Friday, 29 November 2013

Flight Shoot Arrows

On Sunday there's a roving marks and flight shoot in the Deer Park at Windsor (Longbow only)
Roving isn't my fave' but I can't resist shooting in Windsor Deer park with the castle as a backdrop.
I've not done a flight shoot before so it will be good to get a measured distance under my belt.
I was thinking of taking the short bamboo backed Oregon Yew longbow for the flight, but the ILAA who are holding the event don't allow bamboo backed bows in the flight shoot as they feel 'boo gives too much advantage.
So, I'm tweaking up the Elm warbow and making 4 flight arrows in the hope of getting a decent distance.
I've got the first arrow made and it looks the part 661grains in weight, tapered front an rear (barrelled) with a very small nock and 1" x 1/4" flights. The shaft is 3/8" Maple with a Waterbuffalo horn strip glued into a slot at the nock end for reinforcement. The point is a 5/16 field pile turned down to blend in with the taper.
The two arrows shown are have the same shaft material.
I need 4 arrows so I'll probably vary them a bit and see which flies furthest.
Unfortunately I have nowhere to test them before the event other than my 10 yard shot into the garage and my aerodynamic freefall range... that's where I lob 'em up in the air in the back garden and see how they fall!
I've just tried it from 65# bow at 32" draw and it hit the target slightly sideways, flying a bit stiff, which means it's prob ok from the 100#. The other arrow in the pic' flies well from the 100# so it should be ok, as they are made from the same material. I'm not sure how to finish the arrows, I'll probably go with a wipe of beeswax polish as it's quick, easy and buffs up well. Any finish applied with a brush is liable to end up less smooth than simple wax and buffing.

It transpires that they will allow bamboo backed bows in the flight shoot as it's not a championship event
... but' I've started now, so I'll stick with the warbow and 32" flight arrows.

Ah! Testing... theory vs practice. Ignorance vs experience vs guesswork.
Flight is totally new to me, but of course I've read up about it. I'm assuming we want the arrow to straighten up as quickly as possible, but without the big drag of large fletchings.
I tried the arrow at 10 yards from the warbow and it's hitting the target at 45 degrees! the other arrow in the picture hits pretty much straight, but of course it has great big fletchings.
To see if a weaker spine is better I tried a 32" 5/16 shaft (prob about 45-50 spine) with a 100gn field point. It hit the target dead straight. I then cut down the fletchings and tried again... unfortunately I was tiring and managed to shoot the front light of my bicycle which laziness had stopped me taking out of the garage... after all, I'm hardly going to miss the target, am I?
So the upshot of all this is I'm going to end up making 4 different flight arrows, so I can see which goes furthest. I've also got a headache and an ache between my shoulders now!

Monday, 25 November 2013

Yew Stick Longbow

The longbow from the Churchyard Yew is progressing fast. I roughed it out on the bandsaw and it flexes when I lean on it. There is much less wood to remove than with a great stave from a quartered log and nature has started the tillering of the narrowest end already.
For a brief moment I didn't know what to do next as I was seduced by the trappings of the modern workshop. Ah! drawknife and shave horse... Bliss!

It evoked memories of childhood making stick bows from Hazel, but now I'm armed with better tools, knowledge and more muscle power than that 12 year old.
No less enthusiasm though!
The Yew is a joy to work, the centre pith is clearly visible in the outer limbs. Some of the knots in belly and edges are disappearing under the drawknife already, those on the back are old and dead but fairly central. I'll leave the back completely untouched and hope that nature has swelled the sapwood sufficiently around those knots. Plugging knots on the back probably has little value as they will be in tension, but I may well dig them out to explore how deep they go towards the belly, I don't want any pockets of rot or cavities which may collapse.
Once the bow starts to move I'll scrape off the bark or maybe just let it pop off.I'm really enjoying the freedom of working this bow, it's beautifully straight but has lots of interesting features to work around. I do have a target of it being a 90# warbow about 80" long with a good full 32" draw. It may not become that bow, but it is always good to have a target.

