My Grizzly G0463 mill has served me well for 7 years now. Finally getting around to some much needed enhancements. In this post, I’ll cover the steps in adding a tachometer, to get an accurate read of spindle speed. The mill has a simple rotary knob for speed. There are 3 speeds shown on the label, separated non-linearly(!), and as it turns out, are completely wrong.
Sourcing the Tachometer Kit
There are a bunch of tachometer kits to be found online. They include a hall effect sensor, magnet, and LED display. None that I found include any kind of enclosure, and most require you to provide your own DC power source.
I chose DIGITEN brand, found at Amazon, ASIN: B07X4F8QVP. I chose green, as I find it more visible than the blue and red led colors.
It will operate on 8-15v DC. To minimize the load on the regulator, I went with a 9v adapter at 9v DC Adapter, ASIN: B092V92YLW.
You’ll also want to pick up a 5.5 mm enclosure mountable plug.
Bench Testing
To make sure it works, I breadboarded it first.
You can just hold the magnet in your hand, south pole facing the sensor, and wave it back and forth to do a quick test. The specs say 2-3 mm distance, but it works fine at 10 mm.
Designing a Case
I worked up a case design in SolveSpace for 3D printing.
It’s a box, with the back left open for simplicity. There is a cutout in the front that allows the LED assembly to snap in. Any of the clones with insert dimensions of appx 2 3/4″ x 1 3/8″ should fit.
You can find the stl file at Thingiverse.
Assembly & Installation
Using a step drill, a 5/16″ hole was drilled in one side for mounting the 8 mm o.d. DC adaptor plug.
On the other side, I made a 1/2″ hole for the 12 mm diameter sensor.
Wired it up, with heat shrink tubing to insulate the connections.
I used electrical tape to secure the magnet to the spindle. I located everything up top to keep things out of the way. Some double-sided tape to secure the base of the case.
Run the mill up to speed and everything is working.