A couple static curve questions

[WhistlingBadger]

Working on a hickory shorty with what I hope will be static recurves.  I haven't started bending it yet, but I got the curves steamed in.  I'm a little worried about whether they'll be stiff enough.  I was thinking about boiling some elk antler slices and gluing them on the inside of the curves to stiffen them a bit.  If nothing else, it would look cool, but of course I'm more concerned with performance and not having the curves pull out or break.

How to you know if your curves are stiff enough?  Any guidelines?  Thoughts on antler overlays for stiffening?

[SLIMBOB]

Couple of thing's. I typically wont heat bend until I get it bending at floor tiller. Then I will check it on the long string. If the tips aren’t bending, then they should remain stiff as I shed wood from the working limb.   Since you already heat bent the tips, just tiller it out on the floor. If the limbs are not bending yet, the tips I would bet, will remain stiff. Just a guess without seeing it, but I would take the over on this.

[superdav95]

Couple of thing's. I typically wont heat bend until I get it bending at floor tiller. Then I will check it on the long string. If the tips aren’t bending, then they should remain stiff as I shed wood from the working limb.   Since you already heat bent the tips, just tiller it out on the floor. If the limbs are not bending yet, the tips I would bet, will remain stiff. Just a guess without seeing it, but I would take the over on this.

+1 for me.  This is how I do it as well.  Sometimes I’ll get it to 20” draw with stiff flat tips then steam them in and let cool and acclimate really well for a couple days.  After that I’ll set them in with same dry heat.  As far horn or antler on the back it does work too.  Just another step that you may not even need to do.  I would think it wouldn’t take much with a glue line to stiffen up the static.  You’d be surprised how little thickness is needed to stiffen up a recurve.  Another option could be a wood laminate instead of horn on the belly portion of the recurve.  I’ve had success with this when I wanted to maintain the back the way it is.  Best of luck on it. Post some pics would help give better idea too. 

[WhistlingBadger]

OK, thanks, guys.  Looks like I got excited and did things in the wrong order.  I'm hoping to get into the shop today and get some work done, so I'll see if I can get some pictures.

[WhistlingBadger]

OK, here's what I have so far.  Going to back it with dogbane fiber, since it's so short and I didn't really chase a ring.  Hoping for around 50-55# @ 27" when finished.  Do you think the curves will be stiff enough?  They're .6" tall and .5" wide.

[superdav95]

They look plenty thick to me.   Did you dry heat set them in.  Also do you still have some limb thinning to do yet.  If so you could narrow up the transition at those statics a little keeping the thickness at the mini levers. 

[WhistlingBadger]

They look plenty thick to me.   Did you dry heat set them in.  Also do you still have some limb thinning to do yet.  If so you could narrow up the transition at those statics a little keeping the thickness at the mini levers.

How does setting in with dry heat work?  I've never done that, and I'm wondering if that's why my recurves always pull out.  I was planning on heat treating the belly once I'm a little further along.  Is it the same idea?

I am planning on leaving the limbs wide, since they're so short.  Just evening them up a bit.  Should I narrow up the tapers into the levers to make the transition smoother?

Thanks for the help!

[SLIMBOB]

Heat tempering the belly increases the compression strength.
As far as your tips go, it takes very little wood at the tips to make them static. Most of the leverage (stress) felt by the limb, takes place near the fade, or more precisely, where the working limb begins to bend. As you move out toward the tip, less leverage is applied and so less wood is needed. Once at the tips, little leverage felt, so little wood is needed to keep it stiff. Straighten up the angles and have them flow into the tips. It’s a good practice and I think it just looks better.

[superdav95]

Heat tempering the belly increases the compression strength.
As far as your tips go, it takes very little wood at the tips to make them static. Most of the leverage (stress) felt by the limb, takes place near the fade, or more precisely, where the working limb begins to bend. As you move out toward the tip, less leverage is applied and so less wood is needed. Once at the tips, little leverage felt, so little wood is needed to keep it stiff. Straighten up the angles and have them flow into the tips. It’s a good practice and I think it just looks better.

You beat me to it… what he said.  😎

[WhistlingBadger]

OK.  So when I heat treat the belly, I should just go all the way out to the tips to set the curves?

[SLIMBOB]

Yes. Good and deep on the tips.

[WhistlingBadger]

OK, will do.  Thanks for the help, guys.  I'll post some more pics once I have something interesting to show. 

[WhistlingBadger]

So, this happened.  I was heating on the belly side, but somehow the heat got concentrated between the bow and the mold and severely scorched the back side.


Bob, you did say to go good and deep on the tips, but I'm guessing this isn't exactly what you meant.     I'm planning on backing this bow with dogbane fiber, so I figure I'll scrape off as much of the charcoal as I can, then put a double or triple layer of backing fiber on the inside of this curve.  Thoughts?

At least the taper to the levers looks better to me.  It will be a real pretty bow right up until the curve breaks off...

[SLIMBOB]

Yikes!  I have had them get little licks of color on the back, but never anything even close to this. So, I can’t tell you how to fix it on this one, but I can tell you how to minimize it on the next one. I take my caul and bend the tips. Once they are flush with caul, I heat treat the belly. I hold the heat gun at a pretty  open angle pointing toward the tip, as opposed to pointing straight down. I will get a little color on the back in spots, but nothing to worry about.
I burned a hackberry bow this bad a decade ago, heating over hot coals. Just not paying close attn as the daylight was fading. I cut the tips off and made a 62 inch bow instead of 72. 62 inches was long enough to work. Hope you can salvage this one. I will also add that backing one is a lot of work. I would much rather tiller out a good shooter, and then back it, as opposed to putting in all the work on one that may not make a bow. That’s me, and this is your project, so just food for thought.

[superdav95]

That’s too bad WB.  I agree with what Bob said.  Another possibility is backing with boo strip and adding a power lam at this location and see how it work if you are set on keeping the same length. Just grind flat the back and prep for boo backing if you got one wide enough.   Just a thought.  Best of luck with whatever you decide to do.