Boo backed Ipe recurve

[Ballasted_Bowyer]

first time recurve: I am looking to get 60 lbs with a pistol grip handle integrated with the limbs. 64" bow length 30" draw. I have made some flatbows, but I wonder how the width and thickness of the limbs will need to change. I realize natural composites have their points but I want to use what I have. The deflex in the handle will be minimal and the recurve in the limbs about 90 degrees. Is this doable with 1.5" limb width at the fades? Prepared to get schooled.

[PatM]

 You can't recurve Ipe that much. Can you sketch out  your envisioned design?

[Ballasted_Bowyer]

Not tech savvy for uploading a sketch. Basically it would be about 18 inches fade to fade. 1.5" width seem about the most I can get out of a single bamboo strip. I can deflex the fades as needed. I was planing to use two layers of ipe cut from the same board and then turned over so the grain balances to prevent twist. I was thinking to heat bend each layer individually and then set it to the glue form. That way there would be no internal stress on the wood when the bow is unstrung. I figured the bamboo and one layer of wood would go on the back of the fades and one layer of wood on the belly of the fade. About one quarter of the limb would be recurves around a constant radius to 1/4 - 1/3 circle. The other 2/3 would be mor gently recurved to the bring the limb to zero at the start of the hook. Perhaps all this is too extreme.

[bubby]

Yeah pretty extreme, 64" bow with 18" riser only gives you 46" of working limb that only works out to a 23" draw length. Sounds like glass bow dimensions

[Ballasted_Bowyer]

The reason for the long riser is that I want to try a pistol grip. Also geometrically minimizing limb movement to get a draw length saves energy for the arrow. what if I said that the limb width is limited to 1.5 inches because of the material. The riser style needs to be 18" to the ends of the fades. How long do I need to make the bow in a deflex recurve boo backed to get enough limb wood to make 60lbs? Would 78" be too long? It looks in your post, bubby, that you are using draw x 2 +riser as the bow length? I also have a big piece of sugar maple I could use as a core/belly. It's not good enough quality to back Ipe.

[Aaron H]

I have had some success bending ipe, but like Pat says, you can't get that much out of it before it wants to splinter.  I steamed this piece for around 45 minutes.

[PatM]

The reason for the long riser is that I want to try a pistol grip. Also geometrically minimizing limb movement to get a draw length saves energy for the arrow. what if I said that the limb width is limited to 1.5 inches because of the material. The riser style needs to be 18" to the ends of the fades. How long do I need to make the bow in a deflex recurve boo backed to get enough limb wood to make 60lbs? Would 78" be too long? It looks in your post, bubby, that you are using draw x 2 +riser as the bow length? I also have a big piece of sugar maple I could use as a core/belly. It's not good enough quality to back Ipe.

  A pistol grip doesn't have to eat up so much useable length. You can get your desired bow in the shorter length as long as you don't get carried away with the recurving.

 See this bow for inspiration.  http://www.primitivearcher.com/smf/index.php/topic,15459.0.html

[Aaron H]

Wow, that is a very cool bow.  Thanks for the link Pat

[bubby]

First off epe only needs to be about 1-1/4" wide, you could definatlly go no more than a 12 in riser/fade  area. Yes the standard for draw length is 2× the draw plus riser, that said with a full on r/d bow and a 30" draw the shortest i would go is 66 ttt and i have built a bunch of bows.

[Ballasted_Bowyer]

That example is quite fetching. Which lam is the "power lam" in the description? Is that the compression lam, patm?

[PatM]

No. It is a tapered piece between the bamboo backing and the Ipe that reinforces the handle and fades.

[Springbuck]

  THere ya go!  Pat's bow is EXACTLY how you do something like this.

  It's true that less moving limb is good for efficiency......but this is wood.  Sometimes you just need the wood, you need lentgh or width to take the strain.   My experience with really strong backing and really strong woods together is not that they are then less likely to take set or break, just that they still do it ....more suddenly....... if you screw up.  So, I would absolutely start with the 1.5" wide backing and slat, and narrow or even trap it later if you want to.

78" total is way longer than you need, more like 68", but also really don't need that 18" riser.  Squeeze, it all down to 12-14" fade to fade........14"  MAX  .Power lams are the bomb because it allows you to put the "fadeout" between the backing and main slat to start with.  Saves wood.  Then the layered handle lams do the rest, if you execute well.

If you want actual recurves, then, yes put what you can in the lam and backing before hitting the form, but I still believe that Perry reflex give an advantage in stiffness and strain on the wood.

Good luck.

[Ballasted_Bowyer]

The pistol grip on pats bow is a lot like what I have done before on flat bows. I was thinking a handle that is more like the dreaded composite riser. However, I hate glass and won't do a riser that requires glass or carbon. If wood requires more length than such a handle allows, well than I will just be content with what's appropriate where I belong. I appreciate all the pointers. I am going to revise my design with this info in mind and start playing around when I get home in a week and a half. If I can figure out how to post pictures at some point I will share my progress. I expect I may break one at least before I get it right. I've broken at least a dozen flat-bows before I finally started getting results I like. So breaking is part of the learning curve. Its lucky I break so many or I'd have no excuse to make another one.  Any additional advice is still welcome.

[PatM]

Do you mean compound riser? Not sure how different that would be.  As long as you build up enough material depth you can greatly alter the throat of the grip without changing anything about the length of the non-working riser.

   That bow I linked to was drawn 29 with an overall length of 55 so I'm not sure if you need to make it THAT much longer to get  an extra inch.

 I know a guy on here made a straight up reflexed Ipe static that was 65 inches long and drew over 30 inches. Deflexing saves the wood from a lot of bending stress..