Sunday, 30 September 2012

Maple mkII


I wasn't happy with the chrysals on the last bow so I'm now using the better half of the log and what I've learnt from mkI.

It was the club end of Month 3D shoot today, but I didn't really feel up to it and wasn't keen to shoot the Maple bow... I would have done had it been free of chrysals.
Instead I've been going mad on the mkII. I got it roughed out and debarked yesterday, and have worked it down to approximate size today.

My aim is to getting flexing on the tiller and heat treated by Monday night so it can be recovering from the heat while I'm at work for a few days.
Rushing at it isn't how I usually do things, especially with the tail end of a cold, but conversely I like to strike while the iron is hot.
I cut it as close as I dared on the bandsaw but left some judicious width at the tips to allow for marking out errors and twist in the stave (marking out on a curved surface can lead to major errors). You can probably see that in the pic.
I'm making the limbs a bit wider nearer the tip, more the shape of a Spitfire wing rather than a straight taper from about 2/3 along. I've got it all a bit thicker than the previous finished bow as it would be foolhardy to try and get too close to finished dimensions. It will get thinned down on the tiller to give the full draw shape I'm after (almost arc of a circle with just a hint of ellipse)
I will also have the chance to get the grip more to my liking.
The other pics show some of the nice features of the stave, (the bark just popped off cleanly to reveal the cool bits!), these are all on the upper limb and might conjure a suitable name for the bow.
You can see the stave is much straighter than the original and the swoops and dips are less pronounced. This should mean I won't need to do any steam correction. (I will just work with the bit of twist as that's just character and won't shouldn't cause much trouble on a wide bow)

Friday, 28 September 2012

Final Adjustments and Angst


The bow wasn't really comfortable in the hand , so i extended the grip down a bit towards the lower limb keeping a careful eye on the thickness of the limb. I couldn't narrow it down into the thin section.
it feels more comfortable now and the hand isn't pushing the arrow up above the arrow plate.
It shoots sweeter now and the finishing has dropped a pound or two so it now draws about 48# at 28" and I pulled it back to 29" where it showed 50#. (I normally test bows to 1" overdraw)
The second pic shows the nice figure on the belly of the top limb.

I was wiping on another coat of Danish Oil when I noticed a couple of tiny compression marks on the belly on the upper limb. I wasn't amused as they had just appeared out of the blue. This is what caused my angst. Should I just leave well alone or fiddle with it?
Chrysals aren't fatal, they are just ugly! I've had bows with the odd few chrysals which I've bound with thread and epoxy that are still shooting well, I have one old Hazel bow made in 1 hour with it's belly smothered in chrysals running right across that still shoots.
The chrysals basically warn that the bow is overstressed in that area, maybe drawing it to 29" was enough to cause them .
It's not an issue as they are barely visible, however, it's also not ideal and I decided the tiller was perhaps a tad too elliptical and a little judicious relieving of the inner 2/3 of each limb (especially the lower which could be seen as a whisker stiff) was in order.
Basically I ran a coarse file/scraper and sandpaper of the belly areas in question and also rasped a whisker off one edge of the lower limb where it was wider than the upper.
These precautions will take the load off the outer 1/3 of the upper limb, the down side is it sacrifices a hint of draw weight, we are just talking a pound or two here, so the bow is still over 45#.
Hard to tell if it's my imagination but I think it feels smoother now, hard to tell as I have a bit of a cold and I'm only good for 10 minute burst of work.
These things always seem to bite you on the backside at the very moment you think you've finished. I'd just posted some pics of the bow on Primitive Archer and it grieves me to confess to my little bit or re-tillering.
Still a stitch in time saves nine and other pithy old saying.

A bit about nocks:-
Here's a sketch of two nock styles and a shot of the lower nock which has less trimmed off and is rounder and more solid. Two reasons for this. a) it is likely to get rested on the ground. b) leaving a bulkier tip helps to stop the lower string loop falling off when it's being strung or stored upright.

