2nd attempt at a glass bow- FINISHED. Pics at page 2

[arachnid]

Hi guys.
After my first one broke I tried 3pc takedown. After struggling with limb alignment I got it braced but take a look at the pictures- the tiller is WAY off, right limb being stronger. Plus, it came out too heavy for me, pulling at about 50lb. And if that wasn`t enough, there`s a little twist on the left limb. So, I`d like some advice from you experts please:

1) How do I fix the tiller? I guess I need to grind the left limb at the sides but I want to be sure. Plus, how do I get carefull not to over do it?

2) I want to take at least 10lb off it. I was  aiming and hoping for 40lb tops (although if it`ll be a bit higher, 42-45lb, it`ll be fine).

3) How do I fix the limb twist?

4) Where should I place the throat of the grip and the arrow shelf?

Thanks.
Dor

Unbraced:
       

braced (oh my... it looks worse in the picture):
         

Limb twist:
       

[Roy from Pa]

I'm not into glass bows, but it looks like the limb is really crooked on the limb facing this way, just outside the riser.

[kennym]

May be the pic , but first pic  looks like there is more dark accent stripe showing on the left side. May be pic angle. That "might" affect the tiller, but I would also check limb width with calipers at 6" intervals down the limbs.

Make sure pad angles match, you can draw around the riser and flip end for end to check this.

I have to agree with Roy     , the limb looks to be bolted on a little crooked in last pic...

[arachnid]

Well I managed to get an even tiller (apparently the right limb was wider) BUT it's still a bit to heavy and the limb alignment is a bit off.

Any advise on how to lower the weight and fix the alignment?

[Dale in Pa]

In the pics, the R side limb appears much shorter. That would certainly throw tiller off.

In the last pic, to align, you have to narrow the L side tip and cut the nock deeper on that side and take material off the R side mid limb.

[arachnid]

I found some info online that stated that trapping the back should help reduce draw weight.

How much can I trap the back and still keep it safe?
 
And, how narrow cam I get the limbs? Is 1 1/4" at the fades too narrow or is it fine?

[stickmonkey]

1 1/4 or 1 3/8 is fine. Trapping the limbs is the very last thing and not a necessary thing. If you have a good tiller at draw and you are at weight then trapping will reduce the weight more, possibly change the tiller and drop your preload if done wrong.

As long as you have good preload and vertical stability, torsional stability is usually not an issue with deep core longbows, you can continue to narrow the limbs.

Maybe a pic of its tiller at draw would help before advising trapping.

[arachnid]

Thanks Mick. I'll post pics once I'll be in the shop.
About limb profile- can I go full pyramidal profile or should I leave the first inches parallel?

[stickmonkey]

Its totally up to you and the taper rate. Again work the limbs based on stability. For my designs I go for a pyramid but again my limbs have enough stability to them to do so. Its really hard to say a black or white answer here because there are a lot of little things that come into play.

[arachnid]

My limbs have 2 maple cores, 1 parallel and 1 tapered (0.003")+ 2 0.8mm glass lams+ 8" long butt wedge+ 8" long tip wedge. I started the width taper 12" from the limb butt. So I think I'll start by leaving the first 6" parallel and narrow it from there.

[Roy from Pa]

After looking again, it appears as if your string grooves are not cut even straight across either on the end of the tip in the fore front of the picture.

[fujimo]

the limb pads appear to be cut with two different angles.
have you laid the limbs on top of each other to check their symmetry?

[fujimo]

the locating pin may be out of alignment on that crooked limb( or even its corresponding hole in the limb) which will have it sitting differently.

i would go back to the riser- and check all your alignments and angles- just from what i can see in the pics.
good luck mate- hope you get it worked out- its a nice looking bow!.
both limbs, being made on the same form, "should" be exactly the same. did you check all lam thicknesses and taper rates, and wedge measurements- just to be sure- pre layup. i check and check again and re check. but then i am O.C.D. about stuff like that!

if its just the riser- super easy fix- and if its just one limb- just build one more- that is the beauty about 3 piece bows!!

keep looking. you'll get it figured    

[arachnid]

The limbs are even, made on the same form and are the same thickness. I chexked andc re-checked. The problem is the alignment pins. I made a drilling jig but the hand drill I used seem to wobble and the pin holes are off.
I'm thinking about a solution, let me know what you think:
Take off the pins.
Bolt the limbs without the pins.
Align the limbs and check with a string and 2 weights.
Clamp the limbs in place (while bolted)
Drill new hole for the pins, through the limb.
Reinstall the pins.
Cover the holes in the limbs with a thin overlay.

If it's sounds good, please let me know. If not, I'd love to know of a better way.

[LittleBen]

That's probably what I would do. But you will need to fill the current alignment pin hoes before drilling new ones. Super glue in a wood dowel that fits tightly in the holes first. Otherwise your drill bit will just follow the old holes.

[kennym]

I think you are on right track, limb alignment is probably the worst part of a 3 pc TD.

Stay with her!!

[arachnid]

Thanks Ben and Kenny.
The bow maker community is so great and supportive. Fun to be a part of it.

[arachnid]

Well, after spending a few hours in the shop on friday I finally got the bow finished. Far from perfect but I like how it turned out.
Specs:
40#@28"
64" TTT
Limbs are maple core with Berapaw clear powerglass, beech wegdes and overlay (I like the maple/beech combo) and homemade micarta tips.
riser is white oak and bamboo flooring.
I used 8mm bolts for the limbs, tightend with wing nuts and washers (I think it`s not-to-bad-looking, but if anyone has an idea how to cover the wing nuts, I`ll be glad to hear).

Next friday I`ll be participating at the Israel archery championship- instinctive archery category. I hope this bow will get me some good results (although I`ll be against the top archers in Israel).

Unbraced:
     

Braced:
     

String alignment (not perfect but good enough):
     

Riser (front and side):
     

     

Full draw (sorry bout the dark picture):
   

I want to say a big thanks to all the great guys that helped. And a special thanks to Kenny how helped me through PM`s ever since I started thinking of building a glass bow. You guys are the best.

Dor

[Bvas]

Not bad at all!!!
Especially considering all the set backs you had.

Way to stick it out and complete the project!!!

[arachnid]

Originally posted by Bvas:
Not bad at all!!!
Especially considering all the set backs you had.

Way to stick it out and complete the project!!!

Thanks Bvas. I try not to be the "givinig-up" guy. First bow I`ve completed (a wooden board bow) was after 5 breaks in a row. Set backs happen all the time, It`s how you handle`m that matters.