Powder Chamber fit to BB

[smokemjoe]

Today we put the  3AA2400 Argon Tank in the band saw and slowly we sawed it so there would be a 6 in. flat on the end. Came out perfect and  flat, It has a 4 in. hole in the bottom and about 1 in. flats around the bottom. The BB fit is very nice, Will fit the end of the  6in. chamber perfect. When the ball is resting on the bottom of the tank,  1/2 in. of it sticks out the bottom. I got a piece of 1018 that is 6 in. rd. and 5 in. long. When you fit it to the flat on the tank it pushes the ball up and lays on the flat so far, I am going to put a powder chamber in 2in. by 2 in., The ball then will rest on  the hole,But soon as you lay  the  tube to a angle the ball is going to fall  the hole and lay off center, The chambers body is 5 in. long.,  4 in. for safety for the lenght of the 2 in. deep of the powder chamber and 1 in extra.
   My question is, should I make a radius on top of the powder chamber to fit the ball and then make  powder chamber at 2 in. deep, This would make the total depth about 2 1/4 in about with the radius.
    What should I do before I drill this and weld it on, Thanks for your help. Joe

[dominick]

Joe,  To center the ball, it would need to be a large enough chamfer to overcome the weight of the ball at a 45 degree angle [optimum angle for mortars].  This is the only way it will center the ball.  The lower most portion of the radius has to be below and slightly past the bottom center of the ball to divert the ball into the center.  I don't know if you have enough diameter on the plug to do this at 45 degrees  It only needs a slight chamfer roughly to ther radius of the ball.  If you increase the elevation this radius can be a smaller diameter.  I don't think it's that important that ball i'll come out of there a Helen either way!

[smokemjoe]

Dom: I have a flat that is 6 in. across,, 1 in . on each side for the end of the tank to weld to,, leaves  4in. flat and in the center of that is the 2 in. hole, I would have 1 in. on each side of the hole to radius for the ball. - It may work?

[dominick]

Yes, I would radius that part.

[Double D]

Just radius the face of the  powder chamber/breech plug to match the radius of the round section of the bottom in side of the tank.

[SLEEPY BEEPER]

Forgive my spelling, it's late. If you will always be setting the mortar off with fuse. A 2 X 2 chamber will work. But a lot of us have switched to percussion ignition (which could be done latter). With a 2 x 2 chamber at 45 Deg. The powder could be running out the front of the chamber before it covers the vent hole on the top inside. Leaving an air gap between powder and vent hole. This is bad for percussion ignition. I would go with a chamber 1.5 inch dia. and 3 inchs deep. Leaving 2 inchs of steel at the bottom. Also drill the vent hole as far back as possible. But don't hit the bottom with the drill. If it hits the bottom it will probably snap off. And more the wreck your day. Concaving the front of the chamber will not make much difference. Be sure to get a good weld on the inside. To keep hidden rust from starting between the tank and chamber. Do a good job on your BB mortar now. And it will pay you back for years.

[smokemjoe]

I am going to put the powder in tin foil bags or a treated paper  cartridge. Keep the ideas comming, your all helpfull,Thanks- Joe

[Double D]

I am going to put the powder in tin foil bags or a treated paper  cartridge. Keep the ideas comming, your all helpfull,Thanks- Joe

This can be difficult to do in a mortar chamber as it require you reach your down inside the mortar and place the bagged charge in the chamber.  I use a funnel that I made, here is a link. Powder funnel

[dominick]

Joe,  Here's a pic of the chamfer I used.