Wednesday, April 14, 2010

Ashwood Staves

I've been assembling another lute bowl this week using this material. It's flat-sawn ash. Over the weekend I had a great educational experience at the A&M Wood Specialty warehouse in Cambridge, Ontario. It was a musical instrument makers open house with the guest speaker being noted Toronto luthier Michael Schreiner. Musical accompaniment was provided by lutenist Terry McKenna. Mr. Schreiner offered a slide presentation detailing his endeavours in various museum collections to document historical lutes and early guitars. One example of interest to me was the extremely early Laux Maler lute in the Cite-Musique, Paris. The wide ribs of flatsawn ash reminded me of Kenneth Be's six course instrument constructed by Grant Tomlinson. I had the pleasure of listening to a recital of Spinacino played on this lute in Vancouver a couple of years back, and I was extremely impressed by the tonal quality.

As luck would have it, I have a supply of (nearly) flatsawn ash offcuts from a project I undertook a few years ago. The wood was salvaged from a pew removed from the upper loft at Melrose United Church in Hamilton. I used it to construct a scale model of the church organ to present as a retirement gift for music director Faye Grinberg. I also fabricated some Arts and Crafts style furniture for our living room. At the time I had resawn some 1/16" strips to reduce the amount of hand planing necessary. This material has been seasoning for more than eighty years, and I have just enough for one lute bowl. It's not sequentially cut, but I hope that the haphazard grain patterns will add an air of jaunty playfulness. At least that's what I'm telling myself.

I'm scraping the roughsawn staves to near near finished thickness. I wouldn't try to do the whole batch of 15 at one go, as this would lead to crippled thumbs and boredom. Scrape one, bend it, glue it, and repeat. I didn't photograph it, but I have a little digital thickness gauge I use to ensure uniformity. It surprises me how many woodworkers don't have a steel cabinet scraper in their arsenal. It's so ubiquitous in luthiery that it always takes me by surprise when someone asks me how to use or sharpen one. Still wishing I had a third hand for moments like these, the picture shows me pushing the scraper away from me, pitched slightly forward into the direction of cut. Of course, I'd usually have both hands on the blade. For aggressive scraping I flex the scraper with my thumbs. As I want to keep things quite flat here, I'm not imparting much camber. Like the scraping jig? I got tired of messing with F-clamps. This lets me take advantage of my exceptionally long arms.

I enjoy scrapers so much, I've developed quite a
collection! They're made of springy carbon steel. Some are ground into curves for specific hollow areas. I've radiused the corners on others to make them "safe" in areas I don't want to accidentally leave scratches on adjacent surfaces.

The scrapers rely on a very fine hook on the square cutting edge that acts like a microscopic plane. The hook is produced my carefully deforming the sharpened corner.

I start by removing the old hook using a smooth mill file. The object is to produce a nice hard 90 degree square. I file both the sides and the top. I've demonstrated the various Veritas scraper jigs at numerous seminars and wood shows, but in my own shop I've always relied on my hands. Hmm. That might be the reason my knuckles always look so chewed up. (You can see them of course only when they're not covered with dried glue.) But seriously folks, note how I use the knuckle on my index finger as a fence to keep the file square to the edge.

For really rough scraping I'll use the surface produced by the file. Most of the time however, I'll polish things up with my 800x ceramic stone. I like these stones because they don't get scored with grooves, I can use them dry, and they only require the occasional cleaning with soap and water. Again, I hone both sides and top edge. If I'm using the scraper in a very refined way- perhaps to level a finishing flaw, I will forgo the hook and use it with a square corner.

My burnishing tool. So unlike the fancy expensive chrome-polished beauties available for $30 or more. I made it from the shank of a 3/16" drill bit, heated to straw-brown to harden it. Yes, I should buy a better one but I've had this for twelve years now, and I'm used to it.

I lubricate it with with a little paraffin wax. Mr. Lee always suggested using some grease from the side of one's nose. I could never bring myself to do that, especially in front of a crowd of people.
Note that very little pressure is necessary. Most novices really crank down on 'er. Note also that I'm again using my finger tip as a fence. This needs to be a controlled maneuver. Too much misplaced force could require a tetanus shot.

That's better. Little wispy shavings - not granular dust. I have to be gentle with this wood, as I don't have extra to play with. It's special to me as it's absorbed the musical energy of eighty years of Christmas candlelight concerts, countless performances of the Messiah, and my own voice.

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