Home Chapter 15 Power in spinning objects: graphite brushes
Power in spinning objects: graphite brushes

Carbon graphite brushes can be used to bring power into rotating shafts or surfaces. This is how power normally comes into the spinning coils of DC motors. Carbon brushes you would normally purchase for a car alternator are available from auto stores. You can also find them if you GOOGLE the phrase “commutator brushes”.


It takes two carbon brushes, one on each lead of the power supply, to transfer power to a surface.


You can bring carbon brushes into contact with rotating metal surfaces in order to electrify them while they turn.


In this image, carbon brushes are used to light an LED attached to a rotating shaft.


Step Tubing

Telescoping tubes or step tubing are valuable nested tubes that can be used for creating slippery surfaces. With a little oil on the interior of these tubes they can be used for creating bearing-like surfaces for levers and devices.


Telescoping step tubing


The smaller diameter tubes can be cut near the edge of a table. If you are careful you can use a matt knife and roll the tube allowing the blade to circumscribe a circle around the tube.

After cutting the tube you must debur the metal. You can use a utility knife or, depending on the size of the tube you are deburring, a scissor tip pushed down into the opening can bend the lip of the metal outward. You can also purchase a deburring tool with a narrow blade that can be used on aluminum, brass, steel, and cast iron.


Square step tubing


You can also use Dremel tools to cut the tubing and a cutoff wheel is a good method, though goggles are a must. The square step tubing is available with a variety of sizes in your local hobby shop. You can also order this tubing in a variety of materials and thicknesses from Small Parts Inc.

You can silver solder this material. Dremel tools can be use to cut the tubing.

You must heat up the metal evenly and before heating use some flux and I have dound the Harris safety silv works well to etch the metal and allow the solder to wick into he metal.

It helps to sand the metal where there are joints and as you heat it be careful not to let it get too hot. You can hold the work on a brick to allow the metal to be on the material. Tweazers are indispensable for placing the small bits of silver solder.