Yew Primitive Stave

I've started on a piece of Yew which I've been hoarding for ages, it looks like a perfect stave, but close examination reveals two awkwardly placed knots and grain which is very asymetric.
If I avoid the knots I end up with some twist or a bow with lateral bend which needs straightening at the handle.
I'm a bit fed up with heat treating and heat bending so I'm going to just make a bow fom the stave in hand, clean and simple and leave out the overthink!
The way to deal with knots is basically very simple, you leave 'em in or you cut 'em out. Of course you can't always see what dirction the knot goes in. I roughed it out on the bandsaw just leaving the edge of the knots visible so I could carefully remove as little as I could to take them out of the equation.
I'm aiming for a shortish flat bow similar to my Hazel bow (see the website), it will be narrower with nice slim tips, I'll probably radius the belly slightly to give a flatish oval cross section to the limbs I'm aiming for about 40 - 45 pounds but hopefully with little set.

Using the drawknife rips off wood quickly and also tends to follow the grain, some care is needed around the knots, but when a big chunk tears off it's actually telling you how the wood wants to be shaped. There comes a point however where discretion and a rasp takes over to avoid unwanted tearing.
Because of the weird grain on the stave the centre pith of the log runs in some peculiar places. Near the centre of the bow it's near the middle but elswere it's off to one side.
You can see the dark line of pith showing at two points on the limb nearest the camera in this last shot, just above my thumb and the further up and to the right.
There were quite a few drying cracks in the stave but they've dissapeared as I've got down to the centre pith. The cracks tend to radiate out from there towards the sawn face of a stave. They don't seem to run out towards the sapwood.

On this stave the sapwood is nice and thin so I'm hoping to just leave it alone having de-barked the stave carefully. This saves a lot of work following a growth ring and also adds to the nice simple primitive feel I want with this bow.
Some brown streaks of cambium still show, but these will be removed with a scraper in the final finishing of the bow.

Footnote(27/3/2014):- This eventually becomes Twister my favourite field shooting bow. Hopefully this note will help finding Twister when using the search facility.

CRACK!

I heard an ominous cracking noise. The bow has fractured where there is a big S bend in the lower (left in the pics) limb. It's where there are a couple of knots, I'd been careful not to heat bend it at the knots and it's failed just beyond them where I did most of the straightening. The first two pics are with the bow strung to a high brace to open up the crack before I finally broke it.
It's been interesting working with the Hornbeam, but I obviously took on a bit too much with that stave. If you look back at the previous pics, there is no sign of a problem at that point

Once the crack appeared I took pics and finally took it to breaking point, it was still remarkably tough to actually snap. Overall I'm quite impressed with Hornbeam and will try again when I've got a straighter stave seasoned, I'm not too upset as it was always going to be a learning experience and it only cost me my time... well I managed to wreck my heat gun too (They are designed to be left standing nozzle up to cool down after use, but I left it on the floor in my haste to clamp up the bow during heat treatment).
Making bows is slowly curing me of my impatience and making me more philosophical about failure.

Good News, Bad News.

The heat treating has certainly stiffened up the bow, but the bad news is some of the old lateral bend has come back due to the heat treating allowing the wood to relax a bit back to it's former shape.
Ideally one would heat treat and bend at the same time with the bow clamped to a form.
Well, that's ok in theory if the bow is nice and straight and you are just putting in simple reflex.
With a tricky shaped stave like this a bit of messing about back and forth is usually required.
Anyhow I have some other things to get on with while the bow settles down again.
I'm a bit more confident about it now as it's definitely stronger, I could barely get the string on it.
I think I can afford to loose an inch and a half of each limb if necessary too.
I'll have another go at it on Friday.

Tiller Pic with update.

I pride myself on showing what I do 'warts and all'. Well here's a pic of how it looks unbraced and braced on the tiller. You can see it's awful, but the question is why?
I think the heat straightening I'd previously done had stiffened up certain parts of the right limb.
you can see the right limb is bending a lot near the handle and the left bending hardly at all at that point.
The usual way to tiller a bow is to mark the weak points and remove wood from everywhere else (and especially the stiff points).
I'm having to stiffen up that weak area with heat treatment and take out that slight deflex first as I can't afford to loose any draw weight.
It's not going to be easy, but hopefully I'll get it looking like a bow eventually.

