Tune Your Hand Planes

Tuning a plane essentially means making the sole (bottom) of it flat - which is called lapping it - and then sharpening and setting the blade. Setting involves adjusting the cap iron, frog and cutting depth.

Let's begin with lapping the sole.
The best way to lap a sole is to create a lapping plate. Have a piece of (minimum 1/4" thick) plate glass cut to the size of three sheets of sandpaper laid end-to-end. Attach this to a piece of 3/4" plywood cut to the same dimensions, using epoxy. A liberal band of epoxy, spread diagonally from corner to corner and flattened before the glass is applied (use an old credit card!), will allow the plywood to move a little with changes in moisture levels. Don't coat the whole board. To the top face of the glass, attach sheets of wet/dry sandpaper using a spray adhesive. You can apply 1/3 sheets of 80 grit, 150 grit and 220 grit alongside each other (see drawing), so you won't have to change grits in mid-lapping. What you've created here is a lapping plate: the glass is absolutely flat, so now the sandpaper is, too.

Use a small piece of sandpaper to put a few very light scratches across the sole of your plane (in the short direction). They need to be just deep enough to be visible. You could also use a permanent marker. Then turn the plane over, apply a few drops of water, and slide the plane forward and back along the lapping plate. Don't remove the blade and cap iron: retard the blade so it doesn't protrude, but leave it in the plane to maintain normal tension or the sole won't ever be flat. Work your way from 80 grit to 220 grit. When the scratches are no longer visible, the sole should be perfectly flat.

Sharpen the blade next.
You can begin by flattening the back (no bevel) face of the blade on your lapping board or a coarse grit water or oil stone, using the appropriate lubricant. Work your way down to a fine grit: the back should be virtually polished before you start on the beveled top face of the blade. keep this in mind: you really only have to flatten about 1/2" near the cutting edge. The rest can be less than perfect and never cause any problems. Keep flattening that one edge until you can feel a burr when you gently run a finger along the top (beveled) edge. That's your signal to turn over the blade and begin honing the primary bevel.

Set a honing guide to replicate the existing bevel angle, which will be in the neighborhood of 25 degrees. If you hold the work up before a light, you can see when the angle has been met. I strongly recommend investing in a guide, if you haven't already. They are relatively inexpensive, and trying to hone a bevel freehand is asking for disaster. Move the blade (and the guide) back and forth across the stones - coarse to fine - until the angle is fully polished, square to the sides of the blade, and you can feel a slight burr of the previously flattened back side of the blade. Release the blade from the guide, turn it over, and remove the burr before moving to the next finest stone you own. After you're finished with the finest stone, you can decide whether to grind a secondary bevel on your blade. You might want to try it as it is, then remove it from the plane and hone a secondary bevel, and try it again. To create the secondary bevel, adjust your guide up two degrees and go through the whole process again. This time, things will happen a lot quicker as you're only removing a very small amount of metal. The secondary bevel should only be about 1/16" deep.

Set the cap iron
The cap iron and the frog of the plane sandwich the blade between them. It's a good idea to run a diamond hone across the frog, to make sure it's perfectly flat before you place the blade on it. The third key to successful planing (in addition to a sharp blade and a flat sole) is setting the cap iron properly. It has to have full contact all the way across the blade, be positioned so that it guides and breaks up shavings as they are formed, and prevents shavings being trapped between itself and the blade. having any gap whatsoever between the blade and cap iron will cause the plane to jam up with shavings and slivers on your second or third stroke. To prevent such a problem, just flatten that part of the cap iron that comes in contact with the blade (you can do this on a flat stone or even on the lapping plate), and then place it correctly before locking it in place. It should be 1/16" up from the cutting edge of the blade.

The first time you use a plane, the odds are pretty slim that you will have a poetic experience - one where the shavings magically ribbon out of the tool in perfect form. The more you work at it, keeping the basics in mind and your tool in great shape, the more it will begin to sing for you. After a while, your electric sanders will begin to gather dust as you reach more and more for a hand plane to tame wild boards. This is the very essence of woodworking.