Author Topic: Deflexing with a kerf?  (Read 2591 times)

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Offline bubbles

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Deflexing with a kerf?
« on: March 13, 2017, 05:04:19 pm »
Starting to delve into some R/D designs.  I have a maple molle stave with flipped tips, that I want to add a touch of deflex to.  The handle as it sits now is 1.5" deep and 1.5" wide.  I want to leave it fairly deep as I'm going to be shaping the arrow pass close to center.  Unfortunately, after steaming for 1.5 hours without it wanting to budge and trying dry heat for a while with no success, I'm thinking I need a different approach.   

Option 1- thin down the handle to 1", acieve desired bend through steam, and glue on a handle overlay. 

Option 2 is what I'm wondering about -  cut a V kerf into the *belly* of the center of the handle- steam bend to desired deflex, then epoxy in a triangle of wood to fill the kerf (if there is space. 
What do folks recommend?
« Last Edit: March 13, 2017, 07:14:31 pm by bubbles »

Offline PatM

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Re: Deflexing with a kerf?
« Reply #1 on: March 13, 2017, 05:31:14 pm »
Option 1!
Option 2 will act like a back nicked at full draw no matter how long you steam it.

Offline aaron

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Re: Deflexing with a kerf?
« Reply #2 on: March 13, 2017, 06:15:06 pm »
why not kerf on the belly side?- I have wondered about this too...
Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"

Offline bubbles

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Re: Deflexing with a kerf?
« Reply #3 on: March 13, 2017, 07:07:14 pm »
Sorry I said back when I meant belly. Silly me. Kerfing the back would add reflex and seems like a terrible idea. I will correct the original post.  Both options involve the belly side of the handle. I would be kerfing the belly to add deflex. The back would be unharmed.
« Last Edit: March 13, 2017, 07:13:09 pm by bubbles »

Offline bubbles

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Re: Deflexing with a kerf?
« Reply #4 on: March 13, 2017, 07:10:41 pm »
Just a rough idea of what I was thinking.

Offline bubby

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Re: Deflexing with a kerf?
« Reply #5 on: March 13, 2017, 07:12:35 pm »
Thin the handle area down to 3/4" and steam itusing marks localized method, then glue some 1_8" strips in for the handle
failure is an option, everyone fails, it's how you handle it that matters.
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Offline PatM

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Re: Deflexing with a kerf?
« Reply #6 on: March 13, 2017, 08:26:52 pm »
I have seen a bow done with a scooped out handle area that was then steamed and fit to a curved section for the handle. That way the fades were left untouched.
  Just cutting a v requires the back to kink in too short an area.

Offline DC

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Re: Deflexing with a kerf?
« Reply #7 on: March 13, 2017, 08:30:18 pm »
Just a rough idea of what I was thinking.


I think doing this would localise the strain of steam bending right across the handle from the "V". That much strain in that small an area might not turn out so good. 5 or 10 "V's would spread out the strain but then you would essentially doing what Bubby said and it would look a lot messier.

Offline bubbles

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Re: Deflexing with a kerf?
« Reply #8 on: March 13, 2017, 09:55:59 pm »
I have seen a bow done with a scooped out handle area that was then steamed and fit to a curved section for the handle. That way the fades were left untouched.
  Just cutting a v requires the back to kink in too short an area.

That sound kind of cool.   Kind of like a lot of fiberglass bow risers have arcs of laminations through them?  I might try that option.   This is that maple stave I got from you by the way.

Offline Jim Davis

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Re: Deflexing with a kerf?
« Reply #9 on: March 14, 2017, 12:44:06 am »
IMO, the single kerf would work fine, even if you cut within a half inch of the back. If I could think of any reason to deflex a bow, I'd be willing to try that--but, of course, I can't..........
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Offline LittleBen

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Re: Deflexing with a kerf?
« Reply #10 on: March 14, 2017, 10:12:10 pm »
What if you cut a series of kerfs, say 20, each spaced apart roughly the width of a saw blade, then steam, and bend until the kerfs close. Then pry it apart gently, get some epoxy in there, and clamp it back down. Same way you would kerf plywood or Sheetrock to get it to bend.

Personally I would just thin the handle and glue a block on, but just thinking out loud.

Offline Springbuck

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Re: Deflexing with a kerf?
« Reply #11 on: March 16, 2017, 03:03:17 pm »
DC, if it works in a limb, it'll work in the handle.

I have done this (I swear I used to just try every single idea me or anybody else had, just to see......) and I did it with several cuts spaced an inch apart (maybe 4?)  leaving a half inch of thickness on the back. I stayed out of the fade areas.  I used the wet-rag-and-tinfoil steaming method and very little bend at the handle fixed the tips.   I think it was a BL stave, and I think I filled the kerfs with ipe, thinking a harder wood was better than a softer wood, and because the grain on kerf-fillers ran 90 degrees to the grain in the handle.   It took a long time to get a perfect fit on each.

Watch as you bend it forward for the tips to try to lean one way or the other.  If the back is natural, the slots may be irregular, the remaining wood thicker on one side than the other and the tiny bends may try to force the limbs out of plane.

I even tried to make recurves this way with a ton of cuts all along, but my woodworking skills failed me.

Offline Springbuck

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Re: Deflexing with a kerf?
« Reply #12 on: March 16, 2017, 03:03:53 pm »
If you can do it to a limb....