Author Topic: 2nd. BB Mortar (Read 872 times)

smokemjoe · « **on:** October 18, 2011, 03:04:15 PM »

I had the bottom half of the tank after the 1st. build, I started out to just see if I could drill out the bottom, I made sure I had 4 points that would be 6 in. across for the 6 in. slug for the powder chamber, This was a very hard job and will mess up your arm for months.Use a sawall for all you can.

smokemjoe · « **Reply #1 on:** October 18, 2011, 03:17:51 PM »

Next is the trunnion, flats milled for the slug and to rest on the tank

smokemjoe · « **Reply #2 on:** October 18, 2011, 03:20:37 PM »

Next is the slug, 6x6 in. 2 in. hole, 3 in. deep done with a 2in. ball mill,The top is machined to fit the radius of the bowling ball.

smokemjoe · « **Reply #3 on:** October 18, 2011, 03:26:14 PM »

The trunnion fitted to the slug before weld, it was milled to fit center to center and flat on the 2 in. pin to fit flat on the bottom of the tank.
With a 3/8 chamfer for weld. This keeps ever square to the tank.

smokemjoe · « **Reply #4 on:** October 18, 2011, 03:27:51 PM »

Drilling for the vent liner, made from a 3/8s SS bolt

smokemjoe · « **Reply #5 on:** October 18, 2011, 03:30:11 PM »

The trunnion and powder chamber weld to and inside the tank.

smokemjoe · « **Reply #6 on:** October 18, 2011, 03:33:53 PM »

Inletting into the wood.used red shoe polish and oil. The trunnion way was milled in with the 2 in. ball end mill cutter in a CNC tape machine.

smokemjoe · « **Reply #7 on:** October 18, 2011, 03:37:55 PM »

Bottom of tank, its total lenght is 22 in.

smokemjoe · « **Reply #8 on:** October 18, 2011, 03:46:06 PM »

I am trying this base out to see how much it will take and so far shows no signs of moving any of the wood, Its made of white pine, 18 in. wide, 32 in. long and only 5 1/2 tall, used Ape glue. short and long screws from menards that you have screw in with a drill, has a head the size of a quarter, called powerlags, then cross bolts, This skid dont wieght much over 50 lbs. or less. just a try out to see if it holds up. I have added a 200 lb. spring for the base of the barrel to hit against, also is a bushing for a 1/2 in. iron rod 4 foot long to fit into, I use it for a sight and works good, I know this is nothing org. but made for fun shooting.

smokemjoe · « **Reply #9 on:** October 18, 2011, 03:48:02 PM »

Here is the powder chamber in the bottom.

smokemjoe · « **Reply #10 on:** October 18, 2011, 03:53:53 PM »

Finished piece, painted blue, for the wife, shes from the south, Hope youall enjoy the pics.

Cat Whisperer · « **Reply #11 on:** October 18, 2011, 05:30:42 PM »

Great series of pictures, smokemjoe!

Makes it look easy.

Winger Ed. · « **Reply #12 on:** October 18, 2011, 07:08:10 PM »

Cool project bro.

Making a few gongs, I've cut the bottom off these tanks.
The steel used in them is tougher than Chinese Algebra.

If I had to punch a 6" hole like that--WHEW!!
It'd take some 'expert' to talk me down off the roof.

jamesbeat · « **Reply #13 on:** October 19, 2011, 06:15:00 AM »

That is awesome!
I hope to make something like this one day.
I particularly like the way you mounted the powder chamber inside the mortar, gives it a nice clean look.

Mike Scott · « **Reply #14 on:** October 19, 2011, 08:26:46 AM »

Is there any standard size tubing or pipe that is the right diameter and composition for these other than the elusive gas cylinders?

Double D · « **Reply #15 on:** October 19, 2011, 08:35:15 AM »

I have some seamless tubing that is 10.5 OD and 8.5 ID that is destined to be one of these.

Double D · « **Reply #16 on:** October 19, 2011, 08:38:00 AM »

Joe,

Is there any reason you made the barrel so long? AAA guidelines suggest barrel, no more than 2 x projectile length.

It appears muzzle heavy, muzzle long--is it.

It will be interesting to see if the 5 inch pine with stand up to recoil without crackin, since it is really 5 less the diameter of your trunnion thick.

Nice build, that two for you isn't it?

1Southpaw · « **Reply #17 on:** October 19, 2011, 09:58:58 AM »

22" minus the 6" Powder Chamber= 15 " of tube . So it is really only 2 bowling balls length . Much like mine . The recessed area around the powder chamber makes a nice expansion chamber .
Nice work , like the design . Hope the base stands up to the pounding .

I'm motivated to make another now !

smokemjoe · « **Reply #18 on:** October 19, 2011, 04:25:19 PM »

DD: This is my 2 nd. one, I planned on making this one so that the ball was flush with the end of the tube. Total length would of been 14 in., With 2 guns I shoot one and let it cool down after washing and mopping out and then load the next one ., less change of a hot one.

Double D · « **Reply #19 on:** October 19, 2011, 04:56:59 PM »

I keep forgetting these are thinwall tubes and they have the illusion of being long Their bores are the same length as the real mortar, just the barrels are not as big a diameter.