Building a Custom Knife for Sal: CPM S60V

[Deadboxhero]

Trevor inspecting the blade before moving on to grinding.

Nothing escapes his scrutinizing gaze.

he's getting big!

Quad B

[dullmaker]

Your son is gonna need larger handles on his future knives.

[GarageBoy]

From classically heat treated 56-57 HRC to 2024 64+ HRC. Like comparing a stock 1955 small block Chevy that barely made 110hp to a fully built NASCAR small block.

[Bolster]

Trevor inspecting the blade before moving on to grinding.

Nothing escapes his scrutinizing gaze.

Did Trevor find any issues or problems ??

[Deadboxhero]

Trevor inspecting the blade before moving on to grinding.

Nothing escapes his scrutinizing gaze.

Did Trevor find any issues or problems ??

He said "at 0.160" it's too thick, get to grindin."

[sal]

Hi Shawn,

Bringing up Trevor right. Gail and I would spin Butterfly knives for Eric while he was in his crib. he'd smile and go to sleep.

sal

[Steeltoez83]

Trevor inspecting the blade before moving on to grinding.

Nothing escapes his scrutinizing gaze.

Trevor rocking the magnacut swag too. Only a matter of time before somebody calls him big T or T-Bone Trevor. Then just T-Bone.

[WilliamMunny]

Shawn,

How do you balance the need for rapid cooling but avoid warping, especially on such a big blade?

I would have guessed it would cool unevenly and worry on you.

Not sure if this is what you're asking, but he prevents warping by clamping the blade in between two big aluminum blocks. Helps it cool by dissipating heat into the blocks, and keeps it from warping by pressing it flat during the cooling process.

Hey Shawn,

What did you use for the quench?

sal

Large aluminum plates with forced air to race to under 1000f to prevent proeutectoid carbide precipitation on prior austenite grain boundaries.




Water when under~1000f to speed the cooling curve to reduce RA stabilization when cooling to room temp under 1000f.

A large piece like this knife I am making you requires a very demanding quenching regime much different than a smaller coupon or tiny blade.

For example,
1"x1"x0.100" will cool differently than 10"x 10"x 1.00"

Rapid continuous cooling with a good rate is very crucial for all steels to achieve the maximum performance.

For using 52100 however, I will use parks 50 which is a fast quenching oil.

Some simple carbon steels have such low hardenability perhaps only water is suitable.

But it's not something I've had to worry about with stainless steels.

Makes a ton of sense, act like big heat sinks.

[Deadboxhero]

Hi Shawn,

Bringing up Trevor right. Gail and I would spin Butterfly knives for Eric while he was in his crib. he'd smile and go to sleep.

sal

I love it.

Thanks for sharing Sal.

[yablanowitz]

It's going to be interesting to see how it holds up in use. As I recall, the initial run of 440V/S60V Military suffered a lot of chipping at a lower hardness than this.

[Sharp24/7]

First step as a handmade custom knife maker is to select a pattern, I've been designing a kitchen knife pattern that has the same line flow and ergonomics of my trapper knife pattern which a enjoy considerably.



The steel is marked with Machinist dye and the pattern is scribed onto the steel.




The pattern is cut out to final 2d size with a variety of methods




I think this pattern with special heat treatment and laser thin grind will be good for evaluation of S60V and cut proteins very well.



A bold size for a CPM steel. This should give adequate length for drawing the edge across materials for slicing keeping the cut forces low and less smashing of materials, especially with a thin grind.

Draw cuts are always less force than push cuts.



Handle is drilled, reamed and countersunk for mechanical fastening corby bolts and epoxy bridges.



Clean, degrease and deburr and prepare for heat treatment.




I always double check to make sure a pattern pleases my hands and eyes. I am pleased so far.

Everything you’re doing in this thread is awesome, but I’ve got to call out that blade shape. It’s fantastic.

[Farmer]

This is a great thread - thank you! Like so many topics, knife-making seems to be a bit like an onion. You peel one layer off only to find many, many more underneath. Great to read about some of the deeper layers and realise just how little I know

[RustyIron]

Large aluminum plates with forced air to race to under 1000f

Interesting. I've been sitting here for half an hour contemplating this. You can pull the blade from the furnace, unwrap it, stick it between aluminum blocks, and get it clamped before it cools too much? And then the aluminum dissipates heat at a sufficient rate? I guess I learned something today.

