Primitive Archer
Main Discussion Area => Bows => Topic started by: sapling bowyer on February 05, 2016, 01:28:37 pm
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The title says it all. Which one is better?
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Depends on the Bow and the Wood...
Elm Warbow... use both :)
I don't heat treat as routine... to me it's the Ace up my sleeve if I need to find a few pounds or stiffen up a limb or get some reflex to hold in.
It's about having all the tools at your disposal and using them wisely.
Del
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What is trapping?
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Not really an either or type situation, two different processes. The only bows I slightly trap are English longbows. Most selfbows are crowned which is naturally trapped.
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nsherve,
Trapping refers to making a trapazoidal shape. "Trap the back" could be said "trapezoid the back". In other words, if the back is more narrow than the belly, then the bow limb cross section is shaped like a trapezoid.
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nsherve,
Trapping is taking a bow with a rectangular cross-section and shaving the corners off the back of the bow to give it a trapezoidal cross-section(hence the name). It makes the back narrower than the belly.
As i understand it, they both serve a similar purpose....evening the stresses between the belly and back of woods that are tension strong and compression weak. Trapping essentially reduces mass without reducing draw weight (or not by much) and allowing the belly to have more wood to handle compression. Tempering is kind of opposite in a way.... increasing compression strength of belly which also adds to the draw weight without adding mass. Seems like somebody on PA (who had a lot more experience than me with both) felt they both accomplish the same purpose. In a way i guess they do, but i can see some designs being more favorable to one or the other. I've used both, but mostly tempering.
Seems like this discussion may have been had before ;)
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You can also trap belly to back if necessary.
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If you are making a backed bow, trapping is typically your only option. I know some guys have done belly heat treating on backed bows but I suspect the type of glue used for the backing has to be considered.
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I'm very much in favor of trapping. It can be controlled quite precisely, corrected in both directions. Plus, it doesnt leave the ugly blotty burnt pattern on the belly. ??? Just my taste, though. And I should also say that I'm not very concerned about getting the last 3 % of performance out of my bow, so this is not what makes my decision.
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... it doesnt leave the ugly blotty burnt pattern on the belly. ..
If you clamp side cheeks to the bow while heat treating, it spreads the heat and vastylr reduces the blotchy pattern and also speeds up the process and helps prevent heat getting to the back.
Del
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Del, What are side cheeks?
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Del, What are side cheeks?
https://www.youtube.com/watch?v=kM1_A2A0_TI (https://www.youtube.com/watch?v=kM1_A2A0_TI)
There ya go... :)
Note in the video I have a fish tail nozzle on the hot airgun, it all helps to get the heat where you want it.
Del
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Thanks Del, I'll do so if I ever get to heat treat a bow!
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Cool technique Del, I also realized that you were Derek Hutchison and I saw some of your hazel bows on your google site. Cool bows! Planning to make some out of hazel myself
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I have plenty of wide flat staves, so I do both. Cant say for sure how much trapping has helped, but even though it is so time consuming, I would never not heat treat a bow again.
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trapping won't add weight or reflex to a stave
heat treating will,, they are two different applications to achieve different end results,, :)
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Will heat treating add reflex automatically or do we have to bend it
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heat treating can add weight automatically,, but the stave or bow would need to be in a reflex position when heated to add the reflex,,
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trapping won't add weight or reflex to a stave
heat treating will,, they are two different applications to achieve different end results,, :)
Trapping helps tension strong wood from collapsing in compression......
DBar
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trapping won't add weight or reflex to a stave
heat treating will,, they are two different applications to achieve different end results,, :)
If you plan ahead as you should with trapping.... you can have the same effect. With tension strong woods, you can make a faster bow for the mass without overstressing belly wood. Tempering can be a quick "fix" for coming under weight, but planning ahead with trapping can yield an equal cast bow. Not to mention you can heat in reflex without tempering, and still trap the bow, or temper, reflex, and trap if you want to I suppose.
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trapping won't add weight or reflex to a stave
heat treating will,, they are two different applications to achieve different end results,, :)
Trapping helps tension strong wood from collapsing in compression......
DBar
More accurate to say it helps compression weak wood from collapsing.
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planning ahead with trapping can yield an equal cast bow.
so either technique gives about the same performance gains.....
just how much improvement over untrapped and untempered can one expect?
shouldn't a self bow, a trapped self bow, and a tempered self bow, each with the same draw weight, give the same cast?
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"It's about having all the tools at your disposal and using them wisely."very true Dell."You can also trap belly to back if necessary." so PatB, if i iused a crowned stave to make a bow and lensticular tillered the belly would you say its trapped belly
to back?
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planning ahead with trapping can yield an equal cast bow.
so either technique gives about the same performance gains.....
just how much improvement over untrapped and untempered can one expect?
shouldn't a self bow, a trapped self bow, and a tempered self bow, each with the same draw weight, give the same cast?
No sir. That's the same as saying all 50# bows have the same cast. That just simply isn't the case. The draw weight is just that.... the force it takes to draw the string back. Cast has to do primarily with the speed with which the limbs return forward which directly impacts arrow speed. Lighter outer limbs, for example, will return much faster than bows with heavier outer limbs. Trapping and tempering bith have to do with compensating for weak compressive strength in certain woods, tbey have the added benefit of higher performance. How much is gained? A little or a lot, depending on the design, the magnitude of difference in tensile vs compressive strength, and of course the skill of the bowyer.
Do an experiment... make all three and compare. Elm is a good wood for this experiment. While ur at it, go on and make a fourth tempered and trapped!
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What I think is that when heat treating or trapping, the main goal is reached on both techniques as the compression is made stronger to match tension. When it comes to decide which one gives better cast, It depends and the only way to find out is to try. When we heat treat poundage gained per mass is higher so less mass is needed to get it in the desired poundage thus increasing cast. The thing with trapping is that we can reduce mass a lot while equalizing (or trying to) tension and compression forces. It depends on the ratio of pound per mass and cast per mass.The best way to find out is make two bows out of the same wood same dimension and same poundage but heat treat one of them and re tiller to the old poundage and to trap the other bow and compare the cast.
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You can add reflex with heat treating. Trapping just helps maintain what's already in the stave.
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Does heat treating affect the density of the wood?
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Don't let theory discussion get in the way of actually making bows. ;) Good tiller comes first.
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K-hat-
thanks for the explanation of how a (trapped or treated) lighter-for-their-weight limbs can outperform.
theory vs. experience: I was hoping some members that have tried the experiment, and can comment on the gains they have experienced.
elm is said to be a good candidate, but unfortunately, is not found where I live, however some of the local hardwoods (birch) , are reputed to be less responsive to heat treating.
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Willie... buy wood.
I've had many wasted hours making birch bows. What town are you in? Wasilla here.
Michael
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Don't let theory discussion get in the way of actually making bows. ;) Good tiller comes first.
I enjoy a good discussion like this, but "amen" to that! The discussion is only worthwhile if we go do something with it :D
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yeah k hat thats
true