hardness testing files sets

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knifemaniac

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Hi, People. I am trying to find easy and cheap way to measure my knives hardness. I found this - set of calibrated files: 65,60,55,50, 45,40 HRC. I will use 65,60,55 for a knife hardness

http://www.rwnturbinetech.com/index_files/Page1020.htm

or that hardness measurment blocks:
http://www.hardnesstesters.com/test-blocks.htm And hell knows what more I can find.

Anyone uses such tools??? I am aiming the files for now.


Like most of hobby makers - I dont have a budget for a 2000 euro hardness tester. :(
 
I have a set and use it.

The obvious disadvantage is that they are less precise than a ball indentation tester though different hardnesses within the range of each file will feel different so you can get better than a +/- 5 point reading with a little practice.

The advantages are that these files work as well as ever on angled surfaces such blade bevels and on non-homogeneous steels such as damascus.

In a perfect world it would be good to have and use both types of tester but, as you say, cost and shop space are factors.

The hardness measurement blocks are reference blocks used to calibrate and test hardness testers, mainly indentation testers. They're not testers themselves.
 
Thanks, Dan. Files seems to be my choice. My friend have some sort of a tube and carbide ball, that must be set on 90 deg to the detail, and the ball jumps of from the knife. Hardness is measured by the the height that ball jumps. Is that the other tool that you are talking about?
 
No, I was mentioning one of the real penetration testers. Bench mounted ones seem to be $700+ and weigh a fair amount. I have one of the Ames hand held ones which I can't get reliable readings from. Don't know this this is my not knowing how to use it or it being out of adjustment.

Thought about the bouncing ball testers but decide that I didn't trust these to be accurate for small, thin pieces. Aside from requiring a completely horizontal surface to bounce on, I believe that these are designed to be carried around a factory and used to spot check things too big to conveniently move to the tester. I suspect that the rebound from a thin knife blade would be both less and less repeatable. Kind of like a bigger anvil has more rebound than a smaller one. Remember, this is just a guess on my part!
 
I have a set of files and use them, they give you confidence that you are in the ball park that you are heading for. HT specifications usually give a pretty large range of hardness that can be achieved over a range of temperatures, my oven drifts a little but its hard to tell how accurate it really is so I dont feel I can target the hardness with more accuracy than the files. Same goes with temper temps.

The files just provide a little more info.
 
I also use them. After a while of using them, you can get closer than +- 5 points, by the feel of the cut. I had a couple of samples tested on a Rockwell tester, and was within +- 2 points of my guess. Certainly not the best way, but affordable. Kinda, they ain't cheap, and mine are about worn out. At least the one that gets the most use. I don't think you can buy singles, but if anyone knows where you can, I'd love to know.
 
LRB said:
I also use them. After a while of using them, you can get closer than +- 5 points, by the feel of the cut. I had a couple of samples tested on a Rockwell tester, and was within +- 2 points of my guess. Certainly not the best way, but affordable. Kinda, they ain't cheap, and mine are about worn out. At least the one that gets the most use. I don't think you can buy singles, but if anyone knows where you can, I'd love to know.
Click to expand...

Go to flexbar.com , search for rockwell, individual files are on the last page.

Al P

www.polkowskiknives.com
 
There is an article in Blade Mag. from a little while ago. Wayne Goddard described a method of file testing for hardness. He got test pieces 2pts. HRc apart and uses saw files... I think that is an extra-slim three corner file. His point was a person could feel the file on a hardened blade then, by elimination, find the same, or nearly so feel on the test cupon. Wayne had access to a Rockwell tester so making cupons of the right hardness was easy. If you have a junk file, testing on it will give you feel for 65+. Wayne felt he could test +/- 1 HRc and verified that on a penetration tester.

Mike
 
Thanks Al. I will check that out. Thanks again, I was hating the idea of having to buy a whole set to replace one or two.

I just checked. That's great. $17.50 individual files. That sure beats $125.00 for a whole set that I don't need.
 
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Dan Pierson said:
...The advantages are that these files work as well as ever on angled surfaces such blade bevels and on non-homogeneous steels such as damascus...
Click to expand...

The angled surface is definitely an advantage, however the non-homogeneous steel thing is perhaps the largest issue that makes files of any kind less than reliable. Any inconsistent soft zone within the steel, be it rather large or be it a very small microscopic deviation, if it is surrounded by hardened material it will not register as the file just skates off the hardened stuff and gives the appearance of hardness when the heat treat may not be all that good. Due to carbon diffusion the only variations one will find in damascus with more than perhaps 40 layers will be due to alloying alone, so if one chooses steels wisely there will not be the deviation in HRC readings that has been proposed by common beliefs.

All that being said, if you are nailing your heat treat there is no reason why the hardness testing files mentioned should not work quite well for you. If you know you have good, fine grain and have a sufficient quenchant for the steel, much of what more exhaustive testing would tell you is already covered.:thumbup:

I may come off as being dead set against the file test, but I am not, what I am dead set against is using any single test as definitive and allow it to stand alone. It is just that using files alone as proof that a inferior quenchant, or soak schedule is working "just fine" can be the height of naivety one one considers it's limitations.
 
Hi, As you said you need to test the hardness of your product. I am recommending you this product hardness meter I have personally tried it out and I am quiet pleased. I hope you will be pleased as well. Have a look at it
 
I went to this site and checked the specs on this device. I have yet to make or see a 2-5kg knife (4.4 to 22 lb) Which the spec shows as the min weight of the test piece on a stable surface.
 
hrmahib said:
Hi, As you said you need to test the hardness of your product. I am recommending you this product hardness meter I have personally tried it out and I am quiet pleased. I hope you will be pleased as well. Have a look at it
Click to expand...

SteelSlaver said:
I went to this site and checked the specs on this device. I have yet to make or see a 2-5kg knife (4.4 to 22 lb) Which the spec shows as the min weight of the test piece on a stable surface.
Click to expand...

Hrmahib's post comes across as SPAM'ish...

-sh00ter
 
As a poor person, could I just get a regular fine tooth file, cut it up and grind all the teeth off one side of each piece, temper each one back in incremental grades, and have them tested on the smooth side and mark em. Heck, if one person did it with very accurate temperature measurement and tempering them in a big can of sand, industrial consistency is probably good enough for others to be able to copy the same procedure and get within 1 or 2 hrc without needing to test theirs right?

I'm a noob and just brainstorming, so correct me if I'm wrong.
 
Consider also...that a high alloy steel may be more difficult to cut with a file than a lower
alloy steel, even if the lower alloy steel is a few points harder........Always best to have
properly tested reference pieces of the same material.
 
File testing only involves scratching to test hardness, not filing it to any shape, no matter of alloy content. If what you think was true, a Rockwell tester would not be accurate either.
 
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