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Discussion Starter · #1 ·
So I started to collect items to start my bowling ball mortar.
The bottle was for natural gas and is a 3AA2400
The steel powder chamber is 6" round solid steel that is 6" tall.
The powder area is 2" across and just short of 4" deep.
 

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Looks like you are off to a good start. Do you plan to nest the chamber inside the cylinder or cut off the neck and weld it in place?
 

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Discussion Starter · #3 ·
I will cut off the neck of the bottle and weld the chamber to the bottle.
Have decided that I will be buying a new welder to complete this project.
There will be a 2" rod machined slightly and welded to the chamber.
 

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Discussion Starter · #5 ·
Okay...Cut the tank in half today...the neck of the bottle says 3AA2400...why is the inside diameter 10 inches??

HELP!
 

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Don't know. Maybe check with a welding supply company? Here is a pdf of cylinder dimensions. Perhaps the only important dimension in the trade is the volume.
 

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Interesting that two different sizes (300 ft[sup]3[/sup] and 400 ft[sup]3[/sup]) would have the same number. Wonder why that is. Perhaps the number does not contain size info.
 

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I do not understand where the 1" plate comes in. In my opinion, your trunnion is too small diameter for support at the ends even without the thin spot in the middle. I'll bet it will bend on the first shot unless it is supported full width.
 

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With a bolted trunnion those corners of the flat spot machined in the trunnion ar stress riser and will flex and eventually crack.

Even welded they are a weak point and could/ may some break.

That flat spot makes you trunnion bar only 1 inch thick.

Agree with George about 2 inch being two thin. 3"-4" better. Leave the flat spot off. Those trunnions are going to take a lot of recoil. Aesthetically they will look better and not amateurish. This is no place to go cheap and chinsy.

Here is how to attach the trunnion on a pressure tank.



Here is the attachment for the mortar I am building-bolted on.



George, I think he is just saying the breech assembly is just sitting on a piece of plate that is an inch thick.
 

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Discussion Starter · #13 ·
GGaskill said:
I do not understand where the 1" plate comes in. In my opinion, your trunnion is too small diameter for support at the ends even without the thin spot in the middle. I'll bet it will bend on the first shot unless it is supported full width.

The 1" plate is for my base

Most of my information has come from this thread; http://www.go2gbo.com/forums/blackpowder-mortar-and-cannon-sponsored-by-seacoast-artillery/guide-for-building-a-bowling-ball-mortar/
I am not changing much that was in this thread...
And I am not bolting it..it will be welded and its recessed 3/4"
 

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What do you mean recessed? Are you installing the chamber internally?

Make sure you read every single post in that thread you are following. DH2 wrote that as an instruction for a class he was taking. He posted it and asked for the boards feed back. We gave him a number of suggestions which he did use.

For instance in reply 54 SmokemJoe points out the correct tank to use is 3AA2400 DOT300CF. That is also the tank listed in the stickies as the correct tank. Joe also said don't mill the 1 inch flat for the same reason already stated in this thread.

The picture up thread I posted with the chamber inside the bottle was suggested in DH2 post.

Also DH2 never posted anything else on the board and never posted whether he actually ever built a mortar from his instructions.

As far as we know you will be the first person to build a gun From those instructions.

As you build this please keep us all advised on your build. We are interested is seeing how you go about doing things, any problems you run into and anything you do different. Pictures, please.
 

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How are you plugging the neck hole? The fuse should go into the powder at least an inch. I think it is best if the fuse is close to perpendicular to the inside wall and about at the point the neck finishes flaring into the upper dome of the cylinder.
 

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Discussion Starter · #19 ·
GGaskill said:
How are you plugging the neck hole? The fuse should go into the powder at least an inch. I think it is best if the fuse is close to perpendicular to the inside wall and about at the point the neck finishes flaring into the upper dome of the cylinder.
I am not sure what you mean by "Neck Hole"

Here is what my plan is...
They are not to scale, but my question is how far off the bottom of powder chamber should the fuse be?
 

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I see, you are using a separate chamber piece instead of the cylinder directly. You want the vent (fuse hole) low enough to always be in the charge no matter how small the charge is. In your case, I would try to have the vent intersect the corner of the chamber at an angle so the fuse is pointing upward toward the muzzle. Or if you can replace the corner with a radius which would be better, have it enter the chamber no higher than halfway up the radius. What you don't want is for the fuse to come in above the top of the powder charge.

Do you plan to use loose powder or foil bags?
 
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