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yay for hardness testers


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just got done playing with my first test batch of test steel. used 1/2 x 3/16 x 2 unforged straight from admiral L6. used peanut oil and canola oil mesured out into seperate containers, heated the oil to 100 degrees (normally i wouldnt heat but the peanut oil was almost sluge in the cold of my shop so i heated them both to compare better) both pieces of steel were heated at the same time then quenched in the same manner at the same time. i tested them both and got 62-63.5c from the peanut oil and 64-65c from the canola with an after taste of trany fluid (i've got to clean out my bucket better next time) im finally taking the time to verify what i have been using for years, now that i have a reliable way to test. oh and i have a variance of roughly +.5-1. degree of hardness on my tester right now but even if it tests out high thats still harder than most places say L6 can get so im happy with it.

 

any one know what admiral claims it reaches as quenched? i can't find it on their site.

Brandon Sawisch bladesmith

 

eagles may soar but weasels don't get sucked in to jet engines

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i got an ames portable on ebay some one listed it with a buy it now for $49.99 and since with dimond point there going for $185 ($120 if its just the b scale tip)or so i just had to get it (can you tell i have been watching them for a wile) it came broken but i was able to fix it up and its prity dead on consistant considering some one used it as a c clamp after the spring in the dial craped out on them but it was an easy fix now im just trying to dial it in to exactly what the test blocks say insted of one point high

Brandon Sawisch bladesmith

 

eagles may soar but weasels don't get sucked in to jet engines

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i also have had one i got at the wolverine show in michigan but it didnt have the dimond and now that i have one the tester it came with is more consistant and with the all steel finish is a little easyer to read as well but i payed so much for the newer one i hate to get rid of it could always use it as a c clamp :lol:

Brandon Sawisch bladesmith

 

eagles may soar but weasels don't get sucked in to jet engines

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Rc machines are fussy about surface preparation. You need to grind a flat spot to get below the decarb layer. Make sure the top and bottom surfaces are parallel. ASTM has an entire specification dedicated to hardness testing and I have an entire BOOK dedicated to hardness testing. It is more complex than it looks.

Which is worse; ingnorance or apathy? Who knows? Who cares?

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yep i decarbed them and the bars where flat when i started

 

so what grit would you like me to finish my test pices to before your happy with my results :huh: i can go to a merror finish if you think that would help

Edited by dragoncutlery

Brandon Sawisch bladesmith

 

eagles may soar but weasels don't get sucked in to jet engines

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What kind of finish do you think you could achieve if you just pushed it up your..............nose? Do what ever you think feels good, do it under a full moon, do it naked......I was just trying to help you avoid some pitfalls that could lead you down the garden path. If you don't want any help, then carry on alone.

Which is worse; ingnorance or apathy? Who knows? Who cares?

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  • 3 months later...

The idea is to remove the decarb, as it can effect the results. Typically a couple of good swipes with 240 grit paper to remove about 0.003" is more than adequate - unless you really decarbed the surface. A mirror finish isn't necessary - although you will get better results that way. THe problem is the preload. If a light preload is used, then the results are more variable because of the soft surface. If a higher preload is used, then the results are better, because the loading dominates the thin decarb layer. Large forging shops - one that forge things the size of desks - usually use a Brinnell tester because the impression is large, and the loading is high to compensate for the decarburization layer.

 

You are doing the right thing by working to get it to read the same as your test blocks. Realistically, the best you will be able to achieve is +/- 1.5 times the accuracy of the test block when reading the hardness of your parts. Improving the surface finish of your part before taking the hardness reading will only reduce the variability.

 

Also, as a general rule, it is a good idea to take 4 hardness readings, throwing away the first one. You then average the last three. THe reason for this is to take out any backlash in the system.....

 

 

Good Luck

D. Scott MacKenzie, PhD

Heat Treating (Aluminum and Steel)

Quenching (Water, Polymer, Oil, Salt and Mar-Tempering)

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thanks yep i decarbed both sides to 320 grit on the belt grinder like i would for re grinding a knife after heat treat then i took it to my tester and tested all the way up about 5-6 places and avraged it out thats how i came up with my figure above more or less now it just sits in its box wating for me to get a heating eliment to finish off my kiln so i can treat stainless

Brandon Sawisch bladesmith

 

eagles may soar but weasels don't get sucked in to jet engines

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