Recently, a particular thing has been bugging me- the ricasso. So, when you do a flat grind, you have created a completely square shoulder between the bar stock, and the blade. Vs. something like a sweeping grind, with a slowly ascending ricasso. I made a quick pic in paint to show what I mean, but it wont load...says file is too big to upload. I hope you understand what I am trying to get at with my description.
So does this grind not create a weak spot? I know that with my own testing, blades never broke or bent there, but shouldn't theory prove other wise, since it is so square? Is a scandi grind much stronger than a flat grind? I was thinking that for blades 5/16" thick, flat grinds, with a little bit of 'beef' left at the spine, and for 1/4" or less, saber grinds. Shouldnt, in theory, a flat grind be weaker at the ricasso than a hollow, saber grind?
What is the 'science' so to speak, behind the flat grind? I cant find anything on internet about ricasso strength. Thanks in advance!!
I can not answer your question in any extreme detail.
But I will say that at the bottom of the fillet it usually has a small radius and not a sharp distinct 90* angle. This small radius helps to reduce a stress point.
Also, I will say that I have seen many, many knife flex portions of the performance test done.
I have seen knives break.
But I have yet to see one break at the fillet. Usually they break further out in the cutting area.
Unless a knife's steel is drastically mistreated, I think they tend to be much stronger than we give them credit for.
With a little attention to proper forging, post-forging and hardening/tempering practices, I can see most knives performing far beyond any logical use we need from them.
Karl B. Andersen
Journeyman Smith
I am with Karl on this. I have tested many of my own knives to destruction to find out where the weak spots are, check the grain structure, and in general to find out what the proper heat treating temps should be for steels that I was not sure of the composition, but knew they were tool steels.
There are some smiths who intentionally temper back the ricasso area to a spring temper with localized heat specifically to avoid what you are talking about and to "toughen" up the ricasso/tang junction. Either way, as Karl points out, that corner at the plunge cut/blade junction is never really a true 90 degree corner. There is always a slight radius whether you are grinding your plunge cuts, filing them, or using a stone.
Joshua States
www.dosgatosforge.com
https://www.youtube.com/channel/UCdJMFMqnbLYqv965xd64vYg
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Also on Instagram and Facebook as J.States Bladesmith
“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.â€
Okay, thank you! My mind is at ease now. Will be continuing to use a flat grind then. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />
