Digital rotary table

A rotary table using a magnetic sensor to measure the angles

A little venture in to electronics – Mechanical prototyping

Following the connection of the mouse and LCD to the arduino, I needed to have something physical to do further testing on. I wanted a design that would require the minimum of machining and would fit with my existing angle plates and other accessories. I concluded that I should be able to produce some form of spindle that was threaded to hold my lathe chuck or faceplate.

I’d been looking at flanged bearings but was concerned over sideways movement. A further search discovered some SHF20 Round Rail Supports CNC Parts for Mill Router. These have the mounting holes to fit on my angle plates, were not overly expensive and should be easy to drill and tap for any mounting points or clamps.

I prototyped a spindle with air setting clay and tried to get the mouse suitably positiong so that the optical sensor would read the position of the spindle.

This was not particularly successful in that the plastic optics of the mouse were difficult to position in the right place and would required the main chip to be removed from the pcb and remounted.

However whilst doing this I realised that the scroll wheel had potential. There were three wires connected to a small device that looked like a preset resistor, there are a few different types of sensors in a scroll mouse wheel electronics such as an optical quadrature encoder or mechanical encoder. Looking at the data sheet linked as a comment on Steve’s site, it’s likely that my sensor is one of the mechanical ones. Which means it could have as few as 24 clicks per revolution. So to get a reasonable resolution I’d need a very high ratio of diameters between my spindle and sensor wheel.

I’ve been looking at using a dremel sanding drum to provide the drive for the sensor as that has a nice facility of being able to adjust the diameter by a small amount by tightening a screw. I’ll have to do some more testing to determine what I have but I might be back to square one with regards a suitable rotary sensor arrangement.