Flattening a Tandy round knife

[chuck123wapati]

6 hours ago, Klara said:

Can you tell us who makes leather tools out of 20CV or M390? Thanks!

If your blade is newer it may already be one of those and the reason we are talking about modern blades not being as well made. Heres the deal a knife blade steel has three properties. hardness, flexibility and toughness. These three attributes are variables in the matrix of what your knife is going to be used for.  A straight razor for example is made very hard  but it is so brittle it will break if dropped, a fro on the other hand isn't even made to be sharp but to be flexable and tough enough to hammer on without chipping or breaking. So what does you leather knife need to be? It needs to be built to cut leather. That quality will come from the manufacturing process not the steel type. A blade of 56 Rockwell hardness for example can be made from any of the modern tool steels and they will all be 56 Rockwell hardness none will be better or worse than the other all will sharpen the same and hold the same edge. When you buy a knife because of the steel type its like buying a car because its a Ford or a Chevy when you need to be buying because you need either a car or a truck to do the job. When you need to think of it in the terms of the job it is meant to do. You said earlier you like the ability to easily sharpen your knife, that comes from the hardness the blade is tempered to not the type of steel make sense?

Edited June 2, 2021 by chuck123wapati

[chuck123wapati]

13 hours ago, scrapyarddog said:

As I don’t make blades or know how to heat treat, I can’t comment on that. All I can say is I do see differences in Tandy’s head knife, high carbon paring knife from Talas, CPM 154, S30V, D2, 20CV (LW), M390, certain “HSS”, and blue paper steel used by Okada. And if someone wants to get a reasonably good knife without knife making skills, there are good options out there. For sure, the treatment done by individual makers and blade geometry adopted make a difference, but if I had to choose, 20CV and M390. For crazy sharpness (but also a tad brittle), blue paper steel.

the Tandy head knife being sold now is stainless steel so more than likely m390 which can be hardened to about rc 62 or some such, blue paper steel is a very old Japanese steel blend, one of the best, and  is usually tempered to a much harder scale up to 65 then tempered back to about 61 again the difference is the manufacturing process more so than the steel type either can be tempered to what you need or want. The difference you see is the hardness of the tool, simply the Tandy knives aren't tempered to the same hardness for whatever reason the makers decided on. You cant get a good knife without good knife making skills and why some knives are more expensive than others the craft is just like the leather craft, you can buy an off the shelf manufactured wallet at Walmart or you can buy a better wallet at a high end store, both are the same leather but neither are the same quality, one is cheaper to make because the craftsmanship and quality is lost in the bottom line. Hope that makes sense.

[scrapyarddog]

10 hours ago, chuck123wapati said:

the Tandy head knife being sold now is stainless steel so more than likely m390 which can be hardened to about rc 62 or some such, blue paper steel is a very old Japanese steel blend, one of the best, and  is usually tempered to a much harder scale up to 65 then tempered back to about 61 again the difference is the manufacturing process more so than the steel type either can be tempered to what you need or want.

Tandy using M390?? Hmmm... I’ll shoot it with a spectrum analyzer tmrw and see. I’d be surprised if they use SS 201.

[chuck123wapati]

14 hours ago, scrapyarddog said:

Tandy using M390?? Hmmm... I’ll shoot it with a spectrum analyzer tmrw and see. I’d be surprised if they use SS 201.

it would be interesting to know. Keep me posted. I doubt it too however its way to hard to work and more for pocket knives and such. A round knife would cost hundreds and really again the average leather worker just doesn't need it, now maybe if you were cutting all day on a much larger scale.

Edited June 3, 2021 by chuck123wapati

[AzShooter]

If anyone wants to gift away their Tandy Head Knife please keep  me informed.  I could always use another one.  I watched a video from Weaver Leather Co about sharpening them.  Following their lead I was able to get mine sharp and keep it that way.

When cutting curves and angles there is nothing better than the Head Knife.  

[Klara]

Completely OT but not worth a thread of its own: All this talk about steel and sharpening makes me wonder whether I should try to strop my bread knife. A dowel rod a bit smaller than a tooth, some leather stuck to it, honing compound - could work, couldn't it?

[chuck123wapati]

On 6/4/2021 at 12:40 AM, Klara said:

Completely OT but not worth a thread of its own: All this talk about steel and sharpening makes me wonder whether I should try to strop my bread knife. A dowel rod a bit smaller than a tooth, some leather stuck to it, honing compound - could work, couldn't it?

Sure it would work but if you have a plain old butchers/ kitchen steel it works every bit as good on a bread knife as any kitchen knife. Once you have your edge just hit it a few licks with the steel then again after after cutting your bread then wipe it down and put it away for next time. No need to overthink sharpening its been done successfully for centuries. 

[Klara]

The diameter of steel I have is bigger than the diameter of the teeth. My bread knife doesn't have one edge but many - in a book on kitchen knives I've read that bread knives are probably not worth sharpening, one should buy a new one when they no longer cut at all. They do saw pretty well for a pretty well for a pretty long time, after all. But I was struck how well my new knife cut, and I believe it has lost that edge (pun intended. Interesting how many everyday expressions are knife-related, isn't it? )

 

[toxo]

On 4/26/2020 at 4:04 AM, RockyAussie said:

a bluntened off  belt

There's Aussie right there! Made me smile Brian.

I sometimes think thats where I should have been. Three of us were going to do the £10 thing many years ago but I chickened out. But there's defo some Aussie in me. Couldn't handle the flies though.

Edited June 6, 2021 by toxo

[toxo]

On 6/1/2021 at 8:02 AM, Klara said:

Are there even any round knives on the market where the exact kind of steel is known?

I've been thinking whether I should ask my knife-making friend to make me one - or book a workshop to make one with his instruction - but I'd get two new Osbornes for the price, with a more certain outcome...

 

Steel manufacturers know exactly the kind of steel they're making. Good steel can be ruined in the process but starting off with the right steel is half the battle.

Klara, If you want to make a knife try a high speed circular saw blade thats made for cutting steel. cut it out with a grinder but cut it oversize so you don't ruin the edge. Keeping it cool is uber important at all times but more so later when working on the edge. A rule of thumb is the colour of the sparks. The brighter the sparks, the more carbon is in the steel. Put an old file on the grinder to get what I mean. Don't worry about this talk of "too brittle" we're talking about a knife here not a hardwood axe.