Homemade hardness tester

[ghh3rd]

I've been thinking of a way to build my own harness guage - something that would put enough pressure onto a BB size bearing placed against something as small as a bullet to put a dimple on it.

Although I wouldn't know the actual harness, I could still get a relative idea of hardness from one sample to the next. In fact if I had a handful of some control samples of known hardness, I could test on those and use those results to get a good ballpark estimate based on dimple width.

Has anyone developed such a 'home brewed' test?

Thanks,

Randy

[qajaq59]

fecmech put this in one of the forums a while back.....

There is a fairly easy way to measure lead hardness if you can get some pure lead to start with. Take your sample of pure lead, a small ball bearing and the unknown lead sample. Place the ball bearing between the 2 samples and squeeze this sandwich in a vise.
Remove the sandwich and measure the diameter of the 2 dents with a caliper and write down the readings. Square each reading (multiply times themselves). Divide the square of the unknown sample into the square of the pure lead sample and you will get a number larger than 1. (If you don't you went the wrong way). When you get a number larger than 1 multiply it times 5 and that will give you the Brinnell hardness of your sample.
The reason you use the number 5 is because that is the Brinnell hardness of lead. The key is the pure sample and your ability to measure the dents but it is not difficult to do and is accurate.

[WickedGoodOutdoors]

What you need is items that can be procured at your Basement, wifes kitchen stuff or at last resort local hardware store in order to be truly considered "Home Made"

No Cheating by mail order!


So.

Go out in the garage and get your air gauge from your pickup truck and and empty spray can from something that was not gooy. Shaving cream or better yet an empty propane cylinder. now drill a hole in the propane tank (Better hope its empty) and thread in your air gauge. Solder it in place. Your gonna need a propane tourch or big ass soldering gun to do this. Use 50/50/ 50 of Silver/tin/Lead with some flux from a pine tree (the same Pine Tar you use on your basball bat) mixed in with Borax powder from your wifes laundry. Get a Shrader Vale out of an old bike tire and drill a hole and install it in your tank.
This will give you a Pressure reading


Now take that baking thermometer that you liberated from the kitchen. Ye the nice Stainless Steel one and drill a hole in the propane tank and stick it in. Now solder it using the same magic mix. This will give you a tempature base line.

Now take a 6 penny nail and solder it onto the center most flexable part of your pressue can. Hopefull the can will flex just a tad when you push it against anything hard. Try it on your wifes cornbread and see if you get a reading.

You may have to pump up the tank to an yet unknow pressure to calibrate the pressue gague.


Now using Boyles Law that states the P=V*T Pressure is equal to volume times tempeture you can determine to variations in pressure and corolate this into the variations of hardnes of a material.


See Simple eh!

http://www.newamerica.net/blog/files/Rube%20Goldberg.jpg

[mrbill2]

Don't get too excited about a hardness tester. After you know what the Bhn is for a given alloy it's of little use. There is no proven way to take a alloy that tests Bhn 11 and turn it into a alloy that test Bhn 20 or any other hardness. Without a reliable way to adjust the ingredients, knowing the Bhn doesn't help much.
My $.02
Mr.Bill

[fourarmed]

qajaq59 has it right, but I have always found holding two pieces of alloy with a ball bearing between them in one hand while closing the vise with the other to stress both my patience and my vocabulary. I place one piece of alloy on a HORIZONTAL surface, then the bearing, then the other piece, and tap them with a hammer. While this also occasionally results in profanity, it has a better record than the vise method. This is said to work best if the diameter of the ball is at least 4 times the diameter of the impression.

Another technique that has been reported is to place a bathroom scale on the table of a drill press. Set the sample on the scale, the ball on the sample, and press down on the ball with a rod of some sort chucked in the drill press until the scale reads some standard weight. Then perform the calculation outlined above.

[ghh3rd]

Very interesting - thanks.


.

[Dean D.]

Thanks qajaq59! I don't have a boughten hardness tester and your proceedure and formula sounds like a great inexpensive alternative.