Saturday, 31 July 2010

Marking out and Retail Therapy

I tried to find the best line for the bow by stretching a string along the stave, you can see there is some twist in the stave and it's profile isn't a perfect semicircle.
After much fiddling and re-drawing I finally sketched out a rough shape for the bow.

Now I had planned on doing all the work by hand but that Ash is damn hard and my axe very heavy, not to mention my tennis elbow. I spent a bit of time sharpening the axe which helped a bit.
When you can sharpen your pencil easilly with your axe, then you know it's sharp.
Anyhow I succumbed and roughed out the basic shape with the band saw, (having flattened the belly a bit with my axe first to make it sit better on the bandsaw table).
There is still plenty of thickness to remove and it's all axe now (the drawknife didn't like it at all. It makes me appreciate how nice Yew is to work).
So, that's where the retail therapy comes in, I ordered a new axe, a Bahco one made in Sweden, so the steel should be good. It's 0.75kg rather than my current 1kg one, it has a wooden handle. There were some real cheap ones and some with steel handles and rubber grips but that just didn't seem right to me. Anyhow, I'll let you know what it's like once I've tried it.
The bow lets you know when to stop using the axe as the limbs begin to flex and bounce the axe head.

My bandsaw blade is also shot to hell (they say that a decent quality blade makes all the difference) so I ordered a couple of good 3tpi blades with extra set on the teeth for ripping along logs. The internet is great, you can spend money on specialist stuff without leaving the comfort of your own home.
The pics don't need further commentary, except to say, the stave hardly even flexes yet (it thinks it's a roof joist or somesuch!)

When I'm using the axe on the belly of the bow I find it cuts best attacking the edges rather than straight onto the broad flat face, the sketch shows how I'd work down one edge (1) then edge (2) and finally the face (3) as I work down towards the dotted line.

I don't know if this is 'good' technique, I just find it works for me and allows a good amount of timber to be removed when roughing out. It also allows finer control of the axe as you take cuts 1 & 2 close to the dotted line.

The sketch represents a cross section about 1/3 of the way down a limb, as per pic on the left.

You can see the remains of cuts 1 & 2 and the remains of the pith core of the log.
There are a pair of knots visible half way down the limb, they are running sideways out of the stave and will probably dissappear as I work the belly down. The axe can tear out nasty divots around knots so I'll need to work carefully, near there and start using a rasp, or spokeshave.

Any de-crowning, as discussed in the previous post will be done later once the stave is begining to flex, it may not be necessary with a bit of luck.
It would be nice to keep the smooth untouched back, but I do expect I'll need to shave off a tad.

Thursday, 29 July 2010

A Change of Tack & Some Design Considerations

I'm going to let the Hawthorn bow 'rest'. It wasn't going to be the style I wanted.
I've pulled out two Ash staves cut in Feb 09. They are split as halves of a log 3" diameter at the top and 4" at the bottom.
I want to make something in the style of a Neolithic European Bow, (google 'Meare Heath bow') it will be a flat section similar to the Hazel bow on my website, but longer.
The Meare Heath bow has the outer curve of the log as it's back, the problem is that with a stave from a small diameter tree the geometry goes wrong.
Let's simplify the figures to illustrate the point.
Say we want the bow 3" wide at it's widest (a bit of an exageration as 2 1/2" is nearer the mark).
If we say the stave is split from a perfectly round 3" diameter tree, then the cross section of the stave will look like a semicircle 3" wide and 1 1/2" thick. So we have the width we want already but the problem is 1 1/2" is too thick and will give too much stiffness at that width!
So what's the answer? If we make it narrower it's no longer a flat bow and ends up being more like a

My solution is to de-crown the stave, that is to remove the grey area in the sketch below (it represents a cross section half way down a limb roughly to scale) by running a spokeshave along the centre of the back to an even depth thinning the cross section (into a sort of a trapezium, with back and belly parallel). The rectangle represents where the bow sits in the log. De-crowning has a couple of advantages

1. It's quick and easy.
2. It gives a nice flat even profile (logs just aren't perfectly circular).
3. The flatter profile distributes the stress more evenly across the back.
4. You can leave the handle area fully rounded for a nice grip, which also stiffens the handle, which is a good thing as it compensates for the handle being narrower than the rest of the limb (I mean you just couldn't grip a 3" wide handle!)

