Saturday, 9 December 2017

Awkward Yew Stave

Andy, the guy for whom I'd shortened the bow collected it this morning and was very pleased with it, we had a quick try out and he could feel the extra draw weight. We also shot the Chinese repeater and another couple of bows.
I've done some more heat work on the tricky Yew stave and it's beginning to look more like a bow, it's been a bit of a pain, but it will hopefully be a handsome bow eventually. Here's a pic of it at about 65# at 24" so it's coming along.
I took some video to show what I'd done:- https://youtu.be/8-Fk_YIYew4
The deflex dip just right of the grip makes it look weak there and the left limb is stiffer than it appears, as it has some natural deflex near the tip. There's a bit of a kink 2/3 of the way along the righ limb... other than that it's ramrod straight ;-)

Friday, 8 December 2017

Endless Steam Correction!

I got the re-work job finished on the Adrian Hayes Boo backed Ipe bow, I even found some polyurethane varnish to touch up where the tips had been re-worked. It looks very much in keeping with the original and is now 54# at 26"
I then got back to the English Yew stave which is rather S shaped, I've got it down to somewhere near draw weight but the tiller looks awful due to the shape of the stave. I've taken out some of the deflex and a hint of the reflex, and a bit more of the deflex and then some twist in one limb that was in
danger of giving no heart wood on one side and no sapwood on t'other. I'm now taking out even more of the deflex. The corrections get easier as each time there is less wood to bend as the bow has been worked down a tad. It often takes a few goes to get it right and the bow can settle a fair bit after being bent too. It's looking good but now has a bit of sideways bend ...beginning to get a tad irritating now, but patience is a virtue and I've clamped it up and done some dry heat near the grip with it pulled sideways by about an inch. The back was covered in masking tape to help keep the heat off the sapwood. I'll give it a few hours to cool down and have a look, some of the bend will spring out, if I've overdone it a little gentle heat will relax it back. It's tricky to get heat bends right especially when it's just half an inch over the length of a limb, all pretty subtle.
I want to leave some of the character, but I also don't want it to look off kilter.

At the weekend shoot there was a guy I'd made a bow for earlier in the year, I didn't recognise him at first due to his hat, but the bow seemed familiar. Once we got chatting it all flooded back, the bow has some character a bit like this one and is from spliced English Yew billets. The moor I saw of it the better it looked !

I've started on another project, a shooting machine for testing flight bows and arrows. I'm basing it roughly on Clarence N Hickman's shooting machine (pictured). I've got the bottom part done, but it's only really a prototype out of scrap timber to get an idea of how I'll build the final thing. Not sure if it will stand up to shooting a warbow.
I sometimes get people asking if I have plans for stuff, but I rarely draw plans... I can visualize things to a point, but I soon find that I need to work in three dimensions to see and feel how things go together. This part of the machine virtually designed itself once I'd hinged the first two bits together, but to try an draw it on paper or hold it all in my head was almost impossible.

There's still a lot to do and I may have the bow mounted either horizontally or canted at a bit of an angle. The trigger mechanism isn't a problem, but I'll try and make it simulate the archers fingers. I think a good firm but flexible mount for the bow may be one of the surprisingly trick bit.
I'm in no rush with this and it's a fun fill in project which could provide some interesting insights into making better flight arrows for next years forays into flight shooting.

Monday, 4 December 2017

Last Shoot of the Year


I went to the ILAA Windsor Great Park shoot on Sunday with my mate JT in his new(ish) Landrover. mmmm warm seats, nice.
We were lucky with the weather but I stupidly wore my Summer boots which are "water resistant" and we all know that means they are about as good as a sieve. There was a good turn out and much passing of hip flasks, great to meet up with everyone and I even managed a handful of scoring shots. I'd taken 5# off my Hickory backed Yew bow to make it more manageable, I was drawing 28" all day, but took it out to 32" for the flight shot at the end with a new arrow that I'd made the day before and it produced a creditable distance, up hill in damp conditions (about 250 yards).

