Wednesday, 31 July 2013

Draw and Poundage Arithmetic

The 35# Hazel overdrawn against the 50# Yew underdrawn has intrigued me so lets do some sums (well it's hardly higher maths is it?)

35# Hazel with a 5" brace height drawing 28" that gives a 23" power stroke (28-5")
So assuming the draw weight increases evenly (a pretty fair assumption)
That gives 35/23 pounds per inch of draw = 1.52 (I'm just going to 2 decimal places, as there are plenty of approximations)
So overdrawing to 30" gives a power stroke of 25"
25" x 1.52 pounds per inch = 38 pounds at our overdraw.
So the energy put into the bow is the total from zero at no draw up to 38 at 25". The average of 0-38 is 19
We can call this 19x25  = 475 pound inches. An unusual unit but it doesn't matter if we do the same for the other bow.

50# Yew with 6.5" brace height drawing 28" gives a 21.5" power stroke (28-6.5)
That gives 50/21.5 pounds per inch of draw = 2.32
Now under drawing to 27" would give a power stroke of  20.5"
20.5 x 2.32 pounds per inch = 47.56 pounds at our underdraw
So the energy put into the bow will be the average from 0 - 47.56 which is 23.78 times our short draw.
23.78 x 20.5 = 487.49 pound inches

Well there you go, the two energies aren't much different, the lady is getting 475 and the gents getting 487.49

Now if the lady manages the odd shot with yet another inch of draw while the gents are tiring, she could well out range them!
It would give a poundage of  39.52 and an average of  19.76 times the draw of  26"
That would be a total of 513.76 !
That really shows how a little extra draw goes a long way!

Also the lower brace on the Hazel adds extra power contrary to what you might think, as it increases the power stroke.

Sorry if that bored you all to death!
I s'pose I should plot a graph showing where the two lines of force vs draw for the hazel over takes the Yew, but I can't be bothered.
You can all do that for your homework! ; )

Update:- I found this old graph I'd plotted of a longbow vs my Asiatic/Horsebow.
It confirms that poundage starts from zero at somewhere near brace height (if you extrapolate the curves back to zero)


Monday, 29 July 2013

Club 3D Shoot

Had a great shoot yesterday.
My bows, glove bracer and tab were still in someone else's van from the Tudor shoot so I took out the 40# 'bark on' Hazel flat bow, and borrowed a tab. I was slow starting but got going after a while and didn't actually blank any targets.
The format was 10 x 3D targets which we went round three times. This worked out great on a hot day as it gave two brief snack and drink stops. It was quick to pack away the targets too.
Thanks to all those who set out the course and organised it.
Going round three times also gave a chance to improve on some of the tricky shots.

The course was cleverly set out with some shots that should have been easy but were deceptive, a badger partially hidden in a dip and a simple fox with a lot of foliage and Shadow making the range deceptive.
It was mostly in the woods with one walk across the sunny field for a shot at a Rhino (painted face on bales), once in the open the wind was fairly strong and into us/across which made it quite a long shot. Getting back into the cool woods was very welcomed.

I managed a respectable 393 (came 4th). Oddly I felt getting back to my full 28" draw seemed hard, maybe I was still a tad stiff from shooting the heavier bows on the Downs? It probably didn't help that I'd done a dozen or so pull ups at the Weald and Downland Museum, just 'cos one of the fit young guys had done it. (Will I never learn?).
I was shooting with a great bunch of guys and afterwards we stopped of for a pint on the way to collect my bows and stuff.
It was good to finally get all the bows, tools and equipment back with their rightful owners. I was amazed that we hadn't lost or broken more kit.
The final equipment tally was, two lost arrows, one broken. A lost piece of waterbuffalo horn and my white baseball cap.
But I'd gained a red flag which had been our clout target, a handy souvenir.

