Right now the overall length is 76", so will likely yield a bow around 74" nock to nock. This is good, as I'd like to tiller this as an English "warbow" of lighter weight -- maybe in the 60-70# at 30 (or 31? 32?) inches. The extra length will help here. Although it is meant to be a bend-through-the-handle bow, I'll want to stiffen up the handle section a little so that no undue tension is put on the spliced joint.
First, the back. One can see several of the flaws in the sapwood. Because of the narrowness of the resulting stave, there really isn't much room for avoiding some of these problems. The sapwood is also not very thick, so reducing it in thickness would not leave enough to make a decent selfbow, so I'll plan to back this with light colored rawhide, which will allow the appearance of a yew bow with the cream/brown contrast between the back and belly.
The twist at the end of the limbs can be seen fairly clearly now. The two photos below show the orientation of the crown at the tips compared to the center and middle part of the limbs (oriented correctly, with the crown centered).
The twist is not that great, but enough that I don't want to be wrestling with it while I'm tillering the bow. It is also worse at one end (the good end) than at the other. I'll plan to heat treat the belly some, and in the process I'll use some clamps and weights to gently coerce it to falling in line with the rest of the bow's crown.
Problems await on the other side, as the two knots I mentioned before could not be avoided. One is smaller than the other, and it may quite likely come out in the reducing of the belly thickness. The bigger one goes through to the sapwood side (but just a touch) and looks pretty solid so far. Hopefully I'll just be able to leave it along (or shoot it through with a spot of thin super glue) and get along nicely. The third image below shows the two knots in relation to each other; the smaller one is closer to the tip.
After lots of fussing, I managed to capture the center and crown of the stave. I mark it out using a line with chalk. The chalk is bluish-purple but comes off readily with water (or a little bit of sweat from one's palm). I use that as a rough but straight line, then follow up by marking over that in pencil, which does note rub off as readily. Then I marked the full width of the stave, 30mm at the center 4" section of the handle and 20mm at the tips. (Like many others, I switch between units of measure as a matter of convenience, marking out in mm when more precision is needed.)
You'll notice some dotted lines near that big knot. The dots actually follow the grain, and I'll respect that when I cut out the shape, leaving a little more wood around either side of the knot to help compensate for any weakness this section of the bow has.
When cutting out on the bandsaw, I did my best to keep the top of the crown uppermost, rotating the stave as it went through. In this way, the wood at the sides is always oriented perpendicular to the back, with the crown centered. It makes for some glaring twist, now that the excess wood has been taken away, but again, it will (hopefully!) come out when I heat treat and twist the tips into alignment. (In reality, they get twisted a little farther, as wood has memory and they will want to drift back to their previous position a bit.)
The true extent of the rot damage is now showing itself. It travels the limb a fair degree, but that will all be waste wood at the end of the day as the tips finally thin out, as can be seen in the second photo where I've marked the intended starting depth of 20mm at the tips.
Other sections are going to cause some challenges. Here's a section where at one time there may have been a limb. Now it is just an area where the grain runs in a divot and has cut into the working part of the limb. Some will be removed in initial thicknessing (see the pencil lines), and with luck the rest will as the belly is being shaped and tillered.
Similar challenges abound in the spliced handle section. The bow will be thickest here, but it is also where there's the least amount of wiggle room with the remaining wood. Pencil lines again show what will be removed, but there are still some significant sections of beveled wood remaining.
[...time elapse...]
Finally the stave is brought closer to working depth by sawing off the waste wood outside the pencil lines. The dimensions I'm starting with are 20mm by 20mm at the tips and 30mm by 30mm at the handle section. We can't build a bow by numbers, but this is a starting place so that I can try and get the bow bending a bit in floor tillering. A quick weigh-in finds the stave at around 36 oz. -- which is about twice as much as it will eventually be if aiming from 70# @ 30", according to Steve Gardner's Mass Principle.
In working down the limbs, one can see that the small knot is close to disappearing. Right now it is a tiny hollow bit, which will likely come out altogether as the belly is reduced. On the other hand, that large knot has gotten slightly bigger -- and a whole lot more rotten, as the solid part came off with the waste! Just goes to show that one never really knows what lurks beneath.... I'm not sure how far the punky bits go, but I'll no need to plan to scrape out the bad bits and either a) fill the hole with a glue and sawdust mixture or b) make a wooden plug. In either case, since the knot is slightly visible on the sapwood, I'll have to assume that it is nasty all the way through.
No comments:
Post a Comment