Hi Guys,

Based on some very helpful advice and comments I have decided to design and make a Centre Finder Gauge based on the wobbler design which works surprisingly well considering that it does not require a dial gauge in order to use it to accurately centre work in a four jaw lathe chuck.

I've done a drawing with the dimensions on it. I've used colours to identify the major parts. Apart from the 1/4" diameter steel rod with points turned on each end, one to go into the punch mark on the workpiece and the other used as a pointer.

Since this device is intended to be held in the lathe tool post, the black bar is just there to provide a means of support. Obviously it should be at or close to the lathe centre height. The far end of the rod will cease to wobble about when the work is accurately centred.

In use, since this device has a three to one times amplification, one thou of movement of the workpiece will display a three thou movement at the other end. By altering the ratio between the workpiece end and the pointer end the amount of deflection can be changed. In this device the overall length is 12 inches.

Centre Gauge.png
Note that the pivot is a very loose fitting, the rod has to be able to move in all directions. The scale is intended to be used as a guide when adjusting the work in the chuck.
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