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Author Topic: Vent diameter to bore ratio  (Read 412 times)

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Offline SMFanvilhead

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Vent diameter to bore ratio
« on: August 03, 2012, 02:58:48 AM »
Newby Alert! I am in the process of making a "parrott" style BP cannon with a .75 dia. bore. What size- dia. should the vent be? If making a threaded copper vent tube, what dia. should it be? Should the threads be UNF or UNC? I did make a search, but did not see any info for this.
Thanks for replies.
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Offline BoomLover

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Re: Vent diameter to bore ratio
« Reply #1 on: August 03, 2012, 04:04:28 AM »
 Welcome to the Forum, by the way! Usually, your vent will be determined by size of fuse you are going to use, and make it a tiny bit larger. For instance, if your using 1/8th inch fuse, drill your hole at 3/16th inch. That will give your fuse room to burn, and make cleaning the vent a bit eaiser. BoomLover
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Offline Artilleryman

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Re: Vent diameter to bore ratio
« Reply #2 on: August 03, 2012, 06:54:32 AM »
If you are making a solid steel barrel you do not need to put in a vent liner. Vents are lined if you have sleeved the bore.  This provides a continuous passage way, otherwise a gap may open up between the sleeve and the barrel.  This gap could hold an ember that could set off the powder charge when you don't want it to.
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