help with hickory backed open pyramid bow

[ipeguy]

Hello,
I recently came across a large good supply of ipe.  I ordered some hickory backing and ripped some of the ipe into staves.  I made the staves 1-1/4 wide by 72 inches long.  I would like my final dimensions to be 70 inches long with a solid handle and 60# of draw weight.  I have made several bows, ranging from self bow to fiberglass laminate.  I have never made a pyramid bow.  What would be some good dimensions?  Does the fade taper with the limb or does it remain straight?  How thick will the limbs need to be to reach my designed draw weight?  How much reflex and deflect would be good?  I have not made a bow of this design from ipe before.  I plan to use g2 epoxy which is designed for oily wood and had worked well on my glass lam recurves. Thank you for your help!

[Pat B]

1 1/4" by 70" should be a good place to start but you can get shorter if you wanted to. I haven't made a R/D design but have added reflex to a hickory backed ipe with good results. I usually add no more than 3" to 4" of reflex at glue up.
 A pyramid bow has width taper straight from the fades to the tips. The perfect pyramid has the same thickness for the entire limb and the tiller comes from the side taper. I have found that you usually taper the belly some anyway so I usually tiller the same as I do selfbows and backed bows.
 I like to start with the belly 3/4" to 5/8" thick then reduce it while tillering until I get both limbs bending evenly and together and have have achieved the draw weight I'm looking for.

[passion for knowledge]

I picked up an ipe plank - 6in wide, 1in thick a while back. Dark and dense as heck.

Both bows are thin, front to back, compared to a lot of builds I've found while poking around.

I've made 2 bows using it so far - maple backed and a tri lam, hickory back maple core, ipe belly.

Both came in #47 @ 28"

Both pretty much pyramid left-right.

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=014061;p=2#000014

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=014054;p=1#000007

I don't claim to be an expert. Just posting how things worked out for me, so far.

Maple backed ipe has a fair amount of fade (front to back - thumb ache with a scraper!) in the ipe after the handle.

Just glued up a boo backed ipe from the same plank - sitting with eyes, legs and fingers crossed! Can't get back to it until Saturday.

Should get at least 2 more bows and maybe a kid's bow out of what's left.

Cost me $60 - what a deal!

[ipeguy]

So I have the bow glued up and roughed out.  Right now it is 70 inches tip to tip and about 1 1/4 wide and about .65 inches thick in the limbs.  I believe that it is still far too stiff.  I think I will glue on overlays and put it to the long string but I kind of want to thin it more.  What thickness should the limbs be when it's finished for -60 lbs ?
 http://imgur.com/a/hHzIC

[John Scifres]

I would guess much closer to 1/2" thick.  Take it down 1/32" and bend it to 16" and weigh it.

[passion for knowledge]

I think there are too many variables in the wood to come up with a precise number, IMHO.

Best to just sneak up on the weight you want to achieve. It's easy to lose more than you intend if you go too fast.

[BMorv]

From looking at your pictures, it looks too thick.  I'm surprised every time I do an ipe bow at how thin it ends up.  But as suggested, go slow.  The difference between a 40 lb and 60 lb ipe bow is only a few thousandths of an inch.  
And it may just be the pictures, but it looks like  the tips are thicker than the near fad thickness.  I would make sure you have uniform thickness before you start pulling on it.    

This was my last bamboo backed ipe with a mild r/d right after I cleaned it up after glue up.  It ended up a little more than 55 lbs.

[Pat B]

I never measure thickness. Just remove wood, either belly or side or both until both limbs are bending evenly and together and you achieve the draw weight at the draw length you want.

[BMorv]

Keep in mind that Pat is really really good at making bows.  Speaking as a novice, I've learned that the least amount of time I spend with the scraper in my hand the better the bow comes out. I try to nail down my thickness profile as close as possible to final dimensions during the floor tiller stage.

[Pat B]

Once I hit floor tiller I only use a scraper and sometimes a rasp if needed. When I started tillering this way my bent sticks became bows. By using mostly just a scraper I slowed the process down and made less mistakes. It takes longer to tiller a bow but usually they turn out good by slowing myself down. Patience is your best bow building tool!

[BMorv]

Yep, I agree Pat. I only use a scraper as well once I get it to floor tiller.    
What I meant by that statement about using the scraper as little as possible is that I spend most of my time prepping belly thickness before it ever sees tree.  If I did my prep work properly, it's only a few scrapes here and a few scrapes there to get it to final tiller (more or less).  This was a concept that my novice brain didn't pick up on my 1st few bows.  I would throw a big chunk of wood up on the tree and spend hours scraping away unneeded thickness.

[passion for knowledge]

That BBI looks a lot like the one I've got on the go at the moment.

Hoping to achieve #50-55

[ipeguy]

So i have the nocks done and put the long string on it.  Pulling about 40 lbs at 3 inches on the long string.  Looks like I have a ways to go... Caliper measures the limb thickness at about .615 of an inch.  What is the best way to remove this much material?  I did 100 passes of a scraper on either side and made little progress

[Pat B]

Are you exercising the bow after you do a scraping session? That will make a difference by registering the wood removal. If you don't exercise you'll sometime take too much wood off without knowing it. While the bow is still heavy I do 20 scrapes on each limb, exercise about 20 times(only as far as you have drawn to)then check on the tree. I mark stiff spots and weak spots and back to the bow bench.

[John Scifres]

I'd use a bandsaw but you better stick with a rasp. Nice smooth strokes. Mark the sides by scribing a line for thickness.

[BMorv]

I use a belt sander with 40 grit sandpaper ONLY if I have a lot of material to remove and to clean it up after glue up.  I do 5 or so passes on each side until I get the limbs bending a little and evenly.  From then on I only use a scraper.  Ipe tends to gouge out when using a surform.  I haven't tried a farriers rasp on ipe.  You can take off quite a bit with a sharp scraper.

[ipeguy]

How does my tiller look so far?  I have it drawn to 13 inches:  http://imgur.com/a/mmdfd

[monterey]

Could you show a frontal profile?