One of the guys there was talking over his Adrian Hayes bow and saying that he is drawing shorter now due to injury and could do with a bit more poundage. It's an interesting looking bow, lovely and narrow with a Bamboo back Ipe belly and some other wood in the core. It's lovely and slim, as I've not worked Ipe before I offered to take an inch off each tip which should give him another 5# without over stressing the bow as it's now being drawn shorter.
I bought the bow home and took a quick bit of video to see what it's doing at present.
The right limb looks maybe a tiny hint weak and it's drawing about 50# at 28" and about 45 at 26.5"
Of course it's hard to measure that accurately due to parallax errors etc, but at least I've got the "before" shot... Just realised, I hadn't adjusted the rule to allow for the slightly thinner bow, but the odd 1/4" isn't going to make much difference.
I'll take an inch off each end, put on temporary knocks and see how it looks before re-nocking it.
Update:-
I've cut about an inch of each limb and glued on temporary nocks, the string has been threaded through my magic string adjusting ring to shorten it and I've had it on the tiller, it's about 53# at 26" now! So I'll have another look later to double check the tiller and measure limb lengths and then fit the nocks, I may bring the actual nock grooves in another 1/4" on each limb, but I don't want to over do it.


Meanwhile I'll also be working the Yew stave to see if it needs a bit more steam correction.
My replacement camera arrived this afternoon, very clean and it tests out fine. The old one had a small scratch on the lens when I got it off E-bay, this one is perfect, and now I have 3 batteries. there was no software disc with it, but of course I have the software on the PC from the camera. Result!
Dunno if I'm allowed to use it until Christmas tho' as it counts as part of my pressie from my better half.

Friday, 1 December 2017

Waggly Yew ELB

I've started on the English yew ELB, looking for 63# @28" it's rather waggly and first time on the tiller it looked just too weird with a deflex region looking like it was doing all the bending, a bit of an optical illusion I think. Anyhow I resolved to steam out some of the deflex to make it more manageable. The difference is quite subtle but if you click between the two pics you should be able to see it. In the bottom pic (after) the left tip is about an inch further up. Before the steam bending I could put the tips on the floor (back uppermost) and get two or three fingers under the grip, but now I can't.

I was thinking of a new camera for Cristmas, but I found one on E-bay, the same model as the one which I messed up only £40, that's the great advantage of buying the old models, you get good value for money and at that price if it gets full of Yew dust again it's not the end of the world.
I was chatting to my brother about the camera and we wondered how the dust gets in... then it dawned on us. As the lens telescopes outwards, it will be drawing in the surrounding air acting like a bellows as it comes in and out! If I have the same problem again I'll make up a jig to hold the centre section of the lens firmly so that I can replace the outer one without pushing the assembly back in on itself and screwing it up.

I'm also re-working one of my longbows, a Hickory backed Yew, it's the only one I have that's tillered out to 32" and it's a bit of a handful for a long days shooting in cold weather.
I'm hoping to go to the ILAA roving marks shoot in Windsor Great Park on Sunday, so I'm working the bow down from 60# at 28" to about 55# that should be more comfortable and if I warm up I can take it back to 32".
Most of the work is rounding the back some more and reducing the width. There are a couple of pinches on the belly so I'm leaving those areas alone. Hopefully with the narrowed tips it should still be pretty quick. Many backed bows have backs that are horribly flat and square cornered and a bit of rounding can improve the look and comfort in the hand greatly, without jeopardising the performance.


Wednesday, 29 November 2017

Damn


I was testing the re-worked prod on the tiller and the back gave way! It cracked gracefully rather than exploding, which is good as the scale stayed on the string rather than crashing to the floor and needing a rebuild.
I thought it was being videoed, but I hadn't set the camera correctly... grrr, that's 'cos I'm back to using my old Kodak Z1012IS and I'd forgotten how to start recording. I've gone back to that camera due to me rendering my Canon "M.B.R" (mended beyond repair)!

