# 109. Cutting speed in turning, milling

CNC – Cutting speed formulae – turning and milling
The cutting speed equation is the same for both milling and turning.

In milling, where the tool is rotation, the cutting speed depends on: 1. Rotation speed of the tool 2. Diameter of the tool.
On lathes, where the part is rotating, the cutting speed depends on: 1. Rotation speed of the part 2. Diameter at which the tool is doing the cutting.
Metric mode

S in m/min, D in mm, N in RPM The 1000 in the denominator is to convert the D in mm to meters.
Inch mode

S in ft/min, D in inch, N in RPM The 12 in the denominator is to convert the D in inch to feet.
Etc.
Achi Mess in Coimbatore
When I recently stayed in a well known hotel in Coimbatore, I was given directions that said the nearest landmark was Achi Mess. Messes are small simple eateries in South India, and I was wondering why the location of a large hotel would be defined by a small eatery nearby.

It turned out, to my delight, that Achi Mess was one of the top pilgrimages places for the vegetarian foodies of Coimbatore. It’s a bright, clean and airy place where you go only for the food, not to hang around and chat. The food is so good that you wouldn’t want to do the latter anyway. There’s a longish list of things to eat, and the accessories – sambar and chutneys – are heavenly. Everything is served on banana leaves. People in Tamil Nadu have ‘tiffin’ for breakfast and dinner, and only lunch is a full scale meal with rice, sambar, rasam and a few ‘poriyals’ (poriyal = sabzi). Tiffin is the collective word for anything that’s not eaten with a full meal, like idli, dosa, vada, pongal and a whole lot of other dishes.

After a hard day’s work I went back to my hotel, dumped all my work stuff, and popped over to Achi Mess for a light meal (which at night is tiffin). The food being so good, and my will power being rather weak when it comes to food, the light meal became a heavy one. Now I know which hotel I’m going to stay in whenever I go to Coimbatore – not because of the hotel itself, but because of its neighbour.