How to flatten the soles of metal
and wooden planes

 
     
     
 Shop for Woodworking Hand Planes 
     
     
 The sole of a block plane 

The sole of a plane, whether metal or wooden, needs to be perfectly flat, otherwise the plane cannot be held flat on the wood and the cutting will be uneven. The only exceptions are some specialist planes - those for cutting circles and other curved shapes.

 
     
   

How to check the sole of your plane

 
 Checking the sole of a plane for flatness 

If the sole is found to be uneven when you ‘sight’ along it (look along the sole from toe to heel), or place the edge of a ruler or try square along it, you will need to follow a procedure known as "lapping the sole".

 

Another way of checking is to place the plane sole-down on a perfectly flat, hard surface such as plate glass, and see if it’s possible to rock the plane.

 
     
 Sole of plane marked with marker pen to check flatness 

The above checks are ones you might be able to try before actually buying a plane.

Yet another way - which you can probably only do with planes you already have - is to mark the sole with a marker pen and run the plane across abrasive paper on a flat surface 

 
     
 Marking up sole of hand plane to check for flatness; ink wears off unevenly; woodworking hand planes  

If the ink wears off evenly, you have a flat sole. If high and low areas are revealed (by the removal or retention of ink respectively), you need to lap the sole.

 
     
   Wonkee Donkee on lapping soles of hand planes 
     
   

Lapping the sole of a metal plane

 
 Two grades of abrasive paper for flattening sole of plane 

You will need:

 

  • Two grades of silicone-carbide or aluminium-oxide abrasive paper – 120 grit, which is quite rough, and 240 grit, which is smoother. (Self-adhesive abrasive paper makes the job of sticking it down much easier.)

 
     
 Use a hard surface like a granite tile when lapping soles; flattening hand plane soles; woodworking planes 
  • A perfectly flat, hard surface, such as plate glass, marble or granite.

 
     
 Two grades of abrasive paper fixed to a granite tile for hand plane lapping 

Step 1 - Stick abrasive paper to flat surface

Tape or glue two pieces of abrasive paper – one 240 grit, the other 120 grit – to a flat surface. If glueing, make sure the glue is spread perfectly evenly and there are no ridges in the paper.

 
     
 Marking sole of plane with marker pen ready for lapping 

Step 2 - Mark sole of plane

With a fairly broad-tipped marker pen, mark some lines across the sole of the plane. 

 
     
 Lapping a hand plane on 120 grit abrasive paper 

Step 3 - Run sole over paper

With the blade retracted, run the sole of the plane over the rougher, 120 grit abrasive paper, backwards and forwards, a dozen or so times. Put some downward pressure on the plane, trying to equalise the pressure along the sole.

 
     
 Checking the progress of lapping a plane 

Step 4 - Check progress

Take a look at the sole – you should see that some of the ink marking has been taken off by the abrasive paper. The "high spots" of the sole are the parts where the ink has been removed, and the "low spots" are the parts where the ink remains.

 
     
 The soul of the plane now looks perfectly flat 

Step 5 - Continue to flatten

Continue to flatten the sole by running it over the 120 grit abrasive paper until all the ink markings have disappeared and the sole is shiny.

 
     
 Finishing hand plane lapping by running sole over finer grit paper 

Step 6 - Smooth sole

With the the sole now flattened, any scratches left by the rougher paper can be smoothed away by running the plane over the finer, 240 grit paper.

 
     
   

Lapping the sole of a wooden plane

 
 The sole of a wooden plane 

It's usually easier to lap the sole of a wooden plane than a metal one as wooden soles, although usually made of the hardest of hardwoods, yield more readily to abrasive material.

 
     
 Sandpaper is idea for lapping the soles of wooden planes 

You will need:

  • 180 grit sandpaper, the ideal abrasive paper for lapping wooden soles. (Self-adhesive sandpaper will make the job of sticking it down much easier).

 
     
 Use a hard, flat surface like a granite tile when lapping hand plane soles; flatting hand plane soles; woodworking planes 
  • A perfectly flat surface such as plate glass, marble or granite.

 
     
 The sole of a wooden plane 

There's no need to mark the sole of a wooden plane with a marker pen as you do with metal ones.

 

The scratch pattern made by the sandpaper will readily reveal any high and low spots on the sole.

 
     
 Stick sandpaper to a flat surface to lap pane soles 

Step 1 - Tape or stick sandpaper

Tape or stick the sandpaper to your flat surface. The sandpaper should be at least the length of the plane.

 
     
 Run the plane over sandpaper to flatten the sole 

Step 2 -  Run plane over sandpaper

With the iron retracted, run the sole of the plane just once over the sandpaper, pressing down and maintaining firm contact throughout.

 
     
 View scratched areas of sole left by sandpaper 

Step 3 - Check sole

Take a look at the sole. The scratch pattern left by the sandpaper should reveal any high and low areas of the sole – the high points scratched and the lows left untouched.

 
     
 Run the sole repeatedly over sandpaper to flatten sole 

Step 4 - Remove high points

If there are any high points, remove them by running the sole backwards and forwards repeatedly over the sandpaper until the whole of the sole has been affected by the sandpaper.

 

At this point, your sole is well and truly flattened!

 
     
 

Running sole of wooden plane over sandpaper to flatten sole

 

Step 5 - Smooth finish

If the sole looks scratched rather than smooth, you can finish off by running it across higher-grit sandpaper – somewhere between 220 and 400.

 
     
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