I'vedone a bit more this afternoon and exposed some ccraks and a black line of rot at the tnin end where the bark had been rubbed away. I'm hopeful most of these will get removed as the stave is worked down.
As I lean on it hard to flex it the bark is cracking and popping off.


Sunday, 24 November 2013

Churchyard Yew and some Shooting.

I've heard assorted daft opinions and generalisations about English yew and Churchyard Yew.
The cutting of the Yew is blogged here:-
http://bowyersdiary.blogspot.co.uk/2012/11/variability-of-yew.html
Any wood needs to be viewed on it's own merits.
One piece of the Churchyard yew would probably be dismissed by most people (and was almost ignored by me), yet look at this picture of the narrow end which has been trimmed off as I've started to rough out a bow. You'd have to look at a lot of Yew to find a bit as good as that!
You can see the lower edge has been chaffing against another branch and the bark has worn through. The diameter is so small that the grip of the bow will need to be the full size of the brach and the central pith will be incorporated into the limbs for some length.
Now it may not make a bow, but it certainly has the potential to become a glorious character 'stick' Warbow. Certainly a worthy challenge to a bowyer.

The 130# warbow was collected yesterday, we went out to do some shooting to see it perform. It's difficult to find somewhere to shoot, even our club is a bit short of room for long shots.
We went out to a location where there is a huge expanse of open field with a footpath right across it.
Now, some would throw their hands up in horror at shooting along a public footpath, but before you call the armed response unit, allow me to paint a picture.
We drove about a mile up a dead end road to a farm, then walked half a mile up an ancient cart track with trees along each side, and fields of brassicas (kale?) sprouting on either side. It then opened out onto a vast open plain which was once a WWII airstrip.
Stretching out over the farmland, every 1/4mile or so, posts marked the footpath across the open fields of winter wheat which was just showing a few inches of growth. We walk out about 200 yards where the grass of the path way stopped at the edge of the field where kale gave way to the winter wheat.
Shooting along the path we had a clear view at least a mile and a half in front and a good half mile either side. No hedges, nothing. The only thing that concerned us was walking over the crop, so we kept single file and walked along the marked path. We had to divert a little to collect the arrows, but tried to tread carefully.
Obviously this isn't an ideal shooting ground and if we saw anyone we would have immediately packed up.
Anyhow it's only the second time I've shot there in about 3 years, and it's one of the few places safe to test shoot Warbows or flight bows.
I'm posting this really as a counterpoint to the endless 'health and safety' style post that I've seen on some forums, with knee jerk reaction to questions about shooting on public land or in the garden.
Anyhow the shooting was fun and I shot about 9 from the 100# Elm warbow. John warmed up with a variety of bows before trying the 130#, he was close to managing it and got off a couple of shots which went as far as the other arrows (which were all going a similar distance). He wasn't quite getting 'over the hill' with his right elbow to get those last couple of inches, but he was confident that he'd master it in a few weeks and was looking forward to enjoying it over the next year when the weather was warmer and the shooting easier.

Friday, 22 November 2013

Winter's Yew Review

I've got a few bows to make but my stash of seasoned yew leaves something to be desired.
Two long staves both with some big knots going right through.
One has a beautiful untouched back with the bark still on but has very poor heart/sap distinction. I've made bows from similar before and the wood was fine, but it didn't have the nice look of clean heart and sap wood. I also needed to heat treat the belly.
The other piece from the other side of the same log has a better distinction between heart and sap but has an area of sapwood which would need patching due to an up-swelling of heartwood from a knot which is slightly discoloured.
I'm not really sure what to do with each stave. Maybe the one with poor heart/sap would be better sawn into two belly pieces for backed bows.... I have 'boo and Hickory I could back 'em with, but that seems almost sacrilegious with a bit of Yew...
Dunno, and that's the thing to consider when people ask "how long does it take to make a bow".... Errrr about 50 hours if you ignore the years to find the Yew, a day or so to get it cut and sawn, a year to season and ages deciding what to do with it!

The other two pieces are skinny churchyard Yew branches, with nice thin sapwood. Now these may make great 'stick bows', they will still get to heavy draw weight but are full of character, knots and one has the the bark worn away and weathered at one end.
I think I'll make a start on one of those, just to see what it might do.