I've heat treated the handle end of the right limb, here's a before and after shot (the after shot is the lower of the two)
I can't brace it and try it out until the limb has had a couple of days rest. What I can do is press on and get the rest of the limb, and the other limb heat treated... it's a bit of a slow laborious task, just as well I enjoy making bows!

Ready for the Tiller

The bow is now straight (that's to say the tips and grip are in line).
The first limb I worked was forced to be certain dimensions because of a knot in one area of the limb and the basic dimensions of the stave. I've evened up the thickness taper on that limb by staking the thickness near the grip and then the thinnest point and working out roughly even steps along every 6" of length (it worked out at 1.5mm change every 6").
I don't work slavishly to dimensions, what I'm trying to do is get a fairly even taper with no thin spots which could turn into weak points where the bow suddenly bend excessively (known as a hinge).
So with the stave having dictated the dimensions of one limb, I then make the other limb roughly match it, which is where I am now.
I felt the flex of the bow by putting one end against my foot, holding the other end in one hand and pushing against the grip (a bit like when you string a bow). It feels a bit soft for this stage in the proceedings, but there's no way I could have made it much different.
On the plus side, I flexed my 50 pound longbow and it felt similar, so I'm not too far out. The other good thing is the stave is still long and could always take an inch or so off each limb to get the draw weight up. The final trick up my sleeve would be to heat temper the belly.
Ah, but I'm getting ahead of myself, lets get it on the tiller and see how it flexes.
The second pic shows how I make a virtue of necessity.
One big knot couldn't really be in a limb, therefore it must be in the handle, which then takes on a slightly pistol grip shape:- Note the arrow pass is marked, and you may just be able to see the centre line marked on the belly.
Update:-
My suspicions have been confirmed, it's a tad soft and the undulations make the shape look weird. I shall do some heat treating and straightening/adding reflex.
I don't want to loose any length yet as you can't put it back on again!
If I do the heat treating now, it can have a couple of days to rehydrate the wood. Getting the limbs a bit more symetrical will help to see the true shape as it's drawn back on the tiller.
At one point I pulled it back to 30 pounds at about 27" on a low brace height...that's just too weak. The top limb looked to have a horrible bend just above the grip, but as I let off the tension I could see it 's just the shape of the stave.
The doesn't seem to be any set at all (hardly surprising on a long bow at 30 pounds...)
Off to the garage to break out the heatgun.

A Bit Straighter

After two bouts of heat bending, and some slimming down in between you can see it's much straighter now.
The aim is to get the tips and handle in line rather than straightening out all the bends.
I've also lost a bit of a deflex dip from the limb.
You can see the area I've heated by the discolouration. A bit of heat bending on the other limb and it will be in line.
The other pic shows me at work on the shave horse penciling in a line to follow the grain where it dips by a knot. I need to leave some extra strength there, but I don't want a great mass of excess wood, it's all feel/eye/guesswork.
By the way it's 76.5" long now, so I still have plenty to play with.
Iv'e got it back on the heat jig with the hot air gun blowing at 210C on the central portion of the other limb, a straightish section between two knots.
I don't want to actually try and bend it at a knot as that's a weak point and I don't want any aditional strain on a weak point. I'll leave it half an hour and then go and heave it into line and clamp it. A few days rest for the wood will be in order before I start really trying to see how if it will bend like a bow.

Hornbeam

It's a lovely wood to work, the workability of Hazel with a bit of extra crispness, not a lot of visible grain, sot of Hazel with a hint of Beech.
The wood is begining to speak to me, but mostly telling me what it doesn't want to do!
I put a lot of heat and strain on it to try and straighten it a bit overnight, but it's not done very much.
I shall have to work down the limbs and correct the lateral bend when there's less wood to shift.
A couple of knots in the area I was trying to bend also need to be worked out, but if I remove them the limb will be too narrow at that point.
The solution is to move the narrow area nearer to the tip of the bow by sawing a few inches off that tip and moving the centre/grip area down. This works well because it puts the grip onto two other big problem knots and still leaves the bow taller than me (5'10").
That's why any character staves need to start a lot longer than the finished bow. More pics later in the day or tomorrow.
Update:- I've slimmed down the limbs a bit more and tested the moisture content on one of the offcuts, it was still up at 15% so I placed it in my sophisticated drying facility.
That's to say I lobbed it up on the south facing flat roof which is roofed with black rubber membrane and gets nice and hot. Later in the afternoon I got it down (mmmm tasty warm stave) stuck it back on my heatbending jig to try and straighten it some more. I'll leave it overnight, pics tomorrow.