This is a 1-2-3 block on a kanaban.

A 1-2-3 block is a very stable tool used by machinists to make sure things are square and precise and all sorts of other things.  It measures 1″ by 2″ by 3″ and is great for testing, setup and even measuring.

The Kanaban is a nice thick slab of precision ground steel.  With these two tools, things can be fairly quickly and cheaply made flat and square.  Mine is a 10″ by 18″ by 7/16″  slab of O1 steel.   I plan to cut it into three approximately 6″ by 8″ slabs.  They will be more than large enough for most of my work.   With three of them, I will be able to true them to flatness by grinding them against each other.

First you want to make the primary surface flat.  Here is a block plane body being ground with 80 grit Aluminum Oxide grit.

Here I am checking the Body and the mouth in the middle of the process.

This suction pattern that forms when you lift the plane can give clues about how flat you have gotten the sole of the plane.  Here I am using water as a lubricant.

One good way to test is to clean the plane, and then mark it.   In this case I used High-Spot.

High Spot is good for testing large surfaces, but it is a mess, always.

After some grinding, it lets you easily see where the low spots are.

For a small subject like this plane, a permanent magic marker works as well, and is much cleaner.  I had the high-spot out and handy from testing the flatness of my kanaban, or I would not have used it on the plane.

Once you have the sole and mouth bottom flat, you can then use the 1-2-3 block to make things square.

Here is the mouth held against the side of the 1-2-3 block to make sure the mouth is square, side to side.

See the spots of blue on my fingers, High Spot does not come off easily either.

Here it is with the sole of the mouth against the 1-2-3 block making the mouth square across the depth of the mouth.  By sliding the mouth over grit on the kanaban and keeping the 1-2-3 block still, the block is not altered while the plane mouth is precision ground.

Here is how the side of a plane can be made square to the bottom.

Again the block is not moved, while the plane body is.

Here is the plane sole being polished on Linde B.  Note the flaw in the kanaban.  This was caused by me when I was parkerizing the O1 steel plate to make it a bit more weather resistant.  The line is where the five gallon bucket was not deep enough to totally immerse the kanaban in phosphoric acid.  Since the line is etched into the surface, and the surface is still flat, it does no harm at all.  In fact, it seems to help.

I did something rather odd, when I ground this particular plane.  I went from 80 grit aluminum oxide straight to 0.05 micron aluminum oxide.  This means the sole of the plane, while being quite smooth running on a the surface it is planing, will not appear to be polished at all.  On a blade surface, this would be a bad idea.  The irregularities would lead to an inconsistent edge.  On a plane sole, it may actually be a superior.  A plane will lift more easily if a vacuum is not formed while it is slid along a smooth surface.

Flattening a blade on a kanaban is fairly fast, easy and precise, but you still have to run through the grits and polish it.  Here I am using baby oil as a lubricant.

The bed, I had to file carefully by feel and eye, testing with high point and a flattened and squared blade.  I still haven’t figured out a perfect way to hand grind that angle.

Bob