What is the formula to find out gear ratio to cut metric thread on British lathe?
1
\(\frac{D R}{D N}=\frac{\text { Lead to be cut in inch on job } \times 5}{\text { Lead of lead screw in } \mathrm{mm} \times 127}\)
2
\(\frac{D R}{D N}=\frac{\text { Lead to be cut in inch on job } \times 127}{\text { Lead of lead screw in } \mathrm{mm} \times 5}\)
3
\(\frac{\text { DR }}{\text { DN }}=\frac{\text { LeadobecufinmmxT.P.onLS } \times 5}{127}\)
4
\(\frac{D R}{D N}=\frac{\text { Lead to be cut in } \mathrm{mm} \times \text { T.P.I on LS } \times 127}{5}\)