Made a hardness tester

[brucew]

I haven't cast any boolits for over 30 years now and in the meantime wheel weight composition hasn't quite stayed the same. After doing some casting and getting some leading problems I decided I would like to be able to check the hardness.

Lee's guidlines in his book seemed like it would be not too hard to do so I built a lever system for a couple of bucks and it seems to work great. I used the 5/32 ball bearing with 60 lbs of pressure idea. I'm sure someone here has already done this but here's my version.

http://www.minifarm.com/images/bench.jpg
http://www.minifarm.com/images/BB.jpg
http://www.minifarm.com/images/closeup.jpg
http://www.minifarm.com/images/micro.jpg

Ball bearing is mounted offset in the end of the bolt to allow for fore/aft adjustment.

5/32" loose bearings can be found at any bicycle shop.

I'm using a 28" lever & the bearing is mounted 4" from the pivot so my total weight ( lever weight portion & jug o water) is around 8.5 lbs. giving the 60 lbs force on the BB.

Still doing a bit of tweaking and also using a 1/4" thick sample of lead to keep the height consistent but it seems right in the ballpark. Very pleased!

Bruce

[Gelandangan]

Definitely a nice setup.

I go for the easier Staedtler hardness rating tho'.. too lazy.

[bumpo628]

Nice, I like it!
You could out a spacer under the pivot to raise it up, maybe 1" or so. That way you could fit taller objects (boolits) under the bolt without having to move the bolt.You may need to put different height spacers under the boolit to keep the test height consistent. I would also screw a metal plate under the test area to prevent the object from sinking into the wood.

Right now, the difference in height from the pivot to the ball is 1/4". Just try to keep that height difference roughly the same on every test. So if you raise it up an inch in the back, and add a test plate, then you just need a couple 'shim' plates to put under the boolit to keep the 1/4" height difference the same every test.

[lwknight]

I like everything about it. The weight is not too heavy to deal with and there are no springs to hassle with either.
The weight of the water jug can easily be adjusted precisely lighter or heavier by removing water or adding a little solid lead in the jug.

Why didn't I think of that ?
I'm going to do almost the same thing except the pivot will have different levels for easy
thickness compensation.

[brucew]

Guess I'll just have to stick to .25 caliber! :) Thanks for the suggestions, it did seem to be height sensitive which is why I decided to do my tweaking with the fixed size before proceeding with the final setup.

[lwknight]

How did you get the ball stuck on to the bolt?
I was imagining a shallow hold drilled into the bolt then super glued.

[tackstrp]

agreed. tried to do something similar, but using a one ton Northern Industrial Arbor Shop Press. Gave up ordered the cabine reloading products hardness tester. Spendy but can always resell once i get my lead sorted. Maybe can use as a gauge for building a similar set up.

[brucew]

How did you get the ball stuck on to the bolt?
I was imagining a shallow hold drilled into the bolt then super glued.

'xactly!
I may try to braze one on later but I'm afraid brass will travel over the BB surface too much.

[fecmech]

Is the measurement of the indent used against a standard table?? If it is could you post it? I was thinking of just doing that on a bathroom scale.

[brucew]

The table to determine the proper BHN from the indentation diameter is in the Lee Modern Reloading book. I'm not sure if it would be appropriate to show that table here?

[RP]

I got a lead hardness tester and some guidelines you may want to keep in mind. A ingot will not test the same as a boolit due to different cooling rates. Test in middle not near edge on the edge the lead will read softer then it is. And what is being tested needs to be flat on the bottom you can do that with a file to get a better reading. They say uneven surface will compress under the test giving a softer reading then it should. And they did not say anything about temp but I think that will effect it also, But thats just my thinking no proof to back that up.

[zomby woof]

I made something simaler with what I had on hand. I like yours better. I use a .312" ball bearing. I let it sit for 30 seconds. My WW are around .157", pure lead is around .240", Lino is .130".



http://www.hunt101.com/data/500/medium/100_2996.JPG
http://www.hunt101.com/data/500/medium/100_29981.JPG

[RobS]

I ran the route of making my own as well. I welded a disk blade from a farm implement to a 1/2" bolt that has a 5/32" ball baring welded to the other end. Made a die to fit in my Lee press that accept the 1/2" bolt diameter. Simply lift the boolit or ingot with the ram of the press to the tester ball baring and then apply enough force to lift the above 60 lbs up off of the die, wait 60 seconds, lower the press ram, take boolit out and then measure the indention. Attached at the bottom is a PDF chart I use.

http://i612.photobucket.com/albums/tt206/RobS01/3.jpg

http://i612.photobucket.com/albums/tt206/RobS01/1.jpg

http://i612.photobucket.com/albums/tt206/RobS01/2.jpg

http://i612.photobucket.com/albums/tt206/RobS01/6-1.jpg

http://i612.photobucket.com/albums/tt206/RobS01/4-1.jpg

http://i612.photobucket.com/albums/tt206/RobS01/5.jpg

[bumpo628]

I ran the route of making my own as well. I welded a disk blade from a farm implement to a 1/2" bolt that has a 5/32" ball baring welded to the other end. Made a die to fit in my Lee press and accept the 1/2" bolt diameter. Simply lift the boolit or ingot with the ram of the press to the tester ball baring and then apply enough force to lift the above 60 lbs up off of the die, wait 60 seconds, lower the press ram, take boolit out and then measure the indention. Attached at the bottom is a PDF chart I use.

