Tapping Drill Sizes

Or a pointer to "K factor"

Well I managed eleven and a half and I was tapping 22mm deep the other day down 6.5mm holes before the (Dormer Spiral Flute) Tap snapped like a carrot.

I wasn't paying attention and for some reason I had decided that 8mm course was 1.5mm pitch.

These things happen.

OK, further to te ;K; factor, all the Din taps we were supplied with were the 3 in a set and had truncated thread form and the no 3 tap was full form. In fact I found that the no 1 tap almost fell through the hole in brass and diecast Alu.

The taps were not tapered like English taps so little effort was needed to put them through. The Swiss Engineers were sticklers for using the correct procedures and tools, no half measures. I liberated quite a lot of stuff when I closed down outstations, the instructions were to dispose of it, I could not. The Factory did not take returns.

Almost all the tools were from a Swiss firm, Brutsch Reugger, but expensive, Close by the factory in Heerbrugg were tool firms which stocked all sorts of work heads and tooling for CNC and automatic machinery. The holding down tooling, all hydraulic was amazing. To see a Theodolite body machined in one setting was interesting. I also visited the Optical Division a bit further down the road. Seeing lenses ground and polished.Prisms for electronic distance measuring as well.

Clive