BBI width question

[Zradix]

Hey guys

Sold my bow for bow making $$$....so I gotta do this right..hunting seasons right around the corner..
Going to order some boo and Ipe in the next couple days.

I want to end up with a 64.5" ntn BBI around 45-50# @ 28"
With a medium/ med high amount of r/d to it.

Should I start out with 1.25" wide or 1.5" wide?

My thought is to have the boo be 1/8" thick on the edges in the riser section and taper down to 1/16" at the tips.

If I can accomplish the above, how thick should the belly Ipe be when I glue it up?

I'm sure that depends on the width too..so please explain which width you have in mind when you suggest a thickness.
If you would be so kind.

And please..if you find something WRONG in my plan let me know.

for what it's worth, I'm worried that if I choose 1.5" wide at this lower draw weight I might end up with a really thin belly...especially if I have a hard time getting the boo thin enough..

Thanks a lot guys.

[Pat B]

1.25" wide is a good width for an ipe bow. I'd go out 6" to 8" before tapering to the tips. Make your boo 1/8" thick at the crown at the handle. I never measure belly thickness but reduce the belly until the tiller is good and I have achieved the draw weight I'm looking for.
If you do find the belly getting too thin you can tiller from the sides of the bow als.

[Zradix]

I was planning on starting the taper about where you said.
I should have mentioned that.
Thank you for pointing that out to me non-the-less.

When you say at the crown.
Do you mean 1/8" thick right in the middle of the boo?
The middle right to left?

Or have the boo 1/8" thick at the edges in the center of the bow lengthwise?

Thank you
..and please excuse my ignorance..

[Zradix]

I'm a little worried how much r/d I'll be able to get with a 1.25" width using Ipe.
I've never even touched a piece of the stuff but I hear it's stiff as heck.

With 1.25" it'll have to be thicker, so I'm thinking I should get it down somewhere close to final thickness before glue up so I can bend it easier into the jig.

[Echatham]

my limbs were 1.25" wide at fades if i remember right, and my ipe was 3/8" thick when i got it. my bamboo was 1/8" more or less the whole length. i had to remove a whole lot of ipe just to get to floor tiller. the ipe ended up barely thicker than the bamboo at midlimb. the next one i do i am going to make the boo a little thinner.... and im going to use the same form as before, but im going to make the end posts 2" or so higher, so i get more reflex.  not sure i understand your concern about achieving r/d because of the width.  its the glue joint holding your shape. i will give you the dimensions of my form later when i get home and you can use that as a base line for what you want to do, as its a pretty mild r/d. just make the end posts higher for more extreme reflex.  i wouldn't worry about being able to bend it in the jig... the clamps i used in my build along had no problem at all clamping it down. but then it was only 3/8" thick to start with. i think it came out of a 1x6 that someone ripped into 6 bow blanks. can't believe you sold your bow! you're hooked bad!

[Zradix]

Thanks Eric.

My concern was this...
If the limbs are more narrow they will have to be thicker to reach a certain weight.

I was worried that if the board was too thick I wouldn't be able to get them to bend enough without breaking.

I'm glad to hear your 3/8's board wasn't bad to bend.

I can hardly wait to get started.
Matt didn't call today...maybe tomorrow.

[Zradix]

Sounds like I'm gonna start with 1.25" wide and 3/8 thick board.
I'll get the boo thin..somehow..lol
Prob. just sand it down.

I'm going to start working on the jig..maybe tonight..prob tomorrow.

[macbow]

Those dimensions look good..
When you first start cutting out the bamboo to shape the edges will be berry thin less than 1/16. After you cut it to shape the edges will be thicker and I sand them again to get 1/16 on edges ideal no more than,1/8.

[Zradix]

ok..
measure the boo on the edges..not the center..CHECK  

Thank you

[Echatham]

if you have major thinning to do on the bamboo you might try a belt sander, i used a palm sander with 100 and then 150 grit to get it super flat and ready for glue up. it doesn't matter if you measure the edges or the middle (calipers would be great and i need a set) as long as its uniform thickness. keep in mind that near the tips the edges will be thicker even if the crown is the same.  any thick spots will haunt you.  i had a thick spot on one limb and it was always stiffer, worked out for me, that being my bottom limb, but it wouldn't take much to screw you.  Matt will probably have the boo in pretty good shape by the time you get it. he did mine anyway. anyway, i would not go any thicker than 1/8" at the crown... and i say that because my thickest portion of bamboo was 1/8", and the ipe under that was 1/8" as well. I don't think you want the backing thicker than the belly wood.

[Echatham]

oh by the way my ipe was 1.5" wide when i got it. i didn't reduce it down to 1.25" until after glue up... not that you have to do it that way, but thats how i did it.

[Bowjunkie]

I measure the bamboo at the center... the crown... not the edges. 1/8" at the handle and 1/16" at the tips, if possible.

Are you going to pretaper the ipe? Pretapering the thickness of the ipe prior to glue-up helps the limbs bend evenly during glue-up and gets you a real good jump on the tillering. 

I usually leave the handle area, from dip to dip, parallel, then put about 1/8" of taper in the limbs.

[Echatham]

bowjunkie what tool/process(s) do you use do do a taper like that?

[Pat B]

1/8" at the crown, ie. the center of the boo backing, the high point. Your edged might be 1/16" to a razor edge along the sides of the bow.
 I've never built a R/D bow. The backed bows I have built were reflexed.

[LittleBen]

Introducing alot of R/D or even just reflex in ipe is a pain in the butt. You'd need to get the ipe beinding a bit before glue up to do it. The risk is that you can't really tiller the ipe core alone, because it can break ... so you cna only  really get it to floor tiller before glue up. That will make it easier to add R/D.

I also think you need to go 1.25" wide. at 1.5" wide the ipe will be very thin, and it the limbs will have more mass than necesary. 1.25" is good.

My most recent BBI was 67" ntn roughly 1.125-1.25" wide IIRC and pulled well over 60# at 28". the bamboo was thinned down as described and there wasn't more than maybe 3/8" of ipe midlimb.

[Zradix]

Thank you very much for the GREAT info gents.

This is gonna be fun!