The aluminum plates will surely dissipate heat more slowly than oil or water. If we were to take three samples, heat them to the same temperature, and then quench one in aluminum, one in oil, and one in water, would we expect the hardness to be about the same?

P.S.
The kid's rockin' his stylish shirt.

[Wandering_About]

Large aluminum plates with forced air to race to under 1000f

Interesting. I've been sitting here for half an hour contemplating this. You can pull the blade from the furnace, unwrap it, stick it between aluminum blocks, and get it clamped before it cools too much? And then the aluminum dissipates heat at a sufficient rate? I guess I learned something today.

The aluminum plates will surely dissipate heat more slowly than oil or water. If we were to take three samples, heat them to the same temperature, and then quench one in aluminum, one in oil, and one in water, would we expect the hardness to be about the same?

P.S.
The kid's rockin' his stylish shirt.

The wrap is left on the blade for the plate quench. S60V (along with many other steels) is designed to harden relatively easily, so it hardens through without needing to be cooled extremely quickly (the S60V data sheet notes that it can be quenched by cooling a piece in open air). The plate quench helps get better hardness than a slower air quench, and combined with cryo treatment a little higher hardness and more importantly lower retained austenite.

The S60V datasheet notes that a cooling rate of 150F per minute to under 1000F is good enough to get the steel hardened through. That's not exactly a screaming fast cooling rate. A plate quench does much better than that, so no problem getting the steel hardened through.

An oil or water quench doesn't really work the best for S60V because you'd have to heat it without a wrap(which can be done, just not necessarily in a way easy for the small time knife maker's shop), or try to unwrap it before quenching. The wrap prevents the surface layer of steel from losing carbon to oxidation during austenitizing, which causes a lower hardness layer of steel on the surface of the knife (this is called decarburization).

[RustyIron]

The S60V datasheet notes that a cooling rate of 150F per minute to under 1000F is good enough to get the steel hardened through.

Thanks!

[Deadboxhero]

150f per minute is slower than holding in still air and is not ideal for knife applications for reasons previously shared about PEC precipitation on PAGB.

Unfortunately, the spirit of this thread is not a heat treatment class about best practices So I'm not going to get into any more detail than that.

Although, I do appreciate people stepping in and answering basic heat treatment questions to those who just want a general idea.

I'm just here to show progress on Sal's knife and a little behind the scenes of what goes into it.

I love the enthusiasm.

Thanks guys.

[JD Spydo]

Most interesting that you bring up CPM S60V ( 440V) blade steel. I do agree with several of your observations regarding issues like being a nightmare to sharpen and being somewhat undesirable for PE blades. But I still regard 440V as one of my personal top 5 favorite blade steels for full SE models.

What I would do to get another full SE Military models made with that blade steel. But I do agree that it had a lot to be desired for use on a plain edged blade. It's amazing which blade steels I'm finding that make great blade steels for full SE models.

[Steeltoez83]

In my own testing criteria, I'd probably rank toughness around vg10 for what I saw first hand. Sharpening was easier than cruwear too. However I find myself dwelling on what a bulk batch heat treat would perform like. Obviously that's a private convo between Sal and Shawn down the road. I've used and tested my sample from Shawn and I imagine there are marginal difference between my sample and this one in terms of steel performance. I'm looking forward to the next update to see what this knife finalizes into.

[sal]

Hey Shawn,

What is the blade length on that piece?

sal

[zhyla]

There is a photo against a ruler that suggests 12.125” but I’m just guessing that is what he meant by that photo.

What a cool thing to do for Sal. We should all make knives for him. I’ve made a bunch of kitchen knives and I can already see OP’s one or two levels up from my skills. And lots of people here have never made knives. But I’m amused at the thought of Sal having to have dozens of customer made knives that he has to display similar to when little kids give you a drawing.

One of the later knives I made is a 12” gyuto. I’ve been meaning to take it back to the grinder and take it down to 11”. 12” is just a lot of knife on even a very large cutting board. But long knives are so efficient in the kitchen.

What will the grind be like? Are you doing a concave grind on the left side? I forget the Japanese term for this.