Tuesday, 26 September 2017

Tri-Lam Glued Up

I did a dry run of the glue up to make sure everything would go smoothly. I spent a few quid on G clamps (you can never have too many).
Immediately before gluing I ran each surface on the belt sander to ensure it was clean. Having clamped it I proceeded to add rubber strapping between the clamps, this was a good thing, as I could see it squeezing out more glue. After doing the strapping I nipped the clamps up again.
Note, on the glue up I've added an extra clamp at each tip, I need the full length of the bow as the Purpleheart is only just long enough, so I want to make sure it's a good glue up right to the tip.

24 hours later, I've got it off the form, cleaned up the edges with a farriers rasp and I'm now running it through the bandsaw to an approximate shape. 26mm wide at the centre section (for about 2') then tapering to 15mm which will allow plenty of slimming down in the later stages.
I've trimmed off the ends so there are no odd laminations sticking out to get snagged. I'm very pleased with the glue line, e.g, you can't see it :-)
One pic shows a thin sliver taken off with the bandsaw where you can really see the glue line. It's worth all the time and preparation, 'cos if there are gaps, then it all needs re-doing.

I've just this minute glued on a 12" riser blcok made from an off-cut left over from the 3rpi Yew. I like to have bits of wood with some history behind them rather some bit of random hardwood from an old window frame. That's me done for the day, still a bit tired from my cold, but I've been doing 10 push ups night and morning which seems to have firmed up the tennis elbow and left shoulder... been shooting half a dozen or so every day and the decent grouping has returned.




Saturday, 23 September 2017

Boo, Purpleheart, Yew Progress

I've got the purple heart tapered and joined with a short scarf joint. The Yew belly billets have been tapered, a short Z splice cut, they have then been heat treated and glued.
I've got to plane up the boo and the glue it all up. I've asked on Primitive Archer whether I'm better off gluing all 3 at once or gluing the Yew to the purpleheart first. There's a hint of deflex in one half of the yew still and maybe gluing it up to the Purple heart would pull that out. Mind I'm thinking of gluing the whole thing up with a hint of reflex / backset, maybe just an inch or so, although it probably won't take much set during tillering.

Monday, 18 September 2017

More Thicknesser Development

It's almost finished now, here's a pic with the power plane missing, but it's sole plate is screwed to the top to give alignment as it is all built up.
I've put feet across the bottom spaced so that can be clamped on to the workmate. The adjust wheel is more central now, slightly less convenient, but better mechanically, the screw that pushes upwards bears against a bit of steel plate. I've made lots of improvements to take out slop. The biggest factor is probably the thickness of the table which rides up and down smoothly with no real room to twist.
The only problem is I don't know where I'll have room to store it, maybe I need another major sort out.
Most of the wood is off-cuts from shelving that I've been doing and bits that were hanging around.
Just added a pic with it all finished and set up with a length of Purpleheart in there for tapering.

Update:- It works a treat, no perceptible ripple, bit noisy of course and you have to take the cut in stages, con't just rip a great big taper off in one go. An advantage over a sander style thicknesser is it produces chippings rather than dust. The chips are much easier to collect/sweep up. It does throw 'em out of the front with some force so you can feel 'em pinging onto the back of your hand.

Friday, 15 September 2017

Improved Taper Sled and Thicknesser

The thicknesser was made a while back from an old power plane. One fault was the adjustable plate was hinged at the back and didn't come up parallel to the sole of the plane. I've improved this by hinging both ends so it moves parallelogram fashion, being pushed up by an adjusting screw under the front edge.
The other problem was the taper sled which was wooden and not very stiff or flat. I bought some aluminium U channel and made a better sled, it is still somewhat flexible over a 3' length... but then, so is almost anything unless you go to box section steel.
I gave it a quick try out on a strip of Ash, I set it to quite steep taper and a deep cut. It did the job but with some chattering.
I learned a few things.
1. Stick the whole lamination down with double sided tape.
2. Only take a fine cut, and/or maybe gradually increase the taper.
3. don't try to pull it back out with the plane running. It will take other cuts and spoil the work

I'll have another try on a bit of scrap and report further.
Some of these taper/thickness machines that people make use a drum with sandpaper on, I reckon they must take an age to run through if you are taking off any amount of material, though they doubtless give a better finish. I imagine using this for rough taper, then running the lamination over the belt sander.
We'll see how much wood I ruin before resorting to working staves ;-)

Update:- I've given it a go with finer cuts and it works well, there are still some improvements to make as the parallel motion doesn't work at low angles and there isn't enough height for thicker billets. The wooden adjustable plate wasn't flat, but a few strokes of the plane have improved that.
I'll work at the design to try and make it good and rugged and versatile. It looks promising.


