Desktop Gear Hobbing

Toby Kinsey has designed this fascinating piece of gearmaking equipment

- Toby Kinsey

One of my occupations is as a model maker for a small toy and games invention company. We often have to construct prototype toys and use small Module gears for various gearboxes and mechanisms. The deadlines are often quite tight and to avoid the wait for gears to be delivered, the company stocks a range of small plastic moulded gears in different sizes, from 9 teeth up. These are mainly 0.5 Module, but we do keep some bigger module gears as well. These are generally sourced from companies such HPC (ref. 1). But due to the way the world seems to work it is invariably the case there isn’t a gear with the right number of teeth for a particular job or there is only one gear left when you need two!

Another issue is the bores of even the small gears are quite large, 3 or 4mm being common. This leads to lots of machining up of little sleeves to reduce the bore down to suit the 1 or 2mm shafts we use.

I also work on my own personal projects at home, but lack of deep pockets has stopped me from building up a stock of gears in the way that a company can afford to do. This was a limiting factor on what I was able to do at home as again, you never seem to have the right gear for the job in hand. I was faced with the choice of having wait while I ordered a particular gear or “borrowing” gears from work.