Tip issue?

[Chris Lyons]

So I searched around the forum and did not find any real answer to this, so I am asking you guys for some advice.

I am in the middle of my 2nd knife, and after HT and tempering I was hand sanding it. I got to about 600gr and decided to stab it into my work bench and try and pry some wood out of it to sort of test its strength.
The tip did not snap, and took out a chunk of wood, but kind of bend just a little bit.

I am using 1084, heating to "a shade past non magnetic" in my little home made coffee can type "forge", and quenching in 130 degree canola. I was careful not to overheat the tip, but did bring it up to temp at the end of the heating phase just before quench.

File test seemed perfectly fine, so I cleaned it off and tempered. But now, I am a little concerned I did something wrong?

I guess my question is, what should I do about it? should I redo the heat treat (and sadly all that sanding) and try to get the tip harder? Trim/file it back some and make it thicker? Send it out to have it heat treated by someone who actually knows what they are doing? I am not sure if it is my HT, the blade geometry, something else??

Here is a sketch of the blade for reference. nevermind thepin/lanyard placement, I am going to change that, I decided it looks like crap.

thanks in advance!

 

[autogateman]

My guess is not enough material behind the tip. Any steel regardless of hardness will bend or break if it's pried on and thin enough.


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[jdm61]

In my experience a thin tip like that should flex.

 

[Chris Lyons]

Thanks for the replies. I guess I'll leave it the way it is, and maybe file it down a little to thicken it up a bit.

 

[kuraki]

One of the tricks to freehand grinding is varying the primary bevel angle out towards the tip, so that the grind appears continuous but is actually becoming more obtuse. This allows you to form a needle sharp point that has more meat in it than something ground at the same bevel angle and simply swept in to the tip. Constant angle with a sweep necessarily thins the entire tip from edge to spine, where variable angle allows the top of the grind to stay constant thickness (to a certain extent depending on the exact geometry).

Variable

Constant

Those are good examples if you could hold them in your hand but I don't know if the pictures really show what I'm trying to explain.

 

[Chris Lyons]

One of the tricks to freehand grinding is varying the primary bevel angle out towards the tip, so that the grind appears continuous but is actually becoming more obtuse. This allows you to form a needle sharp point that has more meat in it than something ground at the same bevel angle and simply swept in to the tip. Constant angle with a sweep necessarily thins the entire tip from edge to spine, where variable angle allows the top of the grind to stay constant thickness (to a certain extent depending on the exact geometry).

Variable

Constant

Those are good examples if you could hold them in your hand but I don't know if the pictures really show what I'm trying to explain.

This makes a lot of sense. thank you for the explanation AND photos, I dont know that I would have necessarily understood without them lol. So basically my tip is too thin. crap.

 

[kuraki]

It may only mean your tip is to thin to pull nails. Not that it's too thin for the knife. Not all knives can pass the test you're giving it, that doesn't alone make them bad knives.

 

[Chris Lyons]

It may only mean your tip is to thin to pull nails. Not that it's too thin for the knife. Not all knives can pass the test you're giving it, that doesn't alone make them bad knives.

True, but I'm making it for my bro in law as a camp knife and he will beat the crap out of it, so I want to make sure the knife I give him will hold up.
Update: using really coarse emery cloth and sandpaper (file did nothing, so I know it hardened) I took off some material off the tip and reshaped it back to make it thicker and it no longer bends and didn't break, just rips out chunks of wood. Thanks for the... Tips. Ha!

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[kuraki]

:thumbup: