Monday, 14 August 2017

Coarse Grained Yew Test Shots

I got some video this evening of my mate JT shooting the coarse grained Yew. It seems to shoot pretty crisply, and I left it with JT so he can give it a more thorough work out at his leisure.
Meanwhile I'd been tidying up the garage, finishing some new arrows and spending the day doing my yearly batch of cider 12L this time.
 Once I've got the cider making kit cleaned and put away I can get on with some bows. I had a visitor last week who brought a partly finished bow from a friend of his to be finished and one from a well known bowyer that was a bit stiff in the lower limb. I rasped a little off the belly while he was here and had it up and down on the tiller a few times to check it was better.
I took care not to over do it, he can shoot a good load of arrows and see ho it settles down. It's always better to proceed with caution else you can take off too much and next thing you know you've gone from a 80# bow to a 40# bow!
I like to do small jobs immediately rather than have a stack of jobs which can easily get forgotten amongst the clutter of the garage.

Friday, 11 August 2017

Coarse Grained Yew gets to Full Draw

It's back to nearly 100# at 30" still at a slightly low brace, but I'll let it get shot in rather than stress it on the tiller.
It looks very weird but that's a reflection of the unbraced shape. The wood certainly looks handsome and I can't wait to see how it shoots at the weekend.

It's looking good now, I don't know if it will loose weight or take set but it's pretty much felt like almost any other bit of Yew, silky smooth in places, grain tearing in others and needing the rasp, creamy waxy sapwood. Almost no knots or problems except a few pins and one small dark patch in one ring which didn't seem to go very far.
The waggle is a bit extreme and I used heat to take some of the bend out, but one can't expect to completely straighten something that severe. The heat was also used to stiffen that area a bit as the bend tends to be a weak point.

Monday, 7 August 2017

Coarse Grained Yew Warbow

I've started on a warbow using the Yew harvested in July last year, the ring count is as low as 3 or 4 rings per inch in places. It's often stated that fast grown Yew is "unsuitable"for bows, but I'm of the opinion that there is a huge variation in Yew that can't be directly attributed to where it was grown, altitude it was grown at, ring count, colour appearance of the bark or age of the tree.
I've had good Yew and poorer Yew in all shades and from all sorts of places.
This Yew certainly disproves any idea that fast grown lowland Yew is pale with poor heartwood/sapwood definition. I have 3 billets, so I roughed them all down and picked the best two to splice into a warbow, (I don't feel the world is ready for the three limbed warbow, but I expect some wag has made a 3 limbed bow!) I'm aiming for a fairly modest 100# at 31".
You'll see there is a nice waggle in the further limb.
I've also been sorting out my old arrows and making some new ones. The old ones have been mended so many times and I had more with broken off point than whole ones. I've turned all the old ones into a set of slightly shorter arrows and won't bother to repair any further breakages.

Friday, 4 August 2017

Fun Day

The crossbow project has wound it's way to a conclusion. The prod was a bit weak in one limb as demonstrated by the sting not being at right angles to the stock at brace. I eased off the other limb by removing a little from it's lower edge especially from the glass fibre lamination. Finally plucking up courage to cock and shoot it first with the 100gn point on the bolt 141fps and finally with the 70 gn point 151.7 fps . Excellent!After a couple more shots the nock partially sheared off one limb, this adequately demonstrates the problem of searching for greater and greater projectile speed, it simply leaves more energy in the limbs and thus modern compounds and crossbows and up being noisy brutes with shock absorbing buffers built in.
I could go back to the Boo/Yew prod, but I'm not that fussed about shooting, the best speed I got was 244fps from the natural materials and 251 with the glass belly. I've learned a lot and I now have a good design for a shoot through prod mounting and a usable crossbow prod test bed.

Shock horror probe! Del buys a bow! Well I couldn't resist, its a 1950s Accles and Pollock take down steel bow, it's a bit scruffy but for £25 quid i had to have it. I've put a string on it at low brace and drawn it. The lower limb looks weak, but maybe just needs a little judicious bending. I'll probably make a decent string and try shooting it, I can't imagine it will fail as it's steel.
Update:- I've had many people on Facebook warning me that these have a reputation for breaking and rusting from the inside. I'll probably draw it to full draw on the tiller, don't know if I'll make a proper string for it.

