email: tony@lathes.co.uk
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Pearson Model H Turret Miller - USA

Marketed through (and possibly manufactured by) the Graham Machine Tool Company of 19 Cleveland Place, New York 12, N.Y., the Pearson Model H turret miller was current in the late 1940s and 1950s. Its design was an almost successful attempt to out-specify the equivalent Bridgeport, the Ram being of the rigid dovetail type (a design Bridgeport introduced in 1952 to replace the round-type) and the swivelling vertical head fitted with both hand-operated fine and quick feeds together with a power-feed quill as standard A range of 8 speeds from 264 to 4100 rpm was provided by direct V-belt drive from a 1.2 hp motor, with the slower speeds driving through oil-bath lubricated gearing. The travel of the R8-nose spindle was 5.5 inches, at a time when the Bridgeport J-type head had 5 inches, their M-Type head 3.5 inches - but with no power-feed option available on either. However, although the ram on the Pearson could be propelled backwards and forwards through the head casting by means of a handle operating on a rack-and-pinion gear, the head angles had to be set by hand, unlike the easy-to-operate and accurate worm-and-wheel arrangement provided for the Bridgeport operator. The Pearson also appears to have been able to mount a head on only one end of the ram instead of on both, a great time waster when a second head for slotting, or even a duplicate milling head but with different tooling, could be set ready for instant use.
Hardened and ground, the counterbalanced quill was lapped into the head casting for a perfect fit with four rates of power feed available from 0.0015" to 0.006" per revolution of the hardened and ground, ball-bearing spindle.
Well sized at 10" x 44" (or 48") the table had a longitudinal travel of 28 inches, in traverse of 10 inches and vertically 30 inches - figures superior to the contemporary standard Bridgeport - although, as compensation, the latter could be specified with a 48-inch long table with a travel of 36 inches. Generously sized with a 4.5 inches diameter, the micrometer dials were finished in non-glare satin-chrome.

Pearson Model H Turret Miller circa 1952/3

Shown in this picture are the optional power feed to the table, a dial indicators to the cross feed and a dial indicator and precision stops rods to the longitudinal feed.

email: tony@lathes.co.uk
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Pearson Model H Turret Miller - USA