Author Topic: Boring (Read 979 times)

2oakes · « **on:** June 29, 2006, 02:22:26 PM »

I'm boring...

The 3" brass round is chucked up tight, ends faced, turned smooth and shines beautifully. Boring the barrel has started, slowly but surely.

The plan is to try to follow a Coehorn-type mortar plan, almost exclusively for salute use, with a 7/8" or less powder chamber.

I would love to make this golf-ball caliber, but that would leave only 5/8" wall thickness for the bands and maybe 1/2" thickness between them.

The chamber would of course still have over an inch of brass all around.

Please could someone point out a safe caliber to bore this out to?

Should I stop at 1.5" or is the chamber area more critical?

Many Thanks

David

Rickk · « **Reply #1 on:** June 29, 2006, 02:46:29 PM »

could you finagle some bigger material to make the bands out of and solder them on? That would let you make the overall barrel diameter a bit bigger.

2oakes · « **Reply #2 on:** June 29, 2006, 03:54:10 PM »

I was hoping to avoid welding, brazing, soldering and the like.

I'd like to bore and surface finish the whole thing without even un-chucking it.

Maybe I'm just asking for too much and I should settle for a nice looking salute mortar... of sub-golf ball size... a use a 4" round of steel for that one.

I certainly don't want to discover first hand the limits of brass.

Rickk · « **Reply #3 on:** June 29, 2006, 04:06:34 PM »

No need to weld or braze...

you can't really weld brass (unless you consider brazing brass welding), and brazing brass, while technically possible, is a job only for experts due to the temperature control issues.

Brass is easy to work with soldering wise.

You could solder it by preheating on a gas stove and doing the final heating with a propane torch.

You would use with ordinary electrical solder, or plumbing solder if you wish.... not really much different than soldering copper pipes together really... just a bit more mass than 1/2 inch copper pipe.

moose53 · « **Reply #4 on:** June 29, 2006, 04:35:49 PM »

All you have to do is shrink fit the bands on,then clean them up on the lathe .No soldering involved.

Powder keg · « **Reply #5 on:** June 29, 2006, 04:38:44 PM »

Make a confedorate style mortar. The walls should be fine if you have a small powder chamber. Keep the pictures coming!

Cat Whisperer · « **Reply #6 on:** June 29, 2006, 04:51:18 PM »

Shooting golf balls is a relatively low pressure event compared to shooting a sphere of iron or lead. We've had good luck with the mortar contest tubes being made of 1144SP and using a powder chamber allowed some thinish walls. Afterall, that is the principle of the Coehorn mortar.

Pay attention to rounding all inside corners when you come to the bottom of the bore and the bottom of the powder chamber. That will keep the stress risers to a minimum, strentgh maximum.

CU_Cannon · « **Reply #7 on:** June 30, 2006, 02:20:23 PM »

I think the wall thickness would be ok. I would make a small powder chamber. The mortar I built for the contest had a 5/8 x 5/8 chamber. I get ranges of around 200 feet. It is fun for a small area. If you want to go for maximum range I would go with something from steel. The alternative is to make a smaller caliber piece. Consider looking into copper or pvc pipe or fittings for ammo. You should also think ahead. Many of the things we build will out last us or fall into the hands of those with less respect for safety. It is always better to be over built than under built.