Bamboo Backed Ipe R/D Longbow [with Video]

[fujimo]

hmmm...i see they have tints for the glue. so that it can be better matched to whiter woods or darker woods. thats good!

[mwosborn]

Fujimo is correct - not the glue you want to use to glue up a bow.  DAP Woodweld does make a ureaformaldehyde glue similar to unibond, but I have never tried it as my local stores do not stock it.  Shipping on it is the same as unibond.  Your local might carry it?

[bowhunter15]

Originally posted by fujimo:
can see he's not married- bows and boats inna bedroom!!!!    :D  

Haha! My girlfriend apparently doesn't mind too much. Plus she knows I'm going to be buying a house with a big garage sometime this summer.

[mikkekeswick]

Your form needs adjusting as Roy said or use more posts. It's very important to get your form dead on before glue-up.
Also what's really important is that the reflex isn't concentrated in one spot like on your form.
This is happening because there isn't much taper on the ipe. You need the reflex to be gradually increasing from where it starts (inner/mid limb)out to the tips. So the curve is elliptical not arc of a circle and definately not almost a straight line like it is at the moment.  
As far as i'm concerned you shouldn't reduce the extra on the handle area. If you do you are opening up a whole can of worms called handles popping off. That extra thickness on your ipe is there for a reason.
Try not to run before you can walk! R/d bows are hard enough to tiller - make it easy on yourself!

[bowhunter15]

Originally posted by mikkekeswick:
Your form needs adjusting as Roy said or use more posts. It's very important to get your form dead on before glue-up.
Also what's really important is that the reflex isn't concentrated in one spot like on your form.
This is happening because there isn't much taper on the ipe. You need the reflex to be gradually increasing from where it starts (inner/mid limb)out to the tips. So the curve is elliptical not arc of a circle and definately not almost a straight line like it is at the moment.  
As far as i'm concerned you shouldn't reduce the extra on the handle area. If you do you are opening up a whole can of worms called handles popping off. That extra thickness on your ipe is there for a reason.
Try not to run before you can walk! R/d bows are hard enough to tiller - make it easy on yourself!

So if I'm understanding correctly, the lack of tiller on the ipe which is causing the "straighter" looking reflex is actually creating a region of high stress at that bend. An elliptical reflex, on the other hand, would indicate that the stress is more evenly distributed along the limbs? And I could create that type of shape by either tillering the ipe more before gluing, or... more desirably, just add and play around with supports until I get a good shape to start  with?

On one hand, I can leave the handle flat, making tillering easier. On the other, I can make it similar to Roy's form and get more deflex. Considering this is my first bow I intend to learn quite a bit (and I know this is a little different than my last post), but I'm deciding to leave the handle flat. That should save me some time and effort in tillering and give me confidence. Because once I've been through the process of completing the bow, I'll be more ready to build another with changes (like Roy's bow shape).

I'll play around with the supports and post another picture.

[macbow]

In the future building like Roy's form is the best Idea.
With Roy's and mine the handle area will have a bend in it.
Roy grinds his handle to fit this.
My way is to use many 1/8 inch or less slats and it bends to the bow. It is glued on after the bamboo and core like Roy does.

For this one it will be easier to just have it flat.
Agree to adjusting form for better bend, in the future tapering all pieces will aid in that.

You can get all the info you need here, but if you like videos
Dean Torges, building the bamboo backed bow video, covers a,lot of why on where the R/D is put into the bow.

[Roy from Pa]

Garrett, you could glue and screw a full length of 2x4 along each long side of your form. Having the 2x4's edge laying flush with the bottom of the form. That would also work out nice for your posts sitting down inside the 2x4's on the top. I tried a form like you have and you would be amazed at how the resistance of the bow wood causes the form base to bow up.

[bowhunter15]

Okay before I put on more supports, how is this shape looking? The bend is closer to the tips, more rounded, and there's even a little deflex.

