Rockwell Hardness Tester

C

cjensema

Joined
Dec 29, 1998
Messages
288
Awhile back I seem to remember someone asked where to get a Rockwell hardness tester. I was surfing the web and just happened to notice that Mermac has a used Wilson 1JR Rockwell Hardness Tester for sale for $850.

Anyone interested can check it out at
http://www.mermac.com/machines.html

 
Short of using a micro-hardness tester how does one not mar an item being tested for hardness ?
 
when a rockwell hardness tester tests a hardness it hits the blade with a diamond. some testers are non marring.
 
But with a 'C' scale test one uses a hefty load (something like a 150kg ?) so even with hard materials one ends up with a little mark. Other scales with lighter loads can be used but they're more sensitive to surface conditions, and it seems that it would be better to state that one is estimating the Rc hardness using a value converted from another scale.
 
The tester from J&G for $135 that I mentioned on another web does not mar the work. It drops a fairly large ball bearing and you measure the bounce back. It only reads the C scale. And, yes, it is as accurate as you need to get.
 
Who is J&G, and how can I reach them?

I have seen the bouncing ball tester, but never known how to get one of my own!!

Thank You!!

Doug
 
The instrument you want is called a "Portable Hardness Tester" and it is Order Number SPI-30904H, listing at $135.00 plus shipping. It is on page1408 of the J&G Industrial Supply catalog. 1-800 521-9520.
You can call and place a credit card order immediately. They ship UPS 2nd day air at the ground rate as a customer service. Their catalog will be your great wish book.
Just a couple of words here. The catalog says it measures 1/4" or greayer thickness. If you tape a piece of scrap stock firmly to a thinner piece it will measure right on. Just to make certain, heat treat your scrap piece along with your blade.
 
Thanks for posting this thread cjensema. I think it's in response to one of my postings. The $850 price is still high for my current needs.

Thanks also to Parabellum9 for the information on the J&G tester. That is more the price I was looking for. I wonder about how they made the calibration work. What makes you confident about its accuracy?

 
The $135 tester that is mentioned appears to be the one listed in other catalogs at about the same price, and is evidently a Swiss Precision Instruments product. I couldn't find any other info on it, but 'impulse' testers based upon the more sophisticated Leeb principle, which is similar but doesn't measure rebound height, appear to be common, and much more expensive. The SPI unit seems like it should work ok provided the material is thick enough, well supported, and the tester is vertical.
 
To calibrate use test blocks, and to calibrate with thinner than suggested sections use thin test blocks. It might be good to use a thickness like you'd expect to use with knives, over the range of hardness that you expect to use. The test blocks can be ones that you make, and have measured at one or ideally more places. If the measurements have a fair amount of variation from one measurement to the next try averaging three to five measurements.
 
Thanks Parabellum9 (can we call you Lugar for short?), the bounceing ball tester is just what I need!! Thanks also for the tips on use!

Doug
 
Thanks for the info Johno. Do you know if they sell something like gage blocks with standardized hardness values? That could help check calibration.
 
J&G also sells the test blocks and they are listed on page 1408 with the Portable Hardness Tester. They have 3 in the C range, but you can get by with having just 1. They are $53.50 each.
If you know a Toolmaker, perhaps you could work a deal on some pieces of known hardness.
I have been called worse things than Luger. And, now you know what my specialty in Pistolsmithing is.
 
Thanks Parabellum.

So you've been called worse than Luger? What's so bad about being called Borchardt?
At least it's catchier than being called P-38.
 
The tester with the ball is OK... For flat surfaces as a regular tester is. None of them test the edge of the knife . The surface must be flat or the brail on the high end testers will break. On the ball bearing bouncing type it just wont bounce straight up the tube .

So the best your going to get is the hardness of the flat surface on the knife

------------------
Web Site At www.infinet.com/~browzer/bldesmth.html
Take a look!!!




 
The bouncing ball type of testers will also need to be vertical. The more sophisticated type of impulse testers seem to use a sping loaded cell, different weights and tips for different hardness/applications, and they try to determine energy loss by comparing the velocity before and after hitting the surface. The bouncing ball type of tester seems to need to use a ball big enough in order to get it to rebound high enough to see differences in hardness, which is why they're rated for use with thicker sections than most knives have.
 
It is my intent to prepair a sample, just to test, that has a proper shape, heat treat along with my blades and test the sample. My gole is to be even more shure of my heat treat!

Doug
 
Some other things to bear in mind with the less expensive testers: While they are very useful for comparison, they are not sophisticated enough to give you actual numbers that will be exactly the same as you would get from an $800 Rockwell Tester. If you have a heat treated blade that works out well, you can take a reading with the bouncing ball and when you test your latest blade, if the numbers match, you know that you have what, for you, is a good heat treat. You cannot expect an exact duplication of the test with a laboratory tester.
The same is true of ballistic chronographs in the economy range. The companies making them advertise that they will read out muzzle velocity. Not true. M.V. can only be determined by the use of higher math. A chrono reads out in INSTRUMENTAL velocity, since placing the first screen closer that 5 feet will read the speed of sound, not velocity. So, you read what happens 5 feet from the muzzle. This reading will tell you if your handloads are uniform, but not exact m.v. As was pointed out to you, by a contributor much wiser than I, the same holds true for the bouncing ball tester, as you must read the flat portion of the blade. No problem. You are using it as a comparison, not a laboratory perfect readout.
 
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