Small Saw-Blades

Mechanics who want small gig saw blades will find that the steel springs of which hoopskirts are formed will make capital ones of any Lengths; and they vary in width, so as to be suitable tor a variety of uses.

How To Plug Screws And Brad Holes In Finished Work

Glue the edge of the plug; put no glue in the hole. By this means the surplus glue is left on the surface, and if the plug does not hit the screw, it will seldom show. Set the heads of brads well in, then pass a sponge of hot water over them, filling the holes with hot water. This brings the wood more to its natural position, and closes by degrees over the head of the plug. When dry, sandpaper off and paint, and the putty will not hit the head of the brad.

How To Remove Screw

An obdurate screw may sometimes be drawn by applying a piece of red-hot iron to the head for a minute or two, and immediately using the screw-driver.

Screw-Threads

English and American proportions:

Softening Bright Work Without Damaging The Finish

Place the pieces in an iron box, and fill in the interstices with iron turnings; close the box, lute the cracks with fire-clay, and heat to a red, allowing the box to cool as slowly as possible. It is a good plan to let the furnace-fires go out and leave the box in the furnace to cool.

How To Flow Solder

Ordinary solder, 2 parts tin and 1 part lead, will flow smoothly on tin when dipped by previously putting salammoniac on the surface to be tinned.

How To Reduce Elasticity Of Springs

A well-tempered bar-spring will lose much of its elastic strength by filing off a very thin scale from the surface.

Advantage Of Holes Drilled In Steel

The advantage in tensile strength, when holes are drilled in steel rather than punched, is 25.5 per cent.

How To Weld Cast Steel

Apply powdered borax to the weld while heating it in the fire. If the steel is made too hot, it will crack during the hammering process.

Welding Compound For Cast Steel

Mix 1/4 lb. saltpetre and 1/4 lb. oil of vitriol in 2 gallons hard water; heat the steel to a blood red, and cool in the mixture before welding. Then reheat, in sand, and weld by hammering as usual.

Fire For Tempering Steel

In hardening and tempering steel, a clean charcoal, anthracite, or coked bituminous coal fire is required; such as is fit for taking a forging heat on iron is entirely unfit for hardening purposes. The sulphur contained in the coal combines with the steel to form sulphuret of iron, and ruins its texture.

Tempering Steel

The colors shown at different temperatures Fahr. are as follows: Very pale yellowish, 430°; pale straw, 450°; yellow, 470°; brown, 4900; mottled brown, 510°; purple, 5300; bright blue, 550°; blue, 5600 ; dark blue, 600°.

How To Demagnetize Steel

(1) Heat it to a red heat, and allow it to cool slowly. (2) Place the steel on a magnet, with the same poles touching the same poles of the magnet, and repeat the operation till total demagnetization has taken place.