I saw a You-tube vid showing how to get the outer lens element off for cleaning out the dust (it had a ton of Yew dust in there). Hmmm, it came off ok, but I couldn't get it back together!... mind it was an E-bay purchase anyway and had given good service.
I could possibly have mended it, but my eyesight isn't what it was, I don't have the tiny screwdrivers and I'd be doing it just to prove I could, rather than because I wanted to or needed to! So I decided to bin it rather than wind myself up... My Dad could have done it in his heyday as he used to mend cameras as a paying hobby, he's no longer alive, but it brough back some memories.
Just as well Santa will be coming shortly!

The mistake with the prod was cutting out the bamboo backing with the grain all running dead straight instead of bending strips to make the grain follow the curved shape of the bow (as viewed from the front or back).
The main thing is I now have a good idea of the necessary length and thickness to reach my target draw weight. Just got to build it with some care and attention to detail
Bit of a shame really as I'd done the work on the mount, but it just means it's all ready to go once I make the new prod... that may have to wait a bit as I'm a bit fed up with crossbow prods and I haven't got any decent Yew off-cuts for the belly at the moment.
Other than all that, things are going swimmingly!
I'll pick up the Yew bow from the English Yew which was brought round a few weeks back.

Tuesday, 28 November 2017

Crossbow Prod Mount



The crossbow prod has had the bamboo planed off it, about an inch of Elm spliced onto each tip and a new bamboo backing glued on with about 1.5" of deflex. The spliced tips are curved  towards the back in a tiny reflex this allows a stringer to sit near the tips as an aid to stringing.
I've had the prod on the tiller braced (about 2.5") and drawn to 100# at 12" . I'm hoping for 14", but didn't want to push my luck before I had it mounted on the bow.

I've made the prod mount and did a quick dirty tryout with the prod bound in place with a bit of rubber strapping. The final fixing will have leather between the prod and the aluminium and will be bound on tight with 4mm rubber cord (which may be replaced with rawhide eventually).
I may glue some this pieces of wood or bamboo on the top and bottom edges of the prod to help locate it correctly.
The vertical parts of the mount either side of the track may be used to mount rubber bump stops/ string catchers, enabling a low brace and longer power power stroke.
Nervy times as I don't want to do all this work and have it smash, and even if it does work, how fast will it be?
Just as well I enjoy all this!

If all this works, eventually I'll get to work on the proper stock made from some decent timber.

Wednesday, 22 November 2017

Prod Failure Mode

The experimental crossbow pod is too strong. To reduce weight, improve the tiller and increase draw I've been reducing the width, however it came to a point where the back was too stressed and it popped a splinter with a satisfying "crack!"
Of course the splinter started at a node and I can see that maybe I'd rasped down the node a bit too much. The fibres seem to flow up at the node and as I peeled back the splinter it ran up and out of the bamboo at the next node. This gave me the idea of stripping off the bamboo and re-backing the bow. It might be another iteration of the design before a completely new version. After all it would be good to see how far I can get it back at 120#

I've learned enough from this to make a better version, a tad longer, some built in deflex, a bit less core thickness, and a thicker Yew belly to allow removal of wood from the belly for tillering rather than making it too thin in the limbs.
the final test before it broke got it to a 10" draw (measured from the belly) at 120#  which would extrapolate to about 168# at 14" . Ideally I want 120# at 14" draw at 120#

Now I have a better idea of dimensions I can cut my various components for the prod closer to finished size.
To have the prod still in one piece is hand too as a pattern.
Update:- As I started planing off the bamboo it occurred to me that I could try it again. I'd rasped the limbs such that the back was narrower, and as I planed some off I found the back was returning to it's wider dimension. I sanded it up on the belt sander and gave it another go, getting it back to about 13" at 90# . All very promising, the outer fibres of the bamboo are the strongest, but maybe going down about 1mm still leaves decent material, and maybe the back and belly strength is better matched... mind it could all just mean it performs sluggishly.
Anyhow it's all good dimensional info for the mk2 . I'll clean it up further and try for the 14" draw!

