sinew curing question

[hedgeapple]

Would putting a newly sinew back bow in a hot box speed up the curing process or would warm the natural drying process.  I have a pretty good hot box with 2 light bulbs sockets for heat and I have an intake air fan on the bottom and vents on the top.  I can control heat, air flow and moisture content if I need to at more moisture to the box to keep it from drying too fast.

Basically, I would like to do 3 runs of sinew and have it cured up in 3 weeks or less instead of 3 month.  Is it possible?
Dave

[mikekeswick]

It's certainly possible. Make sure each layer is thin (like 1mm cured thickness) and take it slowly intially then gradually speed up the drying by increasing the temp and or lowering humidity. If you go too fast to start with the sinew will essentially check when the surface dries quicker than the underneath layers.

[hedgeapple]

Thanks Mike.  I will let each layer air dry for a day, maybe 2 before I put it in the box.

[loefflerchuck]

If you are using real hide glue 3 weeks is more that enough time. Sometimes I start shooting in 10 days. The sinew will continue to dry and draw the bow up. I have found the same outcome after 6 months after letting the sinew dry for 2 weeks or 2 months.

[hedgeapple]

Thanks loefflerchuck,  I will be using real hide glue made from deer raw hide scraps.

[gutpile]

if its worth the time to sinew its worth the time to let it cure properly..bottom line... 3 weeks min..no need to hot box it either...I gently weight mine in a reflex position between two chairs and tie a weight on handle and give 3 weeks (min) in a air controlled environment..ac...gut

[PEARL DRUMS]

3 weeks is one week longer than I wait for mine. I keep it on my deck sunning in the evening and in our 50% humidity house during the day. I have no complaints about my sinewed bows.

[osage outlaw]

I thought about taking a freshly sinewed bow to work and sitting it next to a 1000 hp electric motor.  It puts off a large amount of warm air from the vents. 
The bow would probably never smell the same though 

[hedgeapple]

Thanks guys for all your advice.

I tend to over-think and over engineer most all my projects.  It's dry as the desert here in KY right now, but that could change to our normal, needing-gills-to breath humidity at any time.

I little background to my question: I have a 50" osage that I plan to sinew and hopefully persuade to be a 45# at 26 out of.  I admit that's pushing my limits as a bowyer WAY beyond my skill level.  I would be happy with 45 @ 24.  I do plan to at least flip the tips.  A slight gull wing design would be awesome. Half the handle/limb is already there.  I just need to heat, bend the other half.

Hey if Gordan and others can make them, then I can probably break'um. 

[gstoneberg]

Dave, it's osage...you can do 45@24 without sinew easily if it bends through the handle.  If you sinew back and have a stiff handle it should be no problem at all as well.  In fact, I don't think 26" is a problem at all.  You are going to notice a difference in the way it shoots when it's humid though.  My sinew backed shorty is a dog right now, I don't even shoot it.  Come fall though...

I have done 3 courses of sinew at one time and shot the bow in 2 weeks.  The longer you wait the better it is though.  If you use a hot box, I'm very interested in hearing your outcome.

Good luck,
George

[Pat B]

Too much heat will re-liquify the hide glue. Use low heat(100deg or less) and lots of air movement to help the sinew cure.

[hedgeapple]

Thanks George for the vote of confidence.

Pat, I didn't think about the hide glue re-liquifying, but I was going to keep it below 100 degrees.  I have a little floor heater, something similar to what Pappy has in his hot box.  It has a "fan only" setting.  I plan to just use the fan.  I have a vent at the top of the box, also.  My hot box stand verticle.

[BowEd]

The 60" hickory I just put 3 full courses of sinew on here will set on top of my dehumidifier here at 45% humidity with a fan blowing across it too for at least 2 months.It has 90 to 100 thousands thick horn full width on the belly though which might slow the drying down a bit.Letting your bow cool completely before bending it would be a must from your hotbox not going over 100 degrees either with a lot of air movement.I think a person has to remember that the sizing and sinew kind of forms a barrier restricting moisture to escape from the wood itself.Only leaving moistire to escape from the wood through the belly.This ones a first time experiment reverse bracing it to 8" reflex.I hav'nt done that many sinew backed bows and am going to play it on the side of caution myself.I just grabbed another roughed out bow and began working on that to floor tiller.It's ironwood with an exposed hollow knot 3/8" round midlimb but not clean through the limb on the belly in the center of limb.On the back it has a convex furrow 1/4" wide running 4" long above the knot on the other side.You guys think that might be another candidate for sinewing,combed flax,super glue,or something in that order.Kind of another challenge or experiment for me.It's beautiful at this stage with 2 and 3/4" natural even reflex 64" inches long.Both these bows are destined to be in the 55 pound range at 28".Good luck with your bow.It sounds like a winner.

[Marc St Louis]

One wonders why all the horn bowyers let their bows season for a year.  They must like to waste their time

[loefflerchuck]

Most traditional horn bowers use fish air bladder glue. This takes longer to cure than hide glue. A year may be overkill though.