Saturday, 9 September 2017

Next Project

I'm working towards making a tri-lam ELB for a woman who already has a couple of my bows. Laminated bows are something I'm not particularly into but I happen to have the necessary materials.
I've recently bought some more bamboo and my mate Matt from Cambridge longbows gave me a purpleheart lamination some time back.
I'm thinking Yew belly, Purpleheart core Bamboo back.
With a view to improving my Thicknesser/Taperer that I made from an old power plane I've bought some channel section aluminium to make a stiffer adjustable taper sled.
For those of you who have no idea what I'm talking about:- A taper sled is like a tapered plank, you clamp or stick a lamination onto it and run the whole thing through a planer/sander etc and it comes out with the lamination tapered to same angle that you set the sled up to. E.G The lamination and sled together come out parallel, thus if the sled was tapered the lamination now has the equal and oposite taper to make the overall pair of  'em parallel. Anyone who still doesn't get it, draw a long thin rectangle with a diagonal line from corner to corner, label the lower portion "sled" and the top portion "lamination"...  you can colour them in too if you like ;-)
I'll post some pics of the tapering sled and thicknesser when it's finished... mind it may be some time as I've a load of shelving to build (so I'm reliably informed ;-) )


Meanwhile back at the story, the woman in question likes her pink arrows and pink fletchings, so I thought I'd make a very "girly" bow and I've experimented with some coloured acrylic for nocks. The acrylic is sold as pen blanks. I quite like the effect but it is deemed not to comply with the rules for longbow which specifies Horn Nocks... that's NFAS and AGB. All a bit silly really as that doesn't allow bone or antler either of which would have been used.
I did a quick try out putting a nock on an off-cut of Yew.
It turns out she wants horn anyway and like how I do my nock at the moment. Still it was a bit of fun and the pen blank only cost a fiver (enough for 3 nocks)

Wednesday, 6 September 2017

Update on the Crossbow

I tried the prod on the tiller and it was just over 100#, but I probably didn't get it quite back to full draw, I didn't want to risk over-straining it. I plucked up courage and had half a dozen test shots and then tried it 3 times through the chrono' (with the heavier commercial bolts), average was about a disappointing 170fps. I then tried the old prod with patched and repaired belly, using the same bolts of course and it was about 5fps faster!
The new prod took a hint of set so that it needed very little flexing to get the string on. The old prod required a little more flexing despite being about 2 " shorter.
My conclusion is that the Yew is a better belly than the bamboo... of course this may only apply to this particular yew and this particular boo (I don't think it's Tonkin boo, which is considered to be the best).
It also illustrates the dilemma of crossbows, trying to get decent performance from a manageable short prod whilst maximising the draw length, without resorting to bolts that are really too light and risk damaging the prod.
I've added a pic, showing brace and drawn superimposed so I can see how it flexes.
I'll probably re-visit this at some time, and if I can get up to 200fps I'll invest in a scope and try it at a field shoot. It's not that much faster than a good primitive at the mo', after all Twister has been clocked at 166fps (prob' a bit slower these days).
One of the Guys on Facebook was suggesting heat treating the inner faces of the boo, but if you've been following this project you'll realise I've gone through enough experiments for now!

Any how onwards and upwards onto my next project which is...

Tuesday, 5 September 2017

Prod Testing


The crossbow prod looks and feels pretty good, it's about 1/2" short of the full brace height and I haven't actually cocked it yet.
The nocks have been made much more substantial than the previous ones and have been reinforced and shaped by binding with fine linen thread which is soaked with low viscosity superglue as it is bound on. The glued thread is quite solid and can be filed and glued again.
I've videoed it being drawn so that I can look at the tiller.
I will tidy it up, enlarge the shoot through hole to take the larger fletchings of the commercial crossbow bolts, increase the brace height by twisting up the string and then eventually shoot it, with some trepidation.
Oh, yes, I must remember to glue on those horn string catchers that I'd put on the previous version, I'm sure they are a good thing.

In the pic where you can see the whole prod, you can see the line along the centre where I have put two slats together to give a flatter belly.