Member postings for John Brown 18

I have a thread gauge whose Whitworth section has a thread designated 13G. What is this? I can't find any reference to it in tables of Whitworth gauge.

Thanks to both. Much appreciated. The trigonometry is the obvious (with hindsight) answer to my question. I'm off to join the village idiots union.

Thank you, John. Viewed from the side the cutter is a right angled triangle and by cutting length I mean the vertical side of the triangle. I need a cutter which will give me 7.5mm on this vertical side. Arc cutters don't seem to have this depth but other advertisers don't specify it. I really am a beginner. What is a "very small witness"?

Is there a relationship between dovetail cutter diameters and cutting length? Most advertised cutters don't seem to specify the cutting length, Stuart Brown

Many thanks to all of you who have replied. Much appreciated and will certainly allow me to proceed. Daresay I will be back with more.

A complete beginner, I have purchased a Warco WM250 lathe. I am nervous about inserting the tapers in the tailstock (MT2) and headstock MT3 in case I can't get them out again. The tailstock taper is supposed to be self releasing which, I guess, means that if I wind the arbor right in it will pop out. Can you confirm this? Is it OK to release the headstock taper by threading a drift into the open end of the headstock and whacking it with a rubber hammer? I have bought a drill chuck for the tailstock but it is visibly shorter than the supplied MT2 centre. It is threaded M10. Could I simple lengthen it with threaded rod to reach a length suitable for the self eject to work?

I,m well on in years but contemplating working in metal. My background is in biology so very different from the world of lathes and mills. I would like to obtain both of the latter but wonder if I will get enough use before the Grim Reaper appears. Nonetheless I do have a question right away. I need to gauge some screw threads and note that guages can be bought for about £5 or about £50. Is the difference important? Which gauges should I get?