Micrometer (Dial Gauge) Holder for MidiPro Lathe

An easy and stable tool to mount a micrometer, a.k.a dial gauge, on the banjo of a woodturning lathe, as may be needed to determine bearing play, and trueness of center of appendages.  

The dimensions are set for the MidiPro lathe, which has a vertical distance between the top of the 25.4 mm bore toolrest holder and the center of the spindle of 75 mm. It consists of 2 parts:

1. An adapter to mount a shaft of 22 mm in the banjo. The adapter has a hole to accommodate the setting screw, and a top plate with a hook to ensure the hole sits here the setting screw is. This is specific for the Midi Pro.  

2. An adapter to mount a micrometer on the top of a 22 mm shaft. The adapter has a provision for an M4 tightening screw. 

The diameter of the shaft was chosen to allow using a scrap piece of central heating pipe. You need between 60 and 80 mm, suitably de-burred and not deformed. There are two holes for securing bolts but a drop or 2 of CA glue there could serve also.

I printed from PLA filament, as stiffness is paramount and there is no need for specific strength of toughness. 

Be gentle on the tightening. I do not recommend to use the banjo adapter and central heating pipe combination for any use that may require structural strength. Tightening the banjo setting screw on the soft thin heating pipe may deform the pipe and leave the combination stuck in the banjo.  

For any structural application you may want to consider using a 20 mm rod or thick-walled tube as available in hardware stores (such as the tube shaft part of wheel barrow shaft https://www.hornbach.nl/p/tarrox-as-toebehoren-set-voor-kruiwagenwielen-naaf-88-100-mm-20-naar-10-mm/6058564/) and use the 20 mm shaft version of the adapter: 

See license for permitted use. Feel free to use in business, contact me for commercial distribution.