Bowling Ball Mortar

[jcs5018]

Does anyone know what size oxygen tank is used for a bowling ball mortar? I know that the circumference must be 29 1/8" but that doesn't give me any of the information I need to order a tank. Does anyone know what volume tank this is or have any info I can use to order one? They look at you funny at the shop when you start measuring tanks and asking if they have one thats 29 1/8". Thanks for any help.

[GGaskill]

Inside diameter needs to be at least 8 5/8".

[Cat Whisperer]

I took the liberty of measuring the diameters of 4 bowling balls:

8.595"
8.579"
8.569"
8.608"

add to the diameter 1/40 for windage

add to that twice the wall thickness

and you'll have the OD of the cylinder.

Check by calculating the circumference - should be 29 and a fraction.

[das]

   Let's make this as simple to understand as possible. Finding the right size tank by measuring the o/d is purely a crap shoot !!!
   We cut 6 tanks before we stumbled on 2 in a row that fit a bowling ball. All tanks were between 29 3/8" and 29 1/2". Each tank had a slightly differant wall thickness. This only shows that you can't trust just one theory. The worst part of this story is that when we went looking for the proper series #'s on these tanks they were already ground off when we bought them { as per govt. regs.].
   Best I can say is Good Luck !

[Cat Whisperer]

Das -

You've done well!

I'm still sorting through every tank I see to fine ONE that is greater than 29" circumference! 

Sometimes they're hard to find!

I'm at the point of making a fixture to shave down the bowling balls!

[GGaskill]

I'm at the point of making a fixture to shave down the bowling balls!

Having turned down a number of bowling balls to fit in my mortar, I heartily recommend that you forget the idea.  It is an immense PIA and should be considered under only the direst of circumstances.  The worst part of the idea is that you need to plan in advance and turn the balls before you can shoot them versus just putting a couple of boxes of BBs in the truck bed and heading out.

[Cat Whisperer]

I'm at the point of making a fixture to shave down the bowling balls!

Having turned down a number of bowling balls to fit in my mortar, I heartily recommend that you forget the idea.  It is an immense PIA and should be considered under only the direst of circumstances.  The worst part of the idea is that you need to plan in advance and turn the balls before you can shoot them versus just putting a couple of boxes of BBs in the truck bed and heading out.

THAT should indicate my level of frustration of not having found a correctly sized tube!

[jcs5018]

Does anyone have the specifications for the tank? Also where are you guys getting your tanks from? They're expensive if bought new and it could get very expensive if only 2 out of every 6 is the right size.

[powder2burn]

tanks that have failed hydrostatic testing no longer have a true inside diameter; they are out of round.  That may be why the bowling balls will not fit when the OD measurements are the 29 and ??/ inches. The cly. only needs to be a tiny bit out of round for the ball not to fit. I had this happen on a few clys. I cut in half. It was not until I got a tank that failed a visual inspection and was not hydrostaticedly tested that a bowling ball would fit.

FRED.....................

[m223]

Thanks for the info Fred, Where do you come across your tanks? Welding supply stores or is there a welding tank graveyard somewhere? Thanks Tracy