Posted by
Easy WoodCraft on
Sep 19, 2016
Since a block plane is often used to plane end grain and other hard-to-plane wood like twisted or squirrelly grain, it's imperative that the plane be tuned accordingly. This involves flattening the sole, sides, and bed under the iron, adjusting the throat, sharpening the blade, and tuning the lever cap.
Flatten the sole
Although a flat sole for a block plane isn't as
critical here as it is for the longer-bodied planes, it's still important to ensure full support around the blade. Just as with a longer plane (
see Tuning A Hand Plane), the key points that need to be flat are the toe, the heel, and around the throat opening. The area around the throat opening is the biggest concern, since this is the area that will ensure solid support for the blade as it cuts.
Flatten the sides
Since block planes are occasionally used
on their sides, it's a good idea to check them to make sure they're 90 degrees to the sole. Use a small engineer's square for this; if you find any deviation, flatten the sides as you did the sole. Stop often and re-check with the square. At the same time, I like to soften the edges of the sole by filing a slight (1/16") chamfer all the way around the body. This makes the plane fit more comfortably in my hand and helps prevent dings on the work-piece.
The bed
The bed that the plane iron rests on is rarely flat, and this is a leading cause of chatter in a block plane. The best way I've found to flatten it is with a paddle style diamond hone like the one shown in the bottom photo. Use firm pressure to keep the paddle flat, and continue honing until the bed is flat over its entire surface.
Throat opening
If you're fortunate enough to have an adjustable throat block plane, you can fine tune the throat opening by loosening the adjustment knob and pivoting the lever to open and close the opening. The mating surfaces of the adjustable throat plate and plane body will also benefit from a stroke or two by a diamond hone.
Sharpen the blade
A razor-sharp blade is essential for a block plane to do its best. I generally grind a hollow bevel on the blade and then hone a micro bevel.
See Sharpening Edge Tools for detailed instructions on sharpening a plane blade.
Fine-tune the lever cap
The lever cap on a block plane combines the functions of the cap iron and the lever cap on a larger plane. It has to press the blade securely into the plane body (
while still allowing for adjustment), and it has to hold it rigid to prevent chatter.
Here again, it's imperative that the front edge of the lever cap make full and continuous contact with the plane blade. The best way to ensure this is to flatten the edge on an oilstone. You'll need to experiment a bit to find the optimal angle; hone a little and then reassemble the plane. Check for gaps by trying to slip a feeler gauge between the lever cap and the blade.
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