Adventures in Hand Plane Tuning: Part 2

At the end of my last post about tuning my seven hand planes, I was ready for step 3: Lapping the Soles, which became an adventure in itself.

Granite Plate Gap

You can see light between the straight edge above and the lapping plate below.

Granite Lapping Plate

There are several methods out there for accomplishing this task, and I decided on using sand paper affixed to a flat lapping plate.  My first lapping plate was a piece of granite counter top 6″ wide and 24″ long.  Before I started however, I placed a straight edge along the length of the stone and realized it was slightly concave.  The widest part of the gap measured .003mm, so I’m not talking about something huge.  How much of a difference could a gap that small really make?  I attached an 80 grit sanding belt to the granite with spray adhesive, and I was ready.

I focused first on the Stanley #4 because it had the most amount of concave and the deepest machine marks along the sole.  I took a strong stance: feet shoulder width apart, hands placed on the tote and knob with even downward pressure, and kept my body out of it as much as possible, moving the plane back and forth across the sandpaper using my arms. After hours holding my hands and arms in a certain way while moving them back and forth (in rhythm with the songs on the radio) I felt like these guys:

Stanley #4 Plane Sole 2

The #4 plane sole after quite a bit of work. You can still see some machine marks (the dull grey).

Anyway, I noticed I wasn’t making much progress after a few hours of work.  The amount of material I needed to remove to flatten out the concave made me realize I should move down to a 50 grit sanding belt.  Once I changed that I was making real progress, checking it from time to time with a straight edge and a machinist’s square.  Then I noticed something else: the heel and toe were starting to curve upward.  The sole of the plane was conforming to the .003mm concave surface of my granite lapping plate.  Oh, bother.  I got on the phone and ordered a piece of 1/4″ glass 6″ x 24″.

Lapping Rig

Lapping Rig: Glass Plate, Sanding Belt, Non-Slip Shelf liner, Straight Edge, and Machinists Square.

My new glass lapping rig worked well.  The slight upward curves on the heel and toe corrected themselves.  Also, the glass plate helped me become more aware of the pressure I placed on the plane.  I watched how the shavings were left on the belt and could tell if I was leaning too much to one side or the other.  Vacuuming the belt kept it from clogging and changing the belt occasionally kept progress moving forward.

Plane Sole 3

Finally, a flat #4 plane sole.

I finally worked the Stanley #4 sole flat and it’s ready for polishing.  By the time I worked six of them to acceptable levels, I probably spent somewhere over 10 hours. One of the biggest lessons I learned from this process is that lapping can take quite a bit of time, so be patient.

Interestingly, the planes that needed the most lapping on the soles were the new ones: Stanley #4, #12-920, #12-960.  That says something about current manufacturing standards, but at the same time, I wasn’t willing to spent money to get higher quality tools.  Don’t get me wrong, I’m not sorry about the work I’ve put into these planes.  I know that when I’m finished they will work just fine for my current ability level.  In addition, it’s a rite of passage for a woodworker to go through.  I’m paying my dues.

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