Homemade hardness tester from 1973

Chris

Chris

Well-Known Member
Many may recall that hardness testers were not commercially available in 1973 (and some of you guys weren't born yet), there no PC's with spreadsheets, and I don't think XRF guns were available.

Sorry the text is a cut off on the right, having scanner issues I can't quickly resolve. However you can readily interpret the last word in each line.

I built one of these years ago, still have it. Essentially it tests hardness (but does not read in BHN) by relative penetration. It allows you to blend alloys of varying hardness/toughness to arrive at an alloy of desired BHN. Today we have spreadsheets that can do this better, but they assume that we know the base alloy.

This thing still has value in determining relative hardness of various ingots/batches. And it's cheap.
 
Brad

Brad

Benevolent Overlord and site owner
Staff member
Sorry the image is so large. Couldn't make it work any other way. Cleaned the thread up a bit too.
 
Brad

Brad

Benevolent Overlord and site owner
Staff member
It's what we are here for. Anytime you have troubles like this let one of us know.

Interesting article. I think we sometimes get too hung up on a specific BHn when knowing how to get a consistant hardness is just as important. Hardness is relative.
 
Chris

Chris

Well-Known Member
Then there is the matter of hardness versus ductility, i.e. water dropped low Sb range scrap vs. aircooled COWW. But this tester tests the native alloy while in ingot form.
 
Brad

Brad

Benevolent Overlord and site owner
Staff member
Wouldn't be perfect but I bet you could use another hardness tester to calibrate one like that. Make a spreadsheet of penetration vs hardness.
That tester isn't a whole lot different than most of the others on the market. Use a known force and measure the penetration
 
F

freebullet

Guest
Still think I'll break out the crowbar pry open the wallet & buy a cabine tree eventually. Do like the do it yourself mentality & past articles though.
 
yodogsandman

yodogsandman

Well-Known Member
Mine's homemade by someone. I had read about it in the "Fouling Shot" and bought the ball bearing, spacer pipe and casting jig from someone on the CB site.The only draw back is having to cast a test piece 1/4" thick to do the tests on. It's a 7/16 ball bearing that gets pressed into the test specimen. I use a drill press and a bathroom scale. I apply 200 lbs of pressure to the ball bearing for 30 seconds. Then measure the indents outside diameter. Best to make many indents to measure and average them. Then plug the numbers into an online BHN calculator.

http://www.ajdesigner.com/phphardness/brinell_hardness_number.php
 
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Chris

Chris

Well-Known Member
yodogsandman said:
Mine's homemade by someone. It's a 7/16 ball bearing that gets pressed into the test specimen. I use a drill press and a bathroom scale. I apply 200 lbs of pressure to the ball bearing for 30 seconds. Then measure the indents outside diameter. Best to make many indents to measure and average them. Then plug the numbers into an online BHN calculator.
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Anybody with knowledge here correct me please, but I think in the engineering world BHN is measured by measuring the diameter of an indent using a ball and known pressure. Isn't this how the Lee device works? Problem seems to me to be how to accurately measure diameter under magnification.

I tested a bunch using the 1973 device and using a calculator way back when (it still leans in a corner) and it is easy to measure depth using the thingy on the caliper. It is fast to do, so you can take multiple samples. I'm thinking this idea still has value to some people. Just put the formulas into a spreadsheet.
 
D

Dusty Bannister

Well-Known Member
Similar idea with the pipe, but my indenter was made from a large long bolt with the end turned to about a 90 degree cone point. Drop the pin through the tube, onto a flat ingot, then draw file to about flush and measure the width of the indent. I had to make up my own chart of course, and have a few known samples to work with. A little loose on accuracy, but I had a lot of ingots that friends had helped me pack up to move and they did not realize that there was a method to the stacks and bins. Good enough for most of my needs at the time.
 
fiver

fiver

Well-Known Member
you can make your own with a reloading press and a larger ball bearing too.
you just need to hang a weight off the handle and have a couple of chunks of known alloys to start out with.
this gives you your own scale to work from but it is pretty good.
 
Ian

Ian

Notorious member
Or spend $50 on a Lee tester if you're lazy like me. Regardless of the unit, you will never get the same reading from an ingot that you will get from a bullet cast from that ingot unless you heat treat the bullets and control the cooldown as slowly as the ingot cooled.
 
Chris

Chris

Well-Known Member
oscarflytyer said:
I LOVE homemade stuff like this! Dean Grennel 101!
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I'm a Dean Grennel reader too! What a doer and writer! Got a bunch of his books. You guys that haven't read his old school stuff should take a look at Abebooks and Amazon, they are a bargain. Lots of knowledge and entertaining as well.
 
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