Monday, 20 November 2017

My Project List

I've got lots of stuff on the go and I'm feeling invigorated. A sunny morning lobbing arrows can do that to you. Especially when you realise one of the fields had a decent length for flight shooting.
I'll write it as a list.
1. Yew longbow bow to make for a chap who bought a stave over a few weeks back.
2. Working on a "shoot through" crossbow prod:-
https://www.youtube.com/watch?v=tvkro2HlNJg
3. Heat treat and re-work an experimental Yew flight bow which was made from dodgy spliced billets which had weird bands of alternating heart and sap wood. It should be good for testing flight arrows.
4. Build a shooting machine for testing flight bows.
5. Build Yew flight bow from a good quality Yew stave, looking at about 90-100# @28" from a short stave. Hard working and fast... in theory.

I've got the prod to a 3" brace now, it needed winching back to 150# on a long string to get it braced! It's been pulled it to 110#, the tiller isn't right yet as it's working most in the centre. If I get the outers coming round I'll increase the draw length at that poundage.
I didn't want to pull it to 120# until I have improved the tiller.
I'm opening out and lengthening the slot between the limbs. There are effectively 4 limbs, so I'm trying to get each one nicely tapered.

Update:- Worked on it a bit as described above, it looks more elegant now, but still needs to work more in the outer limbs.
I've pulled it to 130# thie limbs look more even and it's coming back further. I need to get the string off (not easy!) and see if it's taking any set.
I've certainly learned enough to make a better version already.

On a different subject, I've noticed I seem to be a bit susceptible to dust these days having had two periods of an irritating dry chest cough this year. I can't definitively attribute it to Yew dust, but I'm wearing the face mask when sanding now. I don't bother when using edged tools, but I noticed that just doing a tiny bit of sanding on the crossbow prod kicks up a good deal of dust.
Allergies effect some people more than others and they can switch on or off for no apparent reason. It could just be dust in general and the bout earlier in the year could have been pollen related, but I'm trying to get into the habit of always using the dust extractor when using the bandsaw or belt sander, and using the mask if sanding (especially Yew).

Monday, 6 November 2017

Warbow Tiller Sequence

The bow is virtually finished, and following the comments from the previous post I'll discus it further.
I've added the final pic to the sequence and you can see how once it's braced there isn't much further to pull it back, and yet a little careful work evens up the tiller.
It's frustrating that one guy on a Facebook page got himself to this stage making a warbow, but couldn't seem to follow it through to the finish. I suspect he was taking poor advice that was easy rather than adopting a disciplined approach.
To get that sequence I took at least 7 videos and had it up and down on the tiller about twice that, it isn't quick or easy despite what some will try and tell you. Well, to be fair, maybe with the perfect stave you can get a reasonable tiller straight off doing it by numbers, but it will be at a
random draw weight.

Trying to see how much that reflexed left tip is moving is rather difficult so I taped a spill of bamboo to the limb just inboard of the knot to see how much it moves between brace and full draw.

The final pic shows the overall set, which is very little.

Sunday, 5 November 2017

Horn Nocks On and Improved Tiller

I've got the nocks on, slimmed the tips and improved the tiller it's now coming back a bit further (almost 27"). Not quite full brace yet. I'm starting to scrape out the tool marks and clean off the pinkish under bark where it hasn't popped off on it's own. Doing a little more fine tuning the tiller, get the tips (esp' the left) round a tad more and
It's taken a hint of set from the original stave so it's only slightly reflexed now, it's beginning to look very handsome now.

Saturday, 4 November 2017

Long String On the Tiller

I'm making a 110# warbow from Austrian Yew that I've had waiting for my attention for some months. It's a tricky stave with reflex at one tip and deflex half way along the other.
On one of the Facebook groups there has been someone having trouble tillering a warbow so I thought I'd take regular pictures (captured from video) to help show the progress.
I also wanted to test an observation from one of the hugely respected guys on Primitive Archer (Steve Gardner aka Badger), which is:-

If you have a "long string" that will just slip onto the bow and only dangle down 6" you can read off draw weight and length from that and it will closely tally to the draw weight and length when braced.

It's too easy to take everything one is told as fact, that would be fine if everyone was reliable, the problem is there are a lot of well meaning armchair experts out there. Of course Steve isn't in that category, but seeing is believing, so I did the test.

