Simple hardness test

Status
Not open for further replies.
JTknives

JTknives

Joined
Jun 11, 2006
Messages
8,651
I thought i would post some info for the new blade smith that i have found. first one of the most commen question is, how can i tell if my blade is hard. well if you heat treated it your self there are so things that you need to be awar of. first if you are using a torch to heat the blade and not wraping the blade in stainless steel foil to protect if from the air the blade will be hard but will not seam hard. what this means is you will test it with a file and it will kinda bite in and leave surfaces scraches. but dont let this fool you, what happend is while heating the blade you burned the carbon out of the top layer of steel which is a fue thousandths. if you remove this layer you will see that its super hard and a file wont even tuch it. In my experance i like this because it makes for an easyer miror finish because the top layer that has the scratches is easyer to remove. on my blades I use O-1 and after heat treating my used file will seam to cut like it was never hard. but a quick pass of the belt grinder at 120 grit remmoves this layer. i go back and test with a file and nothing not even a scratch with a new file. I just thought i would let the new people know about this so thay dont keep trying to harden there blade because there file bites in right after heat treat. just thought i would pass the tip.
 
JT, Thanks for the info. I've been guilty of this exact problem. Re-heat treated some blades three times and then said "to hell with it!" and just finished them. They came out OK.
 
Best bet is to get an actual rockwell tester. I have two very small model 2Ames units picked up on ebay for less then 200 apiece. They fit in a small box and take up little space in the shop. I had to be patient in my search but it was well worth it.
 
Arthur Washburn said:
Best bet is to get an actual rockwell tester. I have two very small model 2Ames units picked up on ebay for less then 200 apiece. They fit in a small box and take up little space in the shop. I had to be patient in my search but it was well worth it.
Click to expand...

Now to use a rc tester would i have to remove the softer surface steel to get an acurate messurment.
 
JT,
I heat treated dozens of blades with a torch prior to my evenheat and did not have this problem. It would seem to me you need to invest in an accurate pyrometer.
Matt Doyle
 
I might be heating it to much and burning up the top layer, where can i get a good pyrometer
 
JT,
The Pyro I used before I got the furnace was a digital handheld laser type model. Not sure of the brand, but I know you have to watch which one you buy because many do not go over 1200F. Seems like foolish money tho, IMO. I would think you would serve your needs better by saving the money and putting it towards an oven. I have seen several on ebay for about 500$ new. Also several decent used ones. The higher temperature rated guns are fairly pricey. Would probably put you half way there. Just bite the bullet! It'll give you a reason to have to keep putting out more knives!:D :thumbup: If you aren't ready to bite the bullet yet, try heating at a slower pace with the torch, starting with the tang. If you start with the blade, the tang will suck the heat out and you end up overheating the blade.
Matt
 
I do not know if there are time limits to threads but this thread should be stickied in the newbie section. I just accidentally snapped a blade not thinking it was hard because of this exact reason. wish I would have seen this 10 minutes ago.
 
Status
Not open for further replies.
Back
Top