Thread: Grinding (shaping) a blade for a scrub plane

I have had a few requests for information on grinding a blade for a scrub plane.

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. Of course, the grind angle is between 25 - 30 degrees as with all plane blades.

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. Now, if you are using a Stanley blade, which has a groove down the centre, bolt the two together. If the blade you are using is solid (like the original Stanley scrub plane blade), then clamp it 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 approximately 30 degrees (preferred angle). You then turn the blade against the wheel using the curve of the hardwood template as a guide. See first picture below.

Once you have ground the curve (either fashion), it is necessary to hone the blade (sandpaper, waterstones, etc). It is not necessary to hone as high a grit as other plane blades as you asre not trying for a smooth finish. A 1200 waterstone is adequate, although I would prefer to go to at least 4000 myself.

I do not have a favourite since each seems different in a positive way.

The first one I used was one I made out of a ECE-type horned wooden (Norwegian) smoother. This has a great 1/8" thick by 1-3/4" wide blade. In some ways this is the perfect scrub since it is light and comfortable in use for long periods.

Then I bought a vintage Stanley #40 (just because it looked so cool), and what I like about this scrub is that it has a bit of heft and this is helpful when taking deeper cuts in hardwoods.

The third scrub I use was the result of a disaster. The only plane I ever inherited was my late father-in-law's Stanley #3. I used it for several years, quite happy in my ignorance that it had a very wide mouth and could not cut anything but pine, and even then was more like a short jack plane than a smoother. For some years it had lane on a shelf unused. Then a few months ago I decided that it would be more honourable to find a use for it than to abandon it as it was. So I opened the mouth some more (it really didn't need much more!) and ground the blade to a nice radius. You know what, even with the thinnest blade of this bunch, it does a nice job. What is special is the fact that I can adjust the depth of cut and this makes it possible to go from a trim to a deeper slice, which is useful when taking off high points.

So there are some options: make your own, buy your own, or rescue one.
See second picture.


Regards from Perth

Derek