The top pic shows the stave with no force on it in the upper image, each subsequent image is at 110# on the string that dangles 6".
The final seperate image is with it at a 5" brace pulled to 110#.

It's an absolute pig to get the bow strung and I was having to winch it back to a full 110# on a very long string to give me room to get it braced, and that's where the confusion can lie as the very long string comes back a huge distance because it is dangling down a foot or so.

Right, so in the composite picture, the lowest image shows it at 110# at 24".
I braced it (slightly low about 5") and with some trepidation pulled it back gradually increasing the weight (video running of course)...
At 110# it came back just under 25" which is pretty damn close and very useful.


The moral of the story is:-
1. Make sure you long string only dangles 6"
2. We are all still learning!

There is a slight caveat here, when you have it braced, don't just heave it back to full weight if the tiller isn't good, as the bow will be flexing a bit more than it was on the long string. If you study the pics, you'll see the tips are coming back about an extra inch.
You'll also see that as it's coming back 15" I only have 5 more inches to get the tiller sorted!
That's the rub with a warbow, by the time it's braced you're almost there!
The final pic showing drawn and unstrung together helps to show how it's bending and where I need to take off a little wood. The deflex area middle of the right limb isn't bending enough and the entire right limb is a bits tiff.

Tuesday, 31 October 2017

Roughing Out Some Staves


Had a guy come over on Saturday with a log he'd cut about 4 years ago, I'd made him a bow previously (Ridgeback) and he wanted me to make another. From the pics he'd sent the log didn't look too promising, but once I'd trimmed off the end an had a shufti, I could see one clean face with a bow in it. There is still one iffy knot, but most of that will disappear (see pic)

After he'd gone I ran it through bandsaw and there were some troublesome areas where one growth ring had been damaged/rotted, maybe by fire, lightning, rubbing against another branch or just bad weather. Fortunately it was fairly near the centre and by the time I'd got the save roughed down the bad ring had been cut away.

The other two staves are Austrian Yew cut from a rough half log that was bought at a bargain price by one of my friends in expectation of one good stave and maybe a skinny second. Again there are some splits and shakes, but careful laying out has produced two warbow staves, they are a tad on the short side at 73 and 74" (bearing in mind I like to have a couple of inches spare on a stave), but the bloke isn't very tall and has a 30" draw so they should be ok. It's hard to tell which is actually the best stave so I'll probably work 'em down together and see which is 100-110# and which is good for a bit more.

The paler English Yew stave is prob' going to be about 60# but I've got to discus what's required.
It's good to have a few staves ready to work on, and I've actually got a spliced Yew one as well. I tend to think of this time of year as bow making season, as there's now't much going on in the garden. I'll be thinking of cutting a couple of Hazel staves too with my mate JT, who's going to try his hand at bow making early next year.... I'm sure some beer drinking will also be involved.

I went over to Cloth of Gold as a guest of Mick the Blacksmith on Sunday, had a great shoot around in good company, we weren't scoring and did 18 targets each from two different pegs, so I shot a good few arrows. My shooting seemed back to normal and I made a few decent long shots too. Probably my last outing of the year as it's getting colder, although I might manage the ILAA at Windsor if the weather's good.

Friday, 20 October 2017

Oh Bugger!

It's times like this you wish you hadn't left a tap dripping all yesterday morning!
 I had to spend a good deal of time mopping up the garage floor, fortunately most of the boxes on the floor are plastic rather than cardboard these days. A dustpan and brush got up a good deal of the water, and I have plenty of sawdust to help soak it up.

Next irritation was my bandsaw blade breaking, now this was a 1/4" 4tpi blade with extra set which my mate Stuart had bought as a thanks for the bandsaw usage and stuff. It's a blade configuration I hadn't used and it turned out to be very good, cutting nice and straight. I'd imagined that a wide blade would cut straighter but I found the narrower blade better, also good for following curves. (my other blades are 1/2").
The blade is still pretty new and V sharp so I was reluctant to bin it.

