I felt the need for an accurate depth control for some counter bores so came up with an occasional digital solution namely a cheap tire tread depth gauge with 1 inch travel. My SB lathe tailstock has a round topped casting which is not ideal for this, I am reluctant to machine a flat on this old lathe so another way had to be found. I made a base from epoxy metal putty to fit the top of the casting and epoxied 5 neodymium magnets in the base which hold very well. These gauges are not spring loaded so a bracket and spring were added (I keep every spring I come across of any size) that just left a bracket to make for the barrel which apart from the bore was hand fashioned, good old hacksaw and file was much quicker than machining the whole thing. It only takes a couple of minutes to fit when needed and tooling still ejects with the bracket in place. I should add that the idea is not mine as many variants have been posted on HMT, this is just my take on the application.