WIP, Machined knife

jac_solar said:
Awesome.

I was wondering -- how much does it cost to finish a blade in the machine in terms of parts, gas, electricity, etc. whatever the machine and you use to finish a blade? Is the average per knife blade made in the realm of cents, dollars or a lot more?



Did you make that screw jig or? Does a screw adjustment rig even exist?
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Since I don't make a lot of knives the "conventional" way I don't have a great data point to compare to. Obviously the post heat treat finishing and grinding is the same. I think it is less expensive to mill a blade than it is to grind it in terms of endmill consumables vs grinding belts, but in the grand picture that cost is relatively trivial anyways, and from a machine overhead point of view the grinder is probably a little cheaper there. From a time point of view the time is comparable and power usage is probably similar. I own and am skilled with a knife grinder and I do grind knives. But I prefer to mill knives rather than grind them, not due to a cost savings (I don't think there is one) but because I make better knives when I machine them. I'm focused on the end result. This is not a short cut or a cost savings, though except for some upfront costs I don't think it is any worse either, it is simply a different approach by someone with a different skillset.


I made the screw jig, it's just a plate with some threaded holes - no biggy.
 
Camber said:
Hi Nathan,

Do you do your own heat treat or do you have it sent out to some place?

Thank you
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Peter's Heat Treat.

The Elmax is Peter's Heat Treat. In my testing it is the most durable and overall impressive stainless steels I've ever seen and it doesn't have the reputation it should because some pretty big manufacturers do the HT themselves and some don't do a great job of it. When I bought a sheet from Uddeholm they were very interested to know how or who was going do to the HT. They have a remarkable material with good fine edge stability, edge retention in both soft abrasive materials and in hard materials and rough use. And it's stainless, you'd swear it was a tool steel. Peter's HT developed the process for it for cutlery and since it didn't use the secondary hardening hump I deferred to their experience.

I developed the HT for the 3V based upon tweaks applied to similar materials. My testing is documented here if you're curious : http://www.bladeforums.com/forums/showthread.php/1161651 . I have a pretty good knifemaker's heat treat setup here in the shop, and I know my way around metallurgy okay, but at the end of the day my dinky $5,000 setup pales in comparison to a really good industrial setup like Peter's. These are run on their 4V furnace and quenched under four bar of nitrogen. They're running my protocol and doing a better job of it than I could. The modified heat treat has demonstrably better edge stability and retains the gross durability 3V is known for. The key is a quench to Mf without pause. That's really the main thing.
 
Nathan the Machinist said:
Peter's Heat Treat.

The Elmax is Peter's Heat Treat. In my testing it is the most durable and overall impressive stainless steels I've ever seen and it doesn't have the reputation it should because some pretty big manufacturers do the HT themselves and some don't do a great job of it. When I bought a sheet from Uddeholm they were very interested to know how or who was going do to the HT. They have a remarkable material with good fine edge stability, edge retention in both soft abrasive materials and in hard materials and rough use. And it's stainless, you'd swear it was a tool steel. Peter's HT developed the process for it for cutlery and since it didn't use the secondary hardening hump I deferred to their experience.

I developed the HT for the 3V based upon tweaks applied to similar materials. My testing is documented here if you're curious : http://www.bladeforums.com/forums/showthread.php/1161651 . I have a pretty good knifemaker's heat treat setup here in the shop, and I know my way around metallurgy okay, but at the end of the day my dinky $5,000 setup pales in comparison to a really good industrial setup like Peter's. These are run on their 4V furnace and quenched under four bar of nitrogen. They're running my protocol and doing a better job of it than I could. The modified heat treat has demonstrably better edge stability and retains the gross durability 3V is known for. The key is a quench to Mf without pause. That's really the main thing.
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Awesome. Thank you so much Nathan. This was exactly the information I was hoping for, my interest having been piqued by the thread you linked. The quench was the part that had me most interested as well...avoiding the use of snap tempers. Thanks again.
 
Nathan the Machinist said:
1.jpg~original


1.jpg~original
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I was originally put off by the concept, as much handwork is preferred with the knives I collect...BUT....I remembered how much handwork we did on the knives when I worked at GT Knives...and then really started thinking about the "Brain work" that goes into an idea like this, and was very pleased with this WIP....so, this one....is MINE...WOOT(African Blackwood scales or Carbon Fiber....Nathan chose the AB, and I am glad he did)!

Thanks so much for making this WIP, Nathan, you really did yourself AND the rest of us a great service. Rock on!

Best Regards,

STeven Garsson
 
Hello!

Nathan - another beauty!

STeven - great catch! You will love this thing, I am sure! Some African Blackwood heading my way as well btw. ;)

Best regards,
Alex
 
Congrats. I have been trying very hard to get one of Nathan's knives with no luck. I bought one from a guy in South Africa :triumphant: . . . but the wonderful USPS lost it and it never got here. :grumpy:

Some day I hope to be lucky enough to finally land one of his knives . . . :tears_of_joy:
 
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Kohai999 said:
I was originally put off by the concept, as much handwork is preferred with the knives I collect...BUT....I remembered how much handwork we did on the knives when I worked at GT Knives...and then really started thinking about the "Brain work" that goes into an idea like this, and was very pleased with this WIP....so, this one....is MINE...WOOT(African Blackwood scales or Carbon Fiber....Nathan chose the AB, and I am glad he did)!

Thanks so much for making this WIP, Nathan, you really did yourself AND the rest of us a great service. Rock on!

