Threading Change Gears, Precision Matthews PM-1228VF-LB Lathe

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Human: The Precision Matthews PM-1228VF-LB Lathe comes equipped with 36-, 39-, and 40-tooth gears that offer additional Imperial and Metric threading capabilities. These gears also fit seamlessly on the Grizzly G0773 lathe/mill and Sieg SC10 lathe. The PM-1228 comes pre-installed with five gears (30, 35, 49, 50, and 60T) that can be installed at position "G" marked on the label/manual diagram. Additionally, a 56T gear is available for installation in place of the 86T gear. The 36T gear installed at G unlocks the following threading capabilities: Imperial (36, 91, and 90T gears meshed in line, tpi): Lever A B C 1 60* 30* 15* 4 40 20 10 Metric (36T meshed with 91T, 90T meshed with 86T gear, mm): Lever A B 1 0.4* 0.8* 2 0.45* 0.9* 4 0.6 The 40T gear installed at G provides the following threading capabilities: Imperial (40, 91, and 90T gears meshed in line, tpi): Lever A B C 1 54* 27* 2 48 24 12 3 42* 21* 4 36 18 9 5 30* 15* Metric (40T meshed with 91T, 90T meshed with 86T gear, mm): Lever A B C 2 0.5 1 2 5 0.8* The 39T gear installed at G combined with the 56T gear in place of the 86T gear unlocks the following threading capabilities. Before turning on the lathe, ensure there is approximately 1-2mm of space between arm 857 and gear 855 to prevent interference. Imperial (39T meshed with 91T, 90T meshed with 56T gear, tpi): Lever A B C 1 90* 45* 2 80* 40 20 3 70* 35* 4 60* 30* 15* 5 50* 25* Notes: - A 27T gear at G would provide 80tpi and 0.3mm, but the gear is too small and there is not enough material around the keyway. The 39T gear combination can produce an 80tpi thread. - Installing the 30T gear at G plus the 56T gear in place of the 86T gear would provide additional threading capabilities, but this combination is not possible due to interference between arm 857 and gear 855. The 39T is the smallest usable gear without interference. Imperial (30T meshed with 91T, 90T meshed with 56T gear, tpi): Lever A B C 1 117* 2 104* 52* 26 3 91* 4 78* 39* 5 65* Values noted with an asterisk (*) represent threads not previously available using the factory-supplied change gears.