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Author Topic: Trunnion Center Line  (Read 2450 times)

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Offline keith44

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Re: Trunnion Center Line
« Reply #30 on: July 21, 2011, 09:05:37 AM »
Quote from: Double D on July 21, 2011, 03:49:21 AM

Mine will have a five inch trunnion, but it also will have an adult size powder chamber.

...2 cups of powder, one bowling ball, add ignition... ;D
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Offline michaelfreeland

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Re: Trunnion Center Line
« Reply #31 on: July 29, 2011, 07:05:25 AM »
Although not related to Trunnion Center Line(s), I must disagree with the notion that a powder chamber must be used in BB mortars using HP cylinders. We have built two fine examples using "K" 02 Cylinders. A chamber was created by counterboring and tappingthe plug end of the pivot, and inserting a broad headed 3/8" 2 1/2" bolt.
The ball rests on the bolt head, and is centered by the bore.
That being said, we use ONLY 2FA lift powder. Anything else would put the tube at risk. 2FA is common as "Lift" powder in the fireworks industry; it lifts shells to apogee without damaging the outside case.
I have about 250 shots on mine, and it was Magnafluxed in June. No cracks, no bulges, no problems.
We have also made "Whistler" balls by using (youth) lightweight balls and drilling 3" deep 1" dia. holes in them at even spacing all around the outside. The sound is amazing!
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Offline Double D

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Re: Trunnion Center Line
« Reply #32 on: July 29, 2011, 07:32:20 AM »
Quote from: michaelfreeland on July 29, 2011, 07:05:25 AM
Although not related to Trunnion Center Line(s), I must disagree with the notion that a powder chamber must be used in BB mortars using HP cylinders. We have built two fine examples using "K" 02 Cylinders. A chamber was created by counterboring and tappingthe plug end of the pivot, and inserting a broad headed 3/8" 2 1/2" bolt.
The ball rests on the bolt head, and is centered by the bore.
That being said, we use ONLY 2FA lift powder. Anything else would put the tube at risk. 2FA is common as "Lift" powder in the fireworks industry; it lifts shells to apogee without damaging the outside case.
I have about 250 shots on mine, and it was Magnafluxed in June. No cracks, no bulges, no problems.
We have also made "Whistler" balls by using (youth) lightweight balls and drilling 3" deep 1" dia. holes in them at even spacing all around the outside. The sound is amazing!

What is the "plug end of the pivot".   Do you mean the threaded neck that the valve would normally screw in?

Are saying the powder just lays in the bottom of the tank?

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