Help wanted with my second attempt at a first bow

[bownarra]

You need to get the inner limbs working for sure. I also suspect the m.c. is a bit high, the ash we have here fraxinus excelcior likes to be dry dry. Time isn't really the be all and end all factor - r.h., temperature and airflow are the main things that matter and of course the woods thickness whilst drying.
Another 'problem' with ash is its strength in tension and only so so compression resistance. Trapping the limb eg. making the limbs cross section a trapezoid (narrower back) will take some laod off the belly.
Heat treating is another way to achieve a more optimal balance between compression resistance and stretch resistance. You can safely do both with ash.
Your set is happening where the limb is over strained/bending too much. Watching the set carefully is important. Set is the wood speaking to you!

GreenWood - adding glass to the back of a wood bow will give you the 4" set you mentioned. Glass is about 40 times stiffer than wood. The glass resistance to stretching forces the belly to semi collapse. It has to give somewhere. This is why glass bows are always made with glass on the belly too.  Glass back and belly gives you an optimal balance. The core is really there just to space the glass lams the correct distance apart for the draw weight you want.

[rcoen2]

Thanks everyone that's offering thoughts.  I ended up going for some induced reflex + heat treating with a heat gun.  I did that this morning so I'm going to give it ample time (like a week or so) before unclamping it and seeing how the reflex took.  Then I suppose I'll move forward with the tillering again, starting with getting some more bend in the inner limbs as suggested.

Actually, Is it unnecessary to leave it clamped that long, while the moisture comes back in to the bow?  I know its important to wait before bending the wood again, but I do I need to wait with the clamps too?

[Green Wood]

Backing with epoxy resin saturated fiberglass cloth is the most common form of backing in use today and is far easier to do than backing with another wood such as bamboo.  I doubt that my builds needed backing, but if you have ever had a bow explode in your hand or even on the tillering rack, you give great thought to backing that holds the pieces together should you have such a massive failure.

With fiberglass cloth and epoxy resin, it won't prevent a poor build from failing, but epoxy is very strong and flexible and will work like the membrain of safety glass in your windshield or sliding glass windows to help prevent you from getting seriously injured.  I have had two red oak bows made with big box harware store wood littlery explode due to what I think was over cooking in a kiln to dry the wood fast.  One of the breaks embedded a large chunk of wood into my arm.  I thus don't use kiln dried lumber any more and I continually err on the side of caution and back all my bows with cloth/epoxy. Don't use polyester resin because it is brittle. High quality epoxy is very hard to break. It just bends and bends some more.

[SLIMBOB]

All true, but we are building bows from natural materials. Yes, some will break, but the magic is in finishing one out of natural materials that holds together, and rivals the glass bows. There is a beauty in both, but FG is just not in the mix here.

[SLIMBOB]

No harm in leaving it clamped. Since you are going to let it dry for a bit, might as well leave it clamped. I think you will see a marked change in the compression strength, worth the trouble.

[rcoen2]

Hey Greenwood, thanks for sharing your thoughts and experience.  I'm not personally interested in doing FB backing. I'm much more drawn to self bows and if backing using rawhide or sinew.  So I'd prefer if we kept the FB discussion off of this thread.

[RyanY]

I am thinking the bow set is just a characteristic of the wood.

Don’t start blaming the wood. Next thing you know you’ll be saying “Osage is king!” 

[SLIMBOB]

No need. We ALL know that.

[rcoen2]

IMG_3342 by Ryder Coen, on Flickr

I'm guessing you can't tell if a dry heat treatment was thorough enough for the suggested reflex to hold by color alone.. but I'm wondering if at a glance it seems like I under did it.  Some of the pictures I have seen of other's heat treatments are quite dark. I'm not sure how much different types of wood express the color differently too.  I think I was a little cautious on not wanting to push it too far, so this is what I got.  Thoughts? 

[RyanY]

No way of knowing just on the color as that’s just on the surface. Some guys heat with minimal color and some get it quite dark with similar results. What was your process in terms of heat gun setting, distance from the belly and how long it took?

[bownarra]

Backing with epoxy resin saturated fiberglass cloth is the most common form of backing in use today and is far easier to do than backing with another wood such as bamboo.  I doubt that my builds needed backing, but if you have ever had a bow explode in your hand or even on the tillering rack, you give great thought to backing that holds the pieces together should you have such a massive failure.

With fiberglass cloth and epoxy resin, it won't prevent a poor build from failing, but epoxy is very strong and flexible and will work like the membrain of safety glass in your windshield or sliding glass windows to help prevent you from getting seriously injured.  I have had two red oak bows made with big box harware store wood littlery explode due to what I think was over cooking in a kiln to dry the wood fast.  One of the breaks embedded a large chunk of wood into my arm.  I thus don't use kiln dried lumber any more and I continually err on the side of caution and back all my bows with cloth/epoxy. Don't use polyester resin because it is brittle. High quality epoxy is very hard to break. It just bends and bends some more.

The bow won't break if you select your board well.......as I said and explained above backing a wood bow with glass cloth is a very bad idea.....Compounding poor wood choice with a poor backing choice isn't going to make you a good bow.

[Digital Caveman]

Sinew and glue, or decent rawhide, is also 'indestructible' and won't overpower wood.

[SLIMBOB]

Thought experiment. Attach a steel band onto the back of the bow. When the limb bends, either the back stretches, the belly compresses, or both. With the steel band on the back, the back will not stretch, so the belly does all the work. That is a recipe for disaster. FG will overpower the wood belly with about the same results.