Bread Knife question

[iasg]

Hi!

Can't find good info on HT and serrations. Question is whether to grind serrations on this bread knife before or after HT. Read that grinding before increases risk for heat risers and cracks? After risks over heating and ruining HT on blade. Also read that with 1084/15N20, HT only gets about 1mm down. My blank is about 1/8 now. thinking that will help with warping etc during HT then grind in serrations.

Finally, what about going half way on grind for serrations and then HT and then finishing up?

Thanks for any thoughts!

 

[Aardvark]

iasg,

You would probably have better success posting this in one of the knifemaker forums, such as Knifemakers Discussion Forums Shop Talk -> BladeSmith Questions and Answers.
This forum is mainly about using/buying/collecting (gasp!) kitchen knives and tools.

Good luck.

 

[iasg]

thanks much. Still learning to navigate this stuff.

 

[thebrain]

I would do it after for sure , I see guys do it with a Dremel but it is very easy with a chainsaw file and you don't have to worry about the heat. Doing it before seem like too much of a risk to me.

 

[iasg]

Thanks so much. I split it up thinking that the heat from my small wheels wouldn't be so bad just cleaning up after the HT. At any rate my skills are in development and i had a bunch of "cold shuts" I think (?) when i did the final grinding. Some of the layers just bubbled up in the forge before quench. That sucked.

My serrations were a bit aggressive too. I think you could cut tree branches with this thing... a bit to mid-evil for my sister's sourdough bread.

I like the chain saw file idea. Thanks again!

 

[FunkCoaster]

I have made one bread knife, and 3 other knives with serrations, so not an expert.

Serrations would always be done completely after hardening for the reasons mentioned; avoiding stress risers that could initiate cracks, cause warping, or also cause uneven heating depending on your heat source and method.
In the case of a high-carbon (1084) blade, you are correct that hardening depth is a concern. If you bring your bevel to an appropriate thickness this should be totally fine. In other words, grind or forge in your bevel so that the cutting edge is something like ~0.06" thick. Then when you grind in your serrations they will be at a depth where you are near full hardness.

If you were to grind them in before heat treat you would also need to grind through your decarburized region anyway, which could change the depth of teeth. Again, this depends on your heat treat approach, such as anti-scale compounds, controlled kiln, etc.

When grinding, a fresh belt on a small wheel shouldn't generate much heat if you are moderately careful.

Doing a half-before, half-after grinding for serrations could work, but it would be (in my mind) only for the sake of saving some belt usage at a slight risk to heat treat quality. The belt wear-and-tear in the worst case is on the order of ~$6, so I would just eat that cost and do it all post heat treat.

This is all assuming access to a small wheel on a 2x72 grinder. If you don't have that... maybe a water cooled dremel with a diamond burr will do what you need.