A Topslide DRO for a Boxford Lathe

Egret fits a removable readout to his lathe

- Egret

I have recently ordered two axis DRO equipment for my 1984 Boxford VSL lathe but shied away from including a reader for the top slide, as this would require accurate angular measurement of the top slide setting and associated trigonometry to give a readout in X and Y axes. This means most hobby users would only perform the summing function when the top slide is set at (or very close to) zero degrees.

With the top slide set at 0 degrees a reader can be used. Consoles such as the Easson ES12C 3 axis unit incorporates software to sum two inputs and so are able to use three inputs and combine two of those to give a two-axis readout. For angular settings of the top slide the summing can only be done by the operator using trigonometry, in which case one might prefer a cheap stand-alone reader on the topslide, avoiding the need for signal cabling and minimising costs.

I therefore decided to make an experimental DRO using a cheap digital vernier with the objective of showing me how useful a DRO is on the topslide, seeing how much it gets in the way, seeing whether it can be securely and accurately fitted without drilling and tapping into the lathe. Crucially it needs to be quick and easy to fit and remove.

Lessons learned would help me evaluate the merits and feasibility of making a removable reader to work with the Easson 3 axis Readout.

The fixing method adopted has proven amazingly successful and works very well at the most useful ‘zero degrees’ setting. While it stops the topslide being set at an angle, it can be removed so quickly that this really is not an issue. Furthermore, it does not interfere with routine machining operations as it is well out of the way of both the toolpost and the topslide handwheel.