There are plenty of Youtube videos on brazing broken blades. This blade had broken on the weld, but I don't think it was a manufacturing defect, more likely due to me cutting odd shape 1/4 logs freehand.
I had an off-cut of Dexion which made a handy guide to clamp the blade to. I just sawed two slots and bent a section out of the way, cleaned up the sharp corners with a file and the jig was ready... only problem was finding the flux and brazing rod. I really must make another draw for welding and brazing supplies.
The ends of the blade were chamfered on the belt sander, coated with flux and carefully clamped up on the jig.
I think the brazing rod I have is quite a high melting point as it didn't want top flow at first, but once the joint was really glowing bright yellow it suddenly flowed. A bit of careful filing and then I tried it on the bandsaw, it clicked a bit as it went through the guides so I put a small grind wheel in my electric drill and lightly ran it over the sides and back of the join. It now runs lovely and smooth, good job all round, taught me a new trick and I have the jig for next time.
PS.
Here's a pic of my G-clamp nest, a couple of old shelf brackets screwed to the wall and it keeps 'em all handy and tidy.

Thursday, 19 October 2017

Sawing Some Yew

I've had two 1/4 logs on the garage floor since about January and I trimmed them down a bit the other week. I've taken them down further into 2 big slabs which are wide enough for warbows and some useful off-cuts.
The wood isn't as good as I'd hoped, there is a lot of blueish discolouration in the sapwood and the sap/heart boundary is all over the place even by my standards, I think it's just too undulating, so what I'll probably do is cut it into heartwood staves, billets and slats for use in bamboo backed Yew bows or crossbow prods or experimental work like flight bows.
I won't be too hasty as it requires some thought to make best use of the wood. I dare say plenty of usable yew gets discarded because it's not perfect... and maybe this is what some people mean when they say English Yew is no good, of course the point is I'm sure you could find similar gnarly wood from anywhere, one is simply limited by choice...
What's the best Yew? The bit that you've actually got!

One pic shows how the heart sap boundary doesn't follow the rings. This Yew was fairly large diameter (about 16") rather than the ideal pipe straight 5 or 6" diameter we'd all love to find.

Wednesday, 18 October 2017

Now't Much

I took the tri-lam and re-tillered Twister to the club on Sunday. I shot about a dozen from the tri-lam, not worrying about getting a 28" draw, just shooting as I normally wood (about 27") at the big practice boss from about 25 yards or so at a scrap of paper in the centre. It seemed nice and smooth giving a reasonably consistent group, a tad left of the paper but a nice vertical line of arrows. I was just banging 'em out quick to give the bow an extra few arrows.
I then picked up Twister which had disappointed me a few weeks earlier when it had felt stiff and unyielding. That's what had led me to re-tiller it.
I was a good 25 yards or so from the target. I pushed out my left hand drew, and... thud 1/2" left of the paper... Drew and thud, 1/2" right of the paper... Drew and clatter as arrow number 3 hit arrow number 2 .
Yup, that's how Twister should shoot. My confidence flooded back and I joined the guys to shoot about 7 of the 3D targets with a good degree of success.
I took my leave feeling much happier, I didn't want to over do it as I've been getting a lot of neck stiffness when I shoot, and it's a wise man who knows when to quit.

I've not started another bow yet, just waiting for the urge to hit me, I've been giving the lathe a good clean and adjust and reading some pap sci-fi on my kindle. Those damn Zarlacks keep jumping out of hyperspace into the summer house while I'm in there reading with Emily the cat on my lap. Must transfer power from my old car battery to boost the shielding...

Thursday, 12 October 2017

Re-Tillering "Twister"

