ATARNarchive

Bow Cross section Analysis

5 posts2012live thread
bheggeseth
On my previous bow and my current bows I used a router bit to mill 2mm deep matching grooves. I followed the grooving up with 20 coats of 2% fish bladder glue for sizing. After letting the parts dry for a day I heated up everything with a halogen light and glued the horn and core with 30% fish bladder glue. Clamping was done with C clamps. My previous bow broke during tillering last spring, everybody?s best conclusion for the bow breaking was improper tillering and core dimensions. I cut some clean slices off the broken limb to examine how well the horn/core glue joint was. Below are pictures for everybody to analyze. All comments welcome, thanks.

Note the slight discoloration is from the saw burning.
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Break, note the horn looks to have held well.
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Uli
very neat work. glue-up sounds correct. strange that it broke, what a pitty.
maybe use more sinew next time for security.
redhawk
It looks like the core is not made according to the growthrings of the wood plus there had been a crack within the horn. Is the horn cut from the curves or is it a sidewall?
Grooving and glueing seems to be o.k.
I?m always wondering why many ATARNOS are using fish- bladder glue. O.k. bowyers of the past have used it, but they didn?t have had acces to actual hide- glues which are available in really high quality now, easy to get and to handle. Maybe a well prepared fish- glue is a bit better but much more delicious to handle.
Michael
Kviljo
I'd say that looks very-very good between the horn and core :lol: Makes me want to try it too, hehe.

Regarding the break, I'd say you could have used more sinew, and a lot more on the edges. Without enough sinew on the edges I would imagine the limb could be torn off just like a paper, if there ever was some sideways unstability when bending it.
PAZUZU
bheggeseth
glue line looks good. I would put more coats of glue. my guess is a bad horn strip. I had a similar strip, but to my joy broke it before gluing it. similar dry and brittle wood. and very little elastic ....