This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
In the absence of a full equipment of lathe dogs the amateur can make them cheaply from pieces of iron pipe.
Ill: Two Forms of Lathe Dogs That are Quickly and Cheaply Constructed
One of these is shown in the sketch. A section of pipe, 1 1/2 in. to 3 in. long, is partly cut away, as shown, leaving a projection of metal 1 in. wide. One or more setscrews are fitted in the round part, and the dog is complete. A dog, or driver, may also be made of two U-clamps and two bolts as shown. This is especially useful for large work, where the cost of a dog would be prohibitive. After these two clamps are bolted on the work to be turned a bolt is attached in the faceplate that bears against the clamp, thus turning the work.