Tsubosan test files - opinion?

S

Skinner79

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Feb 5, 2019
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I bought a set of these Japanese test files. Does anyone here use them, and have confidence in their results? Honestly, I can't get a good feel for them. I understand how they are supposed to work, I've read and watched a ton of videos. But, every time I scratch around with them I still really have no clue as to my hardness. I can tell more with a regular file than I can with these things! I realize they can't be exact, but heck I'd like to be fairly confident I am within a 5 point range at least. Opinions? Advice?
 
IMHO, test files are nearly useless. I know there will be opposing views, but as for accuracy, they don't work well. I also think they will dull quickly and then be even more useless.
If you want accuracy with your hardness numbers, you need a proper hardness tester. They have come down in price in the past few years and are getting affordable to the serious hobbyist.
 
I use them. Though they are definitely highly subjective to your technique and consistency of technique, I think they are an acceptable tool to use as a guide. Most of the videos I've seen of guys using them they are using them incorrectly. If you use them properly and per instructions, they shouldn't dull at a rate that would render them useless before you get your value out of them. The instructions are simple and clear, and my limited experience has been that I can confidently land within the 5 pt range that corresponds with the known metallurgical HT curves listed in KSN. When they don't, I have always been able to find a flaw in my process. Consistency of technique is the key to getting as accurate and repeatable results as possible. I list my hardness values as +/-2 HRC, which is about as accurate of a guesstimate as you can get with them. For example, if I skate a 60 but the 65 grabs easily, I'd record as 62 +/- 2 HRC and feel good that I am offering an honest hardness value within my consistency and margins of error of the tool.

All that said, Stacy is right that they aren't the best tool for the task, but we all don't have the benefit of years of accumulating tools or an unlimited budget to do our hobbies, so we do the best we can with the tools we can afford until we can do better and afford more. I think they fill a role nicely and give good information (if you do your part) at an entry-level price.
 
Bühlmann said:
I use them. Though they are definitely highly subjective to your technique and consistency of technique, I think they are an acceptable tool to use as a guide. Most of the videos I've seen of guys using them they are using them incorrectly. If you use them properly and per instructions, they shouldn't dull at a rate that would render them useless before you get your value out of them. The instructions are simple and clear, and my limited experience has been that I can confidently land within the 5 pt range that corresponds with the known metallurgical HT curves listed in KSN. When they don't, I have always been able to find a flaw in my process. Consistency of technique is the key to getting as accurate and repeatable results as possible. I list my hardness values as +/-2 HRC, which is about as accurate of a guesstimate as you can get with them. For example, if I skate a 60 but the 65 grabs easily, I'd record as 62 +/- 2 HRC and feel good that I am offering an honest hardness value within my consistency and margins of error of the tool.

All that said, Stacy is right that they aren't the best tool for the task, but we all don't have the benefit of years of accumulating tools or an unlimited budget to do our hobbies, so we do the best we can with the tools we can afford until we can do better and afford more. I think they fill a role nicely and give good information (if you do your part) at an entry-level price.
Click to expand...

Since you are having success with them, could you elaborate on the exact technique you use?

I think you hit the nail on the head regarding being consistent with technique. In the set I received, the instructions were simple...and brief...but really not very helpful. It basically just said to start with the 65, run the file over the test material, and if it marks, go to the next lower file. I totally understand the concept, but I'm having trouble putting it into practice!

I did take a look at the "official" Tsubosan video on YT, and it did help some. It showed using a fairly light pressure and short strokes, moving the file only about 5mm. So, you're right...other YT videos are all over the place regarding how to use these files. And, apparently I'm not doing it right either! :)
 
I use them and think they are an OK alternative to more expensive equipment.

I use the curved section on flat surfaces…should skate or dig in indication which item is harder. I do think it is kind of a developed feel thing for how much pressure to use. I kinda learned how they should feel on stuff that I knew the hardness of ahead of time. Hope that helps ….
 
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