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Main Boards => The Bowyer's Bench => Topic started by: glbw on March 02, 2021, 05:47:41 PM

Title: Number of laminations
Post by: glbw on March 02, 2021, 05:47:41 PM

All else being equal will 5 laminations be stiffer than 4 laminations? If so how much?

Title: Re: Number of laminations
Post by: Pat B on March 02, 2021, 05:53:19 PM

It's not just the lams but also the glue lines add stiffness too.

Title: Re: Number of laminations
Post by: williwaw on March 02, 2021, 05:59:38 PM

if the fifth lams adds 20%  to the total thickness then the limb will be stiffer.

if you are asking whether 5 x .080   or  4 x .100 is different,  then not really, unless the wood of the fifth lam is a stiffer wood

Title: Re: Number of laminations
Post by: kennym on March 02, 2021, 06:43:10 PM

I'm gonna guess it will add a little but not much, like Pat said, more glue lines for a few thou, and  cheap plywood with few lams isn't as strong as the stuff with more lams...  Just sayin... :)

Title: Re: Number of laminations
Post by: glbw on March 02, 2021, 07:44:46 PM

I mean if you have a stack that is .300 with 3 boo laminations and 2 glass and another stack that is also .300 with 4 boo laminations and 2 glass, will the 2nd stack be stiffer?

Title: Re: Number of laminations
Post by: Pat B on March 02, 2021, 08:13:38 PM

What do you mean about stiffer, better performance, harder to pull? And what does stiffness matter other than you don't want a noodle?

Title: Re: Number of laminations
Post by: mmattockx on March 02, 2021, 08:14:42 PM

Quote from: glbw on March 02, 2021, 07:44:46 PM

I mean if you have a stack that is .300 with 3 boo laminations and 2 glass and another stack that is also .300 with 4 boo laminations and 2 glass, will the 2nd stack be stiffer?

There will be no significant difference between the two.


Mark

Title: Re: Number of laminations
Post by: glbw on March 02, 2021, 09:12:09 PM

Thanks guys,  pat I mean higher poundage.

Title: Re: Number of laminations
Post by: kennym on March 03, 2021, 09:19:57 PM

Someone needs to build a couple to test this.... :dunno:

Title: Re: Number of laminations
Post by: kennym on March 03, 2021, 09:23:35 PM

If I remember correctly , the trade bow I built for Dannon a couple years back , I put a bubinga racing stripe in for a 5 th lam and it came in about 5 heavy. I can’t think a thin strip of bubinga would make 5 difference. After all, you have the guys who say lam material don’t make a diff, it’s only a spacer for the glass... :goldtooth:

Title: Re: Number of laminations
Post by: 4 point on March 03, 2021, 09:53:55 PM

Yes Kenny, I have to adjust the stack on my recurves depending on what veneer I use. A soft wood will come in a good bit lighter than a hard wood. A boo core doesn't make as much poundage as a maple core also.

Title: Re: Number of laminations
Post by: kennym on March 03, 2021, 10:33:12 PM

Same here Travis!

Title: Re: Number of laminations
Post by: Mad Max on March 03, 2021, 10:52:42 PM

this is a stack thickness for a 64" R/D ---1-3/8" at the fades.
7 lams for the total stack.
kenny or someone could compare there stack thickness to this chart, may give some idea  :dunno:
the tips are 1-1/2" in front of the back of the bow riser

(https://i.imgur.com/Qv0Ppy9.jpg)

So the main part of the limb is D shaped with a reflex tip at brace
with 7 total laminations you have to save 1 parallel for last, and measure the stack, and make that lam the correct thickness to hit the stack thickness
(https://i.imgur.com/7Z9TEBo.jpg)

Title: Re: Number of laminations
Post by: williwaw on March 04, 2021, 12:43:50 AM

thanks for posting the chart, Max

any more pics of that bow would be cool

Title: Re: Number of laminations
Post by: Mad Max on March 04, 2021, 07:37:23 AM

This is at the nock, with the tip wedge it's 8 total lams

(https://i.imgur.com/TH7pJTO.jpg)

Curly maple 2017
(https://i.imgur.com/0QyjbtL.jpg?2)


(https://i.imgur.com/YrYKRen.jpg?1)

(https://i.imgur.com/d1Tmd1j.jpg?1)

(https://i.imgur.com/YJiqCT9.jpg?1)

(https://i.imgur.com/U3qwFbQ.jpg?1)

(https://i.imgur.com/jH15nrI.png?1)

Title: Re: Number of laminations
Post by: Roy from Pa on March 04, 2021, 07:48:46 AM

It's hard to beat curly maple for looks.

Now that scary thing drawing the bow is another story:)

Title: Re: Number of laminations
Post by: kennym on March 04, 2021, 08:39:29 AM

Quote from: 4 point on March 03, 2021, 09:53:55 PM

Yes Kenny, I have to adjust the stack on my recurves depending on what veneer I use. A soft wood will come in a good bit lighter than a hard wood. A boo core doesn't make as much poundage as a maple core also.

Yep, when I built the core test bows, aboo and red elm were real close, maple made a few more and walnut was light.   But every tree lumber is cut from is different so results may vary quite a bit.

Title: Re: Number of laminations
Post by: kennym on March 04, 2021, 08:44:07 AM

Quote from: Mad Max on March 03, 2021, 10:52:42 PM

this is a stack thickness for a 64" R/D ---1-3/8" at the fades.
7 lams for the total stack.
kenny or someone could compare there stack thickness to this chart, may give some idea  :dunno:
the tips are 1-1/2" in front of the back of the bow riser

(https://i.imgur.com/Qv0Ppy9.jpg)

So the main part of the limb is D shaped with a reflex tip at brace
with 7 total laminations you have to save 1 parallel for last, and measure the stack, and make that lam the correct thickness to hit the stack thickness.

Different bow Mark, but my 64" takes .365 to make 50#  .  So we can't really get anything out of that comparison...

My original that number is from has tips about even with back of bow and an 18" riser.  1 7/16 " at fades .

Title: Re: Number of laminations
Post by: Mad Max on March 04, 2021, 10:20:21 AM

 :thumbsup: