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  1. #1
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    Default Information on making a lead hardness tester.

    I am a black powder muzzle loader shooter.
    As such, I am constantly seeking pure lead to cast round balls.
    It can be hard to tell at times with alloys about the place, the marking of pure lead with a thumbnail,not withstanding.
    Therefore I seek a hardness tester.

    Too hard to import a manufactured one at the moment, so I am hoping to make one.
    If you have heard of a homemade one and can direct me to an internet article, I would be obliged.

    I already have one from the Cast Boolits Forum using the drill press and bathroom scales but this type is not suitable when you are at the scrap dealers.

    Thanks

    Grahame

  2. #2
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    Well here is the instructions for a commercial unit.
    https://leeprecision.com/files/instruct/LT2140.pdf

    From the instructions it gives you a reasonable reference for tip size and angle from there it should be a matter of determining a spring pressure needed for the indenter and having a reference source of pure lead to get the impression size.

    Of course it won’t give you the BHN value unless you have a reference source to compare against but it will compare against a known product.

  3. #3
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    Default

    Thank you droog,

  4. #4
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    Default

    Shout out if you need something referenced, I have access to vickers, rockwell and brinell testing gear.

  5. #5
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    Default

    Quote Originally Posted by NedsHead View Post
    Shout out if you need something referenced,
    Thanks Mate.

  6. #6
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    Grahame,

    I made one some years back for the same reasons as you......I brew my own casting mix and needed to get an alloy mix hard enough for the purpose.

    There are quite a few versions online but I found the simplest using a bore-scope camera attachment or similar microscopic attachment that you can take a still photo from and these come with a grid pattern that is indexed - you need to be able to see that.

    Those endoscope/bore scopes cost about $10 and you can get them from various highly reputable Chinese suppliers You don't need the mega expensive ones for this..cheap and nasty will do as all you need is a photo of a dent.....they usually plug into your smart phone, tablet, laptop etc and run through third party software such as AMCAP....they allow you to screen capture an image. You can spend more dollars and get one that does it all but essentially that borescope and one of those $20 microscope kits they use for looking at circuit boards are all you need

    How they work being you get a ball bearing of a certain size, mount that to a shaft (I brazed mine on) and them use your loading press in reverse to lower a set weight onto that ball which is placed on top of the pill you have cast - use a flat nose as easier to see....I use about 5kgs....It's important you know the exact weight plus the diameter of the ball bearing as it's maths after that....

    You allow a certain time for the 'dent' to be made...important to maintain the same time for all your samples...say 30 seconds....after that time you lift the weight off then use the borescope/microscope to measure the radius of the indentation by using the screen capture mode and the grid template that comes with the bore scope...that tells you the diameter of the dent.

    Use that measurement to check it off against a scale of predetermined hole diameters or you can use the chart online and just put your measurements in...I wrote my own spreadsheet and keep all my measurements to get various ratios of Sn, Pb and Sb. That gives you the approx BHN of your sample tested

    To test how accurate that method is, I sent some samples away and they returned a range of 3% so that's close enough for me.....

    If you need more info then pls drop me a PM and I will try and sort you out......Lee

  7. #7
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    Hi Lee,
    Thank you. The above sounds like the very thing I seek.

    The set -up can be made to be portable,which is what I need when I am chasing scrap lead.

    Now is the time to loacte and store my future pure lead supplies before the tree huggers ban that

    I already have the camera bit- it will go down a Muzzleloader barrel funnily enough.

    It will need a different cable as my current phone is USB-C but that easily sorted.

    I do hope to use and old drill press frame as was once used with electric corded drills and hang some weight on one the handles.

    A friend has a Lee hardness tester so I should be able to calibrate off it.

    Thanks for your help.I will get back to you once I get this rig going.

    Ta muchly
    Grahame

  8. #8
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by Grahame Collins View Post
    .
    .
    I do hope to use and old drill press frame as was once used with electric corded drills and hang some weight on one the handles.
    .
    .
    I've not tried this method but a student at uni did a Materials Science project on the method and it seemed to work.

    The students also used a press with weights hanging on it but he also attached a digital calliper to the press handle and measure the change in vertical distance (x) with and without load.

    Then he calibrated depth of indent against materials of known hardness and was able to measure the hardness of unknowns

    I remember he did lot of checks, like calculating the diameter of the depression and comparing it with that measured using an optical microscope and they results were within uncertainty.

    Mr Pythagoras says the diameter of the depression will be 2y = SQRT(R^2 - (R-x)^2)
    Screen Shot 2021-02-26 at 5.26.47 pm.png

    A limiting factor for smaller indents was the effect of the backlash of the press on the "zero position". He got around this by using a variety of weights and measuring the depression for each weight and then using a bit of maths.