I also have two lovely lengths (half logs) which are a tad short for even flatbows, but would maybe splice to make a great flatbow or longbow. Maybe the longest would make a great bend in the handle primitive flatbow, so I don't want to rush in and splice 'em, especially as I'll have loads of billets seasoned in the summer.
It's a bit cold outside, which is why I'm indoors with a cuppa writing this.
Oh yes, I also have one gorgeous stave which belongs to a guy who wants it turning into a bow in January by which time it will be seasoned. That will be a pleasant change from the tricky staves pictured here., mind working any Yew is a pleasure, but it can still be quite nerve wracking and stressful in an exciting sort of way... that 130# Warbow certainly had me scrathing my head.
I have more people who want bows than I have wood, so if any of you are reading this, I'm doing my best, but I cannae use wha' I dinnae have!

Thursday, 21 November 2013

Branded Bow

The silver solder I'd ordered on line turned up this morning. It worked a treat, I cleaned up the steel parts, mixed the powder flux with a drop of water and applied it to the mating surfaces, reassembled it and heated it. the silver solder flowed beautifully. Like a lot of joining jobs, be it gluing, soldering or welding cleanliness and preparation are the key.


I branded the arrow pass with my bowyers mark and I think it looks about right.

Now that the mark is well and truly out in the public domain I'm asserting my right to claim it as my logo and trademarkand as such it is thus Copyright.
The original publication of it as my mark being here:- http://bowyersdiary.blogspot.co.uk/2013/03/big-bow-detail-and-hickory-challenge.html
Here are some pics, including one of me with the bow to give an idea of how big it is and the amount of set its taken (bear in mind the stave had a little deflex initially).
It's had a couple of coats of Danish oil and it will get 2 more every day until it's had about 6 then a wipe of beeswax polish.

I can't wait to see how it actually shoots...

Monday, 18 November 2013

Warbow 130# at 32"

The warbow is near as damn finished. My attempt at getting force draw measurements from the video didn't work. At the speed I was exercising the bow each frame of video shows the  pointer of the scale as a blur.
I could pull it slower or get someone to take readings as I do it. No matter, it was a good idea in theory... don't s'pose I'm going to buy a top of the range video camera just for that.
Here's the video and a still at full draw.
I did a force draw curve by pulling the bow to each 10# of draw and looking at the scale, fortunately it happened to generally correspond to a an exact number of inches and is very linear at about 5# per inch.

For anyone interested, here's the raw data. Decimals of inches were just estimates to the nearest 0.25
10#    9"
20    11"
30    13
40    15
50    17
60    19
70    21
80    23
90    25
100  26.75
110  28.25
120  30
130  31.75
I've reposted the graph with the axes round the conventional way (and labelled)

For future reference I've put the long string back on the bow and measured the weight needed to get it strung. It needed 60# to get the tips back to brace. The 60# immediately disappears and the force draw curve shows zero force at brace height! Ain't physics and geometry wonderful?

video

Saturday, 16 November 2013

Tinkering with Stuff


The scale on my tiller rig has been a source of mild irritation insofar as it is pretty unreadable in video.
I set about improving it by painting out the Kg scale... (we don't need no steenking kilogrammes). I used acrylic artists paint, which is about the same as ordinary emulsion paint.
I extended the scale line for each 10 pound line and put a blob every 50 pounds. I used a 'Sharpie' pen from Poundland.
The clear cover was pretty scratched and filthy so I cleaned that up with the buffing wheel I use on the horn nocks. You can see the improvement in clarity, not bad for a little bit of work.

I've also been making a steel tool to punch in or brand my bowyer's mark onto the warbow.
It's made from some steel tube I had lying about, it's slotted together, but needs brazing or welding before it's cleaned up and tested.
The problem was I couldn't braze it up as I just couldn't get it hot enough for the brazing rods I had. A new gas cylinder would brobably help but I've ordered some silver solder rods and flux from the web, it's handy stuff to have, dull red heat will melt it and the result is pretty strong. Soft solder just isn't strong enough, brazing needs too much heat, and it's too small for arc welding (well for a cheapo arc welder and an operator with rudimentary skill!)
Hopefully I'll get some nice video tomorrow and maybe I'll be able to plot a force draw curve, which will be of some academic interest.