At the Tudor shoot I'd take my little 35# Hazel bark on bow in case any ladies wanted to shoot. The lightest longbow was 50# which was plenty enough for the blokes who weren't used to archery.
Now it could cause some argument and discussion as to whether it is authentic and in period... a thorny question, as it would be tempting and simplistic to say it isn't in period. Of course we can't prove it.
Absence of evidence isn't evidence of absence.
Bowyers had obviously made such bows in Neolithic and iron age times, were they still in use for hunting or as bows made by woodsmen, or a child's or ladies' bows? We can't say for certain.

Strangely that bow performed surprisingly well being better matched to the physique of the archer, it was also shooting much heavier arrows than usual (3/8" 32" 150 grain points and 5" flights).
Mind the poor thing was being overdrawn to about 31" without protest!
I suppose the reason is that 35#at 28" overdrawn to 31" ends up being very similar to 50# at 28" being underdrawn to 27". I'll have to play with the figures later.

After the shoot some of the other girls had a go and with a few pointers took to it with aplomb. A bunch of archers encouraging the girls to try their bows? Who'd have thought it!

I'd been in two minds as to whether I should take that bow, but was glad I did as it was a bit of a star.

Friday, 26 July 2013

Tired Out

Been away for a couple of nights doing the re-enactment and visiting family.
It all went off very well but was a long tiring day. At one point I was trying to get a longbow completed from floor tillered in two hours whilst not wearing my glasses! What could possibly go wrong?
All this was down at the Weald and Downland Open air museum http://www.wealddown.co.uk/ which is a great place to visit if you are down south, just north of Chichester.
We did some shooting too on the downs. The weather was glorious and the setting beautiful.
There was some clout shooting and we took some potshots at the anthills on a bank too, most enjoyable. Some passing cyclists on their way up the bridleway to the South Downs Way eyed us with some distrust, and seemed top pedal a little faster.
Afterwards there was a hog roast which had been organised as a thank you for all the volunteers who help out at the museum. It was a great wind down to the day and most welcomed as I was more tired and hungry than I'd realised.
I havn't really got any pics of the re-enactment as I was busy doing stuff all day, in Tudor costume too, which was too tight and rather hot. The felt breeches split round the crotch and the cod piece was rather loose, at least it meant some parts remained cool!
One thing I did manage to get a pic of was this hand cranked bandsaw! this charming pic of a deer in the barley too.

Tuesday, 23 July 2013

Bandsaw Birthday

The bandsaw has been having a tough time of it and I'd noticed it wasn't cutting true.
When I came to change the blade I noticed the lower blade guide had skewed.
Time for a good strip down, it turned out that nothing was broken, but everything was out of adjustment or seized up. Oh the shame of it, I must keep a closer eye on it in future.
I think it was sawing all that fresh cut Yew that knocked everything out of kilter and gummed up the little bearings that act as blade guides. I was pushing the limits of the saw and should really have stripped it down then.
It only took a few minutes to soak the bearings in white spirit to free them up and give them an oiling. Everything was then reassembled and adjusted. I'm prob' a bit naughty in not readjusting when I go from my wider coarse (3 teeth per inch) to my narrower finer blade too.
Anyhow it's running sweet as a nut now.

The Tudorfication process has been carrying on. I've made a Tudor Stanley knife from a bit of old bandsaw blade with a riveted Ash handle. The bandsaw blade is great, it's thin enough to heat up for hardening/tempering very easily and they are actually made with the back and front edges hardened where the teeth are and the back blade bearing can make contact. The centre is soft, so can be drilled for rivets. A 2.5 mm drill makes a good hole for a bit of wire coathanger, which is nice soft steel for tapping over as a rivet.
The Tudorfication has also extended to my face!
I've grown a rather scruffy little 'tache and beard .
I'm no oil paining, but with the bald pate and fairly tight cropped hair on the sides, it adds a certain je ne sais quoi.
Ok it doesn't have the menace of Ray Winstone, but it looks better than last time I tried it... lank shoulder length hair and a scruffy beard... not a good look.

