Calculate the gears for cutting metric threads of following
pitch. i) 4mm pitch, ii) 5.25 mm pitch. The lead screw of lathe
contains 6 TPI. The lathe is supplied with 20 to 120 teeth in step
of 5and an additional gear wheel of having 127 teeth.
For metric threads,
where, n= number of threads per inch i.e TPI
P= Pitch of the thread to be cut
The gear train will consist of 120 teeth on the spindle gear and 127 teeth on the lead screw
Numerators and denominators are multiplying by 10
For 5.25mm pitch, compound gear train to be used with 105 teeth on spindle gear and 127 teeth on the intermediate gear , 60 teeth intermediate gear drives a 40 teeth gear on the lead screw.