# Heat treat test



## robert flynt (Sep 6, 2016)

I had talked about using a 1/4" brass rod to test a blade to see if it was to hard or soft and someone had asked for a visual, so here are a couple of pictures. When you place blades edge as shown, you press down with 30 to 35 lbs. of pressure and under a bright light you will see the edge deflect on the rod. Slide the edge along the rod under pressure at the angle shown in the illustration. If the edge is to soft it will curl, not return to true, and if the edge is to hard you will hear a crackling noise and see that the edge has chips in it. This test is not very effective on knives with thick edges. The second picture is of a brass rod epoxied to a piece of wood so I can clamp it in a vice when needed.

Reactions: Like 3 | Great Post 2 | Informative 1


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## Wildthings (Sep 6, 2016)

That was me that asked for a visual!! Thanks Robert! So you are pulling the knife across the brass rod at a 90 degree angle. Like pulling an arrow back on a bow. And applying pressure to the brass rod with the knife edge. So a good edge will curl and return to true or ?? That picture of the rod helps as I visualized it sticking out the end of the wood.

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## Jack "Pappy" Lewis (Sep 7, 2016)

now that is very helpful.....I was wondering what it was you were trying to teach this old man...thank you Robert...

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## robert flynt (Sep 7, 2016)

Wildthings said:


> That was me that asked for a visual!! Thanks Robert! So you are pulling the knife across the brass rod at a 90 degree angle. Like pulling an arrow back on a bow. And applying pressure to the brass rod with the knife edge. So a good edge will curl and return to true or ?? That picture of the rod helps as I visualized it sticking out the end of the wood.


Yes that is correct, but you angle the blade a little beyond the angle it is sharpened so that you are putting pressure on the edge only. watch for the deflection and then slide it across the rod. If the heat treat is correct it should return to true in most cases but some steel like D2 and a few others are prone to be more brittle. All in all it is a good indicator if blade is to soft and a fairly good indicator if it is to hard. I advise you to put an edge on the blade, do the test, then dull the blade before applying the handle and finishing the knife.

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