Wednesday, 19 March 2014
Ash Bow Woes
The Ash bow seems to have moved some more so I'm heat treating the belly to correct the sideways bend and also taking out a deflex dip in one limb.
I did write some more and was going to insert some pics... however the blogger is playing up and Google Chrome crashes when I try to select an image to insert.
Hopefully it will get sorted... I've even tried it using Internet Explorer which usually solves these issues...
Ah it works if I go via photbucket...groan... ain't computers wonderful....
I'll upload 'em to photobucket and then download them to here when I can be arsed...
Ha! Got it going by downloading Firefox web browser.
The illustration shows a limb with a deflex kink in it. If force is applied in the direction of either arrow common sense says it will do most bending at the kink. Tricky to explain why, but in the case of the red arrow, the force acting straight down the limb is effectively acing on a column which is very strong in compression, at the kink, it is a bending force. Anyhow, experience has shown me that slight bends like that always appear to be weak.Hope that makes some sort of sense.
The bow was insisting on trying to bend sideways and go slightly S shaped. I think some of this is due to the back not being true. Looking down the bow one limb has the back sloping slightly high on the left while the other limb, it's high on the right (slight propeller twist)
Anyhow, it's been a right pain, the first try at correcting the sideways bend left the bow looking rather charred in the centre, the wood seemed to have shrunk a bit too! The the grip seem narrow after the heat treatment! (dunno if it was my imagination, maybe it was narrow to start with).
I was pleased I'd left the cambium on the back as it stopped that scorching too much. Hopefully I can get it flexing seriously now without it trying to go sideways. To be fair, I've been revising my opinion of Ash as it was working rather nicely and any longbow can try and go sideways.
Update:- This thing is a bit of a struggle, it's flexing better but the overall shape is like two straight limbs joined a few inches below the grip with about 5" of back set in the lower limb!
e.g. On the tiller unbraced the left (lower limb) tip is sticking up very high. I got the damn thing to a low brace and exercised it. When I then took it off the tiller and was looking at the alingnment the damn thing kicked in my hand and twisted inside out. That's to say the bow flipped to put the sting over to the back... the only way I could get it off was to lever it off the nock with a screw driver... another good reason for temporary nock overlays.
I'm currently heating some of that backset/reflex out of it, so that the two limbs will be more balanced.