It should be stopped when the boards are in their proper relative positions.

In rubbing together the edges of two boards, handscrews may be fastened to one in such a way that their jaws serve as guides for the other board to slide between, Fig.261.Care must be taken to make the jaws of the handscrew diverge enough not to pinch the upper board.
[Illustration: Fig.261.Rubbing a Glued Joint.] Another method is to clamp a spare board alongside and projecting above the lower board.

This spare board acts as a guide against which the upper board can be pushed as it is rubbed back and forth.

The rubbed joint is especially suitable for short boards.
In joining long boards, a squeezed joint is common.

In this case, the edges are planed so as to be very slightly concave from end to end.
The object of this is to counteract the subsequent shrinkage which is likely to take place at the ends of the boards before it does at the middle.