Friday, 19 July 2013

Tudorfication of Stuff

I'm going flat out getting all my stuff looking medieval for a forthcoming demo/re-enactment.
There's more to it than one might think. I've had to drawknife out any bandsaw marks from all the timber and  put wooden handles on tools that had modern ones. My portable tiller tree has been rebuilt using a baulk of Ash all done by hand and a pulley fitted with natural fibre rope. I got a new pulley off the internet, but of course, it's galvanised, so I've had to burn that off out doors (Zinc fumes are toxic). Once it cooled, a rub over with beeswax polish and some peening on the ends of the pivot with a hammer makes it look good as old!
I'm also getting a bow up to the early tiller stage, I want it to look the part but to be a manageable draw weight.
You'd think it was easy to make a low draw weight bow, but this one thinks it wants to be a warbow. maybe the knots on the belly are making it extra stiff.
I've got arrows to make too, but I'll also be borrowing some decent EWBS spec arrows and a couple of my bigger bows from their owners  (thanks guys). The owner of one big bow, another guy from the club and another archer/bowyer friend will be joining in the enterprise to put on a bit of a clout shoot.
Making those arrows took some time (the 12th one is still on the fletching jig) If you assume 10mins to put on one fight and for the glue to dry. Three flights per arrow, that's half an hour per arrow. So 12 arrows... six hours! Of course you can do stuff in between and I could always make another two fletching jigs....
Had to cut the nocks by hand, get the points red hot to get the shine of 'em and glue them on too.

I particularly like the handle I put on an old padsaw blade (cut down and the teeth filed) It's an off cut of Ash riveted on. The big half round file has a handle made from the smashed warbow... seemed sensible to use what was lying around.

BTW. The arrow shafts are 3/8" Maple from Nidderdale Archery (sadly no longer trading) They come 34 1/4" long, These have been cut down to give 32" to the start of the point. Very nice shafts, tough enough to have a self nock with no reinforcement in moderate draw weight bows. I got 'em spined 70-75 and they seem to shoot pretty sweet. Still fairly heavy compared with my usual 5/16" !

Tuesday, 16 July 2013

Steaming and Finger Trouble.


The clingfilm seemed to do a grand job in keeping the wood dry as it was steamed. I shall definitely use that trick again.

I've been mad busy buying stuff online to make up some reasonably authentic arrows for next week.
I got some lovely Ash shafts from Nidderdale Archery. Sadly they are no longer trading so I have removed the link at a good price, and quick delivery.
BUT but I'd made the fatal mistake of changing my mind as I clicked 'buy' ('Finger trouble' as we call it in electronics design and test) and ended up with shafts 30" long when I wanted 34" (groan).
However they will come in handy for normal length arrows or crossbow bolts.
I tried 'em out anyway, and the 3/8" shafts turned down really nicely on my lathe, to give a taper point which takes the 11/32 taper fit Modkin points (also from them).
The shafts just fit down the spindle of the lathe with a slight push, and after a little fiddling I got the taper just right.

I've got back an line and ordered some more shafts... bit of an outlay but arrow shafts will always get used.


Monday, 15 July 2013

New Steaming Trick

I'm preparing a warbow length stave for a tillering demo/bowmaking re-enactment.
The problem is the only suitable stave was one I'd set aside for a character primitive and it's a tad wobbly.
the string line just about touches the edge of the bow at the grip giving it a tendency to twist on the tiller.

So... I'm steaming it to pull it in line. The new trick I'm trying is wrapping the steamed area in clingfilm to stop the steam and condensate actually effecting the wood so much. The heat will be there still, but the steam and condensing water hopefully won't touch the wood.
It's a shortish area I'm steaming, using my 5Litre plastic container to steam it in situ on the jig.
This earlier post post shows the arrangement.

Some people say steam dries the wood more than dry heat! Well I don't know about that, but it certainly effects the wood, the condensate will drip off red with the colour leached out of the Yew heartwood.
Let's see if the wood looks better, but still bends as well with the clingfilm over it.

