The July 2011 issue of Wood Magazine has a 2-page pattern for a criss-cross clock:
How to Cut Big Holes without Big Forstner Bit
I have a 2-3/8" diameter Forstner bit for clocks, but this movement takes a 3 - 1/8" diameter hole. I looked it up and the big Forstner bit is $30 plus shipping.
The same magazine edition has a 1 page article on how to make big diameter holes, without buying the big Forstner bit........
I am going to try this method for this project. I made a pattern piece from 1/2" thick plywood. I scroll sawed in the 3 1/8" diameter hole.
The magazine plan calls for a light colored cherry for the base clock, walnut strips, and a light colored birch dowel. I plan on using the same woods.
I did have a light colored 5/8" dowel rod, that I used.
I drilled the 4 holes 5/8" dia first, then glued in the dowels, and sanded them off flush.
On my first table saw cut, I got the blade on the wrong side of the dimension. To make the little corners disappear outside the 5/8" dowel, I had to resaw, and make the grooves about 3/16" wide.
I'm wondering why it would be easier to first saw the grooves, then use a drill to remove most of the material in the 4 little squares, then cut 4 little square pieces from colored wood, instead of messing around with the dowels? That way, the exact location of the saw cuts for the grooves doesn't have to be perfect. If I make another one, I might try the squares versus the 5/8" dowel rod.
I used the belt-sander to sand down the 3/16" wide walnut strips..............
I used a 3/4" Forstner bit to remove most of the material in the 3 1/8" diameter hole. Then I hot melt glued the 1/2" plywood template pattern on to the cherry face. I have had poor luck using 2-sided tape (it shifts or comes loose when routing), so I used hot melt glue.
I used the blue Rockler flush trim router bit until I ran out of stroke. This is a very sharp, sweet cutting bit.
Because I ran out of stroke with the blue bit (you start to hit the router shaft/nut, I switched to an old MLCS 1.25" long router bit. I started to finish the job of making the 3 - 1/8" diameter hole, when POWW, the bit dug into the edge grain and kicked hard against my hand. I suspect this old bit is dull and worn out. I am going to replace it with a new Rockler bit........
I finished making the hole using my flush trim drum sander on the drill press.
I removed the pattern, scraped off the hot melt glue with a chisel, then belt sanded the clock face again...........
Next, is making the top piece for the clock.
Below is the new Rockler flush trim router bit I ordered to replace the dull MLCS bit.............
I used a router chamfer bit to put the 1/4" chamfer on the 1/2" thick cherry top.....
The last assembly step was to glue the top to the main clock body...........
I got this clock done, but I was not happy with the 4 little accent pieces, because they did not have enough color to be accent pieces!
What to do Now?
My choices at this point were:
-make a whole new clock and use yellow heart for accents. Drill circles in yellow-heart using plug cutter in drill press.
-re-drill the 4 accents, put in yellow heart, resaw the grooves for the walnut
-try to carefully chisel out the birch dowels, and replace with square yellow heart
I chose to to chisel out the birch dowels, and replace with yellow heart
The chisel method worked better than I thought, but I have done inlays before using a chisel, so I have some experience with it. I used the vertical disc sander to remove small amounts of stock to get good fits. I also used my sharpest 1/4" wide good chisel.
Next was back to the belt sander, to sand down the yellow heart 4 pieces, and the front face. Then 2 rounds of polyurethane and 220 grit sanding. I like the yellow heart accents much better than the birch dowel!
Closing Thoughts on This Project
I learned a couple of valuable lessons on this project:
1.router bits do eventually get dull and need to be thrown away.
-if they start to catch when routing against the grain, this is a sign they are getting dull
2. Think about colors when using accent pieces.
-The magazine pattern picture showed enough color contrast using a birch dowel, but I got almost no contrast with my dowel. I had
to use yellow heart for a good color contrast. Red padauk would also work well.
3. The age-old question when working with cherry. Do I not stain it and let it change color over time...........or stain it with a red cherry color now?
-on this project, I elected no stain, and will let it darken over time.
4. The plan calls for an 1/8" groove made by a table saw blade.
-All of my blades are less than 1/8" wide. I had to make 2 passes to get a wide enough cut.
-the problem with 2 passes, is that it is hard to get the inner and outer grooves the exact same width, so the same thickness walnut
piece can be used for both sets of grooves. It might be easier to use the router table with an 1/8" or 3/16" wide router bit......versus the
the table saw.