Blade thickness behind the cutting edge - again

M

miden

Joined
Sep 9, 2005
Messages
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Hi Guys,
please forgive me for bringing up this subject again. There was a thread not long ago and I have searched like crazy and I honestly cant find it.
I just have to risk being told off and ask some questions because I am really in a lot of doubt and it is holding me back.

I am not a hunter or a woodsman so I dont have first hand experience of what the puritans expect from a knife, I know that it must hold an edge and it must'nt break! ;)
I have only done hollow grinding so far and I read somewhere that a .030" edge is good for a hard use knife but I have also read that some guys go really thin, around .015" a camp knife before sharpening. I am terrified of getting these things wrong and have a knife that I sell either cut really badly or, horror, chip because there isn't enough steel behind the edge.
Can somebody patiently advise me regarding the edge thickness of various knives for different applications?
I am also aware that a hollow grind is inherently less robust than a flat and of course a convex grind.

Thank you very much.

Mike
 
I just chopped a 2x4 a bunch of times with a knife that's about .012 on average directly behind the edge, and it did pretty well. It's in cpm 10v though. So I'll say that I think the steel, and your heat treat are going to really determine how thin you can go.
 
Hi Blankblank, you are right, those are 2 critical factors that count for a lot and I didn’t think of them off the bat.
The blades that I am currently making are A2. I also use CM154 and AEB-L.
I recently bought a piece of CPM154 too.
Thanks for the reply.

Mike
 
I think you'll be able to go a bit thinner with the aebl than the other two, probably harder also. I bet you could honestly take it below that .015 if your just cleaning animals with it. If you want to baton, and do tasks like that the .015 seems like a safe number to me.

I know cpm 154 should be a good bit tougher than 154cm but I'm not sure about that steel really, I dont have any experience with it other than sharpening it for customers, if it means anything to you I don't recall seeing any edges that were particularly damaged.

A2 I think would fall between the two in toughness, I think it depends the specific task that it will be used for, but even still if it's not for extremely hard use .015 seems like it might do well. How hard it is of course comes into play here too. I can say I'm on the side of the thinner the better, but I don't feel like .015 is going to be unreasonable, and if it were me I might go thinner still, unless I know someone plans to use it as a pry bar.
 
I grind thinner and thinner on every knife. Definetly go to or below 0.04" before putting an edge on smaller knives like edcs and hunters, given a good steel and heat treat.
 
I just made a batch of 3v hunters and took them to right around 10thou. On one I took it to about 4 thou, that 4 thou didnt chip on me in some real world testing i did. Obviously 3v is tougher than the steels you mentioned but I recommend taking them down to 10 or so, maybe take one thinner and test it. If it chips, grind away the edge a bit and test at that thickness. 30thou is way to thick.
 
Thank you Blankblank, Scaniaman and Skiller1nc. It seems that my info was bad - you all grind much thinner and you say it works well.
I will do as you advise and do some real world testing on some knives.
I also have a colleague here at work that is going bear hunting later this year, I will let him to take a knife and use it harshly.

Stacy, thank you for the link, it is the exact one that I was trying to find.

Mike
 
One thing I can add as well. Being able to have a thick enough spine that the blade doesn't do a ton of flexing can help. I just measured the 10v knifes spine, and it was actually around .05 and .02 near the tip. Then the blade height was around 1.1 at the tallest part (I honestly didnt realize it was that thin, I had to zero the calipers, and try again when I saw that).

I definitely recommend making the spine thicker than this knife, it was made specifically to be slicey. But if you have a robust spine, I think you can really transition down to a very thin bte thickness, and come out just fine.
 
Blankblank, that knife must cut something fierce with that thickness. My knife thickness is just over 1/8" thick so it will not flex easily.
Just another question. I don't know if you have ever experienced this sort of thing but how would you generally deal with a customer that chips a blade and then claims that he didnt chop/pry/twist the blade excessively and you know for a fact that you did your due diligence and made a good knife?
Those folks are surely out there:confused:

Mike
 
miden said:
Blankblank, that knife must cut something fierce with that thickness. My knife thickness is just over 1/8" thick so it will not flex easily.
Just another question. I don't know if you have ever experienced this sort of thing but how would you generally deal with a customer that chips a blade and then claims that he didnt chop/pry/twist the blade excessively and you know for a fact that you did your due diligence and made a good knife?
Those folks are surely out there:confused:

Mike
Click to expand...
That's a great question I was actually just wondering. Starting to make some knives kind of like prototypes, mostly for friends now, but would like to start selling to pay for materials at least. I had just finished up one last weekend, was carrying a bunch of stuff back to the house, and it slid off and dropped to the concrete landing edge down (of course, and yes I'm an idiot). Small chip (about 1/32") which only took about 30 minutes to take out and resharpen, but could easily see this happening. "nope, I didnt drop it, was just cutting some lettuce and boom, knife edge chipped away".
 
I think you just need to know that if you've done your testing and are confident in your product that it won't chip in normal use. then when a customer does chip or break it, that's their problem, make it clear upon orders/purchases/ whatever that "this is how I heat treat and why" "blades are harder than mass-produced knives and thus cant be abused. If you want to abuse it ill heat treat it softer or make it thicker at the expense of other factors" I do mostly kitchen knives with a few large batches of hunters and I run all my steel very hard and thin. My customers know that they are going to have to take care not to abuse the blade but in return get much better day-to-day properties. For example, I had a run of d2 hunters at 62rc, they tested fine and didn't chip or anything, i was happy with them at that hardness. Come to find out a customer I'm pretty close to was using it as a throwing knife, make me shiver but it held up. I was fully prepared to let him know upon him breaking it that I'm not coving that abuse.
 