I'm aiming for a 40-50# warbow length bow with a 32" draw so that it can look the part, but be manageable for someone who isn't used to drawing a bow.
It's not the ideal stave, but it does illustrate some of the quirks and problems of making a bow from a stave.
I'll report back tomorrow night, as I'll leave the bow jigged up for a day once I've turned the steam off.

Saturday, 13 July 2013

Bowstring Again and a Visit.

I'm getting stuff together for a Tudor bowmaking re-enactment and wanted some pukka Flemish twist linen bowstrings. No body could do 'em for me in time (2 weeks) !
So I set to and made one myself, bit of a pain but it didn't take too long once I'd got the loop done. I followed the instructions in the Traditional Bowyers Bible vol2 . It was rather good when done and waxed up, felt sort of snakelike. I tried it on my 68# longbow, it had very little stretch, much better than Dacron and the bowyers knot didn't slip at all, confirming my suspicion that it's slippery modern materials that make bowyers knots slip.

About mid day I had a visit from a lovely couple. The chap, who also makes bows had contacted me, having been following the blog. They were up in this area visiting and he very kindly brought me 2 lovely Elm 1/4 logs about 7' long which had been cut at their home in Devon. Excellent! There's not much Elm about and the last stuff I had was way back when we had that outbreak of Dutch Elm disease (in the late 1960s).
We got on really well, and while us gents were shooting the bows the ladies were enjoying a chat and a cuppa in the garden. The bows all had a good work out including the Chinese repeater. It was nice that the lady joined in and had a go with my crossbow pistol and watched the Chinese repeater as sometimes it's not of much interest. They stayed for a couple of hours, but I got the feeling that if they didn't need to be on their way, we could have opened  a bottle of wine and some pizzas and made a long lazy day of it.

This blog has been great for meeting interesting people and I've made contact with some lovely people, helped people out with materials and had all sorts of materials in return. It's a wonderful give and take which would have been virtually impossible without the internet.

Meanwhile I'm busily trying to research what tools would be historically accurate in Tudor times, the problem is that tools like rasps and files existed but would probably looked less uniform than the machine made modern equivalents... (Note to self:- Remove plastic handles ;) )

Thursday, 11 July 2013

Warbow Explodes

I'd rounded the belly a bit and cut second nocks so I could get a shorter string on it.
With the winch pulling the long string I had to take it to 110#  just to get the short string on at a very low brace.
I winched it back to about 70# and it looked ok. I thought I'd take it further. At 100# I heard a 'tic' the death knell of a bow (probably the back giving way).
Turn the sound up and you'll hear it, a split second later it exploded.
No point me pontificating as to why, if I have to guess I'd say the back wasn't perfect. It could even have been damaged when the up and over garage door jammed against the bow as I opened it... I neglected to check the back. Of course there are marks on the back now where it smashed into the underside of the door.
The good thing is the splice held solid and the lower limb remained in one piece.
This illustrates the point about a short string applying greater load than a long one.... I'd pulled it to 110# on the long string several times, yet it blew at just over 100# at low brace.
video



Checking the original videos I can see the tip deflection on the right limb with the long string was 3 bricks. On the short string it just about hits 4 bricks and then explodes.
Update:-
video
I've slowed down the video and there is a tiny bit of something or other that pops off from the centre of the back of the bow and flies off horizontally to the right when it goes tick, maybe it's something from the splice glue line on the back? It's certainly from the centre of the bow. You need to view it full screen.
The sound doesn't appear to be there but watch closely! (Maybe it's a UFO ?? ;) and Aliens caused it.
The video isn't hi res because it's compressed. I've studied the original and the break definitely starts at the grip. It probably is the discontinuity in the sapwood at the splice. This confirms my suspicion that a sapwood overlay over a splice is a good safety measure.
You could say I was working the bow too hard in the middle, but don't blame me! I left it slightly over size compared with the Mary Rose bow dimensions... nuffin' to do wiv me mate ;)
You can see from the stills that the crack has propagated along the length of the limb through the heartwood.
Studying the video closely I think the sapwood gives way in the centre, this removes the protection from the tension-weak heartwood which gives way and splits along the right limb, as it splits the limb flexes more and actually breaks at a second point about 2/3 of the way along that limb.
In terms of actual tip deflection it wasn't all that far from a full draw, which on a similar bow is only one more bricks worth of tip deflection.
I'm a bit disappointed, but I think the careful study of it has taught me a few lessons.
Further Update:-
I think I've found the culprit!
I reassembled the centre section and sure enough there is a sliver missing. It's not the actual join that was the problem, more the discontinuity where the sapwood has been rasped to match either side of the join, you can see the crack going from the missing sliver to the edge of the bow.
A thin sapwood overlay would probably have held it all together. Mind I couldn't overlay any sapwood because of the nice feature knot...catch 22!  c'est la vie.

