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Author Topic: Power lam questions  (Read 7137 times)

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Offline Aaron H

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Power lam questions
« on: July 22, 2015, 12:34:40 pm »
So I have decided to embark on my first laminate adventure to see what all the hype is about.  Haven't started anything yet, but I thought I would get a solid game plan together first.  This last weekend at mojam Bob Barnes let me shoot his 50# reflex / deflex BBO and I was very impressed by it's speed. I picked up a nice piece of bamboo, and I have decided to use it as my back. My questions follow:

In your opinion, what is the better belly material, osage or juniper (virginianas)?

What is the best material for a power lam?  I was leaning towards sapele (aesthetics), is this a good option, or would you recommend a different wood?  I want speed and performance my main goal,  followed by looks.

I was thinking about using bird's eye maple for my riser, thoughts?

How long do I make my power lam?

Thank you for any advice you can offer,
Aaron
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Offline Pat B

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Re: Power lam questions
« Reply #1 on: July 22, 2015, 12:50:08 pm »
Aaron, osage would be better in my opinion. Any wood can be used for a power lam. It is between the back and belly, in a non working area so any wood should work. It is used to keep the handle area from bending, preventing the handle riser from popping off.
 If your belly lam is 5/8" to 3/4" thick a power lam isn't necessary. Just use the full thickness at the handle and reduce the limbs as you tiller. Leaving the handle area thick will prevent the handle area from bending which will prevent the riser from popping off
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Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

mikekeswick

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Re: Power lam questions
« Reply #2 on: July 22, 2015, 01:58:47 pm »
Have you got TBB vol4? It has a chapter dealing with lam bows and they make a r/d bow using BBO. I think it's a great bow design to start with.
If you don't have access to the book i'll dig mine out and give you all the specs.
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Offline Gordon

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Re: Power lam questions
« Reply #3 on: July 22, 2015, 02:08:50 pm »
Despite it's name a powerlam doesn't do anything for performance. It's only purpose is to provide stiffness to the handle.
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Gordon

Offline Aaron H

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Re: Power lam questions
« Reply #4 on: July 22, 2015, 02:22:22 pm »
Yea I do have vol. 4 Mike.   I will look through that chapter tonight.  Thanks.
Thanks Gordon and Pat
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Offline KS51

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Re: Power lam questions
« Reply #5 on: July 22, 2015, 09:04:13 pm »
Actually, a powerlam can serve another function.  I use them to increase the overall thickness of the limb and to create a mild r/d when I glue-up.  To explain, I get 4/4 Ipe and will rip it in half so I get 2 pieces,about 7/16 thick.  Then with about 1/8 - 3/16 (final thickness) Bamboo I will glue an 1/8" thick "powerlam", deflexing down about 2" (my form is one big arc). The lam extends, 6-8" down each limb plus the handle area and is tapered from full thickness to nothing through the 6-8" area.  Then I glue the belly wood (Ipe or other) while reflexing about 2".  Then final shaping and tiller as usual.

I do pre-shape all pieces to within about 1/16" of expected finished dimensions before any glueing.

When all done, I often have a mild 1" deflex, 1"+reflex bow.

Ken

PS  I pick powerlams mostly for aesthetic reasons, but I do try and use easy to sand, shape tight grained lower density woods.  Maple, Paduak, Yellowheart, etc.m It also helps if the local Rockler or Woodcraft has the wood available in 1/8" strips.
« Last Edit: July 22, 2015, 09:07:59 pm by KS51 »
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Offline Badger

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Re: Power lam questions
« Reply #6 on: July 22, 2015, 10:39:23 pm »
  I pretty much agree with all the above posts. I like to use a power lam because it allows me to use a thinner belly lam with no risk of the handle popping off, so it is economical. I prefer at least 3/4" thick before I glue on a handle block, a 3/8 belly lam and a 3/8 thick power lam will give me two slates from one  3/4" board. I also prefer to deflex it through the handle when using a power lam, much nicer design than deflexing out of a straight handle.
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Offline GB

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Re: Power lam questions
« Reply #7 on: July 23, 2015, 03:16:05 am »
Awfully tough to beat osage for the belly lam.  It's always my first choice.
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Offline Aaron H

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Re: Power lam questions
« Reply #8 on: July 23, 2015, 07:34:54 am »
What about a high quality glue, or do you guys just use tb3?
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Offline bubby

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Re: Power lam questions
« Reply #9 on: July 23, 2015, 08:55:26 am »
As far as glue tight bond is great, but unless your fit is perfect use a bow epoxy like smooth on or similar, plus you will get a lot more work time
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Offline Pat B

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Re: Power lam questions
« Reply #10 on: July 23, 2015, 09:08:18 am »
I've used TBIII with good results. I've also used Urac185 with good results. Urac was discontinued a few years ago and was replaced with Unibond. Very similar to Urac and probably one of the best wood/wood glues there is. I've not used Unibond but will when the time comes.
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Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Aaron H

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Re: Power lam questions
« Reply #11 on: July 23, 2015, 09:17:26 am »
Unibond 800?
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Offline Pat B

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Re: Power lam questions
« Reply #12 on: July 23, 2015, 09:25:23 am »
I've never used it so I don't know about the 800.
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Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Blaflair2

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Re: Power lam questions
« Reply #13 on: July 23, 2015, 11:08:38 am »
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Offline Aaron H

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Re: Power lam questions
« Reply #14 on: July 23, 2015, 11:27:20 am »
Yea, thanks Blaflair2.  I was reading that yesterday. Unless I missed it though, it didn't say what glue he used, it certainly doesn't look like tb3.
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