Saturday, 25 October 2014

DIY Bowmaking Thicknesser

I'm not into laminated and backed bows in a big way, but decent Yew is scarce so its good to make the best use of the available wood. That means using billets and backing sometimes.
The preparation in doing billets for backing by hand is fairly arduous, so I hit on the idea of using an old power plane I have to make a thicknesser.
The plane was bought years ago on special offer from one of those German supermarket chains (Aldi I think) but you can get 'em for about £25 anyway. I've only ever used it a couple of times (it's a 900watt one)

I scoured the internet taking ideas from various DIY bow lamination sanders etc. I'd been toying with how to do it for a few weeks, but it was only when I took it apart I noticed the fixing holes for the sole plate were asymmetric and there was enough room to drill 4 holes and screw a couple of 15mm plywood side cheeks onto it and then to re-fit it. That's basically the crux of the whole thing. It's then a matter of mounting it onto a base and making an adjustable platform to raise or lower the work-piece.
A picture is worth a thousand words, so here you go.
I've tried it and it works, it needs some fiddling and fettling to improve it, but as with most things its a trade of between simplicity, versatility, complexity, reliability, cost etc. I'll play with it and let it evolve. Ideally the platform should raise and lower parallel to the sole, maybe I'll look at that.
The big pain is the interlock on the power switch trigger which means you only have one free hand to manoeuvre the wood. I'll rewire that to a nice big accessible switch.
The bottom left pic shows the adjuster, it's taken from a bolt and captive nut that was holding the feet onto our old sofa. the adjustable platform was a rail from the sofa too. Gotta recycle stuff. The 15mm plywood side cheeks are actually from a post war 'Furnikit' bureau that my Dad made about 50 years ago! Recycling at its best.
Gotta make an adaptor so I can connect it to my dust extractor to suck up the chippings.

One big reason for doing all this is that I'll be able to machine tapers on billets. How it's done is you make up a tapered sled that the billet rests on and then the pair of 'em go through the thicknesser.
It's easy to make up a sled to any taper you want.
Say I want 1.5mm every 6", I get two bits of 2"x 1" 36" long with a 9mm spacer between them at one end and no spacer at the other. Glue and screw 'em together and the job is done. Could even make an adjustable sled.
Anyhow that's the principal, it needs some more work yet, but it could be a V useful low cost addition to the workshop.

I've added a switch now, which is a big help and here's a pic of a length of cherry I ran through it, a bit ripply but not bad.

Vastly improved version built here:-

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