Friday, 15 November 2013

Warbow at 32" Draw

video
JT, the guy for whom I'm making the bow, came over for a quick try out this morning. The bow was at about 145# at 32" and was just too much. This was despite warming up on the 100# Elm bow.
Originally we'd planned for 120# but decide 130# would allow some settling of the bow.
Back to plan B, I said I'd take it down to 130# which I've now done. Well it's still a whisker over, but that will disappear with the final scraping, sanding and polishing.
The video shows it at a good 32" draw and still over 130#.
I studied the video until I decided where the last few pounds were going to come off. I saw a stiffish spot in the innermost 1/4 of the left (lower) limb. Of course there is you say!... you can see a big bulge there... What you don't see is the deep dip in the back/other side of the bow.
The outer 1/4 of the right limb is a tad stiff too, but the knot there is a bit inhibiting... I took a little more off either side of the knot.
Anyhow I rasped and scraped some off the belly in that region, taking care to avoid removing wood adjacent to the dip. The tiller looks really good now and it's lost those last few pounds.
For such a long bow, you can see it's working hard.
I will have to wait for JT to get in training before I can see it actually shooting an arrow, as I just can't make any sort of impression trying to draw it myself!

Tuesday, 12 November 2013

Cunning Plan

I felt I should exercise the bow a bit more and it would be nice to see a force draw curve, but how to jot down figures without leaving the bow under tension?
Ha! Video it! Then play it back slowly and take off figures as required at one's leisure.
Easier in theory than practice, my lights were glaring rather on the scale, but by careful comparison I can see it came back to over 140# at about 31"
It's been a long day, and I don't want to mess up, so I quit there. I think the method has potential.
Here's a still grabbed from the video. Note the tape with a black mark on the scale is at 100# and the heavier line on the rule is 28"

Monday, 11 November 2013

Warbow Detail Pics


Unfortunately the live testing of the warbow is on hold due to the test pilot having to work.

Here are some pics to whet the appetite.

The darker pic is an attempt to show where I've reduced the sapwood by the dip, whilst trying to follow a ring where possible. The other pic at the top shows the bottom nock and a side view of the dip.

Bottom left pic gives a good view of the dips and character in the back of the bow.
It's a big chunky beast.
82" tip to tip. 80" nock to nock and it's girth at the grip is a whisker over 5".

The white string looks good on it, I couldn't find white serving so I went for some fancy black braided stuff, which whips on much better than the usual plain twisted stuff. Can't wait to get it tried and filmed.

In the pic of the top nock, it looks like I've cut through to the wood, I haven't, it's just wax, dust, polishing compound etc. There is plenty of horn there to take the load.



Sunday, 10 November 2013

Warbow at 27" Video and Still

I'd put in a lot of work yesterday what with the bow and a bit of decorating. I was tempted to do more work on it, but experience told me to leave it alone and start fresh this morning by taking a video to see how it flexes. The improved tiller layout works well, I can sit on the floor with the tiller rope wrapped round a length of 2x1 and pull it in the manner of a rowing machine, the scale is about at eye level so I can exercise the bow and work it back to the desired weight. the video lets me study how it's flexing and look at the draw length and weight at my leisure.
video
It looks to me that the outer half of each limb is still stiff. They both have tricky dips and swirls at that point which make it difficult to simply reduce the thickness without careful consideration. Oddly the still taken from the video looks pretty much spot on 'arc of a circle', I think this shows the value of using video and watching it flex dynamically.
I'm in danger of arguing with myself here, as one of the guys from Primitive Archer was saying how he liked to get the tips moving first and right at the end of the draw you could see the middle starting to flex.
I said this was nonsense as the whole bow is subject to the load and it all must be moving together even if you can't actually see it. So in this case, the outer thirds are flexing but just less obviously than the centre.
How do I know they are flexing? Well the cambium popping off under the tension is a good indicator. If I wanted to measure or prove it I'd glue a couple of thin spills of cane sticking up from the back of the bow, say 6" long. I'd measure the distance between their tips, winch the bow back and repeat the measurement. I'm not actually going to do this, but if I was into maths I'd probably have spread sheets and graphs and all that stuff.
I can now string it manually using a stringer rather than having to winch it back, this is much quicker and more convenient.
When it's finished (assuming it doesn't explode) I'll measure the draw weight on the long string needed to get it brace height. This will be a useful indicator for the early stages of work if I make any more heavy bows.
Update:- I'm only working on the outer limbs and it's now 130# at 28" with a 6" brace height.
Due to some of the features I'm having to take wood off the back, with all the care and attention to following a ring where possible and maintaining an even thickness of sapwood...  Yeah, right, well it may be 3mm on one edge and 7mm on the other. All a bit nervy, but I can see the outers working a bit more. Slow and steady wins the day (insert your own platitude here... ).
If you review the earlier posts you'll see how the dip has slowly been worked around, it will end up being a fairly subtle feature on the finished bow, maybe even unnoticeable to the untutored eye.

