Primitive Archer

Main Discussion Area => Bows => Topic started by: Stick Bender on April 30, 2017, 09:52:45 am

Title: Mass principal ?
Post by: Stick Bender on April 30, 2017, 09:52:45 am

I was rereading the mass principal this morning & trying to figure the mass on a 44 in. bendy that I'm making but sense the base dimension chart stops at 58 in. , I understand the working limb to draw length calculation but does any body know how to calculate the base mass for a 44 in. bow ?

Title: Re: Mass principal ?
Post by: High-Desert on April 30, 2017, 10:27:57 am

I'm pretty sure I've been doing it wrong, but I have always treated the chart as linear, although I'm sure it's truly not. So every 2" shorter bow, reduced mass by a half ounce. And then apply the other rules. It's always worked for a 44 in bow you would reduce mass by 3.5 ounces. I built a 40" bow using this method, of course sinew backed, and it came out what seems like an appropriate width and thickness for its poundage. I'm sure someone else knows more about this tho, this is just how I've done it.

Eric

Title: Re: Mass principal ?
Post by: Whiskeyjet on April 30, 2017, 12:26:43 pm

I have been wondering the exact same thing. 

Title: Re: Mass principal ?
Post by: Badger on April 30, 2017, 03:08:48 pm

Quote from: High-Desert on April 30, 2017, 10:27:57 am

I'm pretty sure I've been doing it wrong, but I have always treated the chart as linear, although I'm sure it's truly not. So every 2" shorter bow, reduced mass by a half ounce. And then apply the other rules. It's always worked for a 44 in bow you would reduce mass by 3.5 ounces. I built a 40" bow using this method, of course sinew backed, and it came out what seems like an appropriate width and thickness for its poundage. I'm sure someone else knows more about this tho, this is just how I've done it.

Eric

  Because it is more of a rule of thumb that a precise measurement I cut it off at certain points and designed more around typical bows. But I have used it linear and it seems to hold up fairly well. I will check out the op's and see what I come up with.

Title: Re: Mass principal ?
Post by: Badger on April 30, 2017, 03:17:15 pm

  If you were going 50# for a 24" draw bendy handle the online calculator says 6 oz. That's too light. The calculator takes off 5 oz for being 44" long. I would not subtract the 5 oz and go for a total mass of about 11 oz.

Title: Re: Mass principal ?
Post by: Stick Bender on April 30, 2017, 03:35:12 pm

Ok thanks Steve I appreciate it that will get me in the ball park !  Good to know for making shorter bows  Thanks !

Title: Re: Mass principal ?
Post by: upstatenybowyer on April 30, 2017, 06:34:12 pm

I just weighed a 42" bendy yew I made and it's 11 oz. Eureka!