Harold Hall

Workshop Projects


Digital Readout

To recap re my comments made in my pages for making and using the head, my reason for adding the digital readout was that my lathe is equipped with power feed to the cross slide that is driven via a key way along the length of the leadscrew. This requires the half nut to be disengaged when using the cross feed else the saddle will traverse also. Because of this, the readings on the leadscrew micrometer dial become meaningless making it difficult, but not impossible, to make a precise change to the saddle's position for the next cut. Even on lathes without a cross feed facility, or one driven differently, the readout would still be a useful addition. Why not then purchase three caliper's for the three axis?


Having therefore chosen to add a digital readout I decided a budget digital caliper would be adequate for the purpose. However, if I used the one I already had I would not have one available for measuring the parts being made so purchasing an addition caliper was necessary. I had seen one listed with a metal body and at a price comparable to the budget ones and I felt it was more appropriate for use mounted on a machine tool. Another plus was that the digits on the display were larger than most.


Due to the wide range of lathes onto which this milling head could be fitted it is impossible to give dimensioned drawings and changes will have to be made to the design in many cases, especially with non flat bed lathes. However, Sk. 2 and Photographs 2 and 3 should give adequate guidance to any one wishing to fit such a device. From the photographs it can be seen that I extended the packing used to raise the head, as mentioned above, to provide the mounting also for the caliper.


Photograph 4 shows the parts that I made (excluding the packing for the rear of the head). The large item in the middle is the packing for the front of the head and being extended to the left provides a mounting point for the caliper. The two parts on the left provide the fixing for the caliper's head, the assembly being shown in Sk.2A.


I chose to fix the mounting facility for the depth bar  using double adhesive tape, adopting the method on the basis that I would not be using the head very often and that I do not like making holes in machine tools using a hand held drill. If the saddle could be very easily removed so that making the holes using the drilling machine were possible I would no doubt have felt differently. However, the method I adopted worked well but it was of course necessary to thoroughly clean the surfaces being joined. The parts on the right of photograph 4 with Sk. 2B showing the assembly.

Digital readout, lathe mounted.
Digital readout, lathe mounted.