Place one end of an axle through a wheel until the end of it projects beyond the outside of the wheel about ⅟₁₆ of an inch. Put some soldering paste on the end of the axle and on the wheel next to the axle and use a well-heated soldering copper to solder the wheel to the axle.
Fig. 70.
Fig. 71.
To do this, place the wheel flat on the edge of the bench so that the axle hole is just over the edge and so that the axle may be held against the side of the bench. Hold the wheel and axle firmly in this position and lay the hot soldering copper, well charged with solder, on the end of the axle wire just above the wheel.
The end of the axle will heat up very quickly and the solder should run down and form a puddle about the axle when that part of the wheel next the axle is heated up to the flowing point of the solder. The end of the axle should not project more than ⅟₁₆ inch beyond the wheel and the soldering copper should be heated thoroughly and be well charged with solder, see [Fig. 71].
The wheels need only be soldered to the axle on one side of each wheel if the holes for the axle fit it very snugly.
Another method of holding the wheel in position on the axle while being soldered is to drill a hole exactly the same size as the axle through a fairly thick block of wood and to push the axle through this hole until just enough of it projects so that when the wheel is slipped over it ⅟₁₆ inch of the axle will project beyond the wheel. The wooden block may then be placed in the vise and the wheel slipped over the axle and soldered to it. The hole drilled through the block must be drilled at right angles to the face of the block where the wheel is to rest. A hole may be drilled at right angles to a wood or metal surface by using a bench or post drill if you have one. Wheels may be set on the axle very accurately by this last method.