INDEXING THE MYFORD SUPER 7 USING A SHERLINE CNC ROTARY TABLE
An ability to index the rotation of a lathe chuck is a very useful tooling asset particularly in clock wheel cutting. Traditionally this would have been done with a mechanical mechanism employing a suitably chosen indexing plate to lock the chuck in place after each incremental rotation.
The advent of electronic rotational indexers such as the Sherline CNC Table makes this task not only easier but also incredibly flexible in the choice of increments. These devices can be programmed to either give numeric divisions up to 999 or similar steps in degrees. The Sherline has backlash compensation included in the design and is a nicely engineered device with a very straightforward controller. The controller has some very useful additional features such as sequential programming of random steps and remote indexing.
My write up describes how to mount the electronic indexer into the rear bore of the lathe spindle using an Expanding Sleeve and a Mounting Plate. A minor modification is made to the rotary table to mount the sleeve.
Before delving into the details of this adaptation I need to emphasise that the idea is not of my making and I am indebted to the late William Smith for sowing the seeds of the idea. I also need to emphasise that my Super 7 is a large bore version with a 26mm ID spindle through bore to accommodate a 1” diameter workpiece. Note that this is the diameter through the spindle as seen at the rear of the spindle. The diameter for the first section at the chuck end of the spindle is larger than this at around 30mm.
I see no reason why the same style of expanding sleeve adapter cannot be fabricated to fit the standard bore spindle size of the Myford family or indeed any other lathe with easy access to the rear of the headstock spindle bore.
Follow the link below for a PDF download
Disclaimer : – I have no connection with Sherline Inc commercially, financially or otherwise and fully acknowledge their registered trademarks associated with this write up. This article is written in good faith to popularise a technique that will be attractive to model engineers and horologists alike.