Author Topic: what does 3/8 inch set at 17 inches tell me?  (Read 2049 times)

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Offline StickMark

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what does 3/8 inch set at 17 inches tell me?
« on: April 10, 2024, 01:22:03 am »
What does that 3/8 of an inch set tell me? Bow is white oak, board, 1 and 11/16" ( 1.69") wide, 60.5" long, with 1.5 inch wide slightly bendy handle design (modified Ishi type bow).
That set is from gradually working up to 17" draw. Draw weight at that 17 inches is 33.5 pounds. Aiming for 25 -25.75 " draw length.
Do I run a risk of more set as I lower the draw weight? Do I take more off the sides or on the belly?
It is about the same depth as a 43# bow, which as only max set on one limb of 1/2 inch, but this bow in question is wider.

Have not posted in a long time, but been lurking. Thx in advance.

Mark


Offline mmattockx

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #1 on: April 10, 2024, 01:38:08 am »
What does that 3/8 of an inch set tell me?

You've overstressed the wood where that set happened. If it's evenly distributed along both limbs then the wood won't take the draw weight you want. If it's concentrated in one small area then that is forming a hinge and will fail there. White oak is usually decent, so maybe you got a duff piece.

If you want to keep working the bow out only scrape from the belly. That will take weight off and remove some of the damaged wood while lowering stresses in the limbs. If you narrow the limbs you will keep getting more and more set as you go because the stresses don't change if the limb thickness doesn't change.


Mark

Offline StickMark

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #2 on: April 10, 2024, 02:07:07 am »
Mark,

The set is evenly distributed, so yes, the bow is too narrow. I will keep sanding the belly and go from there.

Mark

Offline willie

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #3 on: April 10, 2024, 05:34:43 pm »
Mark,

The set is evenly distributed, so yes, the bow is too narrow. I will keep sanding the belly and go from there.

Mark
make a tracing of the set you currently have for future reference
reduce your weight goal for now by 10#  ie. only pull at 25#   --  the bow should pull a few less inches than 17"
see http://www.primitivearcher.com/smf/index.php/topic,61452.0.html
do this badgering until your bow is drawing 22" and re evaluate the set before deciding to pull harder again
monitor the set very closely as you pull harder and draw the bow out towards 25-26"

« Last Edit: April 10, 2024, 05:53:19 pm by willie »

Offline StickMark

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #4 on: April 10, 2024, 09:56:04 pm »
willie,
I can get that science in your post. I felt silly for mentioning the narrowing option last night, had a long day. White oak, in my limited experience, seems to be reluctant to give up poundage.

Have trace it out, and am reducing now. Will let the community know how it all goes. 

Mark

Offline Hamish

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #5 on: April 10, 2024, 10:13:00 pm »
You could use dry heat to put in a small reflex, 1-2" to counteract set. It would also help to drive out any residual moisture that might be causing excessive set.
All my white oak bows(from kiln dried boards), seem to take more set than what I originally expected, even with a little reflex, and wide, flat limbs. That being said its still a decent bow wood, very strong in tension.

Offline StickMark

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #6 on: April 11, 2024, 12:55:36 am »
Willie,

that attachment is great. I recall Badger saying we are really designing bows for 24" draw, IIRC, and I struggled to get what he meant. In that attachment, I think I understand that point of letting draw weight come along as tiller is perfected.


Offline Muskyman

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #7 on: April 11, 2024, 05:17:02 pm »
I agree, great attachment. Got me thinking about how Iíve been approaching my tilling. Good luck with finishing your bow stickmark.

Offline StickMark

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Re: what does 3/8 inch set at 17 inches tell me?
« Reply #8 on: April 26, 2024, 12:09:22 am »
Bow is finished and has sent two dozen arrows down range.
4/8" set one limb, 7/8 on the other. I need to have more bend in the middle before bracing and before getting past 15".
I know white oak takes a bit more set, but 1/2 " is my goal presently, my personal standard. I simply messed up that limb.

Tracing paper is going to be used from now on. Worked well.

Bow is light, about 41.5 on scale so 43 max pondage on fingers, I guess.  Shoots well, and lighter bows are much easier for me to shoot.