Saturday, 28 April 2012

Full Draw & Test Shots

I'm certainly glad I didn't rush at it yesterday. I reviewed the video I'd taken and could see the outer limbs weren't bending much, I got the right limb moving more and then worked on the left, it was still a bit strong on the left limb, and all this was at a low brace height.
I took some time taking out all the rasp marks with a scraper as it was beginning to get close to final draw length and weight. There were a couple of tiny pinch marks by the Devil's thumb print so I put some low viscosity superglue on it. I figured the area had withstood 60# draw weight and as the other limb was going to get eased off it would be ok. I went over the whole bow cleaning up the back and sliding my verniers over any suspect areas to check the taper was even and the bow was always slimmer towards the tip.

I also checked the string alignment by hanging it from the sting and looking along it, there was a hint of 'S' shape so I stuck some wedges of scrap Yew to the back at the nocks to allow filing of temporary nocks on the back which allowed me to narrow the tips from one side or the other to adjust the string line.
This has been an ongoing process through the whole business and is why I leave the tips about 20mm wide to start with. The string line shifts a bit as the bow begins to flex and finds it's curve.
Finally I shortened the string and got it to proper brace height, pulled it back to 60# and whew, it was 28" !
There was pretty much a days work getting this far, despite the temptation to rush to do it yesterday.
The 2 pictures are the taken from video of it being dynamically flexed, first at low brace height yesterday and the other is how it looks now.
I will doubtless have some fine tweaking to do, but I shouldn't loose draw weight as I can bring eack nock in by 1/4 of an inch to allow for any loss of weight. It is good to see the reflex still visible at full draw. There is a bit of an optical illusion as it looks to have increased from the left picture, that's just due to the sliver of sapwood glued to the back.
It still looks a bit uneven as the natural wiggles in the satve show up, that is one of the difficulties of tillering self bows
I borrowed the string from one of my other bows and tried a couple of test shots, it felt good.
No sign of problems around the thumb print. There is another area, a small natural depression where the grain dips just above the arrow pass which looks fine too. I'd been a bit worried early on as it might have been a weak point, but as the limbs were reduced it was apparent that there was probably plenty of wood there.
The finishing will be fun as some of these features will start to show up, there are a couple of nice streaks of purpleish red too.

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