Author Topic: First mass principle bow  (Read 4176 times)

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Offline bradsmith2010

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Re: First mass principle bow
« Reply #15 on: February 24, 2022, 04:04:06 pm »
since its pretty dry,, wood stove and all,,try making one without cooking,,
its probably getting close to 6% inside anyway,,
if your not happy with the way the bow is,, cook later ok,,
shoot first cook later,,

Offline TimBo

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Re: First mass principle bow
« Reply #16 on: February 24, 2022, 05:20:38 pm »
"shoot first cook later"
Good advice for hunting too!

Offline Badger

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Re: First mass principle bow
« Reply #17 on: February 25, 2022, 01:28:24 pm »
  The 12.5 oz figure you came up with would mean you were going to have a bend through the handle bow with an arc of the circle tiller. If you leave the mid section on the stiff side you would have to add more weight. The mass principle makes no allowances or recommendations for width so in that regard it is not much help. I primarily use it when I am closing in on finishing a bow using common recommended widths for a particular wood. In the case of hickory  would have gone with 1 1/4 for a bendy handle. When I am using boo backed ipe I would go for about 1".  I worry more about coming in underweight than I do a little overweight. If I am too far underweight I will simply lower the target weight of the bow and next time make it wider. In your case your bow was still pretty heavy, you should have been taking it off the belly, refining the outer limbs and perfecting the tiller as it dropped in weight.

Offline Morgan

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Re: First mass principle bow
« Reply #18 on: February 25, 2022, 03:08:08 pm »
  The 12.5 oz figure you came up with would mean you were going to have a bend through the handle bow with an arc of the circle tiller. If you leave the mid section on the stiff side you would have to add more weight. The mass principle makes no allowances or recommendations for width so in that regard it is not much help. I primarily use it when I am closing in on finishing a bow using common recommended widths for a particular wood. In the case of hickory  would have gone with 1 1/4 for a bendy handle. When I am using boo backed ipe I would go for about 1".  I worry more about coming in underweight than I do a little overweight. If I am too far underweight I will simply lower the target weight of the bow and next time make it wider. In your case your bow was still pretty heavy, you should have been taking it off the belly, refining the outer limbs and perfecting the tiller as it dropped in weight.

From the fella that wrote the book.

Black Moshannon

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Re: First mass principle bow
« Reply #19 on: February 25, 2022, 03:34:53 pm »
  The 12.5 oz figure you came up with would mean you were going to have a bend through the handle bow with an arc of the circle tiller. If you leave the mid section on the stiff side you would have to add more weight. The mass principle makes no allowances or recommendations for width so in that regard it is not much help. I primarily use it when I am closing in on finishing a bow using common recommended widths for a particular wood. In the case of hickory  would have gone with 1 1/4 for a bendy handle. When I am using boo backed ipe I would go for about 1".  I worry more about coming in underweight than I do a little overweight. If I am too far underweight I will simply lower the target weight of the bow and next time make it wider. In your case your bow was still pretty heavy, you should have been taking it off the belly, refining the outer limbs and perfecting the tiller as it dropped in weight.

Thanks for the advice. Yes, mine is a bend through the handle bow. I have another stave I’m starting on of similar size only I’m going for 64” long this time, 66” is just a little too long for comfort sitting in my blind. I’ll post the work as I go.

Black Moshannon

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Re: First mass principle bow
« Reply #20 on: March 02, 2022, 10:14:12 am »
I'm working on two hickory staves, both 64" long by around 1 1/4" wide. One of them was a former sudbury style bow I made years ago. It had around 2.5 inches of string follow. I put it on a caul and heated treated in 2" of reflex and removed much of the stiff handle section. So from the front view profile it does become slightly narrower at the handle so I'll have to leave it slightly thicker there to compensate. Trying to make it work just a little in the handle. I have it back to 22 inches pulling 45 pounds. It weighs one pound. The other one is from a stave I just cut down to floor tiller size and I heat treated and am giving it some time before I start work on it. It will be a bend through handle.  I have a question, should I leave more weight in the bow to compensate for a longer hold time? I draw back and hold for sometimes up to four or five seconds. Should I go ahead and leave more mass to compensate for the strain this would cause? Also, should I be looking to achieve a certain amount of set?
« Last Edit: March 02, 2022, 10:21:38 am by Kenneth »

Black Moshannon

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Re: First mass principle bow
« Reply #21 on: March 02, 2022, 09:44:09 pm »
Ok I have the first bow pulled to 45 pounds at 23". It weighs slightly less than 15 ounces and has lost about an inch of reflex so far. So right now its got about 1 1/8 inch of reflex. I have reduced the tips to 1/2" and got it working slightly in the handle. So i've got three inches of tillering left to go. Seems like I might have to do some mass reduction first if i'm to come in at the right weight (12 oz according to the chart). Photo included.

