Primitive Archer
Main Discussion Area => Bows => Topic started by: Manolovis on June 10, 2021, 01:20:00 am
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You knowledgeable bowyers enlighten me please!
I just finished a bow and don’t understand how I got to that much set.
Bow is 62 inches DL/DW 28/50. It s 35 mm at the widest. The bow is a trilam bamboo kanuka bamboos and design is a bit of hybrid flatbow, with stiff 1/3 D crossed section outer portion. Decided to experiment with a mixture of features from different bowyers ( Eric krewson, opa, to name a couple). Thanks to bamboo bow , Leon wood, dragonman and Eric I managed to put that first trim lam together. Tiller looks good to me ( used a gizmo) , but bow lost a Lot of reflex.
2” of reflex when tillered the back-core bit and another 2 when I tiller the belly.
Well I d be accepting that and move on if it stayed like that but it seems that when I unbrace it doesn’t come right away to that 0” reflex. Which I read is sign that it’s still taking set /too much stress.
How from here can I settle the set if the gizmo shows me that tiller is good ? Drop the weight to 45# maybe ? Drop more mass ?
Why do you guys think it took that much set ? Scraping belly power fiber too much ?
Design? I thought I would go quite narrow as since I read that bamboo is the the “wood” that takes most set per mass.
Thanks lots for your help all of you :)
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Bamboo bellied bows have the belly lam heat treated really dark. This improves the compression resistance of the boo. Not heat treated it is....ok...in compression. A key thing is to not touch the belly lam during tillering. It should not have any material removed off the face. These bows are 'tillered' before glue-up. You put the taper into the lams before glue-up and through experience/judgement/luck to begin with you arrive at the correct taper rate.
They are a tricky design to get right and it would normally take a few attempts to work out the 'recipe' for your particualr bow design.
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Also unless your bow is a bendy handle design it is too short.
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Mikes' right.It takes a fair amount of diligence and experimenting to get the tapered combo right.Worth pursuing though.Documenting the measurements in a tablet for future bow building.
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Thanks guys yeah I suppose it scan error trial. I did tiller glued core and and back but added way too thick belly so I had to scrap that down. I heat tested belly too bit maybe not enough ( caramel colour)
Do you guys think I can still limit set now? I just don’t want the bow to take anymore than she already has...I just assumed it might get worse observing that the limbs are tasking a while to get back to there initial position after shooting few arrows and unbracing.
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I watched James Parker heat treat the bamboo belly lam. It looked like he was totally burning up the boo. He started at one end of the boo slat with a rosebud propane torch and literally carbonized the outer surface of the boo all along to the other end. Flame, smoke and black boo. I was totally surprised when I watched him do this but he said it's how it should be done.
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I have tried to get the bamboo back, belly bow design down to where I can make them as easy as a selfbow. Hopefully one day I will be able to consistently do so. I will say this if you need to loose some weight do not be scared to tiller the bamboo belly , just pretend the nodes aint there and start scrapping.
I have made a great shooting bow that way. It took many scrapes for it to start dropping poundage but once it did it settled in quickly. If it had been a right handed bow I would have kept it as I was and still am very proud of that bow. One day I will hopefully get the process down, untill then I will keep reading threads like this one and trying to learn something.