All this reminds me of something that has puzzled me for years.
The dog-holes on my type 625 WM, of mid-70s vintage, are 20mm in diameter. as are the shanks on its bench-dogs and on the gripmate. I wonder if B&D was ahead of its time in using metric sizes, or if it was becoming usual at the time. Anyway, it seems the 3/4in size is still the most common standard.
I want to drill some dog-holes in another bench, and would rather not have two diferent dog-hole diameters, so want to make them 20mm.
I do have a pole auger bit in 20mm, but it is rather long at 450mm and the shank is a hex 7/16in, for which I still could not find an adapter for a square tapered shank. Dieter Schmid does sell adapters, but only up to 9mm (3/8in).
I have been looking for 20mm short auger bits with tapered square shanks for use in my bit brace, but so far have only managed to find them in Imperial sizes. Is there any chance of finding a source for short auger bits with tapered square shanks in metric sizes?
Thanks
G.