how to test hardness?

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pintail_drake2004

Joined
Jun 9, 2007
Messages
18
hey guys, i have read on here about testing the hardness of steel with a file...how does that work? i have been wondering 'bout that for a while now and just couldnt figure it out. All i could come up with is hard steel wont be as greatly affected by the file, right?
Thanks
Pintail
 
The file test is just for directly after quenching, I believe. If the file "skates" off the steel, it got hardened, and you can proceed with the tempering, etc.. I'm not sure if the file will still skate after the steel is properly tempered.

..but you're right, that's basically it. The steel got harder (as hard as?) the file, so it doesn't "bite" into the steel anymore.
 
yep...
you both have it right. it is just a test to see if the blade actually got hard. most blade steels get pretty hard before tempering. so the file wont "bite" into the blade. after tempering it will bite in a little more... but should dig in.
take care
~Chris
 
I gotta intercept.
I am a maker of handmade and of custom handmade knives. I am not a hammer and anvil guy, and m,.vxczy neighbors appreciate that.....
SO, If you had a pro like Paul Bos do your blades (and springs). the blades would be with a half Rc point of what you requested and the spring would also.....
that being said, there is a "mystique" about forged blades and the being in control, for better or for worse, of the steel you turn into a forged blade.

If you can afford it, a Rockwell hardness tester would remove any doubt as to where you are at hardness-wise (butchered my grammar didn't I?).

If not, then do you know anyone near you who has one?.....
If not the file test is pretty good but somewhat "interpolative" ( I think I made that word up).......
 
Not to mention how new the file is. A dull file will almost skate on annealed steel, whereas a sharp one might not quite "skate" off a hardened blade.
 
Just for the sake of asking what does the cheapest ACCURATE Rockwell tester go for, and what brand would it be?

There are file sets made SPECIFICALLY for hardness testing to be had for $60 or so on fleabay that will get you within a couple of points. Not the most accurate method but better then nothing

Just my 2 cents

Syn
 
If pin point RC accuracy is not a great factor, you can buy a set of testing files that will put you pretty close. With a little experience with them you can get a feel for the bite, or lack of, and get within a point or two. The set goes 45, 50, 55, 60, and 65 RC. If one bites, and the next one down doesn't, then you are somewhere in between. After using them a little, you get a feel of about where the hardness is by the amount of bite you get. It helps if you have a few testing blocks of a known hardness. Not the best way, but will get you by for any practical purpose, and a lot cheaper than a RC tester. If you knew someone with a tester and HT capability, you might get them to make a set by re-tempering regular files.
 
Thanks for the info but I still don't understand how much pressure I'm supposed to apply. if I put enough pressure on the file, will it not bite on even the hardest steels?
 
oh.. so I wouldn't have to worry about damaging the quenched steel when performing the file test, right?
 
I guess I have the same question as you. The definitive word here is, "test."

Whatever the pressure, how much damage will you do to your blade if the file does BITE? AND......how much extra work might it take to get rid of even a small nick? :jerkit:
 
It doesn't take much at all to rid a small light scratch. Test near the edge, most often it is left a little thick there anyway. An RC tester leaves a dimple, and you can't use it on a bevel. Where ever it is used, you still do not know for an absolute, indisputable fact, the hardness in the edge, at any given spot. If you botched the heat treat, you could have hard, and softer spots all over the blade. Aside from all that, hardness isn't everything, and is only one part of the equation in heat treating.
 
I like using the good old harden Tester here in my shop. This way I know what it is. And it shows up when I start doing my filework on the blade. I like knowing what it is and how hard it is. as in 59Rc on the money. I have 3 test I do in making a knife. Great post and have a great day in the land of knives. --------------:thumbup:
 
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