Hello Sooty,
I can give you some thoughts..... some might be wrong mind you. I'm no expert . Just some of my personal findings.
I've read plenty about blacksmithing....uno, the whole anneal/shape/re-harden/temper process.... but really haven't found the chance to try it all, partly because it scares me to be honest..... bit of magic to learn. So, it take a while to get consistant results I thought.
So as an experiment I tried grinding files into blades with the simple thought.....
'files are obviously hard,,,,maybe they'd be good'. . And too my amazement, I've found that, untouched, they make excellent plane blades. Which is great, because files are dirt cheap. And I personally can't justify buying aftermarket blades for experiments.
I Emailed 'Eddie the Eagle' (Andrew)on the Ubeaut site, whose a metalurgist, who wrote an excellent thread on blades.....
http://woodcentral.com.ldh0138.uslec.ne ... ;read=4444
(might be of interest)
....asking him about files....describing my good results.... trying to get some answers. To which he responded with this email... (I'm shore he wouldn't mind me posting it here)
*******
Hi Jake,
Thanks for your comments on the article/thread.
If I recall correctly, files are tempered to about 60HRC, a little lower
than a plane blade. (which is why they don't cut tempered steel).
They're both minimally tempered.
The steel in a file is about 1%C, which gives max hardness and some
toughness (which is why they shatter if you hit them)
http://www.key-to-steel.com/Articles/Art12.htm gives a summary of what's
going on.
As the file sees more tempering than the blade, it's going to be a
little tougher and less likely to chip than THE EQUIVALENT CARBON level
tempered as a blade (ie: less heat treatment.)
In your case, it sounds as though you've got a winner - the higher
carbon in the file gives a higher hardness than the plane blade steel.
Metallurgy is still somewhat of a black art - the proof of success is
that the file works as a blade quite well.
Best regards,
Andrew F
(eddie the eagle on the ubeaut board)
********
So there you go.....
I think it be unlikely for you to have any brittle problems using a file for handplane applications.....simply because there really isn't any impact cuts going on....uno, unlike say a mortise chisel. Hasn't happened to me yet. I've made about 20 profile plane blades from old files so far on no edge crumbling. But I may have been lucky. I stick to a 'Wiltshire' brand of old file.
They say the old serrations in the file can be break points as well. But again, there really isn't enough shock for that to occur. I won't grind serrations off if I don't need too. Just a waste of time. Just leave them there and no problem.
The edge retention of these blades seems good too. I've never tried a Hock blade or any other aftermarket blade, so I can't give an accurate comparison I suppose.......but I can say, they last longer than the regular blades that come with the profile planes I use. Good milage between sharpening.
The only daunting thing I suppose, is how you sharpen them ? yes ?
Well, they sharpen at a rate similar to a good hard blade I suppose. The first shaping of the tool can take quite a while as you can imagine, but I still think its worth it, cause your bipassing the whole anneal/shape/harden/temper process which takes time in itself I'd say.
Its all done freehand off bench grinders. But use a ALO(white) wheel, or else don't bother trying.
Freehands easiest, with a finger right on the edge to monitor heat.Very simply way of ensuring you don't temper your blade.
If your finger goes ouch, its too hot,,,,,so pull back makes sense, since your fingers will burn way before it looses temper.
it works...
Plenty of light,,,,,eyes in close,,,,burr the edge then knock it off with buffing wheels charged with green compound. You can polish up the backs as well with plane blades, unlike chisels, cause a little rounding is not a problem. I don't bother with your normal water and oil stones. Take the blade straight from bench grinder to buffing wheel I do. Quick.
I can't think of anything else right now. Hope that helps. I need to sleep. Goodnight.
