[stickman]

everybody refers to the rockwell hardness scale.But if I remember back to my trade school days there were two hardness scales the rockwell and the brinell (spelling)hardness scale.dose anybody know the difference or the reason the rockwell is always mentioned?

Its probably because the industry all gravitated to one for ease of comparability.

[mdallensr]

Rockwell hardness testers make a small indent in metal and give a hardness reading immediately. Brinell hardness testers make a larger indent with a hardened ball, and you determine the hardness by measuring the diameter of the indent. Rockwell is quick, reproducible and almost unnoticeable; Brinell takes longer, leaves a large indent, and is more subject to operator error. Brinell also is less suited to testing very hard materials. For that little nugget of knowledge, I had to reach back more years (decades) than I like to admit. Mike

[Capt. Bandaid]

Mike is correct in his explanation of course. I would add only that there are actually dozens of hardness scales that include Rockwell C, B, A, D, E. F, G, H, K, L, M, P, R, S, V and variations in the load applied that include N, T, W, X,and Y. There is brinell, knoop and vickers for microhardness (testing one grain of steel at a time), and the scleroscope. Hardness can be determined by ultrasonic waves, and by electromagnetic probes. All of these scales have applications that make them useful but the good old Rockwell C is the one most often used on hardened steel and the one we are familiar with. Carving tools should be in the range of Rc 55-62.

[Eddy Smiles]

Ouch! My brain hurts! You guys definitely have no worry about senilty setting in! Back when I had shop I can't ever remember learning about hardness and such. But then that was back in the bronze age, most likely before they came up with the system! Ha! Ha!

[stickman]

thanks for the great answers. were you two guys involved in NDT?(non destructive testing)

when I was in high school I went to trade school for half a day and got an associates degree in nuclear metallurgy and NDT.

enden up working in radiation safety .

[mdallensr]

Capt. Bandaid and I were metallurgical engineers in previous lives. I've enjoyed his posts about making carving tools, and it's something I should take the time to learn as well. Several members have posted about their tool-making efforts, and most have had to work hard to gather the equipment and learn to use it. I hate to admit it to Capt., but I have everything I need in our machine shop at work. We machine and heat treat our own tooling for our production equipment, and I could go in on a weekend and make carving tools, or at least experiment with it. We also have an historic village about a half mile from my house, and they have a blacksmith shop with all the equipment I'd need. Opportunity is knocking, but I'm preoccupied. Oh well, maybe next year....... Mike

[Capt. Bandaid]

Mike, no time like the present to learn about the past! I will be moving to Houston an a month or two and have already made contact with the Houston Area Blacksmith Association. This group includes a variety of tradesmen, engineers and craft people and they conduct demonstrations at historical events all over Houston. This months demo is making woodcarving tools! If anyone in the Houston area is interested, go to www.habairon.org for details.

[Hi_Ho_Sliver]

Geez Mike, take advantage of it! nothing like good homemade tools...also nothing like them for passing on to the next generation, so Pop, get with it ha ha!

[Don by the lake]

I make carving knives from lathe parting tools at work when I get time. They check 62Rc and stay sharp once you get them sharp. The only problem I have is finding a glue or epoxy to hold them in the handles. Tried Gorrila glue but it doesn't work that good. Any suggestions?

[Hi_Ho_Sliver]

Don on the tang, if I can get a hole in it I do, otherwise I notch the sides of the tang on my grinder and inlay the tang into the handle with a snug fit, I use polyurathane glue from wallyworld...the notches keep the blade from coming out of the handle