Making Step Pulleys Homemade Machines & Jigs
I’ve been planning a new project, a 2 x 72 belt grinder made from wood, (see a preview of the design on my Google+ page) and will need two step pulleys to make the speed selectable. I went looking online and was surprised to see these are quite (unjustifiably) expensive – anywhere from $40 to $80 for the size I need. So, rather than add an extra $100 – $150 to the cost of the project, I decided to make my own.
To get started, I cut six pieces of Baltic birch plywood into squares (2 @ 5″, 2 @ 4″ and 2 @ 3″), marked the centre and drew circles to represent the outside diameter of each pulley step:
I then cut them out on the band saw and smooth them with the disk sander:
A 1/8″ hole was drilled through the centre of each and the drill bit was then used as a pin to line the parts up while being glued.
With the blank mounted on the lathe, the groove for the belt can be marked:
I’m using a normal 1/4″ wood chisel to do the turning. The plywood is tough on the blade and I need to sharpen it often.
I check the fit of the belt occasionally, to maker sure it fits properly:
With the first step done, I can move on to the other two. Getting the angle on the V groove correct is not as difficult as it seems.
With both pulley made, I need to drill accurate centre holes to mount them on shafts. A spade bit is handy to get it centred and start a shallow hole:
Then switch to a forstner bit to finish making the hole:
A paint job seals the plywood and makes the pulleys look more “professional”.
I made a short video detailing the build:
One of the rare examples of a project that can really save some money. I estimate the total cost of material for these at less than $10, with a couple of hours work to make them.