My idea is a simple and easy-tomakecoolant/chip shield for lathe chucks. Materials needed include a 3/16 3/4-in. steel strip 2 or 3-ft long, three 3/8-in. bolts 3 to 4-in. long, one 3/8 I.D. 3/4-in. O.D. bushing 3/4-in. long, one drawer-pull handle, three 1/4-in. bolts 3/8-in. long, and one 5-gallon plastic pail.
I drill three 1/4-in. holes in the steel strip, weld the bushing to it, and bend it to match the chuck radius. I then drill and tap for the 3/8-in. pivot and stop bolts and cut the plastic pail to fit.
For making holding fixtures, I construct patterns from Styrofoam or balsa wood and create a casting. In the investment process, I burn out the pattern as one would the wax, and for a sand casting, I leave the pattern in the mold and pour in metal that burns it out.
I glue together multiple pieces of Styrofoam for the desired pattern shape. Cross members and ribs strengthen the pattern, which is easily shaped using hand tools or band saws. Adding gates, runners, and sprues ensure the mold fills properly.
I then machine the holding-fixture casting for flat, parallel, and critical dimensions, tooling points, tapped holes for clamps, and holes for pins. For these operations, which are scheduled as a step prior to actual part machining, I typically use the same machine tool intended for the job.
This fixturing works with or replaces tombstones, angle plates, and fixtures made from solid stock requiring large amounts of material removal. It is less expensive as compared with bolting, welding, and procuring new tooling — especially when its cost is figured into a production-castings order.
Santa Barbara, Calif.