This is an excerpt from “The Woodworker: The Charles H. Hayward Years: Volume III” published by Lost Art Press.
The through dovetail is straightforward enough to cut, but sometimes there is a slight complication owing to there being a rebate at the edge, or because a mitre is desirable at the corner. There is nothing complicated about it, but it is easy to make a mistake if it has not been within your experience before.
Consider the case of a tray or drawer which is to have its corners through dovetailed together, but with a bottom which has to fit into a rebate. If you cut the normal simple dovetail you will end with the unfortunate result shown in Fig. 1. The rebate, being worked with the rebate plane, has necessarily to be taken right through, and this leaves a gap at the shoulder.
One way out of the difficulty is to set the dovetail in an extra amount to allow for the rebate depth, and make a square cut on the dovetailed piece (not on that with the pins) level with the rebate. The shoulder is then allowed a projection so that it reaches into the rebate as shown in Fig. 2. Note that no cut is needed on the pins since the rebating automatically removes the wood.
Alternatively the method in Fig. 3 can be followed. Here the top square cut level with the rebate is made as before, and the corresponding cut is made on the pins, but only down to the rebate. It is thus necessary to gauge in the extent of the rebate first so that the cut can be stopped short.
A third method is to use a mitre. This is of special value even when there is no rebate because it gives a neat finish; also because it enables the edges to be rounded over as in Fig. 4, or to be moulded. The joint when there is a rebate is similar to Fig. 4, but the depth of the mitre should equal that of the rebate. Note that there is a square cut level with the rebate on the dovetailed piece, and that this is transferred to that with the pins. It is not cut right through, however (see Fig. 4) but is only cut at the inside at 45 deg. (that is, as far down as the mitre). When cutting the mitre hold the saw on the waste side so that the line is just left in.
— Meghan Bates