Dovetails by hand in a cold shop: marking, sawing, paring

01Marking out with one gauge setting

Everything in a dovetail depends on two lines, and both come off the same gauge setting. I set a marking gauge to the thickness of the mating board, scribe a baseline all the way round both pieces, and then refuse to touch the gauge until the joint is finished. When I used to reset it between pieces the shoulders came out a shaving apart, which reads as a gap you can see from the other side of the room. A knife line rather than a pencil line: the knife severs the fibres, and the chisel afterwards falls into it.

Spacing I now do by eye, which took a while to allow myself. The layouts I drew with dividers and arithmetic were even, lifeless and took twenty minutes. Marking three tails on a board a hundred and fifty millimetres wide by eye takes two, and looks as though somebody made it. What does want care is the slope, because a consistent angle across the joint reads as deliberate and an inconsistent one reads as an accident. I use a scrap of plywood cut once as a template, and I have never measured the angle it happens to represent.

02Sawing to the line and stopping there

A dovetail saw wants to be sharp and the cut wants to be vertical, and neither is helped by gripping the handle hard. I start with the saw leaning back, take three light strokes to establish the kerf hard against the knife line, then straighten up and let the weight of the saw do most of the work. My sawing is not especially accurate, but it is inaccurate in the same direction every time, and paring corrects that in a minute. Sawing that wanders unpredictably is what ruins a joint; sawing that leans consistently does not.

The other half is knowing when to stop. I cut to the baseline and not a hair past it, and on the tail board the sloping lines come before any of the shoulders, because a saw that overruns into a shoulder line leaves a mark no amount of paring removes. In a cold shop my hands are stiff for the first ten minutes and everything cut then is worse than what I cut later, so the first joint of the evening usually goes at the back of a drawer where nobody will be looking.

• Knife the baseline; a pencil line is half a millimetre of doubt
• Three light strokes to start the kerf, then let the saw fall
• Cut the sloping lines first, the shoulders afterwards
• The first joint of a cold evening belongs at the back

03Paring, and the fit I aim for

Paring is where the joint is actually made. I work in from both faces towards the middle with a wide chisel, leaving the waste very slightly proud in the centre and the two faces exactly on the baseline, so that the joint closes on its shoulders instead of on a hump. A guide block clamped along the baseline keeps the chisel honest; without one I undercut every single time, always in the direction of my dominant hand. The chisel wants to be sharp enough to slice end grain across its full width without being shoved.

The fit I want takes hand pressure and then a mallet for the last third, and nothing more. A joint that goes together with thumbs will show a gap in a dry January; a joint that needs a hammer splits the tail board at glue-up, usually at the outside pin where the wood is weakest. Between those two there is more room than I expected. I test-fit once, halfway, and then leave it alone, because every dry assembly compresses the fibres a little and the third one is looser than the first.

04What the glue-up tells you afterwards

Glue-up is a poor time to learn anything, which is why I rehearse it: clamps set to length, cauls cut, a damp rag to hand, the drawer assembled dry and then taken apart again. The rehearsal has caught a transposed side twice and a shoulder line a millimetre out once. With hide glue there is a little time to argue with a joint. With modern white glue in a cold shop there is very little, and a joint that needed persuasion dry will not be persuadable at all once it is wet and starting to swell.

The honest report arrives the following morning, when the glue has gone off and the drawer sits on the bench looking at you. Gaps at the shoulders mean the baseline was shallow or the paring undercut. Gaps between pins and tails mean the sawing wandered. A drawer out of square means the clamps pulled it rather than that the joints were wrong. Writing down which of those three it was, while I can still remember the evening, is why the third set came out better than the second.