Update2:-
That's it for the day, she's 130# at 29" now and I feel that's probably close enough for now, it's been scraped, sanded and given a wipe of Danish oil. That's shown up some of the tool marks which will come out with a bit more sanding. Just the last stage of finishing will probably bring it back another inch or so.
I may make a string for it now, as I'm not sure I'd want to risk loosing an arrow with the tillering string and toggle on there.


Friday, 8 November 2013

Warbow Progress

It's now back to 26" at 130# with a 5.5" brace. (This would extrapolate out to about 160# at 32").
The tiller is looking pretty good now, I'll get some pics over the weekend, it's too dull and pouring with rain at the moment.
I've been working over the limbs checking the thickness making sure there are no areas thicker or thinner than they should be. Checking thickness sounds easy, but with dips along the edge here and there it becomes tricky and I'm sort of looking at average thickness by feel and eye.
The big dip is much less noticeable now as I've been forced to thin the sapwood along high/thick side of the ridge on the back of the bow in order to drop weight whist keeping a reasonable heartwood/sapwood ratio.
I've ended up reducing it along a fair bit of one limb, and it's made the limb far more even in cross section. Another benefit is I still have some heartwood at the tips, however the tips and their temporary nocks are now a good bit thicker than the end of the limb, which makes it difficult to taper the last 6 inches or so.
So I've started fitting the horn nocks...

Thursday, 7 November 2013

Tiller Improvements

I've bought a pulley so that I'll have 2:1 advantage when pulling on the tiller rope by hand. This will allow me to dynamically flex the warbow. The pulley was only about £4 including postage, it's stainless steel and looked a tad flimsy when it arrived, however close inspection convinced me it was up to the job. Heavier duty ones which are actually load rated are more expensive, but 150# or so on the tiller isn't a huge load. After all it's rated as suitable for boat rigging and washing lines, and the lower pulley is just a washing line one from a hardware shop. Here's a vid showing how it moves, most of the bend is still in the inner 1/3 and the right limb looks stiffer, so I may swap the bow round.
The video shows how it is this morning (Thursday) hopefully by the end of the weekend it will be getting V close to full draw).
A worrying development:-
video
There are a few fine longitudinal cracks in the belly, they've been there for ages from the seasoning, probably radiating out from the centre of the log. I was hoping they would disappear as I worked down the stave.
I've done some work on the outer thirds and found it looks better reversed on the tiller. I re-strung it and gave it a pull, I could feel a pinch under my bow hand and one of those cracks has developed a crack across the grain to another fine longitudinal crack, like a 'H', it's only a fine sliver of wood bulging up but not nice....
I flooded it with low viscosity superglue, unstrung it and bound it up tight.
I feel it will be ok as the grip section is still pretty heavy and most of the extra flexing needed to reach full draw will be from the outer bow limbs. Worst case, it will keep pinching and raise a splinter in which case I'll rasp out a section and lay in some fresh wood. At least it's on the belly.
Never easy working with a stave, I'll press on... fingers crossed.
I've taken the binding off now and I can't even see where it was...I'm not counting my chickens, and I'm not going to flex it until I've reduced the outer limbs a bit more.
The actual pinch was sort of on the side of the belly which isn't quite so worrying. If you take the back as 12 o'clock and the belly as 6 o'clock. The pinch was between two cracks which were at about 4 and 5 o'clock.
Dunno if that makes sense. Anyhow, I'm feeling calmer again...whew.

