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SCREW CUTTING METRIC PITCHES.

REFER TO ILLUSTRATION NO.4.

 Remove endgearing from headstock, reverse shaft 12, headstock bracket 29, gearbox quadrant 30 and gearbox "E" shaft 11. Shafts 11 and 12 are fixed and studs 29 and 30 are adjustable.

 Refer to metric pitch plate "Q" affixed to cabinet casting and select the gears required, at the same time noting their relative mounting positions and T.P.I on standard gearbox.

EXAMPLE.

 Assume it is required to cut a thread of 1mm pitch. By reference to plate "Q", the following gears will be used; 48 teeth, 50 teeth, compound 48/127 teeth, idler 152 teeth and gear box setting as for 20 T.P.I

MOUNT 48T gear on shaft 11, boss side on first, (this gear remains constant for all pitches shown); 50T gear on shaft 12, gear side on first; 48/127T compound gear on running bush and stud 29. 127T gear on first and mesh with 50T gear; Adjust stud 29 to obtain correct backlash and tighten nut.

 With quadrant 30 free, mount 152T idler gear bushing and stud, boss side on first, adjust to run with 48T gear on shaft 11, tighten nut on stud in quadrant 30 and move radially to engage with idler 48/127T compound gear. When correctly meshed, tighten both nuts on quadrant binder. Check to ensure free running and re-adjust studs slightly if required.

THREAD AND FEED BOX SETTING.

 Proceed as described on page 5 for screwcutting, set knobs 9 and 10 in this example to 20 T.P.I on dial "R"

REVERSING.

 The chasing dial is not used with metric pitches, the half nuts remain closed and saddle motion reversing must be performed by headstock reverse knob 6.

 To compute for metric pitches other than shown on plate "Q", see pages 17 to 19.

Continued........