Talking of Facebook, there are some odious idiots on there.
A nice woman archer who I know posted her new English Longbow on there... then some bloke asks "what makes it an English Longbow"
I (and the woman in question) replied at some length in good faith assuming he doesn't know that there are various definitions and a difference between a Victorian target bow and a warbow.
Anyhow it turns out he's well aware of the differences and was just Trolling for an argument, complete tosser.
He tried to sucker me in by saying "don't you want to discuss things with people who have different opinions?"
What...? No I don't!
a) He didn't offer any opinion.
b) He asked a question under false pretenses as he already knew the answer.
c) He accused me of arguing, when I was merely answering the question which was originally posed.

My pet hate is people who ask questions when they don't actually want the answer and are aren't interested in it...

Wednesday, 2 August 2017

Bottle Job

I rasped the Yew belly on the crossbow prod down to about half its original thickness and glued on the fibreglass lamination. Gut feel and experience being used rather than extensive computer simulations and calculations!
The first limb went fine, but the second somehow contrived to be a dodgy glue up, not sure how as I'm pretty meticulous, anyhow the excess fibreglass at the tip got snagged on the bench and popped the glue line at the tip... hmm I was V irritated, but I got it all cleaned up and did it again. It seems ok this time, but is very stiff so I've taken about 4mm off the lower edge of each limb and I'm slowly working it towards full brace and being cocked.
Note I'm using the longest string of the 3 that have been made for the various versions of this prod, which is looped through the string adjuster.
 I'll add the string catchers too as there will be a lot of energy in this bow and I don't want to risk it going over center.
It's hard work to cock it, gotta be about 100# .The actual numbers are a bit irrelevant, but if it settles down to be a reliable prod I'll doubtless measure it on the tiller at some point. The pictures show low brace and cocked, I was hoping to see if the tiller looked even but it's hard to see without carefully lining up the camera, it's also tricky with a crossbow as it's possible to pull the string back off centre forcing it to be on the skew, similarly you can force it back dead straight and it will look true as the string won't slip sideways on the latch.
Dunno if that makes sense... on the tiller rig, the string is being pulled buy a long rope and hook, and the bow is supported so that it can rock, this lets you see how it settles under tension, it's not being forced one way or the other. In comparison, on the crossbow, the prod is tightly clamped and the string catches solidly onto the latch.
Just had it on the tiller, still hard to see how even it is, maybe a hint stiff on the right limb, but that looks contrary to the pic above, I took it to 90# and it wasn't full draw, so I reckon it is pretty much 100#
Anyhow I'm basically rather scared of getting to full brace and cocked without making sure everything is as good as possible. I'm even considering some linen binding at a few strategic points along the limb in case it shatters. What worries me is that now the belly is stronger than the back the failure mode could be an explosion of bamboo splinters which would be at eye level (it will be  a safety glasses job). With the previous configuration the likely failure mode would be a graceful collapse of the Yew belly with chrysals and a deterioration of performance.
I am getting a tad jaded as well as scared but do want to see it through, I'm pining to make a longbow or warbow, and there's decorating to do and we want to put some small windows in the summer house as it's a tad dark in there (good for a crafty cat nap tho' !)
Could also do with a holiday, but that will wait until the school holidays are over.
August already, and we've had blackberry and apple pie, the woman next door is leaving me her windfalls for cider making... the year is rolling by, seems like the Summer months all only have about 15 days.

Friday, 28 July 2017

Last Throw of the Dice

Sometimes I'm my own harshest taskmaster and I was beginning to feel I'd had enough of the crossbow project. It's actually performing ok having settled down to about 215fps with the MkI prod, but I'm not really happy with ok.

I realize there are no deadlines, there isn't a spec', there is no boss or customer to satisfy. On the other hand I don't want to plough in vast amounts of time money or effort, so what materials do I have to hand that would beef up the belly? It would be nice to hit 250fps reliably.

