Trapping advice?

[monterey]

First let me explain where I'm at with this bow.  It is 1 1/8th wide at the fades and 3/8 at the string nocks.  Limbs are profiled with a pyramid shape.  The limbs have an arc backset of about 1" at the tips.  The bow is 68" NTN with face and back lams of .050 glass and four wood lams between.

Want to get more bend in the outer 2/3 of the limb.  Thought about doing an "eifell tower" shape but prefer to trap it with a gradual fade in and out of the trap at each end.

Here's the question;    Should I trap on the back side or the face side???

The reduction in draw weight is not an issue.

[GentlemanArcher]

I'll be watching this post...this is similar to the situation I have found myself in with my first glass bow.  All of the bending of the limbs was happening just past the fades.  I have the limbs in a pyramid shape now.  But, like your situation, I'd like a little more bend out of the last 1/3 to 1/2 of the limb.

GA

[macbow]

It's been a while since I've worked with fiberglass.
Just to get this rolling, most of the bending in glass bows is designed in with the tapered laminations.
In this case I don't think it matters where you start. I would start with trapping the belly, start with a shallow trap just past where it it is bending and increase as you get into the area it needs to bend more and going shallow again several inches before the tips. Stay even on all sides and both ends.
Then see where your at. You can then remove more on the same areas on the sides if it needs more.
Some might say to sand off the face of the fiberglass. To reduce the thickness. I've fouund this to be very slow.
Ron

[monterey]

The belly was my thought too.  I see the wood bow builders discussing compression versus tension of the various woods and wonder if its an issue with glass/wood.

I too thought about sanding the surface of the glass and came to the same conclusion.

[bamboo]

mike
what taper-rate did you use?
and if you can post pics of it a brace and possibly at full draw

[Swissbow]

I'd rather sand the glass on the back and belly if I wanted to change the way the limbs bend. Just go slowly and check often how the limbs are coming along.

If you do an eiffel tower shape the limbs might start to twist and since the limbs are already thin, you don't have much room for corrections. Trapping won't help a great deal when it comes to change the way the limbs bend. It's more suited if you want to reduce the limb mass without loosing to much of the draw weight.

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Andy

[monterey]

You guys have me thinking this through again!!  Maybe surface sanding is the way to go.  The shape of the limbs is not that far off at full draw.

[Swissbow]

Do you have any pics ? And what is the total taper rate that you use ?

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Andy

[Jason Scott]

You are going to get your outer limb bend from thickness taper rate on a bow that narrow at the fades. I have successfuly used .006 per inch on bows like that. With a tip wedge. If the profile were wider you could accomplish some of that in width taper.

[monterey]

Andy, I don't have any pics and can't take any at this time.  Taper rate is the root of the problem, it being .002!  :(    At this point I'm inclined to follow your advice and sand in the additional taper.  

Jason, You are right on.  I did some width taper but at the pyramid shape it's now in, the warnings about limb twist are making complete sense.  If I ever make another bow this narrow it will have your suggested taper rate!

[Swissbow]

I agree with Jason about the taper. I your bow profile has some reflex, you can increase up to 0.006 without a problem. Don't forget to compensate the increased taper by making the stack approx. 5 lbs heavier. On top you will notice that the bow will draw much smoother and feel lighter than your actual one.

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Andy

[monterey]

Thanks Andy!  I always find your advice to be very helpful!