How to cut a keyway without special equipment

One of the common methods of transmitting force in the form of torque from the drive shaft to the pulley is using a keyed connection. If the pulley is machined, then it is necessary to cut a keyway inside its mounting hole.

How to cut a keyway in a pulley with an accessible tool

This task is not easy, since in addition to accurately maintaining the dimensions of the groove, it is necessary to ensure the precision of its direction. To do this, we make a simple device from a pipe with a diameter of 15 mm, in which we make a slot along the entire length using a grinder.

If the diameter of the pipe is smaller than the pulley mounting hole, then you will need several more tins to select the gap between the pipe and the pulley mounting hole. We will use a pipe with a slot to set the direction of the jigsaw file, which would otherwise be pulled to the side.

We install a tube with a slot flush with the pulley mounting hole, using tin cans to secure the tube in the hole if necessary.We insert a jigsaw file into the slot of the tube and cut the wall of the pulley mounting hole in the radial direction to a depth of half the height of the key.

Then we rotate the guide sleeve from the pipe with a slot by 5 mm, since this is the width of the keyway on the electric motor shaft, and make a second cut in depth equal to the first cut.

Next, we perform the following operation - we drill the metal in the longitudinal direction, enclosed between two cuts with a drill with a diameter of 5 mm. As a result, we get a shapeless recess at the site of the future keyway in the mounting hole of the machined pulley.

We proceed to the final, most critical operation - finishing the transverse profile of the keyway to the required shape and geometric dimensions. To carry out this operation, we will need simple devices, the manufacture of which we will begin.

Their basis will be two identical-sized wooden blocks of rectangular cross-section. On one of the faces of each block we make a groove into which we will install the jigsaw file with interference. To the opposite edge we glue a file of suitable sizes and sandpaper.

Jigsaw files inserted into the blocks are needed to secure our devices to the jigsaw drive. This will save us from tedious and time-consuming work to bring the shape and dimensions of the keyway to the required standards.