Another sharpening thread, but with a twist...

[Student]

My wife and I have just got back from New Zealand. Whilst there, we visited the museum in Christchurch and amongst their collections are various Maori tools. In addition, there was a film loop being shown on how the tools were made and used; unfortunately, I can’t find a link on YouTube.
However, what was being shown is described in this article.

https://teara.govt.nz/en/kohatu-maori-u ... one/page-1

Although the whole process of making a stone adze was fascinating, I did wonder about how they acquired their sharpening stones. The stone being used in the film was quite flat but I would assume that, with use, the sharpening stone would develop grooves as shown in the pictures above. If so, I wonder how they flattened the stone again or whether they sought out a new one. I also wondered whether they used to argue about sharpening techniques!

 

[D_W]

Can't speak to what the maori did specifically, but have seen elsewhere that the whole idea of rubbing three surfaces together to get surfaces that are true is a technique that's hundreds of years old, and not thousands.

I'd imagine they did whatever took the least effort and still met standard (which would mean using a stone worn hollow).

Perfectly flat stones are nice to have, but not necessary for much. Most of the razor stones that I've gotten (and I've gotten a lot of them over the years, sold most, but have seen a lot that were in use in barber shops) were worn hollow, too. A barber would've used only their stone on their razors, so it wouldn't have mattered much - the dip on a 10" escher stone I acquired years ago was probably 3/16ths of an inch. It wasn't subtle. The stone was flat across its width, but like a hammock along its length.

 

[AES]

Very interesting thread this, which I've only just seen (got sent here by Andy T in response to my Qs about the Ebbsfleet Plane).

Amongst other things it revives an (I'm assured semi-serious/joke) Q in the verbal part of our apprenticeship final exams. "You're in the desert with a VERY special vehicle and it's engine konks out. You establish that the tappets need resetting, otherwise the engine wont run at all anymore. No chance. You've only got a 3 thou and an 11 thou feeler gauge in your toolkit. But the Manual specifically says tappet clearance must be 8 thou, plus/minus nil. No other setting will do. So what do you do?"

Answer. Rub both feeler blades up and down in adjacent bits of sand until the 3 thou blade has disappeared. The other blade will now be exactly 8 thou. ;-)