Update:-Shot it through the chrono'
Normal shot (about 27" draw) 155fps.
Full draw using whole 28" of arrow 160fps.
Max 166fps

Final Update to this post:- I'm not happy with the chrysals so I've started roughing out the better half of the log. It still has some character, but not so severe. It's those small clusters of knots and swoops that cause the problems. You need to leave a tiny bit of extra wood around knots for security, but that can leave weak points between the knotty areas... sort of damned if you do and damned if you don't. The new stave with more gentle undulations will be easier to keep an even thickness. I'll also make the tiller a bit more circular.
Mind I won't throw out the baby with the bath water and go back to a complete arc of a circle, I may make some slightly eliptical templates. Anyhow it's work in progress.

Sunday, 23 September 2012

Maple Bow Gets an Outing


Took it to the club. It shoots pretty fast and hard, we have a marked out 180 yards (not sure quite how accurate it is) I shot to see how far it would go, one of the guys said "you'll be lucky to make 180", it's slightly up hill but the wind was across and slightly behind. I was rather smug when it dropped the arrows 12 paces beyond the marker (5/16 shafts 100gn points).
On the way to the shoot I stopped off at Hertford Town Hall to take some pics as they have two fine sculptures of stags.
The full draw picture shows off the character in the top limb and the elliptical tiller.
It's had about 50 shots through it now and feels pretty good, the grip needs a bit of tweaking and there's the arrow plate and more sanding and finishing, but she's looking good.
PS. the baseball cap is on backwards so that the string doesn't catch the peak at full draw... it's not a fashion statement ;)

Saturday, 22 September 2012

Maple ready for Shooting In

I've been away for a few days, a nice little break round North Norfolk, saw some seals and rode on the North Norfolk Railway, being pulled by a steam engine. Excellent.
I've spent today taking a little off the bow, getting it back to full draw and making a string.
The heat treating has done a good job and the tiller is better. I've gone for a slightly elliptical tiller for a change, it took out some of the set and added a few pounds to the draw weight.
I've shaped the grip a bit and shot about 20 arrows through it, including another damn Robin Hood straight down the plastic nock of one arrow!
I've sanded it a bit too and here's a couple of pics of the quirky deflexed tip of the upper limb, it makes a good character feature.
It's about 55# at 28" at a good brace height. It may loose a tiny bit of weight during finishing.
I may take it up the club tomorrow and shoot it in some more.
Some of the discussions on tiller shape get a bit frustrating, some people preach an elliptical tiller, pointing out the 'problems' of a circular tiller, whilst ignoring those of the elliptical.
If you look at the angle of string and bow limb at the tip you'll notice it is becoming more than 90 degrees, this can lead to the bow 'stacking', that's to say it suddenly starts to feel harder to draw than it should (due to the geometry of the angles). A simple way to explain it is to say you are beginning to pull along the limb as if trying to stretch it rather than bend it.
The difference between a circular and elliptical tiller is fairly slight and it seems a bit dogmatic to insist on one or the other. I daresay I could draw a fairly convincing circle on that picture too... I might even do it to illustrate the point.
Ha! I just tried it and I'm talking complete tosh... it's nowhere near an arc of a circle!
An elliptical tiller is supposed to give more even stress on the limbs and be faster, but doubtless the chronometer will tell when I get round to testing it. Meanwhile I've still got a soft spot for the arc of a circle tiller, especially on longbows.

BTW. Ignore the ripples on the limbs as these can appear to be weak areas or hinges, but they are there when the bow is unstrung too, and are just features of the stave. 
video

Monday, 17 September 2012

A Second Heat Treatment

The Maple bow is pulling back to 50# at about 27" from a medium brace height, so it's very nearly there.
It's taken an inch or so of set which was irritating me a bit, the natural asymmetry was also  grating a tad.
I've decided to heat treat it a second time, this will take out the set (it may pull back in) it will even up the limbs at brace and also give a nice even colour to the belly.
Rather cosmetic as it is drawing really well, but I'm just keen to get the best out of it.
Heat treating is about my least favourite task, back and forth every 5 minutes for over an hour if you want it to look even.
The back has been cleaned up too, it's been painstaking scraping off the remnants of the cambium layer, (Almost as exciting as heat treating, but it does have a sort of Zen thing going for it). There are patches and streaks of discolouration around some of the knots which will give it a sort of handsome natural camo' look. It suddenly feels like a bow, light in the hand and well balanced, It will be good to get a proper string on it and shoot some arrows (I've had one tentative shot already from a short draw).
I'll give it a few days to get over the heat treatment and then get it back that last inch, make a string and start shaping the grip for optimum performance.
It's not that hard to make a bow... of sorts, but to make a good bow is a different story altogether. After all, a couple of Hazel wands bound together with their thicker ends overlapping as a grip will shoot an arrow, and I've seen a guy shooting a completely untillered Holly branch, he could hit stuff at short range too!
For anyone who wants to have a go, any sort of bow that shoots is a worthwhile achievement, and that first arrow from a bow you have made yourself is a real buzz.

