load that small I'd put the fuse in first and use loose powder ,that way at least the fuse will keep the ball from blocking the tochhole if there is too much distance from tochhole to powder .

There are tricks like adding corn meal or cream of wheat to make the packet longer . ALL filler MUST be in front of the charge so it clears the tube completly .

Shoot off some blanks first to kinda learn about this Black Powder stuff . DO NOT use any kind of wad or patch around the ball . THE worst thing to have happen is a stuck ball ,,,,,, !

The 1/40 windage rule brings a GB bore ball down too 42.8 mm and are avaliable at Fox industries .

Gary

[tombstone270]

These are the two I got my specs. from:

SLEDGE BASE FORTRESS CANNON

Barrel Length            :  15"                               Item# FC-9
Bore size                   :1 .75" [golf ball]
Powder Chamber     : 1" X 1.75" deep

Maximum Grains     
Ball charge                :  200 FFg
Salute charge            :  500 FFg

Approximate weight  : 35 lbs.

http://blackpowder-cannons.com/products.htm


CIVIL WAR SIEGE HOWITZER BARREL
Barrel Length            : 15"                                  Item # CB-5
Trunnion Diameter    : 1-1/4"
Bore size                    : 1.75" [golf ball size]
Powder Chamber      :1" diameter x 1.5" deep

Maximum Grains
Ball charge                 : 200  grains FFg
Salute charge            :  438  grains FFg

Approximate Weight    : 14 lbs

http://blackpowder-cannons.com/barrels.htm


tomb

[Double D]

Is your cannon one of these two guns  from Dom?   If so it is built correctly and those are Maximum loads!

[tombstone270]

I had my barrel machined according to specs. from these two....

I am not sure of there OD.... Mine is milled from a 2 15/16" cold roll 1018...

just want to check some numbers before finishing it...


thanks for all the help...

tomb

[Double D]

Doms dimensions do not include O.D.  If you use some one else dimensions you must use them all.   If you use the safety guideline we suggest here, then you should have a minumum barrel diameter over the powder chamber of 3 inches- one inch walls.  You say you have .5 inch walls.  If that is over the powder chamber then your barrel  OD should be only 2 inches. 

Don't worry it can be fixed with a sleeve, but as is I wouldn't consider it safe! 

If you used 2 15/16th material and you are still at 2 15/16th diameter then your walls over the powder chamber are 23/32 of an inch thick over over the chamber.  A bit thin for the safety guidleines, and in the interest of safety I can not recommend you shoot it until you get fixed. Sleeve it!

[tombstone270]

you are talking about just sleeving the powder chamber....correct

tomb

[tombstone270]

The powder chamber is 1"  so leaving me 1 15/16" equals .9687" wall thickness...correct me if I am wrong...

wall thickness at muzzle  is like .5887"

tomb

[Double D]

2 15/16 minus 1 inch leaves 1 15/16th total or 23/32 per side 

[tombstone270]

I must be missing something..... 1 15/16" equals 1.9375" correct which would be .96875"... 31/32" for the wall thickness.... 23/32" would only be .71875"  what am I missing...

thanks

tomb

[Double D]

You are right, it's a fraction thing, change it decimals and you got it...okay so it still a 1/16 too thin---hey its the best I can come with my advanced years and one cup of coffee this morning. 

[tombstone270]

ok...I was lost for a min. there...LOL.

... so the side wall are 1/32" to thin...

so I need a 1/32 sleeve... correct

I would guess SS would be the best...

or would it be better (easier) to sleeve the outside of the barrel??


thanks so much for you help...

tomb

[Double D]

In the true sense of safety that I harp on here, yes it needs sleeved...would I sleeve for a 32nd, no.

[tombstone270]

Indeed.... safety is most is number one on my list ....I just wished I had found this forum 3 weeks ago....
my understanding of this is less than most....

just want do things right....

thank you so much for you time ... in dealing with a newbie it is way above what most forum will do....

I owe you all ...........thanks


tomb

[GGaskill]

31/32" walls with a 32/32" chamber is OK.  You are not going to gain a significant improvement with a 1/32" sleeve.  Leave it the way it is and reduce your powder charge by a factor of 1/32.

[brokenpole]

Tombstone...

That is one of the biggest problems I read about when new people join.  Some are fortunate enough to find us before they get started making or purchasing a cannon or mortar.  It makes me feel so bad when someone comes here and we find out that they have spent their hard earned cash or a lot of time working on a project only to find that its not safe.

So if you know of anyone else who is thinking of entering this hobby, point them in our direction...these folks can help.

[tombstone270]

Indeed....I am very thankful for the info ........ found here and will pass it along...

tomb