Monday, 4 November 2013

Dealing with the Dip

I've been looking over the bow and wondering quite how to progress, it needs probably about 1/8" off the whole belly, but it would be a fool who just set to with a spokeshave and did it.
The outer 1/3 of each limb needs to start flexing, especially the limb with the dip along one edge.
Working on that dip, I've taken some off the high edge of the back and carefully tried to blend it so that it generally follows a ring.
The pic shows the general  slightly S shaped effect where I've thinned the sapwood. It's rather a dim pic, but that's to try and show the grain, it's not finished as the rougher look helps to show what I've done. The dip on the right edge is plain to see, and you can see I actually let the tip of the bow waggle very slightly to the left to try and lose as much of the dip as possible. With a lower weight bow I may have allowed more waggle of even gone for a complete character bow look... mind a lower weight bow would have been shorter and half the problem may have disappeared off the end of the bow. Ah! No point getting distracted with 'what ifs' let's worry about the actual bow I'm trying to make.

I've been fiddling and fretting over it using a scraper too mostly near the outer 1/3 of the limbs... it's far to early to be using a scraper really, but I'm trying hard to keep the integrity of the back where possible, although I've continued the sapwood reduction right out to the tip now. No point having extra layers of sapwood for the last 3 inches!
I'll doubtless get it on the tiller again. If there's much change I'll post a pic.
Interestingly the cambium has popped off in parts of the dip, I feel this is a good thing as it shows there is some flexing there. The cambium layer is a bit like having a load of stain gauges over the back, when a bit pops off you know it's being stressed!
Much better to be going too slow and using a scraper than going too fast and wrecking the bow...
When in doubt, take some pics, come indoors, write up the blog and have a cuppa!
See this blog entry http://bowyersdiary.blogspot.co.uk/2013/10/yew-warbow-stave_31.html for a side on view of the dip, to really appreciate the problem.

Update:-
Now back to 22" at 130#
Where some cambium popped off it's revealed a nice little raised pimply feature in one of the dips in the back of the bow.
200mm out from the centre of the bow.

Sunday, 3 November 2013

Finsbury Mark Roving Shoot

The weather was glorious but with a nippy wind. Surprisingly there was a low turn out of only 10 archers! However this had the benefit of making it easy to chat to everyone and very friendly and informal.
The roving format is shooting at flags at varied distances up hill, down dale, over trees and hedges. We mostly roamed between two fields over undulating grassland also used for point to point horse racing.
One shot was at long range at mannequin, which we also shot at 20 yards.
It was glorious to see arrows at full range drifting across a blue sky on the wind and dropping in around the target.
I went with three other members of our club and Mick the Blacksmith actually won the event. The bows were mostly longbows of varying weight, there was one lady competitor and the ranges could generally be reached by all. With some shots it was very difficult to judge the distance if you couldn't actually see your arrows land. Big fat arrows with clearly visible fletchings are an advantage in that respect, but of course they don't fly as far as slim ones with small fletchings.
I shot my Bamboo backed Oregon Yew longbow, it's one I rarely shoot as I tend to go for my selfbows. This had the advantage of shooting my standard 28" arrows or my heavy 3/8" 32" arrows which I'd brought along so I could try the Elm warbow.
At lunchtime I shot 3 from the Elm warbow, and two other guys had a go too. It threw an arrow with some authority 190 yards uphill into a headwind. My first shot was great, but my bow arm tried to collapse on the second, so I stopped that attempt and had another go. I was very pleased with how it shot and would have liked to see a measured shot on the flat.
Anyone who wants to try a something a little different should check out the FinsburyMark. A great advantage is they not affiliated to any organisation but insure each event on an individual basis. This allows archers who don't have a club or affiliation to have a go. They run shoots all over the country, do have a look at the website, they are a friendly bunch, and although roving isn't really my favourite it makes a great change, and a good day's shooting with plenty of exercise and good company.
Oh yes, and it was only £8 ! Where else can you get a day's entertainment for that?