Now some people will say it's a bad idea because I'll be cutting through growth rings, which will weaken the back.
The answer to this is that the exposed rings (shown as red dots) will actually run up the length of the bow parallel to it's sides and that doesn't cause any problems. There will be a few rings cut across the limb where I leave the handle thick, but the bow isn't going to bend at the handle anyway!

The whole idea of not cutting through growth rings on the back of a bow is a laudable aim, however one has to temper these ideals with a good pinch of reality.
Anyhow, I've been marking out the best stave and I'll start work and post some pics later in the weekend.

Sunday, 25 July 2010

Destined for the 'Corner of Shame'?

The bow pulls back ok, but some of the reflex I'd put in has pulled out and the twisted grain area seems stiff. The other limb is too strong.
So by the time I've worked down the strong limb, it'll probably be a kid's bow. Sometimes it's like that, once you've worked out all the dodgy areas there's not much bow left.
I shall persevere and stream some extra recurve back in, I'll leave it longer to dry out again this time. I get the feeling that too much correction ends up turning the wood into pudding, now that's just opinion, could be all sorts of reasons, the most likely being my impatience.
The one thing I won't be doing is getting drawn into shortening the limbs in an attempt to bring up the draw weight. It's a wise man who knows when to quit.
I shall finish it off, but with a view to it being a ladies or kids draw weight bow.
I'll have to look out for a nicer piece of Hawthorn as it feels like nice wood.

On the plus side, bending it at the handle to alighn the limbs worked out very well.
Oh yes, the other good thing is the 'Perma-Grit' ( small needlefile I bought, it's brilliant for nocks, a normal needle file is too fine and slow and clogs, the permagrit file is tungsten carbide grit brazed onto a steel shaft, it was about £5 but it's a V good tool, cuts fast and clean.

Saturday, 24 July 2010

Steamed it

First I steamed the wobbly limb tip to an even reflex. I left the bend at the handle as it adds some character and a bit of deflex in that limb with it's twisted grain will help keep the stress down.
That was pretty straight forward using my usual steaming technique which has been pictured before.
Steaming the handle was a trickier job as I only wanted the handle region getting hot and bending.
I narrowed the handle and shaped it slightly to encourage the bend to occur where I wanted it. To get the steam in the right place I used an old 2.5L plastic container (it had a bit of windscreen washer fluid left in it, so I topped up my washer bottle first). The steam hose from the wallpaper stripper was pushed into a hole cut in the cap and I cut slots/flaps in either end to push the bow through.
The first attempt didn't quite straighten it enough so I re-did it, this time with the bow clamped in position onto a piece of 3x2 with my plasic steam chest around it. The advantage of this being that there was no cooling time between getting the bow from the steamer to the clamped position. The taper of the limbs is clamped flat against the 3x2, this over-bends it slightly, but there is some spring back after it's cooled, it's just trial and error to gauge how much to bend it.

The second arrangement is shown right, I hope you can see what's what. It shows that you don't need fancy equipment to do steam bending, a wallpaper steamer and a few good clamps is about it, some rag to help keep the steam in helps.

A word of caution, once the steam starts keep your hands well clear, it's nasty stuff steam.

The results are pretty good. During the first steaming the area with the twisted grain took a bit of a twist. I put a G clamp on the limb while it was still hot and applied some force to twist it back as it cooled.

The end result is going to be a bit like an American Flat Bow (AFB, which they sometimes call a 'Longbow' ), I'll probably taper the limbs to a very narrow tip a bit like a pyramid bow (thats a bow of near constant limb thickness which is wide near the grip, tapering to a narrow tip E.G nearly all the taper is in the width) This bow isn't wide enough for a full pyramid style so it will be a bit of a hybrid...well it's a stave bow and it will turn out how it turns out, we don't actually need to label everything.
It sometimes amuses me when people refer to specific prehistorc bow remains as if all the bows at that time would have been identical. A bow is whatever you can make out of the wood, it's your challenge to make it as good as possible, or maybe as quick as possible depending on your circumstances. Whoops I'm getting preachy.

Friday, 23 July 2010

The 2 Arrow Trick, and a late update!