Yes Lehbauer, every now and then we encounter those brutal lettuce...:p. Every knife makers worst fear.

Skiller1nc, your approach to abuse denial is a good one, I like it, thanks. As for the D2 throwing knife...wow, that is disturbing. Just the other day at work, a colleague told me he was surprised when I told him that there are very many different types of steel and not just in the knife making world. He said he thought steel is steel and they are all the same! I guess that if you are not involved with it in any way then you might think that. Maybe your knife thrower is one of those folks.
Would you have any pics of your kitchen and hunting knives? Lehbauer and Scaniaman, do you have pics of your knives?
Thanks,
Mike
 
miden said:
Yes Lehbauer, every now and then we encounter those brutal lettuce...:p. Every knife makers worst fear.

Skiller1nc, your approach to abuse denial is a good one, I like it, thanks. As for the D2 throwing knife...wow, that is disturbing. Just the other day at work, a colleague told me he was surprised when I told him that there are very many different types of steel and not just in the knife making world. He said he thought steel is steel and they are all the same! I guess that if you are not involved with it in any way then you might think that. Maybe your knife thrower is one of those folks.
Would you have any pics of your kitchen and hunting knives? Lehbauer and Scaniaman, do you have pics of your knives?
Thanks,
Mike
Click to expand...
Here are the last 3 (knives 5, 6, &7). 7" chef's knife, 6" utility, and 4" paring knife.
I really need to get better at taking photos.
e6ef38c19f7266ea529fd8a17ba42c3e.jpg

228544d1d6ac9cfc57d6f21ce620847f.jpg
 
Lehbauer, those are very nice knives. 👍Thanks for sharing. I particularly like the shape of the handles.
 
miden said:
Yes Lehbauer, every now and then we encounter those brutal lettuce...:p. Every knife makers worst fear.

Skiller1nc, your approach to abuse denial is a good one, I like it, thanks. As for the D2 throwing knife...wow, that is disturbing. Just the other day at work, a colleague told me he was surprised when I told him that there are very many different types of steel and not just in the knife making world. He said he thought steel is steel and they are all the same! I guess that if you are not involved with it in any way then you might think that. Maybe your knife thrower is one of those folks.
Would you have any pics of your kitchen and hunting knives? Lehbauer and Scaniaman, do you have pics of your knives?
Thanks,
Mike
Click to expand...
He is actually a collector and very educated on steels, more so than just about anyone I know. He still decided he wanted to throw it. I have photos over on Instagram of the kitchen and hunting knives if you want to look. @mooseknifecompany

*Stacy/mods if this is against the rule let me know ill take it down. - No problem with the link - Stacy
 
Last edited by a moderator:
miden said:
Lehbauer, those are very nice knives. 👍Thanks for sharing. I particularly like the shape of the handles.
Click to expand...
Thanks. Kept them nice and simple, to go with my skills at the moment. Plus for kitchen I like a thinner handle.

Back to on topic though. Currently have two cleavers I'm doing. material is 1/8" 80CRV2. Blade height is approximately 3.25" at the widest part. Was going to try and do a bevel at the 1.25" up from edge and try for about 0.035" for treatment, but bring it down to 0.025 afterwards. I'd like them to be able to use them for a bit of slicing too. Should I maybe be aiming more of an 0.015 - 0.02 finished?
 
I've found .015 to be the sweet spot for 8670. It'll chop, slice, and the tip will hold up against moderate prying. 8670 is pretty similar to 80crv2, I've heard.
 
Lehbauer said:
Thanks. Kept them nice and simple, to go with my skills at the moment. Plus for kitchen I like a thinner handle.

Back to on topic though. Currently have two cleavers I'm doing. material is 1/8" 80CRV2. Blade height is approximately 3.25" at the widest part. Was going to try and do a bevel at the 1.25" up from edge and try for about 0.035" for treatment, but bring it down to 0.025 afterwards. I'd like them to be able to use them for a bit of slicing too. Should I maybe be aiming more of an 0.015 - 0.02 finished?
Click to expand...
Its it's a meat cleaver. You can get away with it being thicker. They're meant to go through bone, so its gotta have some heft, and material to handle the impacts.

If it's a general use cleaver (maybe more like a chinese style), you can take those pretty thin.
 
Lehbauer said:
Thanks. Kept them nice and simple, to go with my skills at the moment. Plus for kitchen I like a thinner handle.

Back to on topic though. Currently have two cleavers I'm doing. material is 1/8" 80CRV2. Blade height is approximately 3.25" at the widest part. Was going to try and do a bevel at the 1.25" up from edge and try for about 0.035" for treatment, but bring it down to 0.025 afterwards. I'd like them to be able to use them for a bit of slicing too. Should I maybe be aiming more of an 0.015 - 0.02 finished?
Click to expand...
True meat cleavers are usually convexed in to pretty much zero. Thick thick with a heavy edge convex. They don't need to be particularly sharp or have refined edge to do their job

A cleaver is really an axe. Axes arent good for slicing. Make either a meat cleaver or a nakiri/Chinese chef style knofe. The geometries between the 2 designs are so diametrically opposed if you try to make a knife that does both you'll end up with one that does neither(at least not well).

Also very few people have any actual use for a proper meat cleaver. I process all of my own meat from whole half or quarter beasts and the only task I really like a meat cleaver for is splitting a pig down the brisket. Everything else is done more effectively and cleanly with a bone saw
 
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