Now re-working Twister is at first glance verging on the unthinkable, as it's been my fave' bow for years (made in 2011). On a good day I knew I could punch out my left hand at a target and I'd hit it.
Recently though I'd been toying with taking off a little draw weight, also my draw length has dropped a tad and is nearer 27" than 28".
Having been shooting in the tri-lam longbow at a good 28" draw, I realised that twister by comparison felt "stacky", that's to say I'd get to about 26" draw and it then felt stiff and unyielding instead of lively and supple.
Over the Years Twister has taken a little set mid limb (more on the lower) but is still good by my test of putting it belly down on the floor (unstrung) and seeing how many fingers you can get between grip and floor. One or less is good, which is how Twister is. Two is ok, 3 is poor. It was a superb bow, but maybe the two of us aren't quite what we were, so I thought I'd ease off the outer limbs a tad and maybe that would make it feel smoother, take some stress off the mid limbs and ease off the draw weight.
To get myself in shape too I've rasped a bit off my belly ... just kidding... I've re-instated the dozen push ups night and morning.
Unfortunately I didn't take a pic before doing any work, but this first pic shows the tiller after I'd eased off the tips a tad and lost a few pounds. It's at 40# at 28" where it probably started out and nearer 45#.
You can see the tips are stiff and it's bending quite hard mid limb almost in the style of a Mollegabet bow with stiff levers for the outer third. The two circles (or ellipses as they may not be exact circles) are quite tight radius and I'd like to see the stress spread more along the whole limb. It must have been worse than this before I eased off the outer limbs.

I've heat treated the mid section of each limb with the limbs strapped down and a slip of wood about 4mm thick under the back where the set was. That effectively pulls it into the merest hint of reflex so that when the heat treating is done and the strapping off, the limb is about straight.
It's now about 40# @ about 24" which gives me some room to re-tiller whilst keeping a decent draw weight. I think what I need is about 40# at 27" and I'd like the bow to have it's original speed and feel.
I've done a little more work now and actually shot it. Here's an after heat treating both pulled to just over 27"
The curve is looking much better and I've ended up pretty much where it was when first made about 45# @ nearly 28" , I've shot half a dozen arrows and it feels smoother and faster like it's old self.
The difference in curve is pretty subtle but if you look at the chalk marks on the wall behind the right limb you can see in the "after" picture the limb is nicely on the curved line whereas in the first pic the tip is pulled inside that line with more of the bend in the middle/inner limb.
I'll probably quit while I'm ahead now!
Maybe this last pic shows the difference better, I've done the 2 ellipses and this time you can see they are flatter and the tips conform to the curves better.
Finally another try to fit ellipses as well as I can, this one shows the right limb having a slightly tighter curve, which is fine as generally you want the lower limb a tad stiffer.
Right you can plays spot the difference now!

Friday, 6 October 2017

Spine Measurement

Well we all know about spine measurement... or do we?
I've made a quick and dirty spine tester, having noticed one rogue arrow, and using my digital verniers to measure spine is a right fiddle.

A while back on an archery forum on a post regarding how point weight effects spine I made a comment that infinite point weight would effectively give zero spine! e.g If you take a warbow to full draw, put the arrow point against a brick wall (which approximates to infinite weight) the arrow will just explode when you loose (e.g it will flex infinitely).
This was tongue in cheek, but was to illustrate a point and demonstrate a way of reasoning by extrapolating to extremes.
Well some bloke "corrected" me and said I meant infinite spine.
It became apparent that the target archers way of measuring spine to AMO standard is the opposite to the traditional wooden arrow way of measuring spine!
Now this is what is technically known as bloody stupid, however I'll let you decide the rights and wrongs.
The tradition way is to support the arrow at two points 28" apart. OR any other convenient distance, and this is important for shorter flight arrows. You hang a 2 lb weight on the middle of the arrow and measure the deflection in inches. You divide the distance between the two support points by the deflection in inches. (This automatically compensates for differing support distances... clever eh?)
E.G. If we have the supports 28" apart and we get 0.5" deflection that gives 28/0.5 which is 56
So the spine is 56, this number bears some rough relationship to the bow poundage for an average bow.
Note:- as deflection of the shaft increases the spine reduces, so 1" deflection would give 28/1 = 28 spine.
The spine figures are not linear, this shows on the uneven spacing of the scale. Also note, for convenience I've used 26" between the supports.

As far as I can tell the AMO method simply measures the deflection in thousandths of an inch with an 880gram (1.94 lbs) weight applied using a 29" shaft with supports 28" apart.
Has this annoyed you yet? They are randomly mixing metric and imperial and I have no idea what the 29" shaft length is about!
BUT the most worrying thing is they are just measuring deflection. Why does this matter?

