I wrote this for another forum I regularly visit (I recognise a few names there from here actually). Just my simple way of adding some DRO's to my Super &, probably not the best method or the most accurate but they were cheap and simple and work well for me. The Tailstock DRO I picked up on ebay and the Cross slide is the ARC unit that I saw mentioned on this forum and have been waiting ages for it to be back in stock
As I promised to a few guys here are pictures of the DRO's I have fitted to my Myford Super 7 lathe. I have fitted 2, one to the tailstock and one to the cross slide. I decided that a carriage DRO was not needed since nearly all my turning is diameter critical rather than length, a rule or caliper is more than sufficient for my length measuring needs.
First up is the tailstock DRO to give drilling depth, there is a small ammount of slop due to fact that you cannt fix it too securely to the tailstock barrel otherwise the DRO would get damaged during drilling when the barrel rotates a little (the key way always has a little bit of play) it is accurate however to about 1mm which is more than close enough for any drilling operation I have done. The tailstock barrel was drilling for a piece of threaded rod to act as the pin for the DRO, a threaded collar was made from aluminuim, this serves to lock the piece of threaded rod and also to act as a soft bump when you wind back the tailstock. If you do this mod yourself remember to make sure that the rod does not interfere with the auto-eject of the tailstock taper, mine ejects 3mm before the collar is reached. The rail of the DRO had to be carefully measured and cut to make sure it does not interfere with the tailstock handle when wound all the way back. The readout/sensor section was probably the easiest part to fit, I knew because of the curved and rounded body of the Super 7 tailstock I would have troublefixing anything to it so to make things easy I used 2 large rare earth magnets (sourced from a clothing tag remover) to attach the sensor, even though they only contact a small area of the tailstock they hold it more than firm enough, in fact removal can be difficult!
Next up is the cross slide. There is very little room to fit a DRO to the Super 7 crossslide without modifying certain features, I wanted to avoid any modification if possible and also keep any drilling and tapping into the lathe as minimal as I could. In the end I managed to do it by drilling just 2 holes, one in the cross slide and one on the carriage. As to other modifications I had to shorten the rear cross slide gib locking screw so it sat below the surface (usually this sits proud around 4mm) and I had to switch the bolt on the carriage lock from a hex head to an allen head (turned the head down slightly as well for a bit more clearance) Other than that nothing else was touched.
The hole in the cross slide was tapped 6mm and washers were used to shim out the rail to the correct distance. A bracket was attached to the sensor body and another 6mm tapped hole in the carriage was used to fix the bracket firmly. Both the top of the carriage and the cross slide were removed and placed in the drill press for these operations as the holes needed to be as accurate as possible, they were then tapped with a set of good quality HSS taps. Since the body casting of myford lathes are quality cast iron these operations were very smooth and easy.
The Cross slide DRO seems to be very accurate and repeatable to at least 1/10th MM, probably even better if I were to carry out proper testing. Certainly it will be more then enough for my needs, I want it to help speed up roughing diameters and remove a lot of guess work.
