Hardness tester wanted

Yep! I have one. A Wilson model 4 JR.

Harold

Send it? :>) For sale?

Hell no. You didn't ask that. You just asked if anyone had one laying around. I do. :-)

Seriously, bought it on ebay ($175, as I recall)----no weights, no anvils, no braille, with damaged lenses on the meter. new lenses made, a series of anvils made from 17-4 PH stainless, heat treated to H 900, plus a new set of stainless weights were made. Seems to be well calibrated for the C scale when checked with standards. I'm quite pleased with it. bought the braille form ebay, and for only $40. Shipped to me from Taiwan. Good stuff, Maynard.

Harold

Ive only got one..a bounce tester. Wanna borrow it?

Gunner

"If thy pride is sorely vexed when others disparage your offering, be as lamb's wool is to cold rain and the Gore-tex of Odin's raiment is to gullshit in the gale, for thy angst shall vex them not at all. Yea, they shall scorn thee all the more. Rejoice in sharing what you have to share without expectation of adoration, knowing that sharing your treasure does not diminish your treasure but enriches it."

- Onni 1:33

You tease!

Enco has a new one for 800 bucks iirc.

Wes

That's why I bought the old Wilson. They're quite proud of those things when they're new. I always wanted one, but couldn't justify the cost. Getting one cheaply from ebay made it a reasonable acquisition. I didn't mind the rebuild, and had more than enough material on hand to make the components. Truth be known, it was a fun job. I rarely comment on machining being fun. The shine went off that for me years ago.

Harold

Only a couple weeks ago, I saw one that someone had made. It was based on an arbor press and used a dial indicator and appropriate weights, along with a commercial indentor and test blocks for calibration. It didn't look too difficult to build and the owner claimed it to be fairly accurate. If you are interested, I'll try to track down the person who built it...

Jerry

According to Harold and Susan Vordos :

He's not the only one to have one but not to be willing to let it go. I've actually got two -- a "King" (from King of Prussia PA) with a digital readout, and an "Ames" portable one. The King looks somewhat like a sewing machine with a red crinkle finish paintjob. :-)

Both came from eBay auctions, the King second, as it had the ability to measure the superficial scales as well as the normal ones.

And both worked as they came from eBay.

Enjoy, DoN.

Thanks Jerry, I'll either fall into one or drive the 15 minutes to visit my bud that has one. The only problem with that is we end up going to lunch or such and I don't get back for hours.

Oh! The humanity!

Harold

George is one of the top Physicists on the globe, I love him for his wit and humility. However, time flies when we meet or are on the phone and we both get behind...it's unavoidable. I don't know why he wastes time with me, I'm retarded.

snip------

No comment. :-)

Harold

I have been thinking of making (or rather applying, for there is no actual "making" involved) my own hardness tester for a cost of something like zero.

This is how I figure:

IIRC, at least one of the different hardness tests is designed around measuring the size of the impression made by a sphere, (help me with their names please).

Instead of applying a precise force for a precise length of time, my idea is that if I have a piece of steel with known hardness, and another that is unknown, I put them both in a vise with a ball bearing between them. Then squeeze hard. Now the pieces obviously get indented with the same force and for the same length of time.

So I have get impressions, one in the unknown material, and one in the known. Now I reason that the relative sizes of the impressions must surely be proportional to the relative hardnesses of the materials.

Do you think this idea would work as I think it might? If it does, what should I measure, the areas or the diameters of the circular indents?

S.

In a sense, that's how a hardness tester works, but in the case of the Wilson, it measures the depth of penetration, not the diameter.

Yeah, your idea would work, but I have serious doubts about the ability to read the results and translate them to useful information with a reliable degree of precision.

Harold

Well, I was thinking of buying a loupe with a scale, the kind seamstresses use to count threads, to measure the diameters of the indentations but perhaps you are right, and it would still be too hard to see the exact edge.

Also, since you say it is the depth of penetration that's important, perhaps I should measure that instead. I imagine it would go like this:

1. Measure the thickness of the unknown material before testing with a micrometer. Call the result U1.
2. Take the same measure of the reference material. Call the result of that measure R1.
3. Press together in vise.

1. Measure the diameter of ball bearing. Call that B. (Here I assume that it won't be deformed, but in real life I'd have to verify that)

2. Leave the ball bearing in the indentation it made during the test and measure the combined thickness of the unknown material and the ball bearing (sitting in the little pit it made) with the same micrometer. Call that combined measure Cu.

1. Do the same with the ball bearing and the reference material. Call that combined measure Cr.

2. Calculate the depth of penetration in the unknown material, Pu=U1+B-Cu

1. Calculate the depth of penetration in the reference material, Pr=R1+B-Cr

2. The ratio of the hardnesses would then be Hu/Hr=Pu/Pr, so the unknown hardness would be Hu=Hr*Pu/Pr

All of the above assumes there is a linear relation between hardness and depth of penetration, which I somehow doubt, because of the spherical shape of the ball bearing. In real life, if one was determined to get some accuracy out of this method, I guess one could experimentally produce some tables of factors to multiply with, or perhaps it could be calculated theoretically.

Yet, in spite of all this, I still have this image in my mind from reading about hardness testing with a sphere long ago, that what should actually be measured was the size of the indentation, either its area or its diameter.

Well, luckily, I don't really need to measure any hardness, at least not right now.

S.

The kroop type hardness tester works exactly that way. It has a microscope with crosshairs and a x/y micrometer setup to measure the hole.

John

A-ha! I knew I was on to something! Got to google for kroop now. And perhaps I can get by with a loupe and a steel scale instead of a fancy microscope. I like doing things as simply as possible. Thanks for the input, guys.

S.

-- Perfection is reached, not when there is no longer anything to add, but when there is no longer anything to take away - Antoine de Saint-Exupery