This one is for Betsy, at Lumberjocks.com.
Betsy has had trouble cutting to the line when hand-cutting dovetails. Therefore, she would like to improve the fit, by making sure to better cut to the line. I promised I would try to document how I do it.
I found that using either the index-finger fingernail, or the thumb fingernail, to create a “fence” for the saw, works best for me. Therefore, I first place the fingernail exactly on the line, and then I place the saw on the board (click on the images to enlarge):
Once the saw is on the board, I sight down the cheek of the saw to the extent I can – the back gets in the way, as it is considerably thicker than the saw blade. By sighting down the cheek I get the best feel for the angle at which to hold the saw, thus giving me a good chance at being able to get the angle correctly. Note that the saw appears to be quite a distance to the right of the mark in this photo – THIS is exactly what it should look like:
Keeping my finger nail “fence” in place, and using a very light touch, I start the cut on the push motion (if using a Japanese saw, you must start the cut using a pull motion). Some people refer to this light touch as de-weighting the saw (I think this is the most-used term). This “light touch” also means that you are exerting on the saw *only* the force required to push and pull the saw on the board – no more, and no less.
Once the kerf is established, I remove my finger “fence” and complete the cut while sighting down the cheek of the saw. If the saw is not following the line, I do not try to correct it by steering the saw. It is impossible to do so with a dovetail saw, and it is also not recommended. The best thing to do: Start over.
I am certain that when I first started my hand-cut dovetails practice sessions I was tense, and therefore it was difficult to start the cut on the push motion. And I was amazed at how easy it was once I used as light a touch as possible.
It took me a while to realize this *is* the proper way to be to best cut to the line. With very minor adjustments it is possible to even “split the line” – provided, of course, that the line is wide enough to be “split”.
Edit to add: Dan, at WoodNet, said: The thumb is most definitely the rough cut fence and the index finger for accuracy.
During the Dovetails session at Woodworking in America (Parts 1, 2, and 3), Frank Klausz recommended to “…split the line when cutting the pins; and cut on the waste side of the line – the pins side – when cutting the tails…” Of course, Klausz cuts pins first.
So, Betsy, keep up your practice. And please let us know when you can cut to the line precisely. That will be your AHA! moment.