Home brew Hardness tester results

[Drew P]

So, I have some mystery leads that I smelted up a few weeks ago. Some was selenium alloy, some was seemingly pure, and some had about 3% antimony. So I have a bath scale, and arbor press and a 3/4” steel ball bearing. Using these to exert 205 lbs force on the ball on the lead gave me an indentation of .229” on the pure lead. When I run the numbers into this calculator

https://www.ajdesigner.com/phphardne...r.php#ajscroll

I get a hardness of 3.41 BHN. Now if it were pure I’d expect around 5BHN. So, that’s pretty far off. I know I’ve used this method before with decent results but what am I doin wrong?

[Drew P]

I played with the numbers until I got a result of 5 BHN and that would’ve required 300lbs on the scale so I don’t think the scale is that far off.

[Grmps]

I think you might need a smaller ball
Look up pencil hardness tester and use that to get close on actual hardness then develop proper ball size to pressure.
Just my guess

[longbow]

Yes, smaller ball... and higher load.

Brinell testers use a 10mm ball (.39") and from 500 to 3000kg load which you are not going to measure on a bathroom scale.

No good reason you can't use a smaller ball and less load but you will have to develop your own hardness scale using known samples.

I'm toying with that idea myself as I have been too cheap to buy a hardness tester so far.

Longbow

[warpspeed]

What are you using to measure the indent? If the indent measure 0.200" you'd be right at 4.5. Tape measure or comparator ?

[Drew P]

I’m using dial calipers. I feel I can get within .006 or so that way.

Smaller ball possible but wouldn’t 500-1500 kg push a smaller ball straight through the ingot?!

[John Boy]

ImpossibleI’m using dial calipers. I feel I can get within .006 or so that way.
[/QUOTE]

Wrong but wouldn’t 500-1500 kg push a smaller ball straight through the ingot?!

https://www.walmart.com/ip/New-10X-O...&wl13=&veh=sem
*60 lbs pressure for 30 seconds
* 5/32" ball
Lee Chart
http://www.frfrogspad.com/miscellm.htm

[longbow]

And then as John Boy points out there is the Lee system which shouldn't be too hard to reproduce on your own if inclined.

I should just break down and buy a Lee Hardness Tester.

[Drew P]

ImpossibleI’m using dial calipers. I feel I can get within .006 or so that way.

You don’t know how good I am with a pair of calipers! I’m definitely within .010

https://www.walmart.com/ip/New-10X-O...&wl13=&veh=sem
*60 lbs pressure for 30 seconds
* 5/32" ball
Lee Chart
http://www.frfrogspad.com/miscellm.htm[/QUOTE]

[John Boy]

I’m definitely within .010

If you say so ... so buy the magnifier and a 5/32" ball and use an accurate digital bathroom scale ... and you'll be in business using the Lee chart with imprint diameters
Believe this thread is completed - Good Luck

[OS OK]

You don’t know how good I am with a pair of calipers! I’m definitely within .010

https://www.walmart.com/ip/New-10X-O...&wl13=&veh=sem
*60 lbs pressure for 30 seconds
* 5/32" ball
Lee Chart
http://www.frfrogspad.com/miscellm.htm

I don't think you realize how important it is to read the indent accurately down to the .001" . . . .

For instance, take Clip On Wheel Weights, a pretty common Pb blend we use...now you try to identify COWW's and your accuracy is +/- .010"...here is what your spread will be, depending upon which way your inaccuracy with the calipers measures...

Target BHN is 12.5 & .064"...
*however your calipers read + .010" giving this result_ .074" & 9.2 BHN
. . . or . . .
*your calipers read to the minus side_ .054" & 17.9 BHN.

Thats a spread of 8.7 BHN..."I can hear that BHN difference dropping Pb ingots on cement."

This is only the inaccuracy in your measuring abillity...what about the inaccuracy of the bathroom scale? That would add or take away from this reading too.
I think you would be much more accurate using a quality set of art pencils.

[Yodogsandman]

I think a smaller ball bearing would help, I use a 3/8". The 200 lbs of pressure is good. I would make multiple indents, measure them and then average out all the measurements. A micrometer, light and a magnifying glass helps. Statistically, the more measurements that you average in, the more accurate and consistent your results will be.

[Andy]

Agree with johnboy, that's exactly what I did for my homemade one and the results lined right up with what I expected for 3 different alloys, and I didn't even have a good magnifying glass to measure with.

You can get the right size ball bearings on amazon cheap and just lightly JB weld them onto a bolt head, then chuck the bolt in the drill press and you're good to go. Need to hold for 30 seconds at the right pressure, due to lead spring-back, or so I have read.

Even with this working I still wish for and might buy a proper tester like the cabine tree just for the convenience of having a dedicated tool, and one that is probably more precise/repeatable.

[P Flados]

Check out http://castboolits.gunloads.com/show...rdness-testing

[Drew P]

Yeah I guess that smaller ball makes the difference. I thought I was using the larger one during those tests.