    I wish I had kept copy of his report - I doubt there is one at uni as this was about 28 years ago.

  9. #9
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    Grahame,

    Found a few old piccies of the various setups I made for my hardness tester. I assume you have a lathe and can turn so here's how I went about it (leaving the photo measuring bits out as that's pretty basic and you seem to be on top of that)

    I fabricated a sleeve from a grade 8 bolt that was the same thread as the Press I used ....(Lyman Orange crusher) - saved ruining a die and cutting more threads. Those Grade 8 bolts are a game changer as I have made heaps of dies using them such as powder compression, seating and other ones that served a need rather than order and buy.

    You bore that out and then make a plunger that ties into your shell holder based on the diameter of what you have bored - these are two separate parts but they work in tandem and here's where the piccies may help the description. One end of the plunger sits into a shell holder

    That makes a push rod on top of which you place your flat nose projectile.....you are not going to stuff this pill into any bore it merely has a flat nose and is sacrificial only to test your BHN - it's better than cutting the top off a cast pill. But then if you don't have any FN moulds suppose there are no other options.

    Next you make an insert to fit inside the bore you just cut in the bolt that bore. That insert will carry the ball bearing of whatever size ball bearing you use. I got a few various sized ones from china - I think they come in packs of 10 but cheap as anything. The ball must stick out at least half way from the recess you make and I brazed mine in with some silver solder. It's just to keep it from falling out...suppose super glue may work but not tried that.

    The holder you make to fit the ball is best tapered to a moderately sharp end so the ball protrudes much like a ball point pen. Make the OD of that ball holder the same size as the bore you cut in the die.

    Next make a shaft to allow you to place a few kgs weight on top of that ball holding mechanism as it this will hold the weight intact as you raise the ram with your pill placed under the ball. Mine was long enough to protrude from the 'die' and had a flat plate welded to the top so I could place weights on it without them falling off.

    How it fits together is that when you raise your ram, the pill sitting on top comes into contact with the ball bearing and that lifts under the weight sitting on top of it.

    Don't raise it suddenly else it may give an incorrect reading but gently raise your ram that way the pill is pushed against the ball and it will lift the weights you have on top. Hold it there for a predetermined time and there's your indent.

    There are some other basics such as making it so your ball holder doesn't fall out, the pill doesn't deflect under the weight etc but these are pretty basic and sure you can work that out as you go along

    Apologies I cannot find any better piccies but in all honesty once I tested all my loads years ago, I have not needed to test them since as I recorded all the BHN's and wrote that into a chart that I use now. I know exactly what the BHN will be from the brews I make as I've done them already and recorded the results.

    There is a chart on Cast Boolits Forum (apologies I cannot recall where) which some chap wrote in in 2012 and that is quite accurate. I have used that in the past and retain a copy but not where it was linked from....do a search on their forum and you will see it in excel format.

    This comes in handy because I cast for numerous rifles and each one prefers a different flavour of ingredients..unfortunately one size does not fit all as you probably found.

    My own reference source these days is the charts I made from my testing and I no longer need to BHN test.

    Sorry I can't be more specific but I will try and find the items I made but no doubt they are planted away in a safe spot....
    Attached Images Attached Images

  10. #10
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    Just an addendum to my previous post....

    Where I mentioned I do not BHN test anymore being I now buy my ingredients and do not use recycled wheel weights, or drain pipes for my sources of plumbum .you just never know what the composition is irrespective of BHN and I've come unstuck when it mattered.

    I suppose front stuffers have a bit more flexibility in what their compositions are so maybe not as critical, but these days time is something I don't like wasting cleaning lead fouling out of bores......

  11. #11
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    Dug my unit out and here are some exploded photos of it so you can see how it's constructed Grahame and anyone else who may care to have a go....

    Hopefully the pictures (in no particular order) explain it better than me and I won't go through it again....I've not shown the bullet holder as mentioned in my earlier post just used a flat washer for illustration purposes nor have I shown how the weight is attached to the top - you can easily fabricate those up to suit your own press.

    Also included the cheap and nasty microscope camera I bought (think $10?) as far better than the original bore scope I used...just make sure it has the grid pattern templates included so you can work out the sizes...this one runs through a usb and has generic software so you can take still photos which is all I needed it for....if you have any questions, please ask ........Lee
    Attached Images Attached Images

  12. #12
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    Great thread, forumites!
    One day I may have to brew up my own plain bearing babbitt metal, and hardness would be a handy factor to compare.
    cheers,
    AO'C
    'Waratah' spring hammer by Hands & Scott c.1911- 20, 'Duffy, Todd & Williams' spring hammer c.1920, Premo lathe- 1953, Premo filing machine.

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