Primitive Archer
Main Discussion Area => Bows => Topic started by: mmattockx on October 17, 2020, 11:57:12 pm
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Has anybody done any experiments to quantify the effects that heat treating has on different woods? I'm thinking of how much stiffer and stronger the wood gets after the heat treatment.
Thanks,
Mark
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No but the rule of thumb is lighter, less dense woods respond the best. Ash, elm, elder, locust etc. As the wood gets denser, closer to 1.0s.g. there are fewer air spaces in there so little benfit to gain. Ipe, greenheart etc even if they don't check in half show very little difference after heat treating.
The more a flat limb goes concave the better i've found the results to be.
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I did some time/temp experiments for birch as a bow wood. Heat treating is common in EU for eco friendly preservative.
http://www.thermotreatedwood.com/Researches/heattreatmenteurope.pdf (http://www.thermotreatedwood.com/Researches/heattreatmenteurope.pdf)
see section 8. LITERATURE
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No but the rule of thumb is lighter, less dense woods respond the best. Ash, elm, elder, locust etc. As the wood gets denser, closer to 1.0s.g. there are fewer air spaces in there so little benfit to gain. Ipe, greenheart etc even if they don't check in half show very little difference after heat treating.
The more a flat limb goes concave the better i've found the results to be.
I don't know if it's the only exception to the rule but Ocean Spray responds very well to heat treating and it has an SG of 1.2. I haven't heat treated many dense woods, actually just OS and Black Locust so maybe I don't have a very accurate view of "responds well".
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Not sure I buy the idea that less dense/lighter woods respond better. They might respond well, but more dense woods can respond well too. Hickory comes to mind. Responds very well to heat treating. Eastern hophornbeam, also a very dense wood, likewise responds very well.
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Seems to me that woods which tend to take a lot of set benefit the most and those that break before taking any set don’t benefit at all. I believe heat treating increases brittleness in tension for the benefit of better performance under compression. That’s a worthwhile trade-off for woods like hickory, elm, or hhb (the so called tension strong woods) but not ipe or ERC, which already excel in compression.
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Have you read Marc St Louis' chapter in TBBIV on heat treating? Marc popularized the idea of heat treating bow wood so that would be a good place to start. I think the whitewoods would be best affected by heat treating but it also works on other woods like osage. Black locust does benefit from heat treating.
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seems like quite a few of the respondents in this thread discussed this same topic 9 years ago here
https://www.tapatalk.com/groups/paleoplanet69529/heat-treating-how-and-why-does-it-work-so-well-t43668.html (https://www.tapatalk.com/groups/paleoplanet69529/heat-treating-how-and-why-does-it-work-so-well-t43668.html)
any new thoughts? A test to quantify any density changes and dimensional changes/ shrinkage would be interesting.
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Have you read Marc St Louis' chapter in TBBIV on heat treating?
If this was directed at me, yes I have read that chapter. I was interested to know if anybody has measured the changes in stiffness and strength from heat treating. I guess I will do some testing and see how it goes. I will post results when I have something useful.
seems like quite a few of the respondents in this thread discussed this same topic 9 years ago here
https://www.tapatalk.com/groups/paleoplanet69529/heat-treating-how-and-why-does-it-work-so-well-t43668.html (https://www.tapatalk.com/groups/paleoplanet69529/heat-treating-how-and-why-does-it-work-so-well-t43668.html)
any new thoughts? A test to quantify any density changes and dimensional changes/ shrinkage would be interesting.
Thanks for the link, I will have a read through that thread.
Mark
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Hard maple, 66 inch long, 2 inch wide. After heat treatment, 1 inch set reversed to steady 1 inch reflex, ~5 pounds gain (will measure tonight). Heat works well with maple. No hard numbers about the compression strength gain etc, but take it as general experience, in line with many others.
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Hard maple, 66 inch long, 2 inch wide. After heat treatment, 1 inch set reversed to steady 1 inch reflex, ~5 pounds gain (will measure tonight). Heat works well with maple. No hard numbers about the compression strength gain etc, but take it as general experience, in line with many others.
poundage gain might be a good way to quantify heat treating. What is the draw weight before/after?
a pic of that bow at full draw would be nice to see, Jurinko.