Glass hard Gauge plate?

I'm thinking of making some scraper (wood turning) inserts from some Gauge plate. Hardening is easy at home but I'm wondering if it's worth bothering to temper them afterwards? Scraping wood shouldn't stress them that much and nothing lost if the odd one crumbles. Only issue I can see is safety, I don't really want any bits flying about! What do you guys think? How much hardness will I lose to temper them to a non brittle condition. I should add that I've made trigger parts before and left the extreme tips glass hard and not any any problems.

Hello Vic,

The late and great Tubal Cain used to recommend boiling in water for a while to reduce some of the brittleness from glass hard to improve the fracture toughness, the treatment has no measureable effect on the hardness and is very controllable at only 100 degrees C. Even if you do nothing I can't really believe that scraping timber is likely to introduce sufficient stress to lead to explosive degradation!

It might be worth a go, after all you have nothing to lose by trying.

Regards

Brian

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!

Vic,

Personally, I would prefer to use reclaimed old steel [such as can be found in decent moulding plane blades] ... This was 'crucible steel' and takes a better edge than anything else you are likely to find.

MichaelG.

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P.S.  vintage files are another good source of quality steel.

Edited By Michael Gilligan on 23/08/2015 13:04:47

Thanks for your thoughts guys, I particularly like the boiling water tip Brian! The rest of the tool will likely be mild steel or maybe some stainless I have knocking about. I'll be using gauge plate or ground flat stock as some refer to it simply because I have some pieces of it in stock so it seems daft not to use it.

I make all my scrapers from old bearing outer cases, they sharpen up really well after you have straightened them and shaped them.

bri

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

Just leave then hard. The heat from the grinding is enough to take the temper off them

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