Persimmon Strength

[LivingElemental]

I had mentioned a week or so ago about this stave that had a moderate lateral twist in it near one of the tips. Despite my attempts at figuring out how to make the twist work, I decided I'm not yet skilled enough to make judgement calls like that, and I don't want to ruin the stave.
I cut this thing down to just over 53", and I'm wondering what kind of stress a persimmon bow this short can take if backed with the linen I'm planning to use. I've got an itch to go hunting at the army base where I'm stationed, because archery hunting is allowed year round to keep as few deer from interrupting convoys and training missions as possible.
I'd love to shoot for 60#, so I hope it works.

To the left, you'll see my champion dinner of Zaxby's and Jack Daniel's.

[Jimbob]

Ill be interested to see how this turns out!!  Where are you stationed?

[rossfactor]

Well, take this with a grain of salt, cause I haven't worked persimmon personally.  But by all accounts, and in the wood data base, the stuff is really similar to hickory.  Its actually denser than most hickories, and has excellent tensile strength.

Some folks report quite a bit of set, but, if its like hickory this is often due to moisture.

At 53 inches, with a bendy handle design and keeping the inner limbs relatively wide (e.g. 1.75 inches or so), I'd bet you could get 26 inches of draw as long as you get the whole limb working.

Is there any rotational twist? If not,  i'd deal with the lateral by using dry heat along the entire limb to correct string alignment.  This would keep the lateral twist in the bow tip, but move the entire limb just a hair so the string tracks across the middle of the handle area.  Just my 2c.

Gabe

Gabe

[hedgeapple]

What's your draw length?  As a rule of thumb you multiply your draw lenght time 2 then multiply total times 1.2 OR add the non-bending (non-working) portions of the bow.
Say 26" draw x 2 = 52 x 1.2  = 62.4  for a stiff handle bow.
Or 26" x 2 = 52 + 4" handle + 2" fades + 3" tips =63" ntn stiff handle bow.

If you're making a bend thru the handle bow, d-bow you can get away with draw length x 2
26" x 2 = 52.

I don't know anything about persimmon, it's characteristics, strenghts and weeknesses.  But, my guess is your odds of success would have increase if you had straightened the stave or just made "as is" as opposed to cutting off the twist.  Now go prove me wrong

You don't need a 60# bow to kill a deer.  A well placed arrow from a 40-45# bow will yeild more venison than a gut shot/rump shot arrow from a 60# bow.

[LivingElemental]

Thanks for the information, guys. This will be my first non-board bow, and also the first tree I found and cut down by hand.

Jimbob- I'm stationed at Ft. Gordon, GA. 90% of it is just back woods and training areas.

Ross- there was a small rotation with the curve. I wasn't sure if that would compromise the grain, but it seems like it would have.

Hedgeapple- I've never seen that formula before, but I'll try it out, and I usually draw 28". I also wish I could find some hedgeapple down here. I remember my dad trying to cut a row of them down when I was a kid, and had to take off and sharpen his chainsaw blade between every one.

[hedgeapple]

Living, it is possible to make bows shorter than 2x the draw length.  There's talented bowyer on here who do it all the time.  I'm attempting my first shorty right now.  I'll give it a 50/50 chance of making it to bow status.  But there are things that have to be addressed when doing so.  First can the wood handle it?

Next is string angle. Once you draw the bow half it length your at a 90 degree string angle, i.e. 28" draw from a 56" ntn bow.  Above 90 degrees the string will begin to pinch your finger as full draw.  At least it's uncomfortable, a worst it make getting a clean release difficult.  To reduce the string angle on short bows, most folks flip the tips (make them recurved).  But, like most things bow related, there's a trade-off.  If you flip the tips then you have less working limbs so there's more stress on the working portion of the limbs.

Also, most of the time shorty bows are back with rawhide, sinew, silk, bamboo or hickory to name a few backing materials.

[beetlebailey1977]

I have one persimmon stave that I am going to work very soon.  It is 54" long so it will be a bend in the handle.  I didn't realize until recently that persimmon is in the ebony family.

[LivingElemental]

Yeah I've seen persimmon take a really nice dark color. Im not sure mine is gonna do much more than take the dark stripe you can see in my first post.

And I'll just have to be as careful and slow working as possible to get this thing to work right. And I'll wait on the cow hide my dad is sending me before i back it. Again, thanks for your wisdom. It might save me a lot of grief.

[crooketarrow]

  Thats a short persimmon for someone with exsperance. Just hold on to it untill you builD a couple bows. THEN YOU CAN FORGET THE STWIST AND JUST BUILD THE BOW.

[hedgeapple]

How long has the persimmon bend cut?

[LivingElemental]

Not sure what exactly your question is. Long=time, I cut it back in January. long=length, 53.4inches.

[hedgeapple]

I was just wondering if it was dry enough to work.  You asked earlier about a moisture content meter.  I don't us one.  I do use a temp/humity meter that's for the house.  You can get them at Wally world for around $10.  And I use digital scale for food to weigh my staves.  Digital scales can be purchased at Wally World less than $20.

This website will help you determine the moisture content of your wood using the above tools. http://www.woodworkerssource.com/moisture.php

When I rough out a stave I weigh it.  Then put it in a controled enviroment where I know by using my temp/humity meter that it will be consistantly in the between 8.5 and 10 %, mid 9's are great.  Then I weigh the stave everyday.  When it stops loosing weight for a couple of days in that controlled enviroment, I know it's ready to work.

I have a tempt/humidity meter in my workshop and one in the house.  Also, I printed out the chart from that website.  It hangs in my workshop.  Yesterday morning I went out to the shop, the temp was 74 degrees and humity was 86%, which would have meant the moisture content of wood in that enviroment would have been around 14% (provided it had been in those conditions long enough to accumate to them) must to moist to work.  Fortunately, I had taken the bow that I was working to the air conditioned house, so I felt comfortable working with it.  But, when I took breaks the stave came inside with me.

But, the night before that I had heat bent a stave and it was still on the form.  I brought it inside immediately.  I won't take it off the form until tomorrow, giving it a couple days inside, just to be on the save side.

All of this is to say, once you reduce your stave to a roughed out bow and bring it inside to an air conditioned enviroment, I expect it will loose weight--moisture for nearly a week.  That is unless you've had it in the house since Jan.

[LivingElemental]

I don't really have a workshop. I keep all my tools under the house, and my staves I keep either in the same place, or in the attic to serve as a kiln of sorts. I read in one of the bowyers bibles that a bow should be created in the environment that it will be used in, so that's why they stay in my crawlspace, where the humidity is roughly the same. Things would be much easier if i had a proper work environment, but I figured that my great great grandfather never used modern accommodations, so i strive to build my bows as traditionally as he did, given my funding and wife allow it.

I'll definitely let you all know whether or not this one is successful or heartbreaking.