Author Topic: When is it too hot in temps for sinew backed  (Read 17450 times)

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Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #45 on: February 08, 2021, 11:10:28 am »
Can't say I've ever seen Tom D post anything of his own making.  It's always quotes from other sources or pics from online

That's usually what educated people do. They post material that was authored by experts rather than whatever they think they "know". It's called secondary research.

 Educated people know the C and F difference though.


Ok, please show me where I have erred.

 When you used  the  60C  quote to show "low" heat being used to bend the Scythian replica.  Then replaced it with F.


Please show me exactly where I did this with a copied and pasted quote.

Offline PatM

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Re: When is it too hot in temps for sinew backed
« Reply #46 on: February 08, 2021, 11:28:41 am »
The article by Adam says 60C which is 140f and you then said :" Adam Karpowicz tried to bend a glued up Scythian bow and made sure, using an electric thermometer, that the surface  temperature never exceeded 60⁰F. "

  You then switch back to 60C but your general thought seems to be that 105 f is the danger point when  Adam and others have showed you that the actual danger zone is probably 135-150f  maybe even higher if no stress is induced on the glue at that temp.

Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #47 on: February 08, 2021, 11:44:36 am »
The article by Adam says 60C which is 140f and you then said :" Adam Karpowicz tried to bend a glued up Scythian bow and made sure, using an electric thermometer, that the surface  temperature never exceeded 60⁰F. "

  You then switch back to 60C but your general thought seems to be that 105 f is the danger point when  Adam and others have showed you that the actual danger zone is probably 135-150f  maybe even higher if no stress is induced on the glue at that temp.

What you quoted is clearly a typo and not a misunderstanding of farenheit and celsius scales.


150⁰f is higher than 60⁰c, which is 140⁰f.

All we can infer is that Adam never let the surface of his bow get above 140⁰f, and a joint still failed.

Furthermore, see the video I posted by JWB. He implores his customers to keep his bows at least 1.5 feet from. a hotplate on setting 4, which is low heat. This would imply temperatures of around 105⁰f, and for very routine de-twisting work that doesn't put a lot of stress on the bow.


You are a madman playing with fire if you think it's safe to expose glue to hotter temperatures than that. There's absolutely no credible sources saying thaf this is OK. The best thing to do is to assume temperatures of 105-110⁰f. Which are clearly all that is necessary for just about anything.


125-139⁰f temperatures upset glue bonds. We have evidence from Adam for that. If the joint failed the glue was softened, period.


Offline PatM

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Re: When is it too hot in temps for sinew backed
« Reply #48 on: February 08, 2021, 11:50:09 am »
The joint in Adam's bow "slipped" which likely means creeping as hide  glue enters the equivalent of  glass transition temp in epoxy.

 But you are wrong.  Clearly the heat tolerance is way higher than you think it is and experienced guys are telling you this.

 The video by JWB does not really imply a specific temp but no doubt over 105 is needed to get things moving enough.

Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #49 on: February 08, 2021, 11:59:22 am »
The joint in Adam's bow "slipped" which likely means creeping as hide  glue enters the equivalent of  glass transition temp in epoxy.

 But you are wrong.  Clearly the heat tolerance is way higher than you think it is and experienced guys are telling you this.

 The video by JWB does not really imply a specific temp but no doubt over 105 is needed to get things moving enough.


Lol, gibberish.

When Adam bent the limb, one of the three laminated pieces literally moved upward by a milimeter or so, creating a measureable "step". That's a bond failure.  If it hadn't been sinew wrapped it probably would have separated.

And that's with less than 140⁰f temperature, horizontally transfered. The direction of heat transfer also matters. I bet some of you were putting your bows directly above +150⁰f heat sources. Brutal.


Just turn the stove on to cone 4 and measure the temp 1.5 feet from the coil. It's not hot. These materials are super sensitive to temperature change.

Offline PatM

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Re: When is it too hot in temps for sinew backed
« Reply #50 on: February 08, 2021, 12:03:01 pm »
    You were wrong Tom.  Stay in your lane.

Offline PatM

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Re: When is it too hot in temps for sinew backed
« Reply #51 on: February 08, 2021, 12:22:00 pm »
Quote from: Tom Dulaney link=topic=69664.msg977830#msg977830  I bet some of you were putting your bows directly above +150⁰f heat sources. Brutal.

[/quote

 Yep, fire is hotter than that.

Offline RyanY

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Re: When is it too hot in temps for sinew backed
« Reply #52 on: February 08, 2021, 12:30:43 pm »
Tom, when every thread you post in has a consensus of people saying you are wrong maybe it's time to re-evaluate why that is...

Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #53 on: February 08, 2021, 12:59:47 pm »
Tom, when every thread you post in has a consensus of people saying you are wrong maybe it's time to re-evaluate why that is...

That's not correct. Typically, every thread I make has the same simpletons crying about me while 1 or 2 experts verify everything I said. The simpletons then scram back to the darkness and never rear their ugly heads again until the next thread.

 That the herd doesn't like it when their superstitions are questioned isn't news to me. The herd is always wrong.


Address the subject matter specifically or GTFO of the thread.

Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #54 on: February 08, 2021, 01:00:12 pm »
    You were wrong Tom.  Stay in your lane.

PatM lied, bows died.

Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #55 on: February 08, 2021, 01:05:10 pm »
Quote from: Tom Dulaney link=topic=69664.msg977830#msg977830  I bet some of you were putting your bows directly above +150⁰f heat sources. Brutal.

[/quote

 Yep, fire is hotter than that.

Word to the noobies: you should never, ever put a bow near an unstable heat source like fire. Even literal cavemen like Ishi knew this.

Offline Digital Caveman

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Re: When is it too hot in temps for sinew backed
« Reply #56 on: February 08, 2021, 01:08:12 pm »
Can't say I've ever seen Tom D post anything of his own making.  It's always quotes from other sources or pics from online

That's usually what educated people do. They post material that was authored by experts rather than whatever they think they "know". It's called secondary research.

You're talking to a number of expert right now.
God Bless America

Offline Digital Caveman

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  • formerly Tradcraftsman, formerly Yooper Bowyer
Re: When is it too hot in temps for sinew backed
« Reply #57 on: February 08, 2021, 01:08:31 pm »
Why are we still arguing with this guy, who cares what he thinks?  'The herd' will never be completely correct, but it has done quite well for a long time without this character.

Bownarra, Marc St. Louis, you both have extensive first hand experience with sinew backed bows.  At what temperature ferenhite have you found sinew to start losing its strength?
God Bless America

Offline Tom Dulaney

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Re: When is it too hot in temps for sinew backed
« Reply #58 on: February 08, 2021, 01:41:33 pm »
Why are we still arguing with this guy, who cares what he thinks?  'The herd' will never be completely correct, but it has done quite well for a long time without this character


Not really. Almost every other thread on this forum is "my bow cracked, my bow popped, the fibers in my bow are magnetically opposed to one another"

It's not noobs either, like PatM tried to cope with. There are videos all over YouTube of the "expert" bows detonating.


That's what happens when you treat your bows like a beef skewer.

Offline PatM

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Re: When is it too hot in temps for sinew backed
« Reply #59 on: February 08, 2021, 01:59:31 pm »
I haven't broken a sinew backed bow or a heat treated one.  Sounds like you've made neither.

 Pretty sure the mods are hovering  their finger over the red button next to your name currently.