Why are production knives still sharpened by hand?

retzius

retzius

Joined
Sep 17, 2009
Messages
1,102
Serious question here. Most high value mass production knives are machine cut or stamped and assembled almost solely by mass production assembly methods. Why do they do the sharpening on almost all knives still by hand?

I find that the worst part of most production knives is that the edge sucks. I can tell a worker spent a total of 15 seconds sharpening it before grabbing the next victim.

Why not just have a machine sharpen it? It most likely could make a perfect angle and do it faster.

OCD types (like me) here at Bladeforums end up putting on a Edgepro anyway (a machine) that reduces the human element anyway if we want a perfect edge...
 
My guess is that knife companies think the general public, the main buyer of the knives won't care how sharp a knife is as long as it cuts.
Why spend any money on sharpening machines when the people who put the knives together can also sharpen them?
 
Mephtyrm said:
My guess is that knife companies think the general public, the main buyer of the knives won't care how sharp a knife is as long as it cuts.
Why spend any money on sharpening machines when the people who put the knives together can also sharpen them?
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Exactly! And they probably expect that knife-nuts can sharpen knives for themselves. So the group of people who care but do not have sharpening skills is probably small enough: does not justify the investment.
 
I assume the majority of knife knuts also reprofile the secondary bevel so why bother spending a rather large amount of time on a process that will be redone upon purchase anyway?
 
Could be because they think marketing a "hand sharpened" edge promotes higher quality with the buyer. Speed might be another issue, it's probably faster and cheaper to have someone grind them "freehand" and then sharpen them quickly, than it is if someone had to clamp each blade into a machine individually and sharpen it. That said I have no idea how most companies actually sharpen their blades. I'd also guess even with say spyderco and benchmade quality levels many of the buyers fit into two camps, either how it comes out of the box is sharper than anything else they have, or they already know how to sharpen and will fix it them themselves.

What bothers me more than the hand sharpening is the edge grind angles on many even expensive production knives seem pretty inconsistent. You put them in and edge pro, wicked edge, even a lansky and it's pretty obvious that the edge grind center line is not inline with the spine of the knife. Some are better than others, but some are off quite a bit, enough that it can be easily seen just looking down the blade edge. It creates a lot more work in the sharpening process to re-profile the angle.

The other thing that gets me is how steep of an edge angle most knife companies put on, there are very few 3.5" folders and almost no fixed blades I've bought in the last few years that I can sharpen on a spyderco sharpmaker without re-profiling to a more shallow angle (I have a very old sharpmaker that's ~45 deg inclusive). With the steels these days there's no reason most of these knives unless they are an abuse taking chopper or pry bar need more than 40 degrees inclusive. Using a Lansky it's usually a bit of work to get most of them just down to 50 degrees inclusive, and going down to 40 degrees inclusive is a ton of work, but I personally feel that's about the right angle for most typical folder work.
 
SAK sharpens their blades by machine, and no they don't put one at a time in the machine. They turn out thousands per day. It can be done easily and reasonably if your production numbers are sufficient. The fact that most companies like Spyderco, Kershaw, etc have so many different blade types and shapes, would make the machine route less attractive. Plus, who decides what angle to grind each blade type? Great idea, but not practical in the real knife world. Just my weird/wacky opinion. :o

Blessings,

Omar
 
I'm sure plenty will disagree, but hand sharpening is faster, cheaper and more consistant than using a machine.

I've been in the Benchmade, Kershaw, and Gerber factories and spoken with engineers in each of these factories about why they haven't automated sharpening. The short answer is that the ROI is much longer than 5 years and the resulting blade isn't significantly better than a hand sharpened blade. Based on the information I've collected the processes that shape the blade before it can be sharpened are not repeatable enough to make fully automated sharpening possible, you'd end up with off center edges, inconsistant edge bevels and poorly sharpened blades. Leatherman uses a robot to sharpen some of their blades and their edge consistancy and sharpness are worse than the blades that are sharpened by hand.

The edge pro, wicked edge, and other guided sharpening systems are not nearly efficient enough for high volume production work, especially for setting the bevel on a factory un-sharpened blade, automating a system like the edge pro isn't as simple as hooking it up to a pneumatic cylinder or servo drive. When you use a guided system you are still using human tactile feedback and human response, which is difficult to reproduce electro-mechanically, even in 2013.
 
kornphlake said:
I'm sure plenty will disagree, but hand sharpening is faster, cheaper and more consistant than using a machine.

I've been in the Benchmade, Kershaw, and Gerber factories and spoken with engineers in each of these factories about why they haven't automated sharpening. The short answer is that the ROI is much longer than 5 years and the resulting blade isn't significantly better than a hand sharpened blade. Based on the information I've collected the processes that shape the blade before it can be sharpened are not repeatable enough to make fully automated sharpening possible, you'd end up with off center edges, inconsistant edge bevels and poorly sharpened blades. Leatherman uses a robot to sharpen some of their blades and their edge consistancy and sharpness are worse than the blades that are sharpened by hand.

