Locating a convenient spot for mounting a magnetic indicator base to a milling machine is often next to impossible. To eliminate this time-consuming task, I use a carbon-steel ring with three small plates attached that fastens to quill housings on Bridgeport-type mills. Three setscrews allow for adjustment and hold the setup in place.
Counter-sunk machine screws secure the plates, which provide a flat working surface. The ring front is cut to accommodate machine-quill housings.
I also have a ring for Cincinnati-type mills. The ring is 5 /8-in. thick and 5 /8-in. wide with 1 1 /2-in. flats machined at 120° for a Bridgeport and 90° for a Cincinnati. About 0.005 in. of clearance on the ring's I.D. provides a close fit. I not only use the setup for indicator bases but also for coolant wands.
Rock Springs, Wyo.
Lining up an accurate angle
My idea accurately sets the longitudinal slide of a universal milling machine — in minutes instead of degree increments — for cutting helix angles. What I do is extend the machine's zero line up to the end of the cross slide using a scriber. After marking this line "0," I scribe a "B" line parallel to and at a suitable distance from the "0" line. With the longitudinal slide in the horizontal position, I measure an "A" distance using dial calipers and note the reading.
I then calculate the required dimension for a desired helix angle and set the caliper depth to that dimension plus the "A" dimension. This is done with the calipers at the pre-scribed "B" line ("A" plus calculated dimension equals "C").
East Punjab, India
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Winner for May 2004: Cal Valentine, "The latest in edgefinder repair," p. 62.