This topic has been here and there commented upon, but very on the surface...my sincere apologies if in the past there was a larger debate upon the subject...
Horn plates: do we glue them flattened, in stressed from deflex or stressed from reflex? Any prefererences and directions?
I have a feeling that one or the other configuration will result in the bow stacking at the first inches or at the last ones.
However, are there any other impacts (grip shock, recoils...?)?
Are there any special craft-related impacts (risk of delamination, assymetries...)?
Otlw
Kviljo
I've been thinking of this too today, although perhaps formulated slightly different: is it necessary to use horns with the same grown shape in both limbs in a (near) symetrical bow-design? (if the horns are to be straightened anyway)
I believe the recipe says to straighten the horns before glue-up. In the long term they will probably creep towards the grown shape, however. Perhaps this straightening of the horns before the glue-up helps even out the clamping-pressure and ease the tillering process as the materials are more uniform.
A more important factor for straightening the horns before glue-up, as in glueing straight horns on to a reflexed core, might be to reduce the stress on the surface of the horn when the finished bow is bent.
Let's hope some of the experts chime in.
Outlaw
I believe the recipe says to straighten the horns before glue-up. In the long term they will probably creep towards the grown shape, however. Perhaps this straightening of the horns before the glue-up helps even out the clamping-pressure and ease the tillering process as the materials are more uniform.
Right first, right second Id say. One more to add: one tries to assure that in time simmetry will not be lost; however, this last is almost immaterial since warming up the limbs (Adam commented several posts about the issue) can correct the limb deformation.
About what you said upon the cracks: Ok, that may have been the issue. But, are there any remains on which an educated answer could be given? Maybe is too much for a question.
Great, good stuff, thank you Kviljo!
Kviljo
I'm not sure what you are thinking of? Not sure I mentioned cracks in any way? Are you perhaps thinking of my "MB"-bow that suffered compression-fractures? I do think the main issue there was asking the horn to compress more than it was capable of.
I'm no expert, just throwing out my thoughts and hoping to be corrected if needed... :)
Adam Karpowicz
I am not sure what you mean. Horn has memory, so it is better to keep the slats symmetrical in respect to the orientation on the limbs and to the degree of curvature. On the other hand it can be plasticall deformed at high heat and when stressed a lot for a long time. It means even the most reflexed horn, as glued, will eventually loose the "inner" stress as the bow is flexed.
I suggested in the book to keep the strips somewhat straighter than the core during glue-up for practical reasons. It makes the process more controlled: the excess of glue will squeeze out without trapping air in the joint.
Adam
Daniel T.
The horn can't return to its original shape without bending the core and the sinew layer because they are glued together. I don't believe that the horn can excert sufficient stress for that.
The long term creep of the horn would be accelerated a lot when the bow is heated. If you heat the limbs for e.g. a twist correction, you would reduce the stiffness of the sinew and to a lesser degree of wood as well, while the horn would want to return to its original shape even faster. If the horn would distort the bow shape, it would do so during this process and not at some later point.
