Beach seemed overly intense and schwarz seemed almost frightened of the cap iron but neither particularly explained themselves well enough. Both seemed to have come to their conclusions but couldn't logically explain why (beach is only logical in his own mind), schwarz seemed more interested in the state of the shavings than the finish on the board. My only conclusion to draw from either are that it's the results that will count.
Beach lost me over the whole back flattening thing, suffice to say, the ruler trick is most likely to be used in future, I concluded that you only need the back wear removed to the point the chipbreaker front meets the back of the blade to the blade tip.
As for stones and flattening them or keeping them flat, it seems reasonable to me to keep them flat. I'm not sure what type of oilstone I was given initially, it's a darkish grey on the rough side, a red/brown colour on the smooth side, the rough side had a hollow, it's not deep, it was about about 1.5mm but it covers 2/3rds of the stone.
I tried to flatten it using the concrete floor in the garage, after about an hour of intense working on it, I'd hardly made an impact, in fact, I was probably smoothing out the concrete more than I was smoothing the stone, so to get that thing up to scratch is going to take me a lot more work or I'm going to have to bite the bullet and buy a stone to dress the stone. My conclusion is that it's going to be easier to keep a stone flat from the start than it is to fix a hollow, the method you use is entirely unimportant, just as long as it gets done.
I bet there's no decent way to tell what grit an unmarked oilstone is? I think for redressing this hollow I'm going to end up with some aggressive abrasive paper glued to glass. Which kind of leads me onto my next question, I see that grits from 220 to 8000 are numbers used across the board, with at least 2 grits per person, sometimes more but nothing in the way of reasoning (apart from the obvious, low grit = more aggressive removal, higher grit = smoother finish), are there any upper and lower limits for grit? Is there such a thing as too aggressive a grit? Is there a diminishing return once you get to a certain higher grit?
Richard, the chisel squaring went brilliantly, in the process of flattening to a single bevel it squared itself up