Saturday, 15 September 2012

Getting Close (video)

I've got it at a low brace and been flexing it to 55# at about 25", so it's pretty close now.
This video will let me see where those last few inches of draw can come from.
The left limb is a tad stiff (outer 2/3) compared to the right, but some of that is to compensate for the assymetry of a bow. The right tip could flex more too, and theres a stiff bit about 1/4 of the way from the grip.
Watching it flex dynamically gives a more complete picture than the static full draw view, which looks pretty good.
I shall work very slowly now, trying to even up the tiller, cleaning up the back, slimming the tips and  rounding the belly and edges whisker.
I'm probably aiming for just over 50 at 28", but I couldn't resist working it to 55#.

Friday, 14 September 2012

Maple Progress


The heat treating has done it's job, the 1/2" of set has been removed and at 50# it doesn't pull back as far (I've gone back to a taut string rather than a low brace).
I've taken the spokeshave to the outer 2/3 of the limbs and the wood feels much crisper. The darkening of the wood is still visible after several passes with the spokeshave so the heat has penetrated well into the wood.
It's bending more now, back to about 20" at 50# on the taut string, but I'm thinking it's rather a short bow for 28" draw.
So, how do you lengthen a bow?
You can actually splice a few inches of extra tip on, a bit like the Siyahs (levers) on an Asiatic Horsebow, an extra inch or two doesn't have much leverage on the join so you can get away with it.
I don't want to do it on this bow, as I want it nice and clean and simple. The other way is to extend the other end of the limb by reducing the length of the grip.
I cut back the grip by about and inch on the upper limb and blended the grip into the limb, back onto the tiller and the draw length at 50# had increased by an inch. The grip has been narrowed a bit to give me an idea how much I have to play with.
You can see it's looking more like a bow now, but the outer limbs are still not working hard enough. and the right limb is a bit stiff.

Monday, 10 September 2012

Multitasking

I've been over the limbs of the Maple ensuring the thickness taper is fairly even (about 1mm every 4") and I've narrowed the outer third of each limb a bit (1/2" wide at the tips now) It's looking better on the tiller and coming back to 17" at 50# on a low brace height.
A tiny bit of set (about 1/2") was beginning to show so I'm heat treating it now, one limb at a time with it strapped up about straight. That's to say I'm just taking out the little bit of set.
I've got the heat gun jigged up an inch or so above the belly and I run it for 5-6 minutes then move it along an inch or two.
A kitchen timer is invaluable in preventing me from forgetting it and scorching the wood.
Be be be beep be be be beep. Whoops time to go and move it!
While I was out in the garage checking the first few burst to make sure the time was about right I had a go cleaning up the Oregon Yew billets on the belt sander.
I'm not trying to get them absolutely flat along their length, but flat across and gently undulating to retain some of the feel of the natural timber.
I'm slightly surprised that the sander doesn't take it down quicker, but that's probably an advantage. If I'd got a huge old industrial one I'd probably be wrecking stuff!
I'll have a go thinning down the bamboo slat which I have to back it with later on.
I'll get both limbs heat treated today, then they can be resting for a couple of days.

Saturday, 8 September 2012

Busy Busy Bowyer

I've done a little to the Maple bow as you can see, most of the bend is in the central 1/3 of the bow which is ok for now. It's pulled to 45# in the right pic.
I'll start reducing the mid and outer limbs next, it's a bit tricky with all the swoops and dips in the grain and there's some twist as well, which I shall just follow and tweak the tiller to get the bow to pull back straight.
It should be full of character when it's done.
Below left is a rather poor pic of the upper (right on the tiller) tip which shows the character in the stave with a rather weird deflex wiggle at the very end (untouched back of the bow is to the left).
Here's a pic of the belt sander with the dust extractor plumbed in too.