Best Regards,

STeven Garsson
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Well said! And a fine knife you've got headed your way.
Dozier
 
Congrats STeven.....I've got one of his Hunters and a Shiv.....superlative craftsmanship and I sure do want to get one of these, too.
 
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Nathan the Machinist said:
Oh yeah man, that's a really good question. To explain that I need to explain why one would even want to cut dry when conventional machining has been done wet for forever.

In a nut shell, the reason to run dry is improved cutter life using modern cutters in certain kinds of cuts. The coating, AlTiN (aluminum titanium nitride), forms a very thin coating of highly abrasion resistant aluminum oxide that replenishes itself in use while hot. So the cutter wears better when it's hot so long as it isn't glowing red. The carbide chips less when it's warm and tends to crack when you spray coolant on it while being run at speeds appropriate to carbide. Run it too slow and you get BUE (built up edge) which wears out carbide pretty fast. So there are a lot of good reasons to run fast hot and dry when you can.

But, nothing wrecks a cutter faster than re cutting chips. This is particularly true when cutting materials such as Elmax that form really nasty hard and abrasive chips.

It may not be obvious, but the art and science of machining revolves a lot around chip load per tooth. There is a window for a particular material and cutter combination where you have an optional chip thickness for a given cutter diameter. This changes (often favorably) when there is less than half of the cutter engaged, due to radial chip thinning. But, in a nutshell, your feed rate is a function of that optimum chip load and your RPM. So, when you're able to take a cut where you can feed hard enough and spin fast enough that your speeds and feeds fall within a favorable window that includes a heavy chip and a high spindle speed you can then safely throw your chips out of the cut without risking recutting them. So, when your fixture and part are conducive to machining without a lot of chip accumulation and when you can run a pass that is throwing chips well, you can then safely run dry. When running dry you can also run higher SFM because there is no thermal shock from coolant. This leads to a happy combination of high material removal rates and long cutter life. This is high speed machining. Ask any machinist, cutting a difficult material like Elmax at 41 IPM and getting good cutter life is not trivial.

But, there are times when you need to turn the coolant on. This machining center (loving known in my shop as "The Old Grey Pig") is a heavy boxway mill. Moves like a fish, steers like a cow. So I have to slow it way down for accurate cuts, otherwise it can't get out of its own way and it clips corners. When fed slow, the RPM needs to come down too in order to stay in that chip load window. Fall out of that window in these materials and things rub instead of cut, (with ~15% vanadium carbide by volume = wear, and with 18% chrome = bad work hardening) so things are going too slow to throw the chip. And at slower SFM BUE becomes a problem. However thermal shock is less of a concern and the coolant has EP additives to reduce BUE. So, for slow finishing cuts like that, even if you're using an air blast you probably want to go ahead and turn on the coolant.

So, to sum up, you run dry when you can, and wet when you need to. There is a lot of gray area in there too.
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*****sighs*****

I'm going to need to read and re-read this (maybe a few times) to grok it. The good news is I don't think I'm ever going to have to mull over the variables in those particular decision matrices, because I do make knives (and other stuff) as a hobby not to make my living. I also don't have the kind of shop Mr. Carothers has, so it's even less of a worry.

Just the same I appreciate the wisdom being so freely shared here.

Thank Nathan

Corey "synthesist" Gimbel
 
The Virginian said:
Congrats. I have been trying very hard to get one of Nathan's knives with no luck. I bought one from a guy in South Africa :triumphant: . . . but the wonderful USPS lost it and it never got here. :grumpy:
Some day I hope to be lucky enough to finally land one of his knives . . . :tears_of_joy:
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I PM'd him on this knife shortly after he started this post and expressed interest. We discussed briefly, he quoted a price and it is on the way to me.

How is that hard?

It isn't luck...if you want a knife, you ramp up the effort to get it....knifemakers put in great effort to make their knives, it's not supposed to be easy to get the great stuff, but sometimes it is.

BTW, these are exceptional value!!

Best Regards,

STeven Garsson
 
Nathan the Machinist said:
Okay, so where did I leave this off...

My blades were milled out and ready for HT. The next step is scales. I'm making some in G10 and micarta, but I'm also making a few in wood which is always a little more tricky.

Here's something you don't see in a machine shop very often:

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A wood cutting saw blade in the carousel.
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What did you have to do to get that to mount.

I assume you had to make up your own holder adapters
 
12345678910 said:
What did you have to do to get that to mount.

I assume you had to make up your own holder adapters
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Nope, that's just a regular "precision slitting saw arbor" being abused with a wood saw. I am going machinist's hell.
 
The Virginian said:
Congrats. I have been trying very hard to get one of Nathan's knives with no luck. I bought one from a guy in South Africa :triumphant: . . . but the wonderful USPS lost it and it never got here. :grumpy:

Some day I hope to be lucky enough to finally land one of his knives . . . :tears_of_joy:
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I'm sorry that my output is pretty slow. There are a number of people that have been waiting patiently for months for an 8" shiv. This 6" being a new pattern there wasn't a backlog on it yet. (There is now). There is exactly one of these finished that I ran all the way through the entire process for this WIP and Steven asked first.

I made this WIP to illustrate my unusual process but I didn't go into a great deal of detail. What folks don't see is the amount of time the various steps require. I'm slow. So I truly appreciate the continued interest in my work from folks who have been waiting patiently. I'm working on it.
 
Thanks for taking the time to post all this, I enjoyed it very much. It was interesting to see the process you go through, and it is much more complex than I realized. You certainly have some serious skills on those machines. I think now that grinding the blades is a whole lot easier. Very nice knife as well.


Doug
 
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