A Day on the Warbow

8am:-
Filed grooves in the temporary nock overlays, tied on a rope and put the bow up on the tiller.
I winched it back to about 60#, not much movement.
Winch it back to 100#, I can see the right limb is flexing an few inches, the left is stiff. I need to work it down closer to the Mary Rose dimensions, before I can do any serious tillering.
The tips have pulled down about 1 brick on the wall (about 3 1/2") not enough movement to be worth videoing ...yet.
Note:- 100# on a loose rope is less stress on the bow than 100# with a tight braced string, due to the geometry of a tight string effectively giving you leverage.
Explanation/illustration:-
Imagine a steel wire clamped at each end taut between to walls 10 feet apart. You could pull down on the centre of the wire and get maybe half an inch of movement because you are pulling at 90 degrees to the wire. Now take the same wire and clamp one end to a solid immovable roof joist and pull straight down on the wire, you may stretch it it 1/100" but very little.

9am:-
Been over the lower limb with spokeshave and rasp measuring with vernier calipers. It's pretty much to MR (Mary Rose) dimensions +0.3mm -0
The dimensions given are from the centreline at 100, 200 400, 600, 800 & 900 mm. I spot check at those positions and blend in between them as I work it down. The wood and the spokeshave seem to like that graceful taper as some areas of pin knots which were tearing are cutting more cleanly now.
I've left the tips wide in case of stringline or twist issues. Break for tea and toast.

11am:-
Been over the upper limb and had it up on the tiller with the camera running. It's looking more like a bow now. I'll clean it up, round the belly a bit and check over the back.
Then it will be a matter of trying to get it braced... note use of word 'trying' it will be a bit of a struggle.
video

Monday, 8 July 2013

Hidden Knot

As I feared, the 'good ' knot soon turned into manky wood as I rasped down towards the required thickness. Note 'rasped' rather than used the spokeshave which I'd been using elsewhere. The wood round knots will snag and tear with a drawknife, spokeshave or plane, so a rasp is required. The needle file has been ground to a chisel point for digging out knots, the tape marks the depth of the hole.


The good thing is it doesn't penetrate into the sapwood or come out the side of the bow. I cleaned it right out down to good sound wood and filled it with epoxy and wood dust mix. I may peg it later as a cosmetic measure, but it's good to leave the natural flow of the wood rather than drilling an over sized round hole and pegging.
I recently saw a Yew warbow with some nasty pinches where knots hadn't been pegged and the narrow black line of manky stuff round the knot had compressed allowing the pinch. One knot had been pegged but the smaller ones missed... classic case of "spoiling the ship for a ha'p'orth of tar".

Here's a pic of the back too, work in progress, I'm slowly (and loosely)  following a growth ring from left to right you can see the lines of the rings running roughly along the limb. As the bow progresses this will get further tidied until it is fairly close to a single ring, or a series of rings running along the length.

