Kumiko Sampler - #5 Chisel Sharpening & Lattice Infill – Part 1

Before starting on the infill pieces the chisel that will be used to cut the bevels on the end of each piece needs to be sharpened.  It’s been quite a while since it has had any serious sharpening done other than some honing on a leather strop.  Over time it has gotten a few small nicks in the cutting edge.  To get rid of those I decided to go through a full sharpening series. 

I sharpen my chisels and hand plane blades using a jig that holds the tool at the correct angle.  Some people are good enough to do that by feel but not me.  The photo below shows the jig in use.  On the left side of the photo is a black gauge with red, yellow and green writing.  It attaches to the jig and is used to set the sharpening angle then removed.  For the actual sharpening I have used natural stones, Japanese water stones, diamond plates and what’s used here.  It’s wet/dry silicon carbide sandpaper on a flat piece of granite using water as a lubricant.  I like this method since I can get the paper in grits ranging from 180 up to 2,000 plus they are fairly inexpensive and the granite always stays flat.

When the final sharpening pass is done with the 2,000 grit the last step is to polish the edge using a leather strop.  At this point the sharpened edge is near a mirror finish.

Now the actual cutting and fitting all of the infill pieces can begin.  First are the eight diagonals.  They are about 1 5/8” long with a 45-degree bevel on both sides of each end.  This drawing shows what it will look like when done. 

The first piece is cut a fraction long using a stop block clamped to the bench hook and cut with the Japanese pull saw. 

Next using the 45-degree angle jig the length stop is set to cut a bevel just ½ the thickness of the piece.  Here the unbeveled piece is set in the jig and is ready to be cut.  A finished bevel requires three or four passes taking off a little at a time until the chisel rides flat on the angled jig face.

With one side beveled the piece is flipped over and the other side done.  The piece is then flipped end for end and bevels are cut on the other end.  Here is a closer view of a completed pair of bevels.

The completed diagonal is then test fit.  Since this is the first try to no surprise it was a little long.  Going back to the beveling jig the stop is adjusted and the bevels on one end recut then back for a test fit.  The process is repeated until the piece just fits.  Too tight and the grid of rails will be thrown out of square, too loose and you end up with a gap.  The margin for error is really small.  When a good fit is achieved the overall cut length of the blank is adjusted on the bench hook and the diagonal blanks cut.  Here are five of the eight diagonals installed. 

When everything works out right this is what one of the squares looks like where all the pieces come together.  After all the diagonals are cut, they are removed then glued into place.

After the diagonals comes the wings and there are 32 of them.  Here is a drawing of what the sampler looks like when they are added. 

Like the diagonals they are beveled on each end.  Unlike them the angles on each end are different and on one end they are not centered.

The wings begin by measuring and cutting a couple of blanks to the approximate length then using the 22.5 and 67.5 degree jigs bevel the ends and do a test fit.  As the blanks were long the same process of making adjustments and fitting that was done for the diagonals is done for the wings.  With the wings really, really close but long I could set the stop on the bench hook and start cutting the blanks needed.  The 90 blanks I cut are shown at the top and the almost fit wings are in place in the lower left of the sampler below. 

Why, you ask, are there 90 blanks when only 32 are needed for the sampler?  Well, that’s because in a moment of weakness I decided to make a second full sampler, a half sampler and one small ¼ sampler. 

The process for the final fitting of the wings is to cut the 22.5-degree double bevel on one end of all 90 of the blanks.  That has to be done in phases as after about 45 minutes my fingers are ready to take a break.  This is the setup for doing those bevels.  The other jig has a 67.5-degree bevel and is used for the other end that I used to do the test fitting.  I can’t cut both ends in production because the 67.5-degree end is an unequal split which needs two 67.5-degree jigs using different length stops.  Don’t worry if that does not make sense as it will get covered in a bit.  In the photo in the upper right you can see the leather strop used to touch up the chisel edge every 5 pieces or so.

This is a little closer view of bevel setup.  One minor correction is that most of the time a skew or angled cut is used to pare off the wood and make the bevel rather than the square cut shown here.

Once the 22.5-degree double bevel has been cut on the wings the setup and fitting can begin for the two 67.5-degree bevels on the other end.  As noted above the bevels at this end do not meet in the center but are offset about one-third, two-thirds.  That all has to do with the way the wings and kingpin meet.  Below in the drawing and blowup of the red circled area you can see what I mean.

In order to get the unequal, split the stops on the two 67.5-degree jigs are set at slightly different lengths.  One jig has a depth stop already set close for the two-third bevel from earlier on when doing some rough testing to determine the wing blank length.  The second 67.5-degree jig is set a hair shorter for the one-third bevel.  As before trial and error dials in the right combination so the 22.5-degree double bevel fits tight in the corner.  Here are the two jigs set up and ready to go.  In case you are interested the second cut for the one-third bevel stop is set .02” shorter than the two-thirds one.

Next Up – Completing Lattice Infill & Starting on Frame