When working on a bow with rectangular section limbs (flat bows) a good tip is to use a couple of arrow shafts to check that the limb is true all the way down (e.g not twisting).
It can also show if the back and belly are parallel to eachother, and that the two limbs are flat relative to eachother.
The length of the arrow shafts just maginfies the error making it clearly visible.
Here I've used rubber bands to hold the shafts onto the limb and it shows a little twist at the tip.
I've worked the bow down a good deal and will put a string on it soon. I'm probably going to be pretty vicious with it, as I want to find out if it will take the strain. Maybe I'll set the camera up in video mode to film it if it goes bang, safety glasses and a hard hat may be in order too.
I feel a bit ambivalent about this bow but it's good to try new stuff, I've not used Hawthorn and not tried straigtening a bow at the grip, so even if it goes bang it will be a learning experience.
The other pic shows me 'floor tillering' it. That's really just flexing it to see how it's looking before I put a string on it. The weird bend in the lower limb (it has a bit of deflex in the last 1/3 of the limb which is otherwise reflexed makes it look odd and the upper limb is a tad stiff at the moment. I may not bother steaming that limb into shape as it has nice quirky look.
NOTE:- The bow is upside down in the floor tillering pic... that's because it's easier to see the lower limb, so I try it both ways up. Just happened to get the pic taken with it upside down.

I found a string which is the same length as the bow, I couldn't resist putting it on and drawing it. Of course it's not full draw as the bow isn't braced, but it gives me an idea of how it will be. The top limb looks to be bending sharply back at the handle, but that's just the shape of the stave. I think I probably will steam the limb and grip next as it's begining to feel promising. I just hope I don't get suckered into doing tons of work and then find it breaking. The string lies off to one side and I could feel the bow trying to twist in my hand, the draw weight felt about 30-40 pounds, which will increase when it's braced and the limb straightend.

Monday, 19 July 2010

Wavy Hawthorn

I've roughed out the Hawthorn some more.
There isn't a straight bow in there without having the grain at weird angles or breaking out half way along a limb.
The solution, in theory, is to mark out two straight limbs and then bend the bow at the handle to line them up.
The fore and aft bend (reflex deflex, left pic) isn't a problem and is in a reasonably nice proportion already, I've left extra wood in the handle area so it can be narrow and deep.
The sideways bend is trickier, you can see from the second pic that the far limb is kicked off to the right.
Once the handle is slimmed down, steam and pressure should be able to bring them in line.
The bow is narrower than I'd hoped for, but at least the end grain is running in a reasonable direction.
There is still tons of hard work to do and the bandsaw has just about finished it's job (maybe it will help out on the handle a bit). To have got to this stage with hand tools would have been hard work.
I marked out the limbs in pic 1 by following the grain with a pencil. In the right pic I used a straight edge (an old metal carpet edging strip which is fairly flexible), I had to avoid splits and shakes and try to keep the end grain running in line with the back/belly of the bow.
This is the common and simplest grain alignment as the under bark surface can become the back of the bow.
You can also make a bow with the end grain running at 90 degrees e.g front to back if you are cutting a bow from a quarter sawn board.
You don't really want it at an ange, although I daresay, just about anything is possible.
Hmmm, just had a close look and the end grain at the other end isn't so good, it's at a bit of an angle and there's some grain run off on the far limb.
The Pic below shows what I mean.
The angle of the grain isn't too bad, my Yew longbow has a similar degree of twist. I think the wood in the top right of the pic is sapwood, I'll probably remove wood from the top edge to get down to the more even looking wood.
The next stage is working down the back of the bow with a spokeshave to try to get it somewhere near following a single growth ring. (I shoved the tip of the bow through the paper to give the camera something bigger to focus on and to help avoid the shot bleaching out)

I don't know! I've done a bit more this evening.
As I work it down, I'm hoping the grain will appear more orderly, but it's rather wayward.
Viewing on one edge the grain takes a sudden turn off twards the belly, but on the opposite edge it sweeps towards the back!
As it gets slimmer it feels lively, I think it wants to be a bow, but it could be just waiting to smash.
I shall keep my head well down when it's time to start pulling it back on the tiller!

Maybe it'll be a great bow, or maybe it'll beak in two and slap my face.
Sorry if I'm getting a bit fanciful here, but this one is a real tease!

I think I'll press on fast to see if it will work before I straighten it. If it blows up, I'll admit defeat and make a nice well behaved Ash pyramid style Ash bow with a nice bit of recurve on the tips.
The Hawthorn does feel like a good wood, but maybe this just isn't the right piece?