Black Moshannon

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Re: First mass principle bow
« Reply #22 on: March 03, 2022, 09:28:02 am »
I got impatient and finished the bow. 47 pounds at 26 inches right now, I imagine it will drop just a little weight after a bunch of shots. It weighs 14 oz. So 2 oz overweight. It goes down to 1/2" of reflex after being pulled many times. The limbs ended up being 1/18" wide. This piece of hickory seems really dense. I finished it with a cherry stain. Time to move on to the next stave. We'll see if I can make the weight...

Black Moshannon

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Re: First mass principle bow
« Reply #23 on: March 07, 2022, 05:00:16 pm »
The second stave is now 50 pounds at 24 inches. The limbs were narrowed to 1 1/8”. It’s weighing 14 oz. It’s holding an inch or reflex.  And it’s out of tiller with the top limb bending too much, and the handle area not bending enough. I was afraid during the floor tiller stage because of the last bow blowing up. I removed more wood than I should have during the floor tiller and long string stage because I was afraid to string it. I think I’ll get out the heat gun and stiffen up the top limb some and then keep working it. I may be able to lose a couple ounces and bring it into good tiller
« Last Edit: March 07, 2022, 05:06:36 pm by Kenneth »

Black Moshannon

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Re: First mass principle bow
« Reply #24 on: March 12, 2022, 12:00:17 pm »
Finishing up the second one. It’s still 14 ounces and I’ve already reached 50 pounds at 25.5”. . It’s
1 1/8” wide at the widest point with 1/2” nocks. Retains 1” of reflex. Maybe I can play with scraping off on the sides and bring it to 26” draw. Maybe I can lose at least one more ounce.

Black Moshannon

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Re: First mass principle bow
« Reply #25 on: March 12, 2022, 07:44:00 pm »
Ok it is finished. I got it down to 13 ounces but dropped the weight down to 46 pounds at 26 inches! Probably partly due to struggling to correct the tiller. I don't think I could make the tips any thinner. Oh well, it seems like its going to shoot fairly decently. Still holding maybe just under an inch of reflex. I put some black walnut homemade stain on the back. I burned in my keystone arrow pass and rubbed lard into it and put on a deer leather handle wrap. It should be a lighter bow to shoot once I start shooting again.

Offline StickMark

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Re: First mass principle bow
« Reply #26 on: March 12, 2022, 09:54:33 pm »
Nice build along. I bet the bow gains a little draw weight in colder weather, so it will, at times,  be 47#... :)
(I like 1.25 handles as well. Good compromise, and lets me use stiffer arrows compared to 1.5 or thereabouts.)

Offline Badger

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Re: First mass principle bow
« Reply #27 on: March 13, 2022, 04:10:15 pm »
   Looking at your tiller shape and considering you had 2 1/2" reflex I would have brought that bow in at closer to 16 oz. Your middle section does not bend as much as the mid and out limbs so I would have made an allowance for a 4" stiff handle and fade area. At least the center 12" bends much less than the outer limbs.

Black Moshannon

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Re: First mass principle bow
« Reply #28 on: March 13, 2022, 04:44:18 pm »
Ok, this bow’s middle section is as thin as the limbs but I see I didn’t really get it working that much. So if I’m to make a bend through the handle bow perform at its best I’d better really have that handle working more I suppose.

Offline Badger

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Re: First mass principle bow
« Reply #29 on: March 13, 2022, 08:49:12 pm »
  The stiffer mid section is fine as long as you allow for it by keeping your mid limb area a little wider. Just making a pyramid with the middle 8" not tapered would probably come out pretty good.