Friday, August 26, 2016

A "Honey-Do" Project With a Curved Rebate

SWMBO asked me to make a cutting board that would fit over the small part of our kitchen sink.
The need arises
You can see in the picture that there is a small step-down from the uppermost flange to the level of the separator of  the two sinks.  This would allow a cutting board to nestle nicely in the opening.  I wanted to put a rabbet on the underside so that the cutting board would fit down in the opening and not move much when in use.  As you can see, this means cutting curved rabbets.  Recently I read an article in "The Woodworker: The Charles H. Hayward Years (Vol. II)" about working curved rebates.  It was not necessarily too helpful, but gave me some ideas nonetheless.

So I got myself a piece of maple and glued up an oversized panel.  I was surprised at how easy this maple was to plane.  For the glue-up I got one side flat and one edge straight.  I planed the edges together to guarantee good flatness of the panel.  I also oriented the grain of the two pieces so that I could plane them both the same way after being glued together.
The panel glued up, ready for sizing
After gluing, I gauged to about 11/16" thickness and planed to it.  The two boards were about 7 1/4" wide, so the panel was almost 14 1/2" wide.  Since my combo square blade is just 12", I use the square and a straightedge to strike a square line across the end.
Squaring a line across the width
Made a little step down with a chisel
... and cut the end.  Clearly I need some practice cutting squarely.
Fortunately this maple planed beautifully on the end grain.  FAR, far better than any pine I've ever worked with.  I got a nice, square end.
You can still just see the knife lines around this end grain
I repeated the process at the other end to get the (roughly) 16" length I needed.  After straightening one edge, I used the new homemade panel gauge to mark the (roughly) 12" width.  You really have to be careful that the panel gauge fence stays tight to the edge.
Marking the width with panel gauge
In the picture of the sink, you can see that the rabbets I need are not as simple as those used for rectilinear furniture.  But at least I can start with 5/8" rabbets, about 3/8" deep all around.  I started with the ends.  This would help ensure that any blow-out at the corners would be inconsequential because of subsequent rabbeting of the edges.  I gauged lines for the width and depth of the rabbets.  This being one of the first times I've done cross-grain rabbeting, I got to use the nicker in the Record #778.
Nicker not yet in position.  Had to sharpen it as it had apparently never been used.
After setting the plane fence and depth stop, the rabbeting started.  It went slowly as I took small bites.  I've been having problems with the plane shavings jamming in the throat.  Since then I got feedback from Bob and Stephan that I hope helps with this.
Rabbet started
You might be able to see in the above picture a small saw kerf at the left, just above the gauge line.  I cut the kerf also to avoid any blow-out below gauge line level from cross-grain planing.  This worked well.
Almost complete rabbet
One of Bob's comments was that my left hand might be keeping shavings from exiting the plane.  I'll have to look into different hand positions to fix this.

Once the two ends were done, the long grain rabbets went easily, though slowly.
Long grain rabbet started
For the rabbets, I've been clamping the work to the bench using the slot in the middle of the benchtop.  I align the edge being rabbeted with the front edge of the bench and this gives me more surface for the plane's fence to slide along.  It wasn't critical for this project, but all the rabbets came out quite square and clean.

The next step was to mark the curves that needed to be added to the rabbeted area.  It turned out to be about a 3 1/8" radius.
Curves marked on one end ...
... and the other end
You can see a mistake here.  With the rabbets going so slowly, I decided on one of the ends to saw a kerf down the gauge line to make it easier.  I went a little too deep with the saw.  At least that's on the underside and won't be seen.

I thought about how best to chop out waste.  I don't trust my sawing enough to saw out most of the waste.  So out came the chisel and mallet and I chopped away.
Chop chop choppin'
Here I used a couple of wedges (and the bench slot filler strip) to fix the board between two bench dogs.  I love wedges.  I know they were used extensively years ago (and sometimes still are), but I've only scratched the surface of how much they can help.
Wedgie on left
I managed to get a fairly clean curved shoulder with the chisel, but I cleaned it up with a shoulder plane as well.
Cleaning up shoulder
I also finished up the bottom of the rabbet with a router plane (no picture).  The rest of the corners went well, although I really got chopping hard at times.  And although the tip of the chisel didn't get into the "keeper" wood, the force of chopping deformed some keeper areas and they didn't look too good after oiling.
All corners with curved rabbets
You can see here that I've also shaped the corners of the top (non-rabbeted) surface.  A test fit had it fitting pretty well in the sink.

The last material removal step was to form an elongated hole both as a handle and as a place to push unwanted vegetable waste to the disposal drain.  The hole was to be 2" wide.  I have a 2" hole saw and thought about using it, but the shank did not fit my drill chuck.  It would fit my drill press, but that's in storage.
Can't use the hole saw.  That's OK, I thought it would give too rough a cut anyway.
So I laid out the hole, drilled a small hole for the coping saw blade and went to town.
Coping to the lines
When that was done I used rasps and files to clean up the inside surfaces.  I also laid out lines for a rounding over of the hole on top and bottom and used a chisel to do the work.  This was good practice in chisel work.
Chiseling the round-over
I used plane and spokeshave to ease the outside edges of the board and then sanded to smooth them off.  Then a final smooth planing top and bottom followed by light sanding.

For finishing, first I raised the grain with water, let dry and sanded (twice).  Then I applied mineral oil with a rag, slathered on and wiped off about 1/2 hour later, with a day between each of the three coats.
Easy finishing
And there you have it.  Fit's like a glove.  Happy wife ... happy life!
A nice fit - and looks good, too!