Friday, 31 January 2020

The Curious Case of the Heartless Walnut

I went down to the South coast yesterday to visit my Brother and to fell a Walnut tree which he planted from a nut about 30 years ago. This tree has been bearing nuts since it was about 13 years old but it was getting a bit big for the garden as it was overhanging his neighbour's garden despite regular pruning back.
The leaves fall into his garden pond, he normally takes the leaves out quickly enough to prevent any problems, but this year he left it too late and they poisoned the pond killing all his Rudd. That was the straw that broke the camel's back persuading him to take the tree down.
 It's about 13" across at the base, and relatively clean for about 6-7 feet. I wanted to make a bow from it as we had the whole back story of the tree.
My brothers friend Kelvin came over to fell it with a chainsaw and we were flabbergasted to see the wood was white all the way through, there was a faintest hint of pinkish colour near the middle but nothing resembling what we expected.

 I won't be posting it on Facebook because there will be hoards of armchair experts pontificating that it is Ash not walnut or that it lowland walnut or too fast growing or some such. To be honest I don't think anyone will actually know why it is like this, but if anyone has any actual personal experience of felling Walnut I would be interest to see their comments. Bear in mind, we've had mature walnut cut from within 400 yards of this sight which has yielded shotgun stock quality walnut!
Anyhow we split the log with only some success as it ran off one side, but after some more splitting and trimming we ended up with one reflexed piece which should yield 2 staves. I brought it back home on the roof rack and I'll persevere to see what it will do as a bow, treating it much as I would Ash or Hazel. One lesson seemed to be split it from the narrow end, although the next log I split may prove the opposite!

However despite the disappointment of the Walnut there was plenty of compensation in terms of good company, good conversation an Indian meal and a few pints!

By the way, the repair to the grip of the Bamboo backed Yew primitive (see previous post) seems successful, it's been back to 100# @ 29 on the tiller and will, weather permitting, get an outing on Sunday.

Monday, 20 January 2020

Repair re-re-pair


The Boo backed Yew primitive that I made about a year ago for my mate JT showed some nasty cracks in the grip area the other day so I've been working on a repair. There were cracks showing on the side of the grip, these had run down from the riser section which was a piece of small diameter Yew with the central pith showing and a few radial cracks, one of which had opened up severely.
I sawed off the riser section and rasped it down to the belly which is spliced Yew billets. I didn't want to remove too much wood and risk loosing the alignment of the limbs or creating twist in the bow. I investigated the crack by carefully wedging it open, I flooded it with low viscosity superglue and clamped it up in the vice. A new slightly longer and thicker riser section of Walnut was glued on and blended in. I thought that this repair would do the job and after a couple of days to allow the glue to cure thoroughly I put it up on the tiller. Slowly working it back and exercising it, I got it to 28" and ... BANG...

The Walnut riser split! The good news is the the crack didn't run down into the belly, and as it was on the tiller it didn't get drawn further and smashed (this is because it's a controlled pull via 2:1 leverage which can be stopped virtually instantly), so I can try a second repair. It dawned on me a day later that I could check what draw weight it failed at, by looking at the peak hold needle on the scale... it failed at 83# .
I spent a good deal of time deciding on a more solid repair and wondering why the Walnut failed, I think it was just some poor quality Walnut. Speaking to my Brother who has worked with a fair bit of Walnut on shotguns, he reckons it's possibly not Walnut, maybe the table top from which it was made was just some random tropical hardwood which was stained up to look like walnut. The surface of the table was certainly darker than the inner wood.
The plan I came up with is to let in a strip of Bamboo edge on into the Yew core, like a reinforcing I beam, then top it off with a riser of Ash with gain edgewise. To give some idea of scale, the groove was milled out using a 4mm end mill,

I've go the bamboo glued in, and then cleaned off flush. The Ash has been glued on and it's ready for shaping and the testing. The last pic shows the Boo strip ready for gluing in, the Yew is protected with masking tape, The pic shows the profile gauge which allowed me to fit the bamboo to the curved slot... it's curved to avoid too much of an an abrupt discontinuity at each end.
Update:- The repair was successful and the bow has been shot a good deal since.

Friday, 10 January 2020

Mechanical Stuff and a Boo Yew

 I've mostly been working on converting my Mini Mill to belt drive and the bow making has just been once a week helping my mate JT make a Boo backed Yew warbow, which is now almost finished.
The Boo Yew is one of the interesting projects done with the materials that were available. The Yew is stuff that JT had from a local farmer which had dodgy sapwood and the stave itself was rather knotty, requiring a long section let in at one of the tips, it also had a lot of deflex. The Boo had been previously prepared by JT for a slightly shorter bow. Anyhow, it's now virtually done and when we finished yesterday it was pulling 110# at 28" (target draw length 31").
Link to video of the bow on the tiller:-
https://www.youtube.com/watch?v=os6Q2fxy0as&t=11s

The belt drive was up and running yesterday and I made some test cuts with a 10mm end mill into some angle iron, a 5 thou cut, then a 10 thou, then a 30 thou, all went well with the mill running much smoother and more quiet (on the slower of the two speed ranges)
I then moved to the other end of the work piece and milled across at 3mm depth!
It took it in its stride with a slow steady hand over hand feed. That's something I wouldn't have dared to try with the plastic gears for fear of stripping them. This is a great improvement and will really speed up roughing out cuts.
The ugly blocks of ply are just glued to the aluminium base plate with rapid epoxy... it looks rather Heath Robinson, but it's a quick dirty and effective way to mount the belt guard and speed controller.
 All I have to do is make the belt guard, which I've tried out, made from card and am now fabricating from thin sheet steel which I saved from the back of an old electric oven many years ago.
That's made now and just needs fitting. I may clean it all up and paint it... but maybe I'll just leave it and get on with the project of making a steel quick change tool post for the lathe.


