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General discussion => Gun Building => Topic started by: eddillon on March 28, 2014, 08:08:29 PM

Title: Octagonal barrel dimensions
Post by: eddillon on March 28, 2014, 08:08:29 PM

Anybody out there have a quick method of calculating the "across the flats dimension based on the diameter of the round barrel blank.  Trying to figure the least amount of material to be removed to make a swamped pistol barrel for a Boutet build.  Also looking for a Damascus blank or a 9-10 inch piece of an old Damascus barrel that can be made into an 8.5 inch 52 cal. barrel.

Title: Re: Octagonal barrel dimensions
Post by: Kermit on March 28, 2014, 09:38:42 PM

Ed--use this. Enter "A" and all the other dimensions magically appear. Is this what you need?

http://www.pagetutor.com/octagon_layout/

I'll keep looking, since this one's really for large octagons. Works for furniture, gazebos, and such.

Addition: this may work better for you. It's the method I use for oar looms, spars, chisel handles, and other small stuff.

http://www.popularwoodworking.com/woodworking-blogs/chris-schwarz-blog/octagons-made-easy

If you prefer to use a calculator, this might help:

http://www.had2know.com/academics/octagon-measurement-calculator.html

Title: Re: Octagonal barrel dimensions
Post by: eddillon on March 28, 2014, 10:06:15 PM

Thanks Kermit.  I'm getting too old to remember my trig from college.

Title: Re: Octagonal barrel dimensions
Post by: Kermit on March 28, 2014, 10:14:41 PM

There was trig in college?  :-\

Title: Re: Octagonal barrel dimensions
Post by: eddillon on March 28, 2014, 11:04:29 PM

Part of calc in the mid 50s.

Title: Re: Octagonal barrel dimensions
Post by: Charlie B on March 29, 2014, 01:13:41 AM

Generally you need 1/8" extra round stock to cut flats. I.e.1-1/8" round makes 1" across flats. This works up to 1-5/8" round stock.