Saturday, 2 November 2013

Warbow Tillering 120# 5" Brace

The warbow is at a low brace and moving nicely. The cambium layer is beginning to crack and pop in an alarming fashion, so it's all a bit nerve wracking.
I have decisions to make:-
Do I leave the back untouched and have very little heartwood at the tips?
How do I cope with that weird dip near one tip? The surface of the back and the heart/sap boundary dips along one edge such that it's sloping at about 45 degrees or more.
I could just square it off and ignore the flow of the wood, but I'd be really cutting across growth rings at an unacceptable rate.
If I follow the wood exactly it will end up wanting to bend sideways.
Like most things there's the compromise, maybe I can aim for a sort of oval section with the axis of the ovality being slightly on a slope. I can relieve the high edge of sapwood a tad if it's done over a long gentle line and maybe allow the heartwood to get a bit thin along one edge of the belly.
Maybe I should reduce the sapwood thickness over the whole bow?... a laborious process if I'm going to maintain the integrity of a single growth ring.
It would all be much easier on a low poundage bow.
The answer is to tread slowly and carefully, tease it back and see how it progresses. If I do have to reduce the sapwood thickness over the entire back, then do it slow and steady over a few days.

After lunch I went over it checking the thickness taper, looking, feeling and measuring, and teased it back to 5" brace. I had to winch the long string back to 140# to get the string on it, yet once braced it drew back to 19" at 120#. All a bit counter intuitive and that's why so many beginners make under weight bows.
This means I'm ok for draw weight and the there's a fair bit of wood to remove to get the tiller spot on.
I still have the various problems to solve, but I'm on the right track.

The lighting for the pic is a bit harsh and the shadows make the limbs look rather different. Holding a CD up to the pic shows the outer 1/3 of each limb isn't doing much flexing. This is going to be problematic for the right (upper) limb where it has the weird dip.... maybe that will become the lower limb. It's still early days.
That raises an interesting point about the 'Lower Limb is always stiffer' mantra. On casual examination of the Mary Rose bow dimensions, that seems to be true, but I happened upon several bows where the upper limb is actually wider and thicker. The real answer is, what does it look like on the tiller? Never believe the figures rather than your eyes.


Friday, 1 November 2013

Warbow Flexing

I've pulled the warbow back to about brace height on a long string. the scale is reading 140# at this point.
However it's deceptive when pulling on a long string. Once the bow is braced in that position the scale would be reading zero! If you plot a force draw curve for a bow, it goes from full weight at full draw to zero at brace height. So that 140# becomes stored energy in bracing the bow and it's hard to judge what it becomes as a real draw weight from a braced bow.
That's why it's important to get a short string on a bow as soon as it's safe to do so.
E.G. I took the 100# Elm warbow and put it up on the tiller with the same long string and winched it back until the tips had come back 6" (to about brace height). The scale read 55#, this gives me some sort of reference and implies I'm about on track with the big Yew bow.
Most of the flexing is on the inner third at the mo', but again, a short string changes the angles and leverage so I want to get to a low brace pretty soon.
I may put the Elm bow up on the tiller at 32" and draw round it to give me a reference curve... dunno
Update:- I had to make a tillering string out of the last of my Angel Majesty as the Dacron is like damn rubber at these weights.
Got it to a 2" brace now so I can see it has plenty of draw weight still.
I've ordered some Astro Flite... dunno what that's like, the vast proliferation of string types oft' referred to generically as 'Fastflite' leaves me stoatally* confused. The Astroflite is about half the price of Angel Majesty and twice the price of Dacron, so hopefully it should be ok.

* stoatally...
As in the old joke:-
What's the difference between a stoat and a weasel?
A weasel is weasilly distinguished whereas a stoat is stoatally different. :-)