Crossing Out a Great Wheel

The first picture shows a great wheel being crossed out in 5 mm brass. The roughing cut (shown) is done with a 1/8" slot drill at about 6,000 RPM, cutting to a depth of 1/16" per pass. So in three passes the segment slug is removed. This is followed with a 1/16" slot drill removing .002" from the periphery, and removing the corner fillets, again in three passes.

To start, a piece of brass is clamped to the table, then:

• The centre hole is machined to .002" undersize for later reaming

• The spoke segments are cut out

• The outside diameter is cut, moving the clamps as it progresses

Finishing Cut with a 1 mm Dental Burr

The second picture shows a 90 tooth wheel in 1/16" brass, being finished with  a 1 mm  dental burr running at 10,000 RPM. A cut of .002" is being taken. It leaves the corners virtually sharp. Surface finish is not as good as with a 1/16" slot drill. Feed rate must be quite slow. I use .6" per minute. The cuttings come off as dust.