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Half Blind Dovetails with Blue Tape

Rather than over-detailing the description of building drawers with the dovetailing, I am writing this additional chapter which one can choose to read, or not. This is not just another dovetail post, however. It demonstrates how useful the use of blue tape is when your eyesight is similar to mine – not great when up close. My reading glasses plus extra lighting are not enough to see the lines scribed in dark woods, such as the Jarrah here.

A few years ago, I reported using blue tape to transfer tails to pins. The technique has developed a little, and so I will present I once again.

As used here, the blue tape simply makes it easier to see where you need to saw. Good saw technique is still needed. However, the ability to saw to the (blue) line will be rewarded. I generally go saw-to-saw (no tuning needed) with 95% plus of my dovetails.

Above: The tail board is marked out, and blue tape is laid across the baseline.

These are going to be “London” style dovetails, that is, saw kerf width at the apex/point. The ratio is 1:7.

I find the use of the Glen-Drake Kerf Starter helpful in guiding the saw for those very important crosscuts.

The completed tail board.

The top (only) of the pin board is covered in blue tape (note that there is an uncovered section in the photo above. This will be sawn away here as this drawer front is curved).

Score the top baseline for the pins with a cutting gauge. The line will be easily seen against the tape.

Add a line of tape at the lower baseline.

Now turn the pin board around to transfer the measurements from the tails.

I use a wide chisel as a straight edge to align the sides.

For transferring the lines, the only marking knife I have that fits in the saw kerf (while riding flush against the dovetail wall) is the Vesper thin “Cohen” knife. A Stanley knife may work as well, but note that it has a slight double bevel (will not cut flush with the wall).

One advantage of the blue tape is that only one knife score is required, in contrast to the repeated score marks on bare wood, which is often necessary to create an indelible line.

Peel away the tape from the waste sections. Drop pencil or knife lines from the dovetail to the lower base line.

It is much easier to saw against the tape with a contrast this distinct.

To aid in removing the waste, I use the Tage Frid trick of deepening the kerf. He used a bandsaw blade. One can use a scraper blade (as long as it is the same thickness as the saw kerf). I made a “kerf chisel”, which I tap in with a gennou. Be sure to add a clamp when you do this to prevent any potential splitting.

I use a small drill bit at the lower baseline to aid in severing the fibers.

The holes make it much easier to split away the waste.

Cleaned up.

Dry fit. I’m happy with that. It will look even better when glued and cleaned up with a block plane.

Regards from Perth

Derek

December 2015