Hi Simon, to answer your questions- it is mm. Most of the dimensions are approximate- the only one that has to be spot on is the diameter of the lip and its rebate. The step on the hole can be left out. The main problem I have with working out how to do this is that while I have turned many bowls, I've always turned the outside first and if I need a thin wall, used calipers to gauge it. This one can't be done like that as I don't reckon there's enough meat in the foot to support the thing while the inside is being turned. I guess when turning the outside, I could do a bit, take it off and check the wall thickness, and so on, etc. Have you ever turned a bowl inside out, as it were? If so, how did it go? Also, interested by your suggestion to make the blank long grain rather than cross grain as is usual for bowls. I've only done that once and found it quite difficult. Could you explain your thinking?
Cheers!
Pete