The edge pro, wicked edge, and other guided sharpening systems are not nearly efficient enough for high volume production work, especially for setting the bevel on a factory un-sharpened blade, automating a system like the edge pro isn't as simple as hooking it up to a pneumatic cylinder or servo drive. When you use a guided system you are still using human tactile feedback and human response, which is difficult to reproduce electro-mechanically, even in 2013.
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I agree 110%. Watch the benchmade factory tour vids, and they use some sort of crazy laser scanner to check their sharpening. They even explain why they don't use automatic sharpening machines. In a factory where they produce many different models, its easy for a human to switch from blade to blade than it is to tear down and re set up a machine. Much, much more cost effective.
 
kornphlake said:
I'm sure plenty will disagree, but hand sharpening is faster, cheaper and more consistant than using a machine.

I've been in the Benchmade, Kershaw, and Gerber factories and spoken with engineers in each of these factories about why they haven't automated sharpening. The short answer is that the ROI is much longer than 5 years and the resulting blade isn't significantly better than a hand sharpened blade. Based on the information I've collected the processes that shape the blade before it can be sharpened are not repeatable enough to make fully automated sharpening possible, you'd end up with off center edges, inconsistant edge bevels and poorly sharpened blades. Leatherman uses a robot to sharpen some of their blades and their edge consistancy and sharpness are worse than the blades that are sharpened by hand.

The edge pro, wicked edge, and other guided sharpening systems are not nearly efficient enough for high volume production work, especially for setting the bevel on a factory un-sharpened blade, automating a system like the edge pro isn't as simple as hooking it up to a pneumatic cylinder or servo drive. When you use a guided system you are still using human tactile feedback and human response, which is difficult to reproduce electro-mechanically, even in 2013.
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What he said..
 
kornphlake said:
I'm sure plenty will disagree, but hand sharpening is faster, cheaper and more consistant than using a machine.

I've been in the Benchmade, Kershaw, and Gerber factories and spoken with engineers in each of these factories about why they haven't automated sharpening. The short answer is that the ROI is much longer than 5 years and the resulting blade isn't significantly better than a hand sharpened blade. Based on the information I've collected the processes that shape the blade before it can be sharpened are not repeatable enough to make fully automated sharpening possible, you'd end up with off center edges, inconsistant edge bevels and poorly sharpened blades. Leatherman uses a robot to sharpen some of their blades and their edge consistancy and sharpness are worse than the blades that are sharpened by hand.

The edge pro, wicked edge, and other guided sharpening systems are not nearly efficient enough for high volume production work, especially for setting the bevel on a factory un-sharpened blade, automating a system like the edge pro isn't as simple as hooking it up to a pneumatic cylinder or servo drive. When you use a guided system you are still using human tactile feedback and human response, which is difficult to reproduce electro-mechanically, even in 2013.
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Thanks! Thats great info!
 
The human machine still works pretty well if the employee cares about his job and the product he is helping to produce. If you sharpen all the time, it isn't so difficult to be consistant.
 
Sonnydaze said:
Machines don't take long coffee breaks or ask for union insurance plans.
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My Speedform 2 is reason enough to justify machine sharpening nicer knives. Elmax steel sucks to reprofile. It is worse when you aim for like 30° inclusive and the edge comes at about 15/30. I just gave up and had it professionally done, and there had to be a TON of steel removed.
 
dkb45 said:
My Speedform 2 is reason enough to justify machine sharpening nicer knives. Elmax steel sucks to reprofile. It is worse when you aim for like 30° inclusive and the edge comes at about 15/30. I just gave up and had it professionally done, and there had to be a TON of steel removed.
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The speedform 2 seems like it's way too thick behind the edge to take that kind of an angle.
 
fzla226 said:
The speedform 2 seems like it's way too thick behind the edge to take that kind of an angle.
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It took it. That knife had a wicked edge on it. If it was lefty friendly I would have never gotten rid of it..
 
Thanks OP, i was wondering about the same thing. I acquired a new Benchmade 943 a few months ago and found the factory edge underwhelming. Using my Sharpmaker at 40 degrees inclusive, the tried-and-true sharpie method showed that I wasn't hitting the edge at all. After reprofiling to 30 degrees on the diamond rods (and swearing at my cramped hand), I finally had some edge geometry I could work with.

I've had better luck with the out-of-box edges on Spydercos and Kershaws, but getting a nice edge (even grinds, no burrs, consistent angles throughout) from the factory is still a mixed bag. If nothing else, it guess it gives me a chance to maintain my skills on the Sharpmaker!
 
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