If you plot  distance between supports divided by deflection (x) as a graph y=28/x you get a curve and as x gets bigger y gets smaller.
If you plot simple deflection y=x you get a straight line and as x gets bigger y gets bigger...
So the AMO spine runs the opposite way to the old method, bigger number is weaker rather than stiffer!

Now which is right?
Not for me to judge, but I'll just mention that  bending stiffness of a beam k=p/w Where k= bending stiffness.  p = force.  w = deflection

Oh, btw, my 2 lb weight is just a carefully calibrated bag of pebbles :-)

Wednesday, 4 October 2017

Trilam all Done


I've got it finished and over 60 arrows through it (I'll take that up to 100 before final waxing). I've just had it on the tiller and it's almost 50# which is odd, as it looked more like 46# the other day, this illustrates the difficulty of getting good data. The camera is mounted about level with the bow so is effectively looking down on the string at full draw giving a parallax error. Whereas if I sit down to pull the rope my eye is about level with string at full draw removing that error, so in reality it's a tad over 47# generally it's prob' sensible to give draw weights rounded down to the nearest 5# as a bow is likely to settle a bit rather than gain weight (unless it starts off not fully seasoned).
It's been interesting shooting the bow, the arrows seemed to wag their tails rather, but a little work around the arrow pass and inlaying the Abalone helped. Then I got suspicious that maybe there was one odd arrow, so I marked the one that flew high and right with an inconspicuous dot. Next five arrows, sure enough, one waggled off right, when I looked, yes it was the same arrow. Maybe that accounts for some of my poor shooting at the last field shoot as it was marked as a number 1 arrow.
I shall try the same test with my field bow and see how that throws 'em, I suspect the effect will be
slightly less marked as that bow is prob' a tad slower.
In terms of feel the tri-lam is lovely, it feels like it would draw further just as smoothly and I've been making sure to shoot it from a good full 28" draw which is extending me slightly. It's good to be shooting more as it seems to be helping the tennis elbow and shoulder niggle. I've been doing push ups night and morning, at least 10 and 15 or so if I'm feeling bouncy.
Couldn't resist adding the pic of the grip again as it is so gorgeous :)



Friday, 29 September 2017

Tri-lam Nearly There


The outers still need to come round a bit more.
I'm mostly adjusting the tiller by rounding off the corners, so the inner third is a sort of rounded rectangular section and as you move up the limb it gets narrower and the belly gets more rounded until at the tip it's circular as it goes into the nock.
Since that pic (shows it at 27" ) I've had it back to 28" from a full brace, I've also blended in the riser block a little more so it looks a smoother transition from riser to limb.
It needs the proper string making and then it's on to the pretty stuff. I've given it the first wipe of Danish Oil this evening so tomorrow I can pore over it taking out any remaining tool marks. Then string, arrow plate, grip. Maybe I'll get a load of arrows through it on Sunday to confirm the arrow plate position before doing that.
I'm not usually one for going bonkers on the finish, yes, I want it good and my standard is probably pretty high, but on this one I'm going for broke.
If I can find the right materials I'm trying for a top notch finish. Mind there are limitations with the wood, a few belly knots and the residual marks from the heat treating of the Yew billets before it was glued up, but hopefully I've dealt with them in an appropriate manner and in any case you want some character in a bow...
Right gotta get out the sub-aqua gear and fly off to South Africa to wrestle some Abalone for the arrow plate .... or maybe E-bay has some?
Need some Unicorn tail hair for the string too ... anyone know a good source?

The pictures don't really do it justice as it's hard to photograph something long thin and shiny! This is just the first stage of finishing too, anyhow  a load of perfect lams machined and glued up with robotic precision would be soulless.

Just to give an idea of scale, where the top limb enters that nock it is 10.65mm diameter, that's why I've left the pics small.
Also note the top nock is shaped to take a stringer above the string groove and the lower nock has one big deep groove which will accommodate both string and stringer.
Should get the final full draw vid/pic tomorrow, unless I get called up for sliding wardrobe door fitting duty!
Update here's the grip and arrow plate:-