toolmaker ground a groove in the surface gage and inserted a blade of spring steel with a curve in it. It was much nicer than having loose balls. After all the discussions and writing about squareness and squaring techniques I decided I wanted to make one for myself. For a month or so I doodled in my notebook working out the details of the gage making it easy and inexpensive to make.
For the squareness comparator a pivot is needed to butt the gage against the part to be checked. The indicator is moved up and down as required for the surface to be evaluated. The picot in my design is made from blue tempered shim stock and is the same thickness as the flexure.
Hougen Rotabroaches. They make accurate holes quickly and with less chips and arm power. Their claim to fame is in the annular cut like a hole saw. More of the cutting force goes into the annular cut instead of making the entire hole into chips like a drill bit. I have a bunch of these in various sizes so I tried to make most of the hole with the rotabroaches. The first cut was with the one inch diameter. This is the size of the actual indicator rod which might be risky to get an accurate hole plunging with an on size cutter. I have done this enough to know the limitations of the tool. Rotabroaches can be relied on to make holes within +/-.003 of the nominal size of the cutter. This is just what I wanted dimensionally anyway. Design around your machines and tooling and you won't ever be disappointed.
More soon. I still have a couple of days off.