Author Topic: thoughts?  (Read 866 times)

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Offline stuckinthemud

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    • avenue woodcarving
thoughts?
« on: April 12, 2023, 07:22:08 am »
Right, so, this is my current project, the dimensions are taken from a medieval example in the Kristianstad museum, Sweden.  The taper is 1mm per 1 inch of thickness, except for the central 8" which fade to a stiff centre of 4".  Front taper is constant from centre to nocks.  The original is 27mm thick by 37mm wide at centre, I am a little under this at 25mm and so I am about 2mm too thin along the whole length.  The original is yew, probably compression wood - it was drawn in 1945 as straight, but now shows a very slight deflex (set?) - the humidity of storing conditions changing would explain the difference in profile as compression wood moves with humidity changes.  I figure I am about 10% below the original's draw weight.  Does that seem fair?

Also, the centre 1/3 of my bow has a tiny amount of reflex, the photo shows the centre as straight where the reflex is affecting the draw profile. I figure I need to soften the inner 1/3 but would welcome any opinions on this.  For what its worth, the draw length will be 10.5 inches measured from the belly - brace height is 4"

the original



Getting near to brace height



Side profle (unstrung)


« Last Edit: April 12, 2023, 07:26:08 am by stuckinthemud »

Offline Del the cat

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    • Derek Hutchison Native Wood Self Bows
Re: thoughts?
« Reply #1 on: April 12, 2023, 08:53:40 am »
Taking stiffness as proportional to the cube of the thickness...
25mm cubed vs 27mm cubed would give about 80% of the stiffness.
Dunno how valid this is, but it's probably pretty good.
Del
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