When I was a kid my dad and I built a homemade electric motor from
plans in a book or magazine.
Components were a frame made of a cut and bent tin can, an axle made
out of a nail, and windings made from magnet wire.
The wiring on the armature had a lot of scotch tape for some reason.
There were windings on both the motor and the tin-can frame, and
commutation was from brushes made out of little pieces of brass sheet.
Does anyone recognize this project, and know of a website or the title
of a book that will help me recreate it with my kids?
Tim.
You can simplify it by using one or more of those Neodymium Iron Boron
(NdFeB) super strong magnets that you can buy now instead of windings, for
the fixed magnets. This way it will go better even if it isn't very well
made.
Get a cork for use as a former, and use a piece of heavy gauge copper or
brass as an axle, so the axle won't keep sticking to the magnets. First
cut two grooves the length of the cork on opposite sides, about 5mm (3/16")
deep. Then figure out a way of sticking the copper / brass axle through
the axis of the cork. Then wind a few feet of single conductor insulated
wire (e.g. conductors out of phone wire) around the cork, up one groove and
down the other, repeat until slots are full of wire. Now for the
comutator, build up an insulating layer of adhesive tape around the axle on
the end that the wires stick out. Build the layer of tape up until it is
maybe 1.5mm (1/16") thick. Strip the ends of the wire where they are
adjacent to the tape section and somehow tie them to opposite sides of the
insulated section of the axle so that each end of the winding is a bare
wire running parallel to the axle on diametrically opposite sides,
insulated from the axle by the sticky tape but bare on the outside for the
brushes to touch. Fit the axle into some bearings which can be just paper
clips bent to form small loops which slip over the axle, and fixed to a
wooden board or tin can. Now you need to make "brushes" which can be just
two more pieces of telephone wire which have the ends stripped and bent so
that at a certain angle, one of these wires touches tangentially onto each
of the ends of the winding on the commutator. Position a strong magnet so
that the pole points radially through the winding towards the centre of the
cork when the cork is rotated to the position where that the brushes touch
the ends of the winding. It should go pretty well when powered from a
single C or D size alkaline cell. You need to spin it gently to get it
going.
Chris
