bow-pen

It is safest and best to have the two legs of the bow-pen and pencil made from one piece of metal, and not of two separate pieces screwed together at the top, as the screw will rarely hold them firmly together.

Mechanical Drawing Self-Taught Joshua Rose

A small spring bow-pen for circles, a lining pen or pen for straight lines, a small spring bow-pencil for circles, a large bow-pen with a removable leg to replace by a divider leg or a pencil leg, and having an extension piece to increase its capacity.

Mechanical Drawing Self-Taught Joshua Rose

In applying the ink to the bow-pen as to all other instruments, care must be taken that the ink lies between the points only and not on the outside, for in the latter case the ink will flow down too freely and make a broad, ragged line, perhaps getting on the edge of the square blade or triangle, and causing a blot of ink on the drawing.

Mechanical Drawing Self-Taught Joshua Rose

The spring bow-pen should have a stiff spring, and should be opened out to its full capacity to see that the spring acts well when so opened out, keeping the legs stiff when opened for the larger diameters.

Mechanical Drawing Self-Taught Joshua Rose

The same is the case where a piece having a curved outline is drawn, which is shown in Figure 107, where the set of the bow-pen is gradually increased for drawing the shade lines of the curves.

Mechanical Drawing Self-Taught Joshua Rose