Primitive Archer
Main Discussion Area => Bows => Topic started by: wizardgoat on January 17, 2015, 05:47:21 pm
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Im trying a couple hard backed yew bows out. Hard backed bows are not really my thing, but I got a couple really nice yew boards and backing strips for cheap, so why not.
When making a recurve would you bend the core, then thin the backing enough at the tips that it'll just clamp to the curve?
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_2710_zps30155469.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_2710_zps30155469.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_2711_zpsb5f79887.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_2711_zpsb5f79887.jpg.html)
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Havn't tried with yew.i like to preshape the recurve on a caul using the localized steaming method and then bend the backing strip on the same caul to get a good fit.takes very little heat to do this.i also like to heat treat the cores belly prior to glue up.
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Yup prebend both, the boo may swell a bit on the gluing surface so check that prior to glue. Boo bends well with dry heat,
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I've made two hickory backed osage recurves; tri-lams actually with elm cores just because I wanted to get two osage belly lams from a 5/8" thick board. I just used a heat gun to bend the osage belly lam and that went easy being only 1/4" thick. I didn't heat bend the 1/8" backer or core. Have to say the glue up probably would have been a bit easier if I had, but I wrestled the lams in place and used extra pieces of strapping tape to keep them from slipping and sliding in the Unibond. :)
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Does it make sense to clamp the core and backing together at the handle, then bend one recurve.
Clamp the recurve side well after it cools, then bend the other one?
Has anyone done something like this?
Bending them separate seem sketchy to me
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Don't know if this answers your question, but my form looks like this and I can heat and clamp both ends. As you can see, I originally made it with an insane amount of deflex and built it up with blocks when I came to my senses.
(http://i376.photobucket.com/albums/oo207/okdoak/recurve2_zps56faf11e.png)
The curves came out like this off that form.
(http://i376.photobucket.com/albums/oo207/okdoak/Wooden%20bows/2recurves2_zpsb99a4819.png)
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Any which way will work. I'd say it's seldom necessary to pre bend the backing.
BTW, you may have an ELB on the edge of one of those planks...
Del
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I have clamped the backing strip to the pre shaped core for shaping.i like to have a near perfect fit prior to glue up because gravity like to make tbiii go to away.
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You can also use the kerf bending method.
Make parallel cuts into the tip section where it needs to bend about 1/16th apart. Then make up some strips to fit into the kerfs left by the blade. If you make them out of yew and get good gluelines you will hardly be able to see. If you want to jazz it up a bit then use a contrasting colour wood. I like this method because you can glue in short 90 deg recurves (tighter than you can steam in). Short, sharp recurves have always given me the best performance.
If I didn't want to do the above then I would steam both bends in at the same time on the same form so they have matching curves not the same curve as they would if done on the same form separately.
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GB - you should try a bow glued up on that form without the block at the handle to decrease the deflex. More deflex at the handle is a good thing :)