Friday, 16 July 2010

Hawthorn Log

I've been roughing out a big old Hawthon log which I cut in April 2009, It was lying across a footpath, still attached at the root, so it wasn't dead. Cutting it helped clear the path, I don't know if the wood will be any good as it has split a fair bit. It's nicely dried to a warm Yellowish colour, the grain isn't very striking and looks a bit like Maple in parts.
I didn't have the band saw when I got the wood so I just chopped away some of the worst half and attacked it with a power planer.
Here are some pics, I still don't know if there's a bow in there yet, but at least it's manageable now.

I've tried to saw it following the curve of the grain which is pretty wild. The end result is quite promising for a bow with some natural recurve, there are still some splits and weird sworls in the grain so there is a fair bit of pondering to do.
The stave is 78" long so there's some room to find a nice 65" flatbow of some sort.

The pictures are all of the Hawthorn in it's various stages of being worked, you can see some of the splits and turns in the grain.

I've also done a bit on the Yew longbow stave to get it closer to it's final dimensions, I've taken measurements of my 75lb Yew bow at 12" intervals along the limb and transferred those onto the new stave, I've used a plane to get it roughly down to those dimensions (plus a mm or so for good measure) fairly square in cross section. It should finish seasoning quickly now, I'm trying to avoid the temptation to do too much to it until September, which is why I've been playing with the Hawthorn.

Monday, 12 July 2010

The Comfy Chair

I've de-barked the Yew stave I'm working on. I'll share some of my thoughts on using a spoke shave. It's a very versatile tool, I only aquired mine about a year ago and it's a firm favourite... There's no 'wrong way' to use one, it works well bevel side up or down, pushing or pulling. Sometimes I hold the left handle still and work the right one back and forth. You rip off take off big fat shavings, or hold it with the handles vertical and push it away from you like a scraper taking off very fine scrapings.
One of the big problems with a stave is how do you hold the darned thing firmly, these pics show a few of the tricks I use and where the 'comfy chair' comes in (or rather a cushion I rescued from an old one).
Please excuse my state of dishabille as it's been rather hot.

Sunday, 11 July 2010

Saxon Bow

I've been away for a short break up near the Dunstable Downs, some nice old hill forts there. Totternhoe Castle (Totternhoe knolls) was surprisingly spectacular, a steady walk up a wooded track and then out onto a clearing and up a reasonable sized mound. The panoramic view from the top was glorious as you didn't realise how high it was until you reached the top, some very steep banks and ditches too.
I always wonder how far an arrow would carry from the top of these hill forts. Enough musing here are some pics of the Saxon Bow which I re-worked from an old Elm Longbow.

You can see it really is bending in the handle.

I like to do new stuff, so for this bow I made a linnen string, it wasn't too difficult, but it's not easy to descibe. I won't waste the effort trying! Suffice it to say I followed the desription in The Traditional Bowyers Bible vol II which has an excellent section on strings. It's made out of 3 plies, each of 5 strands of linnen thread (bought from Quicks Archery), each strand has a breaking strain of about 8-10 pounds.

The first pic has my adjustable tillering string on it. below is a pic showing the side nocks and the linnen string, it also gives a good view of the Elm with it's nice 'hen pheasant' colour and grain.

Sunday, 4 July 2010

Re-working Old Bows

As well as reworking the '1 hour bow' I've been looking at an old Elm longbow, which I made many years ago, but was never shot a great deal.
It has chrysals on the belly, is about 70" long drawing 36 pounds at 28". I'm going to cut it down to 61" as a Saxon bow at 30 lb for re-enactment.
I don't like making bows much below 35-40lb, but this seemed a good opportunity to try something new, revitalise an old bow and have something to tinker with.
There is not much Elm about these days and it's an attractive dark wood.
I've been playing with it most of the weekend off and on to see if it's feasible.
First I sawed 5" off each end...a bit irreversible, so I hope it works!
A lot has been taken off the belly with a spokeshave, I was surprised how deep the chryasls went, more than 3mm. The handle has also been drastically recuced, as the Saxon bow will need to bend through the handle to get 28" draw from a short bow. Although the bow will be 61" the nocks are 2" in from each end, which gives a working length of 57" and thus half of that as a realistic maximum draw, that's 28.5"
I've roughed it out and had it on the tiller back to 30 pounds at 26", it really is bending in the handle which is a nice change for me as I have a tendency towards making bows whip ended (or at least this old Elm bow was...)
By the way, I put the giant ladle back together on Friday, it needs some more work, but at least it's back in one piece.