Hardness tester

Greetings,
A friend and I are building a heat treating oven for his knife making hobby
and my general home machine shop. He wants to be able to test the hardness
of his knife before and after heat treating (C50-C55 range) and I am
interested in being able to test metal in general (anneal, machine, reharden
to Cxx various sized items that may surface to be worked on) so we are
looking at buying some kind of harness tester. I see lots of larger Wilson
and similar models on ebay but there are many different models (3JR, 1JS,
3JS, 5JR, 12A, and huge variations on prices. Most come with weights and
some come with diamond and different sized ball indenters, which I assume
are all changeable for A/B/C scales. I haven't run one of these machines
before, and while the idea of various weights vs. various sizes of
penetrators makes sense, I'm assuming the plug in cord and remarks of motors
may be to raise and lower the penetrator gently onto/into the test surface.
I also see some smaller portable models, but I have no idea on whether they
would work well enough to be worth buying.
My question is this: does anyone have any comments on specific makes/models
which would do what we want, or anything I should be looking for (or looking
out for) when buying a used tester? Thanks.
Al MacDonald
Reply to
Al MacDonald
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You can purchase a set of test files and use them to determine which is harder the file or the steel being tested. Otherwise you might be able to use a hardness tester at a local tech school .
Reply to
bamboo
Do you have a local heat treater by you, to check out theirs? Or school?
I don't know how expensive these things are, but I imagine they ain't cheap. I think, tho, that unless you really want to calibrate your stuff against laboratory standards, *relative* hardnesses are about as useful ito of effectivenss of heat-treating processes. You could maybe make an air/blowgun w/ shop air and a carbide/diamond ball, or a ball cemented to the tip of a suitable projectile. Might do you while yer hunting for the real thing at a good price. Might find use in neighbor control, as well. :)
Also, they make (and I have one!) an air-operated arbor press/punch ditty, which might could be calibrated. It's a small benchtop jobby, weighs about 75 lbs, packs a helluva wallop, very fast. Iffin yer innerested, I'll dust off the nameplate. I fire it up once in a blue moon, when I'm bored, or if I just wanna scare the cats. :)
Knife-making is da bomb. I'm going to a good show here in Manhattan tomorrow. There's a guy from LI who found a way to bond/melt titanium onto steel, w/ a mother-of-pearl effect. Incredible, as is the price--about $5K for a blade w/ a so-so handle! ---------------------------- Mr. P.V.'d formerly Droll Troll
Reply to
Proctologically Violated©®
I have a Japanese bench tester that has worked fine for as long as I've owned it (about 20 years) (it looks like the Mitutoyo tester if you have seen one of those). I traded with a fellow-knifemaker for the Swiss portable tester I had before that. I'd say the Swiss hand-held and the bench tester were roughly equally accurate and repeatable. I can't comment on the Wilson models, though they have always been the "standard" make, since I've never used one. The diamond indenter is required for C scale readings, as you probably know. I wouldn't pay a nickel for motorization, unless I was running a heat treating shop. I never resented the few minutes it took to take three hardness readings on a knife blank. Someone who has experience with motorized units, may chime in and prove me wrong.
If you haven't heat treated your own work before, you are going to love the freedom it brings, not having to decide in advance what the next twenty blades are, batching them together for commercial treatment. Not to mention the positive effect of having someone doing the heat treat that actually gives a shit!
Where I would definitely spend a bit of money is on the controller, and on adequate insulation of the box. My oven has a fiberfax hot face, which makes a tremendous difference to the time it takes to get to temperature: 0 to 2000F in about 18 minutes, 15A 220V.
Good luck with the project,
Adam Smith Midland, ON
----- Original Message ----- From: "Al MacDonald" Newsgroups: rec.crafts.metalworking Sent: Thursday, November 10, 2005 9:58 AM Subject: Hardness tester
Reply to
Adam Smith
I don't really agree with the comment about "relative hardnesses". Most of the higher alloy materials have a pretty narrow range for a really good heat treatment, and you want to know that you have hit within the range. Example is the "twin peaks" in the torsional impact curve for tempering A2. You want to hit one of the peaks, you definitely want to stay out of the valleys. I paid pretty good money for the first tester, at a time when I wasn't all that flush (much more than the prices I see now on ebay), never regretted the purchase. Fine knives deserve fine heat treatment, and if there is any appreciable alloy content, you want to be able to test the outcome. (These comments are not as true for lower alloy steels: working with W2 or O1 the ranges of acceptable results are much wider than they are for more hardenable materials).
Adam Smith Midland ON
Reply to
Adam Smith

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