Author Topic: Bang!/Crunch: What I've learned about Chokecherry so far.  (Read 9556 times)

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Offline zenmonkeyman

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Bang!/Crunch: What I've learned about Chokecherry so far.
« on: January 28, 2010, 04:12:56 pm »
Chokecherry selfbow #2:  BANG!!







If you don't heat treat it, it takes lots of set and chrysalls.

If you heat treat it, it fails in tension

Next time:  Wider, or longer, or both.  Probably wider.   Heat treated, then backed.  I'm taking my latest kindling over to a buddy who has a good moisture meter; there's a good chance this stave was over dry.  Thanks for looking!  Suggestions/comments welcomed/requested.

Garett
If the ppl ever allow private banks to control their currency, 1st by inflation, then by deflation, the banks & corporations that will grow up around (these banks) will deprive the ppl of all property until their children wake up homeless on the continent their fathers conquered. Thomas Jefferson

half eye

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #1 on: January 28, 2010, 04:29:56 pm »
Hey Zen,
       I dont build any stave bows...but in that second picture (with the middle sliver sticking out the side.....it looks like there was a bunch of side pressure, or is that just the way it looks? Does the grain take a whoopy-do at that spot?....just wondering. Sorry about the bow :-[
       Blew up my share and it aint too much fun at all.
half eye ;)

Offline mox1968

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #2 on: January 28, 2010, 04:33:44 pm »
hey zen unlucky was looking good too!!just gotta get on to the next stave huh?

Offline Badger

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #3 on: January 28, 2010, 05:52:22 pm »
Zen, give us the gory details, how far was it drawn? how hard were you pulling when it broke? how much set had it taken. Once a bow starts to take set it is time to start taking weight off the bow, if you pull harder it will eithr brake or just take more set.

Offline Stoker

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #4 on: January 28, 2010, 07:26:14 pm »
Ouch..What was it pulling at time time.Did you scrape the outer growth ring?I've blown up a few chokecherry
I starting to think if you want good poundage gonna have to back.
Thanks Leroy
Bacon is food DUCT tape - Cipriano

Offline zenmonkeyman

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #5 on: January 28, 2010, 08:09:14 pm »
Thanks for the responses, guys!

Half eye, there's no whoop te doo in that spot, that sliver is just one of the several separated laminations that ended up outside after the calamity befell it.  Did I jus say calamity?  ???  ;)

Thanks, Mox, I thought it was looking good too.  I had a little evening-up to do on the opposite limb, but this one was impressing me (up until the bang) with its nice circular tiller.

Badger, I was at about 50# and 28".  There wasn't much set up until that point, I'd lost maybe an inch off my reflex near the tips.

Leroy, I think I'll be throwing every precaution I've ever heard of into the next one.  I'd thought of backing this one, but I like the natural knotty look.  There weren't any nicks, either, maybe a few dents from clamping not very carefully, but there's no evidence of a dent where she blew.

I just got back from my buddy's place.  We set his moisture reader at .78 (since that's what I got by dunking the wood earlier).  0.0 it said.  We thought it was just not reading the wood, like maybe we weren't finding a flat enough spot for it to register.  Finally I set the SG down a bit, to .72, and it read something like 2% moisture content.  I thought "this can't be right, ok what if I erred in my measurement, AND the wood I tested had some moisture in it when I tested it.  I set it down to .65, then .60.  The highest moisture content reading I got was about 5%.  And there's no way the specific gravity of the wood is that low.  So obviously, the wood was too dry.

Maybe it would have failed anyways, maybe not.  But I weighed the stave immediately after heat treating so I could monitor the re-hydration process, and 3 days later it had LOST moisture if anything.  Obviously this dry prairie winter air prevented rehydration.

