LancsRick":xxvc5mkf said:
I've got into restoring hand planes and the only thing that I ever write a blade off for is heavy pitting.
FWIW I've never found an iron that was too pitted to restore, even ones I know others would put aside as a sacrificial electrode in their electrolysis bucket :lol:
LancsRick":xxvc5mkf said:
...some blades are softer than others, doesn't matter.
It can matter. There's a spectrum of hardnesses out there and how soft is too soft is partly a thing for each user to decide for themselves, q.v. David C.'s references to the unusable irons in 70s planes!
But hardness below a certain level begins to be a practical issue of edge retention/honing frequency. While there are certain workarounds for an iron that's a little softer than ideal they're not always desirable, and sometimes not possible. Irons for block planes are a particular case since a steeper bevel is actively discouraged because it directly affects the cutting action, and back bevelling may not be doable.
And below a certain number softness can be a dealbreaker, the steel isn't just softer than you'd like, it's too soft to use: edges fold over at any reasonable included angle.
Jacob":xxvc5mkf said:
I don't think I've ever encountered a 'dud' blade as such. Some damaged ones, or worn/rusted beyond use, but nothing inherently 'dud'.
Modern mass-produced irons (chisels too) are occasionally sold where the heat treat failed, or the tempering temperature went up too high, or something, because the steel ends up too soft. Also sometimes seen is something that leads to crumbly, brittle steel; overheating seems the most likely cause – too high a temp reached or they were kept at critical temperature for too long.
Warped irons are also a regular occurrence as we all know, and although warps are usually minor they aren't always and bowed irons are hard to fix at the best of times. Couple a warp with the second thing above and you have a big problem, as an attempt to flatten the iron, either with hammer blows or by bending in a vice... will lead to swearing to make a sailor blush.
Jacob":xxvc5mkf said:
'Lapping' is also something I've never found necessary. I'm not sure why people do it - it seems to take up a lot of time rather pointlessly.
Not everyone means that in the OTT way, for some the term is just synonymous with prepping the back fairly minimally to get that narrow strip near the edge ready, not the wholesale flattening of a big swathe of iron that's a waste of time.
