Author Topic: Roy, BMorv, other gurus i need help with trilam Taper?  (Read 1604 times)

Offline John Malone

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Roy, BMorv, other gurus i need help with trilam Taper?
« on: April 29, 2018, 09:40:54 AM »
Ok, so I must have transferred those measurements wrong.   So I have the lams you sent me 36 inches long 7/32 to 3/32. For a 66 inch #50 bow should I z splice em, scarf joint, 4 inches? That will lose some thickness in the joint if I z splice. Mostly what I'm wonder is what the taper rate per inch should be on the average trilam bow at 1.5 for 6 inches then 1/2 at the tips? I got the 1/8th backing 1/4 inch belly.
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Online Roy from Pa

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #1 on: April 29, 2018, 11:46:10 AM »
Z splice them, won't hurt a thing.

I don't worry about taper per inch on a wooden bow.


Offline John Malone

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #2 on: April 29, 2018, 12:04:47 PM »
Ok, gonna play on the tractor for awhile first. Got to get ready to put these maters in the ground.
Life is to short to pass up anything that could potentially be bow wood!

Offline John Malone

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #3 on: April 29, 2018, 03:04:23 PM »
If you get the taper pretty close to start with, do you still tiller out the reflexed area or will it bend automatically? Or with minimal tillering?
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Online Roy from Pa

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #4 on: April 29, 2018, 06:15:56 PM »
The reflex will straighten out on it's own, so that means that part of limb did in fact bend.

You don't induce reflex then tiller it out.

These type of bows will have stiffer flatter outer limbs.

See how straight the outer limbs are at brace?

They are flat.



« Last Edit: April 29, 2018, 06:31:41 PM by Roy from Pa »

Offline John Malone

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #5 on: April 29, 2018, 07:07:30 PM »
OK, mine looked just like that at brace. At full draw it looked like a drunk redneck trying to dance to James Brown. :laughing: 
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Offline Bvas

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #6 on: April 29, 2018, 07:57:42 PM »
OK, mine looked just like that at brace. At full draw it looked like a drunk redneck trying to dance to James Brown. :laughing:
So it looked perty effin sweet :dunno:

I know I look sweet when I get down with James Brown :goldtooth:
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Offline John Malone

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #7 on: April 29, 2018, 08:13:52 PM »
Hell Yea Bvas!! :thumbsup:
Life is to short to pass up anything that could potentially be bow wood!

Offline BMorv

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #8 on: April 30, 2018, 12:35:12 PM »
Here's what I do: I do 0.006"/inch total taper,  .002 on the back, .002 on the core, and .002 on the belly.  That gives you a nice arch type bend which is what I'm after.  If you want your outers to be a little stiffer, I would take out the taper on the belly, like Roy and some others do.  I also add tip wedges to stiffen the outer limbs, but I'm currently playing around with no belly taper and seeing how it affects my bend. 
The way I see it, you are determining how your bow will bend by precisely pre-tapering your lams and width tapering pre-glue up, so you really don't have to mess with tillering one area or another.  I just more or less remove wood evenly from the entire limb to balance them out and reduce weight to get to my target.  I let the shape take whatever shape it wants, since I already know it's going to bend evenly because I spent my time in prepping the tapers. Your eyes will fool you every time if you try and play the I don't think it's bending enough here game when you are adding reflex and deflex.  What you are looking for with your gizmo is sudden dips or flat spots, not worrying about gradual changes as there will be changes in the gap because of the R/D.   
You can use whatever crazy fractions you want, but you are working on a thousandths per inch level, so it just makes it easier to address everything in thousandths of an inch.  Roy's fancy thickness sander is accurate down to less than 0.001" of an inch.   You shouldn't be off more than a couple thousandths of an inch IMO on these types of bows. 
I use a scarf joint.  I've used a z-splice but don't find them necessary, especially when I add a power lam. 

 
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Online Roy from Pa

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #9 on: May 01, 2018, 07:55:00 AM »
I've used a z-splice but don't find them necessary, especially when I add a power lam. 

Yup that would help.

I once had a bow fail just butting the core lam and gluing.

Never again, I z splice them now.

Offline John Malone

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Re: Roy, BMorv, other gurus i need help with trilam Taper?
« Reply #10 on: May 01, 2018, 08:46:05 AM »
Ive had issues with butt joints In stressed joints, I don't trust them, seems to place to much stress on the other pieces. I cut dovetails by hand so a z-splice or a good 4 inch fishtail is no problem. I have a 4 inch scarf joint in the belly of that boo backed lemon wood i made, no issues and i shoot the heck out of it. The guy i got it from had spliced it and never used it, so i got it cheap. Long scarfs are much harder for me to cut by hand so z or fish splices are the way to go.
I used to be better with thousands but its been so long, i made a chart and put on the work bench.

Thanks guys, gonna crawl around under Moms house and fix a water leak, hope to get a pan of biscuits out of the deal.  :thumbsup:
Life is to short to pass up anything that could potentially be bow wood!

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