The upper limb is about to dimension now, I've got to go over the lower one and get it a bit closer before I put it on the tiller.
I've glued on some wedges of Yew (offcuts from the splicing) to cut in temporary knocks. I'll just lash it with rope for the first try on the tiller, but I don't want to rush into it today.
Instead I got my wife to put one foot on the middle of the bow, one tip was on the floor while I held the other tip about 6" off the floor. She just about put all her weight on it making it flex nicely and the splice held firm.
I had asked what she weighed, but I was told a gentleman doesn't ask!
Good progress, but I won't spoil it by rushing.



.

Sunday, 7 July 2013

Whew What a Scorcher

Summer has finally arrived. I got lift up the club and gave the Yew Stickbow a try out, it pretty much did the job and would certainly have made an effective hunting weapon. It's a testament to the properties of Yew.
The field had been mowed and there were big bales of hay, we lobbed a few arrow at them clout style. It was a relief to get into the woods where it was much cooler and to shoot at the 2D animal target faces.

I've spent a fair bit of time on the Warbow tidying up the back approximately to a single growth ring, and one limb is about roughed out to dimensions. It does flex very slightly if I lean on it.
I'm not being over fussy at this stage. The rings don't run concentric to the curve of the back anyway, so there will be places where the rings show as lines running down the length of the bow.
I'm pretty much going to follow the dimensions from Weapons of Warre but keeping a very square section initially, then I'll put it up on the tiller and see what it does.
I'll probably add temporary tip overlays, maybe slivers of horn to protect the back at the nocks. I'll winch it back to a decent poundage before worrying about rounding it off.
There is one knot on the belly that doesn't go too deep, but is manky round it's core so I've dug it out and will peg it.
More worrying is what looks like very sound knot on the belly with an associated bulge on the back and a red/purple blush on the side, maybe there is rot lurking under there? The red blush can be a sign of hidden trouble.

Saturday, 6 July 2013

Warbow Splice

The splice has come out well, I've cleaned it up and I've looked through 'Weapons of Warre' to find a suitable bow to use as a reference. I've found Mary Rose bow 81A3960H which is described as "Big bow, handled, broken tip, squared, coarse grain " Being gripped and squared means it's pretty chunky in the middle which will give extra strength at the splice. Of course I won't copy the broken tip ;) . Its 2005 mm long.
The first pic shows it marked up and how one billet has been glued to an offcut of MDF to give it a flat stable base to help when running it through the bandsaw. The otherbillet had a nice flat face already. Last pic on the bottom right shows how the heart/sap boundary has lined up well, I'd llike to say this was carefull planning, but there is a fair bit of luck involved it trying to line everything up.

In the morning Paul who I'd met on the Archery Interchange website came over to try some bows. It was great to see a recurve target archer having a go at shooting primitive. I think it's good to try the different disciplines although I'm slightly abashed to admit I've not shot a sighted recurve. Mind this could be due to never having been offered a go with one, as I'll give anything a try. We had a fine time and gave the Chinese Repeater an outing to. Paul left with a Maple primitive which had been looking for a home and a few arrows.


I also heard that the Dogleg Yew longbow was throwing full weight medieval arrows all the way to the 180 yard clout, much to the delight of it's new owner.

Friday, 5 July 2013

Knots in Yew

I've been sorting through my seasoned staves and billets, I had one great fat knobbly Yew stave which might make a character warbow, but it had a huge ugly knot on the belly near one tip. If I cut the tip off it would be a bit short.
I decided to lop off that limb and use the good limb with another billet to make a spliced warbow.
Out of interest I sliced through the knot on the bandsaw, it shows how much rot can be hidden beneath a tiny pin on the sapwood.
Conversely I also sliced through one of the big knobbly features and found lovely sound wood!

 I've marked out the splice and got it glued and clamped. I'll see how it looks in the morning.

In the pic with the knobbly bit cut through there are attractive streaks in the wood radiating up into the knobbly bit. There's also a big knot going through it on the diagonal. I was pleasantly surprised that the knobby bit was sound and I've left one on the good limb which will sit just above the grip on the finished bow. I've done a 2 pronged Z splice this time rather than a simple V. More pics in a new post tomorrow.