Advice On Hardness Tester

millejn3

Well-Known Member
Hello eveyone,

After about 10 years of sending my blades out to be heat treated, I took the plung and bought my own kilm about eight months ago. As of right now I only spot check the blades that I produce in house as I have been using a tester at the local community college when I can make it that way. When I say local, I use that term losely as I live in the middle of the sticks and it's about a 50 minutes drive one way... :15:
I have decided that with the price of gas today that it wont take me long to pay for a tester with the gas money that I will be saving from not having to travel every time I have turned off my oven.. :57:
So here is what I looking at. http://leebhardnesstesters.com/THX31-portable-hardness-tester
(I'm not dead set on this tester. There are several out there that are less money and will do what I need)
Can anyone give me any advice on these type of portalbe testers?
Is there something better suited for the knife maker out there?
Is there one out there that is more cost effective?
Help on this matter would be great!!

Thanks,
Jeff
 
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I looked into those once and found that most, if not all, of those hand held units cannot measure hardness in thin parts such as knife blades. I know that some people use the Ames hand held units but I think that most people who do hardness testing use a bench top unit.

Doug
 
Thanks!! I saw this unit posted earlier on another thread. I was hoping to keep things as compack as possible due to shop size. My shop is not tiny by any means but not large either and counter space can be an issue from time to time when I fail to keep things picked up. I have heard the same thing as to this type of unit is not suited for thin material. Thats why I was hoping to get some input on if a knife blade was to thin or not. I have thought about calling the manufacturer of a couple of the protable units but I'm afraid of talking to a sales man that works on commision... :15: Thats way I figured I would see if anyone here has or is using a portable unit..
 
The bench top Rockwell testers are the most accurate and durable. Some things to remember about the bench top models:

You want to keep them on a solid, level, surface in an environment that is clean and steady as far as temperature fluctuations and humidity.

If you apply the major load and then step heavily on the floor and can see the needle bounce, you should probably find a more stable bench for it.

If you can find a clean dry place that stays around 65F-70F year round it will work well. But if your shop is dirty and unheated it will cause problems. The rate at which the major load is applied is critical and the oil filled hydraulics is heavily affected by temperature swings. So if you have an unheated shop you will be adjusting the cylinder speed all the time and will have to recalibrate all the time, this will result in plenty of used up test blocks.

Dirt, grit or dust on the penetrator mechanism will be all she wrote. The same things on the elevator screw or anvil assembly will throw off your readings. Rust will do the same things. Even if kept clean each day that the unit is to be used it is good to do a couple of sacrificial tests to squeeze any oil residue out of the elevator mechanism.

I have worked quite a bit with ones like the one linked to above from Enco and they are pretty good units for the price if you calibrate them with good blocks.
 
We have just shot a video and it is in editing now. We hope to have it posted by the end of this week. It will show two styles of hardness testers (typical bench and hand held) and how they work. You might hold off a few days until we get that up and posted and you will have the benefit of seeing the two most common styles in action.
t
 
I have the ames style hand held , I got a good deal on it when I bought it or I would have bought the table top as there is not much price difference, I put mine in a vise "wrap the handle in leather of course"when I use it I have the test blocks its usually within 1 hrc of the test block.
Anthony
 
Thanks for the input everyone,, I'm in no hurry to spend the money and want to check any and all angles before I take the plunge. Looking forward to the video Boss Dog !! ANd thank Kevin!! Always love the pro and cons of your posts.. Its very helpful
 
I have used this hardness tester for over twenty years with great results. It is a PTC 415C hardness tester. It is portable and chucks up into a drill press. It is very precise instrument and comes with test blocks. Also needs to be used in a warm environment like Kevin said. I have checked this tester against a high dollar tester where I used to get my heat treating done and it gave same readings, plus it always been right on with my certified test blocks! They cost about $1,000 bucks, witch is about five hundred more than what I paid twenty some years ago. PTC stands for Pacific Transducer Corp. Here is a link to there site, once on there home page look for the steel hardness tester link. P.S. always unplug drill press before using this tester, you do not want to spin this sucker !! I would put this up against any bench tester, and better yet it is made in U.S.A instead of China.
www.ptc1.com
Just another option for us makers,
Clint
 
Looking at the accuracy of the hardness testers listed on that website, ptc1.com, their Rockwell hardness testing machines have an accuracy of +/- 1.5 points!!!! I don't have any experience working with hardness testers, or how accurate they SHOULD be, but plus or minus a point and a half seems WAY TOO much. Imagine trying to shoot for a 62RC, only to have the machine read anything from 60.5 to 63.5. I don't know how accurate other testers are, like Wilson's or what have you, but I don't understand how there can be such leeway in a hardness tester. I know the final hardness is an average of 3, maybe 5, readings....but how does that sound to you guys who have experience testing RC numbers....a variance of 1.5 points one way or the other?
 
Looking at the accuracy of the hardness testers listed on that website, ptc1.com, their Rockwell hardness testing machines have an accuracy of +/- 1.5 points!!!! I don't have any experience working with hardness testers, or how accurate they SHOULD be, but plus or minus a point and a half seems WAY TOO much. Imagine trying to shoot for a 62RC, only to have the machine read anything from 60.5 to 63.5. I don't know how accurate other testers are, like Wilson's or what have you, but I don't understand how there can be such leeway in a hardness tester. I know the final hardness is an average of 3, maybe 5, readings....but how does that sound to you guys who have experience testing RC numbers....a variance of 1.5 points one way or the other?

any hardness tester under $1k is probably going to have at least an error factor of +/- 1 and I'm not at all surprised by 1.5.
To get more accurate, you will have to start looking in the $5k range and up. For what we do in knife making, plus or minus 1 isn't bad. IMHO of course.
 
Looking at the accuracy of the hardness testers listed on that website, ptc1.com, their Rockwell hardness testing machines have an accuracy of +/- 1.5 points!!!! I don't have any experience working with hardness testers, or how accurate they SHOULD be, but plus or minus a point and a half seems WAY TOO much. Imagine trying to shoot for a 62RC, only to have the machine read anything from 60.5 to 63.5. I don't know how accurate other testers are, like Wilson's or what have you, but I don't understand how there can be such leeway in a hardness tester. I know the final hardness is an average of 3, maybe 5, readings....but how does that sound to you guys who have experience testing RC numbers....a variance of 1.5 points one way or the other?

My tester lists the same 1.5 variance. When I get below Rc50, it seems to be out by 1.0 or more. Right around Rc60, it seems to be within Rc0.5. The testers are more accurate in a certain portion of the range, and mine is good where I need it to be.
 
The Leeb scale hardness tester is not good for knives, or anything that thin, without careful coupling of the part to a heavier piece. They are intended (and we used them) for thick sections that cannot be moved to the lab, such as pressure vessels, heavy structural steels (thin beam flanges or joist chords/webs are right out), or other sufficiently heavy pieces. I've never gotten a trusted reading on a knife blade from ours. I have a fair amount of distrust for the accuracy of most portable testers. They tend to be highly dependent on user training and skill.
 
update, we are still editing the video. It turns out it is going to be quite a bit longer than we thought.
It will show heat treating via oven using tool wrap, plate quench, cryo using both liquid Ln and dry ice. We will also show hardness testing with both a bench and portable model.

We have Bill Nye the Science guy helping us in this video to give a brief (and probably incorrect) view of what happens when heat treating.
The out takes will probably be better than the rest of the video.
 
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