Dovetails

My main instructor, Dan, is not good at pacing the class.  Because of this, a few of us keep running out of things to do.  After a week of seeking him out every day to tell him I had nothing to do, he finally decided to give those of us who have been moving quicker a special instruction session on how to cut dovetails.  This gives us plenty to do because they are used a lot, so we need to get really good at cutting them.  It is a very strong joint because it is held together both by the interlocking of angled pins and tails as well as the glue, whereas something like a finger joint is just held by glue.

Dovetail joint. Pins in blue.  Tails in white.

Finger joint

The process is fairly straight forward.  You start by marking the width of each board on the other board with a marking gauge (I will be posting about marking gauges soon).  You then lay out the pins on one of the boards.  Next you cut close to the line with a dovetail saw

Dovetail saw

Then you pare to your lines with chisels.  It is important to have very sharp chisels in order to get clean lines.  When you have the pins finished, you trace them onto the other board.  On that board you cut out the pins, leaving the tails.  In order to get a perfect fit you must pare to your lines exactly.  Because the lines are an outline of the pins, if you cut into the line at all, you have gone too far and it will show when you put them together.  Here are the first dovetails I ever cut byt hand:

They had a good, tight fit, but there are way too many gaps.

This is the same joint from the other side.