| Tails First | Pins First | |
|---|---|---|
| Marking out | It is more difficult to make mistakes. For example you are unlikely to draw shovetails. It is usually preferable to work so that you face the workpiece surface that will be visible on the finished job. You can therefore mark the tail outlines on the outside face. | It is easier to make a serious mistake. You have to take care that the broadest part of the pin is on the inside of the job, ie the face-side, See:Shovetails. Also see:Face Side and Face Edge Marks. It is quite easy to make a zig-zag instead of a box. |
| Scribing the mating part | It is usually easier to align the pin and tail bearers for the scribing operation. See:Completing the Pins. Scribing the tails from the pins means holding the pin bearer upright against the face of the tail bearer. This can be difficult if the job is a big one, eg a bookcase on which through dovetails are visible from the bookcase sides. Since in this case you are scribing onto face grain, the marking tool can be prone to following the grain. If you are making fine cabinetmaker's dovetails, you have to scribe inside a small dark space, usually having to use an awl or a very thin knife blade. It can be difficult to be quite sure that the marking tool has not wandered. However, the marking tool will be working onto end grain, possibly with a reduced chance of the tool following the grain. It is again possible to scribe the lines for the pin sides on the outside face. To overcome this some people offer the tail bearer to the pin bearer before they open the sockets. They insert their dovetail saw into the kerf and with a backwards pull, use the leading teeth of the saw to scribe the end of the board. | Scribing the tails from the pins means holding the pin bearer upright against the face of the tail bearer. This can be difficult if the job is a big one, eg a bookcase on which through dovetails are visible from the bookcase sides. Since in this case you are scribing onto face grain, the marking tool can be prone to following the grain. There is usually plenty of room between the pins for the pencil or other marking tool to to reach. The results of the scribing are easily verifiable. However, the scribed lines have to be made on the inside face of the job - see opposite, above. Working from the inside face can mean that you can be not quite sure about the quality of the kerf on the other side. |
| Tickling up | Prior to the scribing stage it is prudent to check for any small inaccuracies. This also means working inside a cramped space. | It is easier to see and rectify any small inaccuracies. |
| In any event… | If you make lapped dovetails (half-blind dovetails to the Murricans) it is easier to make the tails first. | If you makeSecret Mitre Dovetail, you have to make the pins first. For:Secret Lap Joint, the pins need to be made first. |
Whether you make tails first, or the pins first, you will scribe the marks from the surface that is not visible on the finished job. In the 'tails first' case, this will be the surface indicated on the diagram by the downwards-pointing face-edge mark. In other words, the pins will be marked onto the shape of the underside of the tail bearer, ie the part you do not see when the job is glued-up.
This implies that the mating part must have sockets with flanks that are at right-angles to the face side (but see my tweaking tip). (See: Face Side and Face Edge Marks). Otherwise, as in the tapered socket marked 'A', although there is a correct outline on the underside of the tail bearer (ie at the entrance to the socket) you'll get an unwelcome gap round the pins. Other forms of error can lead to a joint that is too tight or even to broken pins from an over-enthusiastic assembly.
See:Completing the Sockets(the tweaking tip is at the bottom of the page).
Though it would require a different illustration, the same limitation applies if pins are made first.
