ARTICLES & REVIEWS
Grinding a Scrub Plane Blade
by Derek Cohen (in Perth Australia)
There are two ways to grind a curve onto a blade. The first is just do it freehand at a grinder. Since the surface is going to be chewed up (although this can be chewed up neatly!), the blade shape is less critical. So just get as close a curve as you can. The grind angle is ideally around 30°.
The second method is the one I prefer since it produces a clean, smooth curve. Cut a piece of hardwood the same size as the blade. At the end of this piece, shape the curve you want to grind. The typical radius is 3". Now clamp the blade to the hardwood.
What you are going to do is use the curve on the hardwood as a template for the blade. The curve runs up against the edge of the grinder rest, and the blade (bolted to the top) is extended until it contacts the grinder wheel at the 30° preferred angle. You then turn the blade against the wheel using the curve of the hardwood template as a guide.
A while back I upgraded the grinder to a belt sander and custom made a blade holder along the lines of a Tormek. The same principle remains for grinding. This machine is pictured above and at left.
Once you have ground the curve (either fashion), it is necessary to hone the blade (sandpaper, waterstones, etc). It is not necessary to hone to as high a grit as other plane blades as you are not trying for a smooth finish. A 1200 waterstone is adequate, although I would prefer to go to at least 8000 myself since this makes a difference with hardwood.
There is an article on file in the Articles Section that deals with using the Lee Valley Honing Guide to hone a fine edge on a scrub plane blade (my upside down guide)—Advanced Angles on the LV Honing Guide MK II.
These are templates with various radii for the Stanley #40 and LV Scrub planes
. . . Derek Cohen (in Perth Australia)
© 2005 by Derek Cohen (in Perth Australia). All rights reserved.
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