That is a nice design too. I like the use of the press.
Thanks for the chart, btw.

[brucew]

Great chart! Yours goes further down to dead soft lead which the Lee one does not, that makes it much easier to calibrate results with the soft stuff.

Thanks Rob!

[RobS]

'xactly!
I may try to braze one on later but I'm afraid brass will travel over the BB surface too much.

I found a nut that was just big enough to allow the ball bearing to sit about 1/2 way in or so and then welded the back side, ground it flat and then welded the nut/ball bearing to the bolt. Just an idea for getting some more metal to work with.

[brucew]

Great idea Rob! I don't expect mine will stay on there with super glue for very long then I'll have to do something like that.

[fecmech]

Thanks for the chart Rob!

[RobS]

Not a problem on the chart guys, anything to help get us to where we are going. :cbpour: I even color coded it for everyone's viewing satisfaction. [smilie=w:

[brucew]

Ok after working with my lever tester for a while and doing some tweaking the thing seems to be right on from dead soft lead to superhard. I'm really pleased!

[RobS]

It's cool when you make your own stuff!!!

[rtracy2001]

I like it. I'll have to build one myself now.

A couple of observations/tips/hints/whatever you want to call them.

The lever used in the OP setup should be completely level when testing in order for the lever law math to work out most acurately. A couple of degree tilt as shown in the OP is not going to affect results much, but if you get a really thick sample and the lever ends up at 20* or something, it will make a difference.

Using the eye lupe and micrometer to measure indentation diameter may introduce error and decrease the repeatability. Another method that seems doable would be to use a second 5/32 ball bearing then measure the sample thickness and the thickness with the second ball bearing in the indent. Once the sample thickness is subtracted from the second measurement, the indent diameter can be calculated using geomety thus eliminating the "uncalibrated eye" from the measurement. Downside of this method is the math can be hariy to come up with the first time (it is too late for me to derive it). On the upside you only have to derive it once, then it is a simple excell plug and chug method.

Don't test boolits, test alloys and methods. Testing a varitey of different sized boolits introduces new variables as it complicates the design of the tester. Use identical sample sizes for every test, maybe even make a test sample mold (or dedicate a single mold to testing hardness). Test several samples of the same alloy, throw out the softest and the hardest test then use the average as the approximate hardness.

[brucew]

It's cool when you make your own stuff!!!

Especially when it works! :)

[brucew]

Thanks for the input rtracy. Right now I'm doing all my tests with the sample shimmed to make sure it's always at the same height. When I make up a batch of lead I pour a 1/4" thick wafer 1" in diameter for testing so that it's uniform each time. (hardwood mold)

No problem for me reading the diameter with my ancient micrometer even with my not quite as ancient eye balls. Micrometer mandrels are right on the dent with no parallax error and I can easily creep up on the reading.

Yep, those formulas are hairy!

Bruce

[RobS]

You could have a little play there with your bolt height as well. Looking at your pic Bruce, screwing the bolt down or up to make things level for the ball baring to make consistent impressions seems easy enough.

[bumpo628]

You could have a little play there with your bolt height as well. Looking at your pic Bruce, screwing the bolt down or up to make things level for the ball baring to make consistent impressions seems easy enough.

Especially if you use wingnuts instead.

[rtracy2001]

Yep, those formulas are hairy!

Actually once I sat down and looked at the problem (and overcame a brain cramp) it turned out to be pretty simple.

Variables:

S = sample thikness
D= Ball diameter (5/32)
M= Measured total thickness of imprinted sample with 5/32 ball in imprint.

Formula:

X= imprint diameter = 2 * SQRT[ (5/64)^2 - (M-S-5/64)^2]

That would go into excell nicely.

Or to simplify even more:

X= imprint diameter = 2 * SQRT[ .0061 - (M-S-5/64)^2]




Ray

[lwknight]

Ray , I might be reading it wrong but , I think that Bruce was saying to find the indent diameter ( or chord in this case ) by ascertaining the indent depth from the ball height subtracted from the ball diameter.

I agree that it could be extremely precise if the test sample had a machined surface and a depth micrometer were used. I could do it if I were on the job being paid to set it up.
Otherwise its like he said " hairy " to work with.

[white eagle]

just a question
why the 5/32 ball bearing
I have some that are rather large 19/32,.(593)
would I be able to use them to make one..........?

[lwknight]

You can use any size ball. You will have to test it with pure lead to get the right weight then make a chart for your specific setup.

All you really have to do is add weight till the ball goes in exactly 1/2 way into dead soft lead.

