Well, the board is either fixed, or it's going to run terribly. Cross your fingers and hope for the best. I'm at my technical limit right now.

IN PASSING & FWTW

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OLDGUNNER
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IN PASSING & FWTW

#1 Post by OLDGUNNER » Fri May 11, 2018 5:24 pm

METAL HARDNESS TESTING - -
Scan.BMP.jpg

Some times one may wish to know the hardness of a piece of metal, be it BHN (Brinell Hardness Number) or HRC (Rrockwell C), or any specific scale, and they don’t have access to a testing device. One can be made easily for as low as just some scrap and in the case of HRC, a 10 dollar Chinese Diamond Indenter. I see them advertised for in the 10 to 40 dollar range. The design that I have pictured can give one a ‘relative’ reading, i.e., above or below a given ‘standard’. The standard being a sample of known hardness...the more standards one has the closer they may get to the hardness of their unknown.

There are no given dimensions to this – they can be any size – out of wood or steel. And the economical Chinese Diamond Indenters are not of the ‘Certified’ type. But usually for one’s personal use this should suffice. The idea being hang a weight on the top beam and measure the size of the diameter of the indentation in the unknown as compared to the size of the indentation in a piece of metal of ‘known hardness’. Use a magnifier to view the indentation.

The proper HRC testing device measures the depth of the indentation but for simple purposes the diameter will give the same working measurement. Measuring the depth would be more involved for me. A timing device such as a second hand on a clock is required.

The other half of this tester involves having the samples of known hardness. These can be bought but are relative expensive – can be in the neighborhood of 50 or 60 dollars each. So I would suggest make one’s own ‘Standards’. I will give one way of making these standards in an added posting.

I have made three of the Direct read-out BHN testers and they have all worked fine for me.
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Re: IN PASSING & FWTW

#2 Post by OLDGUNNER » Fri May 11, 2018 5:35 pm

https://www.ebay.com/itm/HRC-3-Metal-St ... SwKQpayXCW

Here is just one Diamond HRC Indenter---ones made in the US can be 200 $.
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Re: IN PASSING & FWTW

#3 Post by ffuries » Fri May 11, 2018 8:26 pm

Amazing how simple the design is, and it's nothing more than basic mechanics. I think we learned stuff like this in 5th or 6th grade science when I was a kid.

Never thought of it being that damn simple, thanks I learned something today!
Mike
TSgt, USAF Retired
Jan 86 - Sept 08
Aircrew Life Support
"Your Life Is Our Business"
(122X0, 1T1X1, 1P0X1)
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OLDGUNNER
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Re: IN PASSING & FWTW

#4 Post by OLDGUNNER » Fri May 11, 2018 11:29 pm

DSC_0043.JPG
Brinell Hardness Number Tester -

Here is one that I made years ago. I made it to read-out directly the hardness of lead alloy. The blocks that I have made are to adjust the sample to be tested to the same height as the pivot point of the top beam.

I have made a much simpler one but I can’t find it right now. Although this one I think is pretty simple to use. On the scale the lowest number is ‘5’, the hardness of pure lead and above that is the reading of the sample in increments of BHN harder than that.
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Re: IN PASSING & FWTW

#5 Post by OLDGUNNER » Fri May 11, 2018 11:59 pm

DSC_0044.JPG
A retake without all of the back-ground clutter.
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Re: IN PASSING & FWTW

#6 Post by OLDGUNNER » Sat May 12, 2018 11:30 am

https://www.bing.com/search?q=brinell+s ... =QBRE&sp=1

A common hardness scale for ferrous materials is the HRC scale (Rockwell C scale). And I can see where these testers can run from say 500 $ for the Chinese versions upwards toward 100,000 $ for the more sophisticated and precision better ones. These are for the commercial use or for the ones that just want to have a way of testing their own products such as knife makers. I could make one like this but it would involve a lot of trial and error...more than I would care to bother with at this time. Besides, the design that I have pictured will do exactly this for as I say the cost of the Diamond Indenter. The commercial ones use the same principles that I used but just in a more presentable package. Most would not want to pay too much for something built on a piece of 2 X 4. https://www.alibaba.com/product-detail/ ... 89443.html
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