Posts Tagged ‘dividers’


In:In the Shop

Comments Off on Dovetail Joinery: Part 2- Laying Out the Joint

With the boards prepped as discussed in part 1, it’s time to lay out the tails for sawing.  To do this, you will need two sets of dividers (also referred to as a compass, but I don’t want to get into that right now).  I own four Starrett sets which covers just about anything I’ve ever done.  The tips should be ground to a point and I prefer to have them all in different sizes so I don’t confuse which pair has which setting.

No repeat sizes helps avoid confusion

Use one set of dividers to mark the side pins.  These tend to be a little thicker so they don’t split, I’m using 1/4″ here.  Mark that distance in from each edge of the board, then set that pair of dividers aside to use on the following joints in the other corners.

Mark in from each edge

The second set of dividers will walk off the number and width of the tails and consequently the pin space between each tail, all without the fuss of measuring.  To do this, guesstimate the size of the tail, set the tip of the divider into the pin hole (on the left in this example) made by the first set of dividers and step it across the board until it passes the far pin hole (on the right side).  Each step will be a tail, so if you want three tails, you need to take three steps, four tails, four steps, and so on.  Be careful to walk the dividers lightly across the board.  You don’t want to create any pin holes until you’ve finalized the setting on the dividers.

Starting in the pin hole on the left, walk the dividers until they pass the pin hole on the right.

The distance the dividers overshoot the pin hole on the right will be the gap between each tail.  Don’t actually create a pin hole here, just gauge the gap by eye and decide if it needs to be thinner or thicker.

The distance the dividers overshoot the pin hole will be the gap between each tail.

Adjust the dividers and repeat the process until you have the correct number of tails and are satisfied with the gap size.  Now you can step the dividers off one last time, this time pressing hard enough to mark the board.  When the dividers cross the pin hole on the right, stop.  Do not mark a pin hole here.  Instead, shift the dividers over so the leg falls into the right side pin hole, then step the dividers back to the left.  Now you’ve got a board with pin holes in the end… so what?  So now we pull out our trusty friend, the dovetail marking guide.  There are a variety to choose from, I wrote about some here.

All kinds of angle options

Place a pencil in the pin hole on the far left, slide the guide over until it hits the pencil, then mark both the face and end of the board.  I stop the pencil line on the face of the board at the baseline of the joint.  This helps avoid sawing too far which we’ll discuss in the next blog entry.  Sliding the guide to the right, mark every other hole, then repeat the process from the other direction using the opposite slope.

Drop the pencil in the pin hole, then slide the guide to it.

Mark both the face and end of the board before moving the guide.  Note that the face line ends at the baseline.

When the layout is complete, mark the waste areas so you don’t get confused…

Finished layout

…and get ready to start sawing.