All that is now required to switch between the normal "Imperial Mode" and the "Basic Metric Mode" is the few seconds it takes to loosen the yoke and to move the sliding gear into or out of mesh. It also means that it's not necessary to remember to double everything - as would be the case if the sliding gear was driving off the 32-tooth part of the shielded tumbler gear. and feed settings (as per the chart on the gearbox). However, placing it away from the headstock maintains the bulk of the t.p.i. The 30, 24 and 20 positions, or 60, 48 and 40 positions, become the desired 1 mm, 1.25 mm and 1.5 mm pitches, depending upon whether the 52-tooth gear of the 52/44 pair has been placed closest to, or away from, the headstock. However, with the 40-tooth sliding gear in the other position, it engages the 44-tooth gear of the 52/44 combination and introduces the 52/44 ratio into the train. With the 40-tooth sliding gear engaging the 52-tooth gear to the box, the 52-tooth gear is acting as an idler (with the 44-tooth gear as its spacer) and the gearbox operates in its normal `Imperial Mode' - but with the exception of the coarsest (seldom-used) range. Because the 52/44 combination fits neatly in place of the 48/48 idler the job can be done. The tumbler gears in the Atlas set include a 32/16 shielded gear driving a 40 tooth sliding gear which in turn drives the box through a back-to-back pair of 48-tooth idlers.
#Atlas lathe gears how to
Close, but not close enough, so how to get this closer to 1 mm ? Using 52 and 44-tooth gears gives 0.8467 x 52/44 = 1.0006 mm - which is almost spot-on. position to 1 mm pitch, then the 24 t.p.i and 20 t.p.i positions would correspond to 1.25m and 1.5 mm. Because the 30 t.p.i., 24 t.p.i and 20 t.p.i positions represented the same ratio intervals as 1 mm, 1.25 mm and 1.5 mm pitch if one could convert the 30 t.p.i.
However, there is a simple way (cleverly worked out by Atlas-owner Carvel Webb) to generate a limited range of the more common metric pitches.
Issued with the Atlas gearbox was a special handbook, though in its first edition this omitted several key factors in its explanation of how to generate metric pitches-a mistake not corrected until 1959 when an updated version was published for the same gearbox when fitted to the later and heavily revised 12-inch Atlas and Craftsman lathes. and described by them as the "New-All" unit. Just before the introduction of the official gearbox another was offered by the Western Aircraft Tool Co. An unusual Pick-o-Matic semi-gearbox was also available, where gears, clustered into sets, were supplied pre-assembled to speed up the thread-cutting process. It took a little over 10 years for a screwcutting and feeds' gearbox to become available as an option for the Atlas lathe but, when it was introduced, in 1947, it was also offered as complete conversion kit to for retro fitting to earlier lathe - both those with 3/4" and 5/8" diameter leadscrews. Screwcutting Gearbox and Pick-O-Matic Threading Atlas Factory Atlas Wood LathesĬatalogue Covers Accessories Countershafts Atlas Miller Atlas Shaper Atlas Drill Presses With a complete data pack for the Atlas 10-inch and other LathesĪtlas Home Page Atlas 6-inch Atlas 9-inch late-model Atlas 12-inchĪtlas Utility Lathes Restored 10-D & 10F Acorn, Halifax & Sphere Copies Early 9-inch Metalmaster Lathes Atlas Screw-Machine (capstan)
#Atlas lathe gears manuals
Machine Tool Manuals Catalogues Belts Books AccessoriesĪ dedicated manual was issued for the gearbox unit - copies are available - together
#Atlas lathe gears archive
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