# Tsubosan tester files, how do they work?



## blokey (Oct 20, 2022)

Hi, I recently acquired some Tsubosan testers for different purpose, but just for fun I used them on my knives, it seems even the 65 HRC just glide on the knives with their method of using back of the file, but using the tip I'm able to leave some very shallow marks. However by applying some force on the tip it seems 60 HRC is able to leave marks on most of the knives except some super hard ones, even 55 is able to leave some on the 60 HRC knives, tho the marks are nowhere as deep as they suppose to leave. It also seems despite M390 being only around 62-63, the 65 file had a much harder time to leave any mark at all. Does anyone have experience with these? How they suppose to work?


----------



## blokey (Oct 20, 2022)

I also see the result should come from if the file bites or skates the surface, then the 65 doesn't even bites the supposely 61 HRC Shihan A2 which is also weird.


----------



## Troopah_Knives (Oct 20, 2022)

blokey said:


> Hi, I recently acquired some Tsubosan testers for different purpose, but just for fun I used them on my knives, it seems even the 65 HRC just glide on the knives with their method of using back of the file, but using the tip I'm able to leave some very shallow marks. However by applying some force on the tip it seems 60 HRC is able to leave marks on most of the knives except some super hard ones, even 55 is able to leave some on the 60 HRC knives, tho the marks are nowhere as deep as they suppose to leave. It also seems despite M390 being only around 62-63, the 65 file had a much harder time to leave any mark at all. Does anyone have experience with these? How they suppose to work?


I'd say you get somewhat accurate results within 10HRC but not much accuracy above that. The problem is that force is a huge factor in determining the hardness of the steel. Something that skates with x amount of force might not skate with 2x force. The best way to get an idea of the right amount of force to use is to find a know hardness steel (ex a 61 HRC knife) and find a consistent amount of force to apply to the 65Rc file such that it bites and the 60RC file doesn't. Using that method you maybe able to get them to work as intended.


----------



## blokey (Oct 20, 2022)

Troopah_Knives said:


> I'd say you get somewhat accurate results within 10HRC but not much accuracy above that. The problem is that force is a huge factor in determining the hardness of the steel. Something that skates with x amount of force might not skate with 2x force. The best way to get an idea of the right amount of force to use is to find a know hardness steel (ex a 61 HRC knife) and find a consistent amount of force to apply to the 65Rc file such that it bites and the 60RC file doesn't. Using that method you maybe able to get them to work as intended.


Thank you, seems like a pretty vague way to determine the hardness... Is there any service that could test the hardness for you?


----------



## Troopah_Knives (Oct 20, 2022)

blokey said:


> Thank you, seems like a pretty vague way to determine the hardness... Is there any service that could test the hardness for you?


Yes but usually only for samples and it is fairly expensive. You might see if there is a knife maker or machine shop near you that would be willing to do it.


----------



## blokey (Oct 20, 2022)

Troopah_Knives said:


> Yes but usually only for samples and it is fairly expensive. You might see if there is a knife maker or machine shop near you that would be willing to do it.


Thanks, with the file testing seems all my knives are on the hard side so I'm not worried.


----------



## HumbleHomeCook (Oct 21, 2022)

Rockwell testers will also leave a dimple mark.


----------

