Today you get a great tip for nothing – that’s right – FREE!
I was ready to make the 90° cut on the glued-up desk top, to separate the board that aligns with the backs of the legs on the desk. But at the last minute I chickened out, to think it over. Something did not seem right; should it be a 90° cut? Or should it be something else?
A little background: From an old blog entry, the following photograph shows the relatively narrow width of the board that will at the back of the desk top – it is the flat area where the clamp is located. It will be just over 6-1/2 inches wide from the back of legs to the point where the slope starts toward the front of the desk:
The more I though about it, a 90° cut did not seen the right thing to do. I decided to get a second opinion from Rick, one of the master cabinetmakers in the area, and a member of our Guild; he is the guy who showed us a new way to fold a band saw blade at a recent Guild meeting. Very quickly he zeroed in on why the cut must be something other than 90°: regardless which side gets the right angle cut, one of the boards will end up a little “thick” (proud), relative to the other. Rick suggested that each side should get the same identical bevel cut. That was it!
The second part of my dilemma had to do with what kind of jig to use to assemble the desk top during glue-up. A little more discussion ensued, and Rick suggested the desk frame itself would be THE best jig available (of course!), with a few biscuits inserted on edge to assist with alignment. This will be one of the few times I use biscuits to assist with edge alignment.
It was time for some test cuts. I spent yesterday with some test boards, zeroing in on the angle. I had originally determined the angle indirectly, by simply measuring the back and front heights of a very old stand-up desk. From those measurements, the slope toward the front is approximately 7°. I used a cheap metal protractor to mark the angles for the aprons and the divider I cut on the table saw. But for the desk top I needed to be right on the angle. Test cuts at 3.5° on each of two boards were not quite right. Additional cuts helped me zero in on the perfect angle of 7.6° total, or 3.8° for each cut. How was this accuracy possible on the table saw? The Wixey Digital Angle Gauge, of course!
In the following photo I show the results of the test cuts at 3.8°, with the test boards set on the apron, and no clamps used for to hold the boards together:
I inspected the aprons under the boards, to make sure that at this angle the boards would be flush with the aprons. It worked.
Now that I know the angle, I will make a very simple jig to cut the biscuit slots accurately. Once the slots are cut on both sides, it will be time to make the final cuts on the boards that will make the desk top.
— Al Navas