I decided to finally upgrade my HF mini's with DRO's, Tachometers and Power X Feed on the mill. Since the lathe and mill both cost under $400 to begin with...this upgrade needed to be inexpensive as well. The IGaging DRO's were $27 to $42 each (Amazon), the Tach's were $19 each (Amazon), power supplies were $8 each, plastic enclosure boxes were $2 (WalMart) each and hardware was scrounged around the garage. Most costly item was the Mini Mill power feed at $200 (Little Machine Shop). Although the DRO's came with brackets, I had to fabricate sheet metal brackets to fit each to the lath or mill....Part of the fun...I'm still trying them all out but they all seem to be functioning as expected. The DRO's are battery operated and come with two sets of batteries. The Tach's were connected to power supplies in the enclosure box. The sensors just pick up a magnet attached to the rotating spindle of the machine. Lots of pictures hopefully speak a thousand words.