Primitive Archer

Main Discussion Area => Bows => Topic started by: Black Moshannon on February 22, 2022, 10:05:10 am

Title: First mass principle bow
Post by: Black Moshannon on February 22, 2022, 10:05:10 am
Since I have to wait about a month without shooting to rest my shoulder i'm trying new things. This is my first time weighing a bow. It was roughed to 66" long, hair over 1.25" wide. I gave it a strong heat treat over the coals inducing 2.5" of reflex. Target weight is 47 pounds at 26". Today I had it bending by floor tillering. It feels like its maybe thirty pounds over my target weight. I weighed it and reduced the sides and now it weighs nineteen ounces. its down to 1 1/4" to 1 1/8" width. According to the chart in TBB vol 4, it should finish around 12.5 ounces. I got to that because of the induced reflex and the lower weight cancelling each other out. I thought I read in one of these posts Badger said that he would recommend going on the heavier side to reduce string follow, heavier than recommended in chart... It seems like I have a lot of weight to lose, six to seven ounces. And its already getting pretty narrow. Maybe this is just going to be a narrow one? here's a photo of the stave
Title: Re: First mass principle bow
Post by: Pat B on February 22, 2022, 10:43:41 am
What wood are you using?
Title: Re: First mass principle bow
Post by: Black Moshannon on February 22, 2022, 12:28:07 pm
Its hickory
Title: Re: First mass principle bow
Post by: Pat B on February 22, 2022, 12:31:52 pm
It seems a bit narrow for hickory.
Title: Re: First mass principle bow
Post by: Black Moshannon on February 22, 2022, 12:50:43 pm
I guess I could have started out with a wider profile. I don’t care to have the limbs on my bows wider than 1 1/4”… This one was started narrow because it’s a bend through handle design which is comfortable for my upright and vertical shooting style. But as it stands now, according to the chart it looks like I should continue narrowing the sides more to lose weight before I tiller, or you think just start tillering now..
Title: Re: First mass principle bow
Post by: Selfbowman on February 23, 2022, 10:08:50 am
It’s to thick. But as Pat said your getting to narrow for hickory. It will probably take excessive set if you go more narrow. My bows come in at 18 -23 oz on fifty pound bows. That’s with a stiff 9-10” handle. My handles usually weigh in the 7oz range
Title: Re: First mass principle bow
Post by: Black Moshannon on February 23, 2022, 10:36:50 am
Ok next one I will make wider to expect mass reducing narrowing to get it to the desired 1 1/4 and under width. For this one, I will quit narrowing as it’s at 1.25 now and just tiller, and try to reduce weight at the tips as much as possible…
Title: Re: First mass principle bow
Post by: meanewood on February 23, 2022, 03:03:00 pm
I'll be the first to admit that I don't know much about the 'mass principle theory'
What I do know is that your Hickory stave has not read the TBB vol 4.
If you don't follow what the stave is telling you, your not going to get a good result.
Title: Re: First mass principle bow
Post by: bradsmith2010 on February 23, 2022, 03:36:22 pm
you wont know what the mass weight is,, until you string it and tiller it,,then start weighing it,,
just take weight off belly to tiller it,, dont worry about the mass weight till the bow is too target weight,, at your intended draw,, then see where you are at,,
Title: Re: First mass principle bow
Post by: Black Moshannon on February 23, 2022, 04:44:19 pm
I'll be the first to admit that I don't know much about the 'mass principle theory'
What I do know is that your Hickory stave has not read the TBB vol 4.
If you don't follow what the stave is telling you, your not going to get a good result.

Well that’s a good point…
Title: Re: First mass principle bow
Post by: Black Moshannon on February 23, 2022, 04:45:12 pm
you wont know what the mass weight is,, until you string it and tiller it,,then start weighing it,,
just take weight off belly to tiller it,, dont worry about the mass weight till the bow is too target weight,, at your intended draw,, then see where you are at,,

Ok I’ll do that then. I’ll have it strung tonight and hopefully tillering work tomorrow
Title: Re: First mass principle bow
Post by: Black Moshannon on February 23, 2022, 09:43:12 pm
It blew apart tonight while after I just braced it, and had pulled it to fifty pounds at 20 inches. The sound was so loud it hurt my ears. It’s been very dry here and I cooked it probably too long. I was cooking another one along side it and as a result of fooling around i May have cooked this one over two hours total. Ridiculous and stupid and atrocious. Starting on another stave now
Title: Re: First mass principle bow
Post by: Allyn T on February 23, 2022, 11:26:07 pm
Man I wish you had been video taping when it blew, that would be cool to see
Title: Re: First mass principle bow
Post by: meanewood on February 24, 2022, 03:27:18 am
Cooked over coals for two hours!
In medieval times they called that torture.
I knew you weren't 'listening' to your stave.
If you had been, it would have told you to please stop.
Title: Re: First mass principle bow
Post by: Black Moshannon on February 24, 2022, 07:54:06 am
In addition to that it sat drying down by my wood stove for some time. I knew hickory can be pushed to some limits with moisture but I really went too far with this one. This new stave I’m working on will be cooked for roughly an hour until it shows a light brown toasting and that’s it. Then wait at least three days to re-hydrate
Title: Re: First mass principle bow
Post by: bradsmith2010 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,,
Title: Re: First mass principle bow
Post by: TimBo on February 24, 2022, 05:20:38 pm
"shoot first cook later"
Good advice for hunting too!
Title: Re: First mass principle bow
Post by: Badger 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.
Title: Re: First mass principle bow
Post by: Morgan 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.
Title: Re: First mass principle bow
Post by: Black Moshannon 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.
Title: Re: First mass principle bow
Post by: Black Moshannon 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?
Title: Re: First mass principle bow
Post by: Black Moshannon 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.
Title: Re: First mass principle bow
Post by: Black Moshannon 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...
Title: Re: First mass principle bow
Post by: Black Moshannon 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
Title: Re: First mass principle bow
Post by: Black Moshannon 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.
Title: Re: First mass principle bow
Post by: Black Moshannon 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.
Title: Re: First mass principle bow
Post by: StickMark 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.)
Title: Re: First mass principle bow
Post by: Badger 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.
Title: Re: First mass principle bow
Post by: Black Moshannon 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.
Title: Re: First mass principle bow
Post by: Badger 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.