First Laminated Longbow. A Few Questions.

[b0whunter]

Well, I went ahead and glued up my bow tonight.  What a MESSY job!  I hope I'll get better at it.  I went through about a half a roll of paper towels.  

 
 
I did a dry run and everything looked ok, but after glue-up, it doesn't look like I have enough of, or the right kind of clamps.  I can see some air gaps along the edges of the lams.  I don't know how deep they go or if they will be cut away when I shape the bow, but it doesn't look good now.  It will probably be junk.  What kinds of clamps do you folks use?  I've seen some build alongs that use these spring clamps, but mine don't appear to apply enough pressure.

[okie64]

I use pretty much the same setup you got there with the same clamps. I use a flat steel bar pressure plate on top of the back to make sure it gets the pressure distributed evenly. I use one under the belly too if its a thin belly lam. What kind of glue did you use?

[b0whunter]

Ahh, ok.  Maybe that's what I'm missing.  I will gave to get a piece of aluminum or something, and some more clamps.  

I used Tite Bond III for this one.  Once I get better at building them, I'll get some URAC.

[okie64]

You can use another wood lam about 1/4" thick and it'll do the same thing or you can get the steel bars at home depot. Ive never used anything but TBIII and never had a problem with it. If you got all your clamps right down the middle of the bow then the edges are probably curling up a little. Maybe the gaps wont run too deep into it and it will still work. If you use some kind of pressure plate on the belly side be sure to put masking tape on it so it doesnt get glued to your bow.

[b0whunter]

Okie,

I'm hoping the gap doesn't run too deep.  I'll buy some metal pieces this weekend.   What thickness should I get?   I also need to get some more clamps.  I bought 4 of the trigger style clamps and 2 of them broke, so I'm going to spend the money to get some better ones.   I have a friend that is a cabinet maker and he warned me that I should buy good quality clamps and that they cost more.   I should have listened to him!  He "told me so today, lol."

I think I used too much glue, also.  What do you use to apply the glue?

[okie64]

My metal pieces are 1/8" thick by 2" wide. I use big screwtype C-clamps for the center and deflex posts. I use a popsicle stick to spread the glue around and I'm not sure you can use  too much. I always  glue both sides of all the lams to make sure I dont leave any gaps.

[b0whunter]

Thanks.   I used my finger to spread the glue.  I had a lot squeeze out.  When I clamped it up, I couldn't see any gaps at all, but once it started to dry, the small gaps appeared. It looks almost like the wood curled a bit.  It's been 24 hours, but I will wait until tomorrow to take it off of the form and check how deep the problem is.

[Loren Holland]

bowhunter,
as far as the mess, get a roll of stretch wrap and some painters tape, tape up outside, wrap it to keep glue from getting everywhere. use this method and it will stay clean enough to do in the kitchen, and your old lady won't kill you.

you shouldn't have any trouble just using TB3, unless you are backing with boo, while i have used TB3 before with boo, it was about 80%.  I would go ahead and use the Urac.

remember to alternate the side of the bow that you clamp...if you put them all in the middle then you can get the edges to curl up some

how long is the bow you are making? how high is the riser? if it is not so high then, the angle of the bend for the belly lam won't be so great.

another technique is to steam or heat bend that porion of the lam. I have shaped a belly lam to fit, by bending it that way, clamping it take that shape, letting it sit against the other two lams till it dries (let it sit a couple days to adjust moisture content before you glue) then pull off the clamps, tape, glue, wrap, and clamp again...the beauty of Urac is since its not going in a heat box, you don't have to do all the layers at once

[Loren Holland]

oh i forgot...the boo flooring sections that were mentioned earlier...i tried it unsuccessfully last year

while vertically glued flooring is practically action boo, and will make a lam or go under glass well, its not a good backing...i became a lot less frustrated trying to build a boo backed ipe when i broke down and just ordered the right boo

[b0whunter]

Originally posted by Loren Holland:
bowhunter,
as far as the mess, get a roll of stretch wrap and some painters tape, tape up outside, wrap it to keep glue from getting everywhere. use this method and it will stay clean enough to do in the kitchen, and your old lady won't kill you.

you shouldn't have any trouble just using TB3, unless you are backing with boo, while i have used TB3 before with boo, it was about 80%.  I would go ahead and use the Urac.

remember to alternate the side of the bow that you clamp...if you put them all in the middle then you can get the edges to curl up some

how long is the bow you are making? how high is the riser? if it is not so high then, the angle of the bend for the belly lam won't be so great.

another technique is to steam or heat bend that porion of the lam. I have shaped a belly lam to fit, by bending it that way, clamping it take that shape, letting it sit against the other two lams till it dries (let it sit a couple days to adjust moisture content before you glue) then pull off the clamps, tape, glue, wrap, and clamp again...the beauty of Urac is since its not going in a heat box, you don't have to do all the layers at once

The bow is 70" knock to knock right now and the handle is about 1-1/2" to the belly.  

I cut the bow to shape and did some preliminary sanding on it today.   Good news!   Most of the air gaps were gone after cutting and sanding.  There is still a couple, but they are very small.  I think they will only be a cosmetic issue.   I started tillering the bow and have it pulling about 55# @ 16".  It is still way too heavy, so I have some more work to do. The lower limb is about 2" stronger than the upper, so I need to do some more work on it.   My target weight is 55# @ 28".  It still has a bit too much reflex in the limbs.  I added about 2" extra, hoping that it would lose close to that in string follow.   If all goes well, I hope to take it hunting next weekend.  

I glued up another yesterday, using better clamps and 1/8" aluminum strips to spread out the clamping pressure and it looks like it is going to work pretty well.  Hopefully I'll have two new bows to take to the lease for hunting.

[b0whunter]

Now, bad news.  While tillering, I noticed this on the belly of the upper limb:

 

Tillering had been going well up to this point.   I was trying to get the upper limb bending a little more toward the tip, but I guess I took off too much wood in the area through the reflex.  I strung it up at a low brace height and exercised the limbs and thought it looked ok, but I noticed a the little "X" pattern on the limb after I unstrung it.  At first I thought I scratched the wood with something, but on closer inspection, they were hairline cracks.  I tried removing a little more wood on each side of this area, but when I restrung the bow and flexed the limbs a few times, I could see a slight hinge forming, along with more of these hairline cracks.  Are these crysals?

I will get started on my next bow hopefully tomorrow evening.  I hope the next one goes better.