[bumpo628]

just a question
why the 5/32 ball bearing
I have some that are rather large 19/32,.(593)
would I be able to use them to make one..........?

The chart in post #13 of this thread is already calibrated for a 5/32" ball bearing and a 60 lb load. No need to repeat all of that work for the price of buying the right size bearing.

[white eagle]

I want to use what I have on hand
I have read this thread as well

[atr]

Very nicely done guys !!!!
my hat is off to you all
atr

[rtracy2001]

This is the setup I was thinking of.

http://i156.photobucket.com/albums/t23/tracraym/hardness.jpg

Personally I would use the same ball bearing that I used for the indenter to eliminate variations in ball bearing size.

C is always the radius of the ball, B is found by subtracting the sample thickness and one ball radius from the measurement M. After that it is just the Pythagorean theorem.

I just have to find some other way than eyeballing a micrometer over a crater. my eyes won't see that!

[montana_charlie]

Ok after working with my lever tester for a while and doing some tweaking the thing seems to be right on from dead soft lead to superhard. I'm really pleased!
That is because (like the Lee tool) it uses exactly the same criteria as a lab grade tester.
It improves over the Lee by using a weight instead of a spring.
A spring can only be checked for accuracy while a weight can be adjusted.

Your arrangement may be a little 'unhandy', but it should be dead-on dependable.

CM

[lwknight]

I imagined dim. X as a chord rather than the second square. The Pythagorean theorem is simple top use compared to trig. Excel is a royal pita to me because it only works in radians and we think in degrees. I always have to use a hidden translator cell reference for angular inputs or outputs both.

[morme@gte.net]

Homemade Lead Hardness Tester (sorry about the big photos. I was too lazy to resize and re-upload
after I saw how big they came across.

I bought a Lee Hardness Tester, and it was just too hard for my old eyes and shaky hands to use.
So, I used what I had around and made one myself.

http://1.bp.blogspot.com/-t401WFcIgi8/TW-2fMnnsWI/AAAAAAAAAqo/SZPpS6iH3A4/s1600/DSC00353.JPG
I have a 1/2 ton arbor press which is perfect as a starting point.
Unfortunately, the mechanical advantage ratio was a PIA to calculate because my postal scale only goes to 5 pounds,
and the force of the handle alone was more than that.
I ended up using cast iron pipe on the back side to counter balance the weight of the handle and used a
hanging pan on the end.
I just added bullets until I got to the scale limit, and then weighed the bullets, and did the math. (all science is math)

It seems that the force mechanical ratio is about 18:1.

I ordered 5/32 and 9/32 chromium steel balls from Small Parts on Amazon (about $2-3 per pack of 25) .

The weight I use is cast from lead contaminated with zinc. It weighs more than my scale can measure,
but back calculating produces a result of 139 lbs of force at the press (including the weight of the handle)

http://2.bp.blogspot.com/-QHbMZNYIDJU/TW-2eg9WOMI/AAAAAAAAAqg/t2_x3PxCeUc/s1600/DSC00352.JPG

I use a bit of soft bullet lube to "glue" the ball to the test piece,
then wipe it off and measure the indentation diameter with calipers.

http://3.bp.blogspot.com/-XP1zQUcG2d0/TW-2fucD9JI/AAAAAAAAAq4/YcAjCfsrpvQ/s1600/DSC00355.JPG

I plugged the formula into my G2 cell phone, which has the QuickOffice spreadsheet included,
and just plug in the indentation diameter and it gives me the hardness.
I double checked with the Lee hardness tester, which I will sell.
Since 5/32 is the size of the ball in the lee tester,
I could use the spreadsheet to replace the chart Lee provides (which does not go below BH 7,
so it can't measure pure lead)

http://3.bp.blogspot.com/-w6aBMQDzdfI/TW_BnL41iWI/AAAAAAAAAro/J5QvoUPLguM/s1600/DSC00357.JPG

I made the spreadsheet on my PC, then copied it to the MicroSHDC card on the G2.

http://2.bp.blogspot.com/-693p8vcnBUU/TW--fVyTddI/AAAAAAAAArc/ASMsaQhr2PY/s1600/hardness%2Bspreadsheet.jpg

Here is the actual spreadsheet formula entry
=B3/(PI()*C3*0.5*(C3-SQRT(C3*C3-A3*A3)))



BHN = P / {pi * D * 0.5 * [D - sqrt(D*D - d*d)]}

where:
P = the imposed load in kilograms (63.0 kilograms in our example,
and it should be approximately one to five times D*D) (13 to 65 kg)
pi = 3.14159
D = the diameter of the ball in millimeters ( 0.143" or 3.63 mm in our example)
d = the diameter of the indentation in millimeters (0.177" or 2.9718 mm in my example)

http://3.bp.blogspot.com/-J1BApbZjrXg/TW-2ffOE81I/AAAAAAAAAqw/FbBOh2QcKXk/s1600/DSC00354.JPG

[Jal5]

Thanks for the spreadsheet calculator that is really helpful!