[bowhunter15]

[bowhunter15]

Another thought that had occurred to me was, "why do I have the supports as high as they are?" In Roy's picture, he uses a bunch of c-clamps and needs the clearance. My plan was to use spring clamps, with c-clamps only at the supports. In that case, I can translate the entire bow closer to the base by cutting an equal amount off of each support, and probably could clamp the center with handle block right onto the flat base without any support whatsoever. The main advantage of doing this would be to cut cost in the C-clamps. The 8" cost $15 all by itself.

[Roy from Pa]

Do a dry run first before you glue it up, to see how it looks. If you are leaving the bows handle area as it is, then you could glue the separate handle block on at the same time. With the bow as it is now, the handle area is not going to bend anyway. Why not forget the deflex on this bow and just induce about 4 inches of reflex with your end blocks. If you insist on spring clamps, fine but I would put one on each side across from each other, butting together at the center of the limb, every two inches. Putting just one in the center could leave gaps in the glue line along the side.

[bowhunter15]

Here's the dry run. I will add C-clamps where the Red arrows indicate and double up on the spring clamps like you suggested.

   

[Roy from Pa]

I like it..

[LittleBen]

Originally posted by Roy from Pa:
I like it..

Me too, watching this one

[Roy from Pa]

Pay attention, Ben. This rookie might learn ya something...  

[mikkekeswick]

Looking better but I just wouldn't use spring clamps. Go to the local bike shop and get some innertubes. Ask for the ones they are going to throw away (from repairs). You probably want about 8 mtb ones (26 inch).
You can still tweak the shape by adding more posts.
Another tip to give you a better clamping surface is to get a strip of steel about 1/8 thick and drill/screw it to your posts. It will give a nicer more even curve to your form.

[bowhunter15]

Originally posted by mikkekeswick:
Looking better but I just wouldn't use spring clamps. Go to the local bike shop and get some innertubes. Ask for the ones they are going to throw away (from repairs). You probably want about 8 mtb ones (26 inch).
You can still tweak the shape by adding more posts.
Another tip to give you a better clamping surface is to get a strip of steel about 1/8 thick and drill/screw it to your posts. It will give a nicer more even curve to your form.

Man, this forum is full of ideas! I hadn't even considered that yet. I just did a bunch of reading on inner tube clamping. It seems like (along with being free) it would do a great job of ensuring the entire width of each layer is in tight contact (like putting opposing clamps on each side). Something like the picture below might work fine. I could keep the C-clamps in place, but lose the spring clamps in favor of inner tubing. I'm still waiting on the Unibond, so I am still open to changing the clamp process. From the pic below and Roy's clamp pic, it looks like plastic wrap isn't used. I've read other builds where people used it beneath the clamps or tubing to help with clean up. Does it make a difference with Unibond800?


 

Originally posted by macbow:
I moved from all clamps some time ago to less clamps and the inner tube rubber.

 

Picture is pretty cluttered but shows the ratio of clamps to inner tube. I use bicycle inner,tubes cut up.
Main clamps are at the center and where the spacer blocks are located.
Small c clamps for the area around the power lamination if used.

[takefive]

I always wrap mine in plastic food wrap, but I use C clamps with wooden shims.  O/w the shims will wind up epoxied to the bow and the bow to the wood posts on the form.  

Maybe you don't have to worry about that if the bow is completely wrapped with inner tubes?      

[Roy from Pa]

I wrap every bow with plastic wrap at glue up. If you don't, you will have a mess...

 

The picture of Macs tube wrap isn't what I was expecting. I was under the impression of cutting one inch wide cross sections from an inner tube and stretching them across the bow, down onto hooks or pegs along side the form. Like super wide gum bands.

[Roy from Pa]

Another "Important" thing Garrett. Before you glue this bow up, clamp it down on the form and run a string weighted on each end down the center, from the center of one limb tip to the center of the other limb tip. Clamp it down tight once it's aligned straight. Then what I do is drill 2 small holes in the center of the handle about 2 inches apart where the leather grip will cover them, and I drill a single hole in the very end of each limb tip. Then after I apply the glue to all surfaces, and remember that, you need a coat of glue on every surface that will come together. Then I stick a tooth pick into those holes I drilled. Those tooth picks will keep the bow aligned while you clamp it up. Otherwise, the glue joints will be slippery and your bow could get glued up out of alignment...