Thursday, November 26, 2009

SANDING & SCRAPING INSIDE CURVES

          The tighter the curve, the harder it’s going to be to sand. A gently curved chair leg, for instance, can be easily sanded using the exposed drum on one end of an edge sander. A curve with a 2-inch radius (four-inch diameter) requires a smaller drum which might be an option on a spindle sander. Curves with less than a 1-inch diameter might not be machine sandable and might require sandpaper wrapped around the end of your index finger or a mechanical device such as the Rockwell SoniCrafter detail sander with the finger sanding attachment.


    In the end, all curves, regardless of diameter, will require some degree of random orbital or hand sanding to remove the linear scratches left by drum sanding. I have found scrapers to be useful in this regard, as well. I am referring to the kind of scraper that is made from a rectangular piece of steel and which is sharpened with a smooth mill file to true the edge and then with a burnishing tool to create a small “hook” on the edge. It is the hook that does the work and so, as the hook wears away, the scraper must be burnished again and again to restore the hook.

    Scrapers are also available in shapes other than rectangular for conformation to the type of curve being scraped. Some of these scraper shapes, by their very nature cannot be accurately trued up with a flat mill file but burnishing can be accomplished with a hand-held burnishing tool or jig. Scraping should always be followed by sanding with a fine grit sandpaper (220 or 320).

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Bob Gillespie
Woodworker
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