Ah, there's the old horsebow which I smashed by overdrawing, I could use the fibreglass laminations off that, that would give them their third outing! What about adhesive? Some of the specialised bow making epoxies are ludicrously expensive but I've got the epoxy resin left from when I made the glass fibre socket for the take down bow. As a rough guide to dimensions (mainly thickness) I have the glass fibre/rockmaple prod which exploded at the start of this project.
So a plan is coming together... Boo back Yew core glass fibre belly, what's not to like?
I've already split/peeled the glass lam's off the belly of the horse bow and started rasping down the belly of one limb of the prod.
Here's a pic of the chrysal and the various prods/bows/lams I'll be working with.
Just out of interest, I reckon that with the two Boo Yew prods being re-worked at different lengths I've gone through about 7 iterations of prod. A lot of work, but you never get anywhere if you are too keen to quit. Of course it helps if you enjoy what you are doing and you've only got yourself to please... mind I'm reliably informed that there is some decorating that needs doing (Yes Dear!)

I'm feeling a bit more cheerful about the performance I've been getting, it's better than the cheaper split limb (centre shot) 90# crossbows and only just slower than the more expensive ones. The bows that are up in the 240 - 300 fps range are much higher draw weights and have 36" prods and longer power strokes.

PS:- For anyone who can't spot the chrysal or doesn't know what they are looking for. It's a silvery hairline fracture travelling up and left from the lower edge of the limb, just above where you can see a pencil lying on the bench.

Wednesday, 26 July 2017

Crossbow Development

I think I'm homing in on the optimum prod length etc.
Having shortened the prod to about 34.5" after the nock shearing off the performance has stayed pretty much the same as it's taken more set. I've found what I consider a sensible brace and I think I spotted why I got a couple of misfires (putting aside the whole "fire" misnomer for now). I think what has happened is that I've pushed the bolt back, but it has stopped up against the fingers of the latch rather than going snugly between them and onto the string, this has allowed the string to impact the very top edge of the bolt, scrape off a very thin sliver and propel the bolt in a haphazard manner. (making a nasty noise and scaring the crap out of me in the process)
To prevent this happening again I've slapped myself around the head with a rolled up copy of the D G Quicks catalogue, I've also opened out the fingers of the latch slightly and tidied up the back of the bolts.

I think the optimum prod length for this bow is 36", but before rushing in and cutting down the mkII prod, I have first heat treated it.
I did that last night. The pic shows the set up, with the side cheeks clamped on to keep the heat off the glue line and the back. I put copious layers of masking tape over the back and sides fbefore clamping up. I've strung it this morning (with some difficulty). It has certainly raised the draw weight and I haven't quite mustered up the bottle to cock it yet!
I'm leaving it strung for a while and I'll give it some exercise before plucking up courage to test it through the chrono.

This project is beginning to pall a tad, but it's good to persevere and get to a conclusion. The rear sight I made looks really good. Dunno what I'm going to do for a front sight, let's see if the crossbow works decently first.

Update:- I had to re-make the string catchers as the heat treating had weakened the glue and burnt the horn.
It shoots fine with the speed about 219fps, which is reasonable being an increase on the un-heat treated version. I'll now take 1" off each tip and hopefully it will be about optimum.
I'm now using the 14" bolts, 5/16" cedar with 70 gn points as my "standard". The lighter bowpistol bolts don't gain much speed and may be too light for the bow.
The bolts slide home into the latch better now too.
Update 2:-
Bit of a downer, the MkII prod always seemed slower than the MkI. Shortenning it by an inch has done nothing and it's showing a slight chrysal where there is an "island" of growth rings on the belly. It shot 120fps, but has dropped back to 110, I may stick on a fresh belly lamination ('boo? Horn? more Yew?) or go back to the MkI or maybe shoot it, or maybe have a break and do a warbow. It seems like I've pretty much pushed the wood as far as a can, shame I'd have liked to get to 250 fps, but we can't always get what we want.
There's been a lot of work in there, mind the trigger mechanism is working well, so maybe it will get an outing some time.