Hello!
I fitted a couple of DRO's do my old Nuttall lathe - with a remote readout unit. The sensors were powered by button type batteries, which, while they worked alright were a pain to replace because of their location (down the back of the lathe for the longitudinal, and under a perspex casing for the transverse). I finally succommed to the irritation of this setup and decided to make dummy batteries - ie perspex discs with contacts to activate the unit as required, but which were connected to an external power supply with external leads. I made the dummy batteries as an alternative to rewiring inside the battery case of the DRO units. I made a shape identical to the battery out of brass - a cup for the bottom and a disc for the top separated by a perspex plug that fitted in the cup. Glued the three bits together and soldered on a pair of flying leads which were connected to the readily available variable output transformer (the sort that have switched value outputs of 3, 4.5, 6, 9 12, 15 and 18 volts). The dummy battery fitted into the battery cage in the DRO (being identical size) and the flying leads were run inside the protective casing for the readout wiring. I did it this way to make it totally removeable, but there is nothing to stop the leads being directly soldered onto the =ve and -ve battery connections in the DRO unit itself, using a small point soldering iron and limited heat.
I also replaced the battery setup powering the readout unit with a simple external wire connection to an power transformer.
Seems to work well for me, and best of all, no more batteries to replace!
Steamboat Willie.