Once again I asked Santa for a bow, and once again I got socks.  ::)

Oh well, this setback coincides with another trip home to the farm, there are many potential bows still standing!  Maybe I'll be optimistic and cut some arrows too...
If the ppl ever allow private banks to control their currency, 1st by inflation, then by deflation, the banks & corporations that will grow up around (these banks) will deprive the ppl of all property until their children wake up homeless on the continent their fathers conquered. Thomas Jefferson

Offline Badger

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #6 on: January 29, 2010, 04:17:14 am »
Zen, do you have any idea how much the bow weighed when it broke ( mass weight) Steve

Offline Marc St Louis

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #7 on: January 29, 2010, 11:12:38 am »
Looks like a typical tension failure.  How dry is it where you are?
Home of heat-treating, Corbeil, On.  Canada

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Offline zenmonkeyman

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #8 on: January 29, 2010, 02:25:49 pm »
Steve, it was 17.3 oz, all the wood was working, flexing nicely in the handle.  It was basically at its final weight other than minor tweaking.

Marc, it's very dry here in the winter.  My wife is always after me to put lotion on my hands, the dog is itchy bordering on scabby, and shampoo companies from around the world test their latest dandruff-battling concoctions on the local populace.  We have a humidifier in the apartment that for the first time I regret not filling with water...
If the ppl ever allow private banks to control their currency, 1st by inflation, then by deflation, the banks & corporations that will grow up around (these banks) will deprive the ppl of all property until their children wake up homeless on the continent their fathers conquered. Thomas Jefferson

Offline Badger

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #9 on: January 29, 2010, 02:37:43 pm »
  Mass was way too low, I think like Mark it failed in tension. You can use the mass formula to figure of the wood is too dry also. If the wood appears to be very strong for it's mass, inother words it is not taking set but still strong inspite of being low in mass then it is almost certainly too dry. Bow could have proably been about 20% wider. Steve

Offline zenmonkeyman

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #10 on: January 29, 2010, 02:52:15 pm »
Yes, it's obvious the bow failed in tension.  That's a good tip about using the mass formula to monitor dryness, working the formula backwards sort of.  I should reread that thread in which you describe the no-set tillering again.  Any chance of getting that in the archive/read-only section?  The next one will definitely be wider!  Thanks again.
If the ppl ever allow private banks to control their currency, 1st by inflation, then by deflation, the banks & corporations that will grow up around (these banks) will deprive the ppl of all property until their children wake up homeless on the continent their fathers conquered. Thomas Jefferson

Offline DanaM

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #11 on: January 29, 2010, 03:20:55 pm »
zen PM Justin and request that it be included in the Arcieve section.
"Prosperity is a way of living and thinking, and not just money or things. Poverty is a way of living and thinking, and not just a lack of money or things."

Manistique, MI

Offline Stoker

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #12 on: January 29, 2010, 05:25:05 pm »
Hi Zen.. Just a thought,I was thinking about bending and straiting with heat.Most of the chokecherry we have around here is fairly
fine grained..Did you use dry heat? If the stave you had was to dry..Would it be better to use steam? I'd like to back one with boo
I think it would be a rocket and hit like a train..cut, rough out ,dry on form, laminate it might take a while but worth the effort.
so many trees so little time..
Thanks Leroy
Bacon is food DUCT tape - Cipriano

Offline loefflerchuck

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #13 on: January 29, 2010, 08:37:35 pm »
A long time ago I made a chokecherry self bow and eventualy it looked like that. With a sinew backing though chokecherry will last forever.

Offline sailordad

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Re: Bang!/Crunch: What I've learned about Chokecherry so far.
« Reply #14 on: January 29, 2010, 10:52:14 pm »
A long time ago I made a chokecherry self bow and eventualy it looked like that. With a sinew backing though chokecherry will last forever.

thats good to know
i just got a nice chokecherry stave,and some nice sinew
any suggestionss on demensions?
i would like a 26" draw,50 ish lbs.
i always wanted a harley,untill it became the "thing to ride"
i ride because i love to,not to be part of the crowd