I have almost finished making the MK2 version and not yet found any obvious drawing errors, so you can proceed with confidence that there won't be any scrappers as a result. Only maker malfunction! I admit to cocking up a couple of parts from which I learned, older n wiser! One example being the Swivel Base 31, I put the 4 – off, M3 tapped (blind) holes in the wrong edge, next to the M6! "Sod it, not scrapping, I'll tap other side as well!" Not happy with my blunder, particularly as M3 so small there's a risk of tap breakage, especially a blind hole. Didn't break a tap, thank goodness. Something I've noticed is that HH has arranged things that only just work, e.g., thicknesses of metal to be threaded. The tap required is just long enough to do the needful. Wish some of the past locomotive designers could have matched Harold's skill. I basically want repeatability in grinding lathe tools and endmill sharpening but I'm looking for a simpler way of holding endmills as I don't want so much extra work like what's involved with his design. My sadly missed pal once said you can spend half your life making tools to make more tools and not get on with what you really want to make.
John