Author Topic: Tri-Lam Bow. Why?  (Read 43419 times)

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Offline arachnid

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Re: Tri-Lam Bow. Why?
« Reply #60 on: April 27, 2014, 05:23:58 am »
Well, I`m glad my questions opened this very interesting discussion.
I think I`ll go for a backed bow for now.

I have another question-
I`m planning to make a flat bow using the vintage projects dimensions (more or less).
I`m shooting for a 40#-45# DW and It`s going to be white oak/ash/maple backed ipe (depending what I`ll find).
They are using lemonwood on that build and I was wondering if these dimensions
will suit my target DW while using ipe belly OR do I need some modifications?

Thx

Dor

Offline toomanyknots

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Re: Tri-Lam Bow. Why?
« Reply #61 on: April 27, 2014, 09:07:57 am »
With a dense tough wood like ipe, typically you will need less wood.
"The way of heaven is like the bending of a bow-
 the upper part is pressed down,
 the lower part is raised up,
 the part that has too much is reduced,
 the part that has too little is increased."

- Tao Te Ching, 77, A new translation by Victor H. Mair

Offline Dances with squirrels

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Re: Tri-Lam Bow. Why?
« Reply #62 on: April 27, 2014, 09:50:43 am »
I concur with the benefits mentioned so far. Another benefit I've found with tri-lams is that since the pieces are thinner, they can be bent into more drastic shapes than a two piece backed bow... i.e. more severe deflex, reflex, even full recurves are easily glued-in that are impossible to accomplish in blanks with thicker pieces.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline arachnid

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Re: Tri-Lam Bow. Why?
« Reply #63 on: April 27, 2014, 09:57:02 am »
I know it doesn`t take a lot of ipe to make a bow.
I just don`t know how stiff lemonwood is (we don`t have it around here...)

Offline DarkSoul

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Re: Tri-Lam Bow. Why?
« Reply #64 on: April 27, 2014, 10:44:05 am »
"Stiffness" appears to be related to specific gravity of the material to a high degree. If your piece of ipé is about 20% more dense than the average piece of lemonwood, I would make your bow about 20% narrower than the lemonwood equivalent.
"Sonuit contento nervus ab arcu."
Ovid, Metamorphoses VI-286

Offline arachnid

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Re: Tri-Lam Bow. Why?
« Reply #65 on: April 27, 2014, 11:39:04 am »
Thanks jorik.
Should I make it thinner also?

Offline adb

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Re: Tri-Lam Bow. Why?
« Reply #66 on: April 27, 2014, 11:47:28 am »
The thickness taper will be determined by the tiller. However, if you want around 40-50# and you're backing the ipe, I start with a 3/8" thick belly slat for a pyramid bow, and make it from 1.25" to 1.5" wide at the fades, tapering to 1/2" or less tips.

Offline arachnid

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Re: Tri-Lam Bow. Why?
« Reply #67 on: April 27, 2014, 12:18:29 pm »
The thickness taper will be determined by the tiller. However, if you want around 40-50# and you're backing the ipe, I start with a 3/8" thick belly slat for a pyramid bow, and make it from 1.25" to 1.5" wide at the fades, tapering to 1/2" or less tips.

And if I don`t want a pyramid, but the width taper to start at the last 20" (from 1.5" to 3/8") ? Should I start with
3/8" thick belly? Will it get me close to my target DW (or is it too much)?

Offline adb

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Re: Tri-Lam Bow. Why?
« Reply #68 on: April 27, 2014, 12:33:27 pm »
I would.

Offline arachnid

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Re: Tri-Lam Bow. Why?
« Reply #69 on: April 27, 2014, 12:38:49 pm »
Good to know.
Thanks a lot guys.

Dor

Offline toomanyknots

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Re: Tri-Lam Bow. Why?
« Reply #70 on: April 27, 2014, 01:32:07 pm »
Good to know.
Thanks a lot guys.

Dor

I agree! Info appreciated from all!  :) Thank you for the ipe dimensions Adam, will use those as I don't make too many ipe flatbows.
"The way of heaven is like the bending of a bow-
 the upper part is pressed down,
 the lower part is raised up,
 the part that has too much is reduced,
 the part that has too little is increased."

- Tao Te Ching, 77, A new translation by Victor H. Mair

Offline Marc St Louis

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Re: Tri-Lam Bow. Why?
« Reply #71 on: April 27, 2014, 02:46:39 pm »
I think the problem with multi-lam bows, as it pertains to performance, is that the glue line on the multiple laminations slow the bow down through hysteresis which negates any advantages you may get through mass reduction.

Personally I've never found the need to make an Ipe bow any more than 1 1/4" wide even for bows more than 60#.  Bows approaching 100# on the other hand would need 1 3/8" to 1 1/2" in width. 
Home of heat-treating, Corbeil, On.  Canada

Marc@Ironwoodbowyer.com

Offline adb

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Re: Tri-Lam Bow. Why?
« Reply #72 on: April 27, 2014, 03:18:29 pm »
So, the glue line will change the hysteresis of the wood? How? The gluing happens at the molecular level. A good glue line really isn't a line at all. Just because two different woods are glued together, doesn't mean the hysteresis of each type of wood will magically change. The entire hysteresis of the total limb may change depending on the combination of woods used. Sounds to me like you're guessing.

Yes, it doesn't take much ipe to make a bow. But, we were talking flatbows here (I was, anyway) when I offered dimensions. One of my bread & butter bows is a backed ipe flatbow. I easily make more backed ipe flatbows than any other type (and recurves, as well). It just works out for me... easy access to good quality reasonably priced ipe is a no-brainer.

66" ntn for longer draws and heavier weights, and down to 60" ntn for shorter draws and lighter weights. I make them all with an 8" long handle/riser with multilams to a total thickness in the grip of 1.25". They're pyramid bows, 1.5" wide at the fades, tapering to 1/2" or 3/8" tips. For bows up to 50#, I use 3/8" thick belly lam slats, with a 3/16" backing. Above 50#, I go with 1/2" thick belly slats and 1/4" backing. I've made bows with this design from 25#-75# with no failures.  Dead simple, foolproof design and material.

For ELBs, even warbows >100#, I would never go more than 1.25" at the handle with ipe.
« Last Edit: April 27, 2014, 03:22:35 pm by adb »