Vic – if these are just inserts on the end of a tougher steel shaft – as per inserts used for metal turning – then I wouldn't bother tempering. If it's the full tool, shaft as well, then I'd be wanting some give in the shaft before it broke in case of a dig in or snagging an inclusion. I know with a scraper you only grazing the surface, but I'm thinking more if you hit a bit of wild grain or a nail someone banged into the tree 75 years ago. I had a salutary lesson in how brittle tools can be, when a 3/4 BSW tapping drill rolled off a bench and fell less than 2 feet on to a concrete floor – and I had to pick up the two pieces of it. 10 minutes before I'd used it to drill a hole in steel!

I'v made gouges for wood turning from the outer race of a ball bearing , I'v also used old files for making wood turning tools. Un-tempered, hardened Gauge plate will cut the wood like a bit of glass used as a hand scraper, and will hole it's edge until it gets a bit hot, it's surprising how hot the edge can get on a bit of hard wood. ex wood turner

Ian S C

A local boat builder uses / used ( now deceased ) glass as scraper..now thats brittle.
But defo sharp and hard..
From my reading scrapers “should” be as hard as possible ( if its difficult to sharpen with file then thats about hard enough).
I use hss hack saw blades ( 1/8″ thick ones from power saw)..as they say..takes an awful edge but holds it forever.

Edited By jason udall on 24/08/2015 18:11:39