Tuesday, 31 December 2019

Archer Automaton Extra Details

I've been asked for more detail about the Archer Automaton, so I've done a video here:-
https://www.youtube.com/watch?v=YIuBXjywir0&feature=youtu.be



Here are a few pics too showing elbow, bow hand and shoulder joints.
Note it's not supposed to be a nicely finished piece, just a proof of concept model to see how it could work.

Monday, 30 December 2019

Tail End of 2019

The best news this year is that I became a Grandad on the 23rd of December! :-)
My Daughter produced identical twin girls which made for a rather odd Christmas day and will doubtless keep us all busy next year.
As they are identical twins I've just shown one of 'em ;-)


I've had a bit of a break from bows as I've been modifying my Mini Mill (a Clarke CMD10, which is the same as a Sieg X1) to make it belt drive which should make it smoother and quieter. The pic shows the small stepped motor pulley standing on top of the big one which is still work in progress, centre hole being bored with a boring bar.
I found a nice article on the web where a guy showed how he'd done it, I pretty much copied what he did with slightly changed drive ratios and a few other details.
Once that's done I'll finish making the steel quick change tool post (QCTP) for the lathe. I bought a cheap Ali' one which works well for light work but has quite a bit of flex for any heavier work, bearing in mind by "heavy" I mean relative to size of the little lathe. Being fair to the lathe, it is doing a stalwart job and is even managing to turn 4" diameter Aluminium billet for the V pulleys for the mini mill belt drive.
I'm waiting for delivery of a 3/8" BSF tap at the moment so I can tap an alternative toolpost mounting hole on the compound slide of the lathe to enable the turning of the largest diameter V pulley.

I'll have a bit of a clean up ready for Thursday when my mate JT will be over for some bow making fun... currently working on the Boo backed Yew warbow.
Boo backing has been a bit of a theme over the past year, I made a series of 4 boo backed yew 50# flight bows, taking the best of them to a comp' and refurbishing the other two as gifts. I made a heavy boo Yew primitive and a boo yew warbow too, plus the usual sprinkling of primitives including a Wych Elm one.

Thursday, 19 December 2019

Seasonal Break

I'll be a bit quiet over the holiday period as we are expecting a busy time due to the imminent arrival of identical twins courtesy of my daughter. Fingers crossed all goes well and I'll be a granddad!


I'm also busy doing some mechanical work converting my mini mill to belt drive and making a steel quick change tool post for the lathe (the cheapo Ali one works quite well but has a lot of flex).
Pic shows V pulleys for the motor (it will have 2 speeds) being turned for the belt drive. Good fun working out how to do it :-)

BTW, I found some nice stainless steel rings from http://www.gwr-fasteners.co.uk/
I bought a couple of 8mm x 40mm diameter to replace my broken string adjuster. The 8mm thickness works out to be about an inch adjustment for each turn of the string through the ring.

Anyway, seasons greetings to one and all, and I expect I'll post a round up of the year plus some news in a week or so.













Mr Hare says happy Christmas!

Thursday, 12 December 2019

Updatey Update Post

JT came round and he did a good deal of work on the bow under my watchful eye. There was the usual panic as the spoke shave or plane dug in and started to tear, but careful use and resorting to the rasp kept things under control.
The bow progressed nicely to about 100# at 20" at a modest brace which is pretty much the amount of work I'd hoped for.
The oddest occurrence was the magic aluminium string adjusting ring breaking whilst try to brace it for the first time! I wouldn't have believed it, had I not witnessed it myself.
Update:- I got an E-mail from my mate Mick the Blacksmith, he said :-
The break is a typical stress fracture and probably started from a small crack sometime ago.
In industry when they test the tensile strength of something by pulling it apart, the fracture is the same as you have on your string thingy.

We took some good video at three stages of the progress.
https://www.youtube.com/watch?v=dvSI_onb42o

Previous day my mate Rob came over with some stuff to do. He had a half log of Wych Elm which we ran through the bandsaw laid out as a primitive. The stave has a huge amount of reflex so I though a wide flat design would have less stress than a longbow. He also had a warbow that had over 4" of set... it was pretty obvious why... the bow was over 1mm thinner at the arrow pass than it was for about a foot either side of it! It was obvious to see and to feel, dunno how someone can make a bow like that (he'd paid good money for it). He felt it was no good, so it was worth risking drastic action.
We got the bow strapped down mid limb on one limb (back down). We'd protected the back with multiple layers of masking tape and lightly clamped side cheeks to the bow to keep the heat on the belly. About 5 mins with the hot air gun and we pulled the bow down straight, strapped it down and heat treated the belly over the thin area. After lunch, we had a look and found a series of short transverse cracks had opened up. I recon these were fine chrysals that weren't obvious before, but opened up as the bow was heated and straightened. What to do? Well we rasped out that area of the belly and glued on a patch of heat treat Yew which will allow the bow to be re-tillered with the grip at the correct thickness. Rob left with patch all strapped up (it takes overnight for the glue to cure).
While he was over here we glued some horn tip overlays onto a Yew kids bow he's made for his son.
Heard back from Rob, he's re-shaped the belly where the patch is, and done a bit of scraping here and there to take off some thick areas. The set is now just 3/4" and the draw weight is up from 112# to about 150# ! The tiller looks much better now. Result!