While a few other manufacturers advertise AT3 grade toolholders, Gassman states that only Collis has the quality procedures in place to certify its products to the standard. Collis's machining accuracy begins at the blankout stage. Where most manufacturers turn the nose end of the toolholder first, Collis begins at the taper end. ODs are turned before IDs, said Gassman, because the pressures involved in OD turning are so high, that previously worked IDs could be pushed off-center, affecting concentricity. After the nose end is turned on an identical lathe, parts are transferred to an Acroloc Series 1000 VMC and other processing equipment, where drive slots are milled, setscrew holes drilled and tapped, and orientation holes drilled and chamfered.
Quality assurance plays a critical role.
The Digital Dimensionair gage is programmed to calculate the rate of taper by comparing the two OD readings, and to display results as deviation from nominal in millionths of an inch per foot. Federal supplied custom air tools for a number of different taper sizes and toolholder styles. Before air gaging comes into play, however, another Federal gage performs a critical quality role by ensuring accurate setups. Using the gage's touchscreen controller and Windows -based software, machinists check tapers for roundness at several locations. We needed true geometry gage capabilities right on the shop floor, to measure roundness quickly and easily.