I've had some insulated plasterboard delivered which I've got to get screwed up to the ceiling to improve the insulation in our extension which gets B cold in the winter.
The belt sander has come in handy already cleaning up some old rough sawn 2x1 which had been used outside as a fruit cage. Now it's cleaned up I will make a couple of props for holding up the plasterboard whilst I screw it up to the ceiling. It will be a good job to get done as it will cover over the scruffy artex too.

The belt sander is very useful for the area where bow limb fades into the grip, because there is a lot of end grain there it's difficult to get a good finish and there are often tool marks which take an age to get out by hand to really show the grain to best effect. The rounded nose of the belt sander cleans it up nicely once the fade has been rasped to shape.
If you enlarge one of the pics of the bow on the tiller you can see how even the fade is. I've used a bottle with sandpaper wrapped around it before now to acheive the same effect. Normally I would be getting that dgree of finish much later in the process, but I just wanted to give the belt sander a try out.

Friday, 7 September 2012

Belt Sander

I've been after a bench mounted belt sander to sand down a Bamboo backing and my Oregon Yew heartwood billets.
There was a good solid one on E-bay but the price escalated beyond my target.
In the end I bought a cheapo one, like many cheap tools, it does a good job if tuned up a bit. I modified the guard and end stop to allow me to sand long parts and I modified the dust extraction spigot to work with my dust extractor..
It's amazing how strong atmospheric pressure is.
My dust extractor (standing on the floor behind my bandsaw) has a long flexible hose 4" in diameter.
I connected it to the sander via some old plastic plumbing fittings and switched it on... whaaaa! It dragged my bandsaw across the garage!!! What was going on???
Effectively it was trying to suck through such a small hole it was creating a partial vacuun and the flexible hose was collapsing concertina fashion.
But how come it pulled the bandsaw (on it's castors)?
I did some quick sums:-  4" diameter hose has a cross section of pi x radius squared. That's about 3 x 2 x 2 square inches. Atmospheric pressure which is almost 15 pounds per square inch so, that comes out to 180 pounds, which rather explains it.

So, I opened up the silly small holes in the sander spigot to make it full bore, but I could still see it trying to concertina the hose, I then added some 3/8" holes around the periphery of the adaptor which joins hose to sander, to allow more air to bleed into the hose.
That stopped the bandsaw marching across the garage.

Cautiously I cleaned up the belly of the Maple bow a bit using the belt sander, the rounded pulley end of the belt was good for following the undulations in the bow where there are knots.
I was very careful as power tools enable you to screw up in the blink of an eye.
The bow has had a good few days to stabilise after it's steam bending. It's beginning to flex now on a taut string and looking more symmetrical.
I'll take some pics over the weekend as it comes back to brace height. At the first hint of any set I'll heat treat the belly. I want to get it moving first as there's no point heat treating and then taking off the heat treated timber as it's worked down.

Saturday, 1 September 2012

Steam Bending Maple


The Maple bow is begining to flex on the tiller on a taut string, but one limb has a lot of reflex which makes it rather asymetric and difficult to judge the bend. It's a fairly short stave (62.5") and I'm after a reasonable draw weight (50#) so I've decided to take a bit of reflex out of the limb rather than adding reflex to the other.
Dry heat or steam?
I've used both and find steam gentler, more easy to control and quicker, however if I'm heat treating then the dry heat can also be used to add reflex at the same time.
The bend I'm doing on this bow would be difficult with dry heat as I've jigged it with the back upper most and you don't want to to be drying out the back with dry heat (heat treating is done to the belly of a bow to make it stronger in compression).
I use an old 5L plastic container to hold the steam (from a wallpaper stripper) where I want it.

I may heat treat the belly of the bow later on. Fo now I'm just trying to get it a bit more symetrical and flexing back about 6".
You can see the result, it's still got a hint of reflex at each end.
I've taken it off the jig to dry it off, I'll leave it another day off the jig before flexing it again.
video