the effects of humidity on draw weight (updated 10/4)

[The Burnt Hill Archer]

i tillered a hickory bow this week. it came out to 59#@29.5". its already been exercised about 700 times on the tree, shot about 200 arrows through it,  and I sweated in the tiller twice for about 9 hours each time. i heat treated the belly 2 times, and induced 2.5" of reflex. no chryssals at all,  the set is still close to nil on the upper limb, and just a bit over 1" on the lower (because of a deflexed but that just wouldn't work out), and which tells me that is was definitely dry enough. not to mention that it just felt about perfect. i did the final sanding today, which wasn't a whole lot because i like to keep them pretty clean through the whole tillering process. the most it should have dropped was 1 maybe 2 lbs.

 
i put it back on the tree this evening and it said 54#@29.5". a whole 5 pounds. i started to freak out, but then i thought of the weather. its been misty and foggy all day long with 92% humidity, and i had it out on my porch sanding it today, and figured it must have gained a whole heap of moisture.

right now Ive got it where i keep all my bows when I'm not working on them, over the kitchen cabinets. its pretty dry and warm up there, so i think ill let it sit for a day or two and see what happens.

i guess the whole point of this thread is just to point out just how big a part moisture has on final draw weight, and how closely it should be watched through the building process. i never really thought allot about it before, i knew it played a part, i just didn't realize just how much it actually effected the final product.

ill try to get it finished up later this week and ill post an update on the drawweight and of course pictures.

Phil

[sailordad]

yup that will happen


but ive got two words for ya   "hot box

it can help alleviate those tpe of headaches

                                                                         peace,
                                                                                tim

[JackCrafty]

I've heard that heat tempering helps reduce moisture absorption in hickory...so your bow might have dropped even more # if you hadn't heat treated it.  Personally, I've had to heat treat the crap out of my hickory plains bow....

[mullet]

  Welcome to the world of whitewood in the land of high humidity.   Yeller' wood rules!

[Sidewinder]

I'm with Eddie on this one. Makes a heckuva case for yeller wood don't it. Like I said on PP I'm done with Hickory as long as I live in Kansas. My Virgin Hickory lost about 15# since spring and I guarantee it was because of moisture transpiration.  How does elm and mulberry hold up in humidity, anyone know?  Danny

[mullet]

  Hard to tell the difference between Mulberry and Osage. They're cousins.

[JackCrafty]

Mulberry is more like osage's little brat brother.....

IMO, mulberry performs a little better than hickory in humid weather, but not much.  The elm I've tried performs about the same as mulberry but feels more like osage in terms of overall characteristics.  In either case, neither elm nor mulberry can compare to osage.  Only ipe performs better than osage in humid weather.

[PeteC]

Phil, I've been experiencing a similar problem with an eastern HHB flat bow.I can't seem to dry it by normal air drying.I've never built a hot box,since I work primarily with osage,but I may have to just to be able to finish these whitewood bows .I had it tillered 50# @ 26" ,and had shot about a hundred arrows through it.Then,we started getting some rain,not a lot,just a couple of showers.The next time I got out and shot it I could feel the tiller change.I put it on the tree,and not only diid the tiller change,but the weight had fallen to 36#.After fixing the tiller,then allowing it to dry a few weeks,I tried it again.The humidity had dropped,so I shot a number of arrows,then checked tiller and weight.This time,it stayed in tiller,and drew 45#.I'm going to heat treat the belly,(in reflex),then check tiller.and finish it.I hope to get the 50# back,but we'll see.I'll post it when it's done.Hope yours works out.  God Bless

[mullet]

  The Mulberry growing down here in Florida does not seem like the same stuff I got from N.C. It is denser, very heavy. The growth rings are very large and it turns dark brown like Osage.

[mullet]

  Pete, I've had to toast the crap out of white wood bows, seal them and ship'em before the tiller changed. I keep most of the whitewood bow, almost finished , projects in the "gun, bow room" in the air condition. It usually runs 24/7 at least 10 months out of the year. It will dry some wood out quick.

[JackCrafty]

Eddie, how much of that Florida mulberry you got growing down there?  Any chance you are willing to part with some of it?  The mulberry I get around here is a lot like ash.

[PeteC]

That's a good idea Eddie.I'll bring it the house for a few days,then finish it.  Thanks,  God Bless

[Hickoryswitch]

It's been really dry here and my dogwood bow picked up 6 pounds. It picked it up real quick. I noticed it was getting harder to pull so i put it on the scale it went from 49#s to 55. Wondered why I was shootin high. Thats my excuse and I'm sticking to it!!

[The Burnt Hill Archer]

good call on the hot box. ive got one its just burried in the garage, im am going to be implementing it asap.

i kept the bow in my bathroom overnight with a small space heater going, took it out this afternoon and put it back on the tree. it jumped back up to 56#@29.5". i also kept track of the humidity throughout the day. this morning it was 86%. then at 2:30 pm it was down to 58%. i didnt realize that it fluctuated so much, but there are quite a fiew things ive been realizing lately.

yup im deffinately going to try some osage just as soon as i get my last stave of hickory used up. im confident enough in my tillering now that i feel comfortable with forking out some cash for a stave, and as soon as i can find one im gonna do just that. it doesnt grow anywhere near where i can get it easily so im kinda stuck untill i find someone who wants to part with some.

ive got a friend comming back from nebraska in about a week, he said he might be able to find me something, but we'll see.

Phil

[Gordon]

I seem to have the opposite problem. I do much of my bow building in the winter months, and in the Pacific NW that means high humidity. By the time summer rolls around I've had some of my bows gain as much as 10 pounds! One of these days I'm going to have to breakdown and build a hotbox.