Knife edges too thick from factory???

[boki_zca]

Does anyone find most production knives way too thick behind the edge so that it doesnt cut the way it could? I had to thin out most of my knives on a belt sander and they perform way better!Even some spyderco knives are too thick behind the edge.....

 

[HoosierQ]

I sure do. I just re-profiled the edge on my Spyderco Military last night. It was very sharp but judging by how it indexed on my Sharpmaker, it must have been close to 45 degree inclusive. At the angle, I will say it was perfectly apexed...so it was very sharp but I like them more acute with a microbevel at either 30 or 40. I am in a 40 phase right now except on Scandis where I like a 30.

Watching the Sharpmaker video Sal Glesser states that Spydercos do their edges at 30. I have not seen that. The closest was a Manix 2 XL and it was probably more like 35. I am a big fan of Spyderco and I've only had one knife that wasn't very sharp and perfectly apexed, regardless of bevel...and that knife was so perfect in every other way I was unfazed by that.

 

[Obsessed with Edges]

I'm absolutely convinced, over the course of the 30 or so years I've been accumulating knives, factory edges are more often too thick, than otherwise. By a large margin, in fact. I've pretty much come to expect it, and consider a 'good' one to be the rare exception.

The other variable is edge symmetry. Even if or when the included angle might be OK, often it's 'lopsided' one way or the other. For example, a 30° included edge angle (good) might be 12° on one side and 18° on the other (not good). Even worse, many factory edges are way too thick and asymmetrical.

This is why I almost always get around to re-bevelling virtually every knife I buy.

 

[boki_zca]

I thin out most of my knives that I use......and they all performed well, even the ones with aus8 steel or 420hc!I JUST prefer thin blades overall...they cut so much better!

 

[Indianbladenoob]

I'm absolutely convinced, over the course of the 30 or so years I've been accumulating knives, factory edges are more often too thick, than otherwise. By a large margin, in fact. I've pretty much come to expect it, and consider a 'good' one to be the rare exception.

The other variable is edge symmetry. Even if or when the included angle might be OK, often it's 'lopsided' one way or the other. For example, a 30° included edge angle (good) might be 12° on one side and 18° on the other (not good). Even worse, many factory edges are way too thick and asymmetrical.

This is why I almost always get around to re-bevelling virtually every knife I buy.

Why is this so? I mean if the edge on most if not all knives is too thick why do factories/makers not provide them thinned out? Even with slightly uneven bevels. And shoudn't machinbe made bevels be even? I am certain the cost factor is at least partially responsible because this seems to be less and less of a problem as one pays more and more but people still reprofile busse's and custom knives. Is there anything more to it? Possibly a material strength issue?

Also I have read enough reviews that describe knives as "shaving sharp out of the box" and my Ranger, Kershaw folders and BK14 all were pretty sharp out of the box but I re-profiled all of them. My reason for re-profiling is that I am compelled to set and follow the angle on my Lansky kit.

 

[dartheo]

This is just a wild guess, but maybe they keep the edges thicker because:

1) It's easier to achieve on mass produced items.
2) If the edge is thicker, its generally stronger which would reduce the amount of returns/complaints regarding rolled edges?

Again, just my personal thoughts.

 

[Obsessed with Edges]

Why is this so? I mean if the edge on most if not all knives is too thick why do factories/makers not provide them thinned out? Even with slightly uneven bevels. And shoudn't machinbe made bevels be even? I am certain the cost factor is at least partially responsible because this seems to be less and less of a problem as one pays more and more but people still reprofile busse's and custom knives. Is there anything more to it? Possibly a material strength issue?

Also I have read enough reviews that describe knives as "shaving sharp out of the box" and my Ranger, Kershaw folders and BK14 all were pretty sharp out of the box but I re-profiled all of them. My reason for re-profiling is that I am compelled to set and follow the angle on my Lansky kit.

Most production blades are machine ground (as a whole), but are still sharpened at the final stage by hand, on belt and/or bench grinders. So, the individual skill of whomever does that final sharpening makes all the difference. On a vast, high-volume production scale, an individual employee might sharpen dozens, or perhaps hundreds of knives in a single work shift. Disregarding the variation in skill between workers, just the one employee is bound to produce 'good ones' and 'bad ones' in any given day.

I'm sure cost of production influences how & why manufacturers do it this way. The vast majority of knife users will be satisfied with the factory edges produced on most knives, which really do seem 'sharp enough' by most 'normal' people's standards. I'm sure manufacturers know this, and they also know that those among us who aren't satisfied with factory edges will likely re-do them anyway. We here on the forums, and others like us, have put ourselves in a more difficult fix, in that we are a lot more picky about what constitutes a 'sharp edge' on a blade. It's a slippery slope, when we start noticing things like this...

 

[Indianbladenoob]

a) How difficult would it be to set up a cheap jig that standardized even that last stage sharpening. Reducing the human error.
b) What dartheo said seems to make sense. Thicker edges are stronger and sharp enough for non-knife people who in turn will probably have a higher chance of damaging a finer edge and then asking for warranty work or replacement.
My wife says I am obsessed with edges. I told her no I am not, but there's a fellow named David........................
Slippery slope indeed.....................sort of like an edge bevel

 

[BluntCut MetalWorks]

a) Easy & cheap for serrated knives because grinding wheel jig with very coarse grit can abrade 1 side of the blade at high speed, with the back side of the blade against a solid ridge backing. 'Coarse' grinding generate less heat, this essentially the main reason why edge double-bevel knife must be thick. Thicker edge can take coarse grinding and able to disfuse heat better. The finishing grit (much finer than serrated wheel) will generate much more heat, which doesn't take much to de-temper the blade. And to get a nice thin polish edge, it requires wet-grinding, which is a very expensive process to setup & operate.

b) more a) than stronger & warranty I don't see 1/2inch thick drinking glasses because thicker is better. Knife maker want their knives the best as can be but high cost forced them to compromise.

 

[G. Scott H.]

You wanna talk thick behind the edges? I mentioned in a thread the other day how thick the edge was on my Gerber Steadfast. I took a caliper to it last night and the thickness where the secondary bevel starts averages about .062-.063". I mean, it's designed as a heavy duty beater of a knife (5.6mm spine), but come on! I did manage to finally reprofile it from about 60* included to 40* last night and now the bevels are a good 1/8" wide. I joked in the other thread that they'd probably be 3/16" wide at 20* per side and I wasn't too far off. I honestly don't find the majority of knives too thick behind the edge, but this one is an exception. I guess the upside is there's not much chance of rolling this edge over.

 

[pwet]

Thick behind the edge is more a concern for me than obtuse factory angles. Most high end knives that are not marketed toward hard use are ok ... But once you get a couple utilitarians custom you see what a proper grind should be and even a caly or military seems thick ...

 

[Buffalohump]

I dont have a problem with production knives so much as custom knives. I have recently had a custom knife re-profiled by a friend of mine who is very proficient with an Edge Pro and the results are just incredible. Whereas before the knife would not push cut paracord (which is my go to test for sharpness) it now push cuts through the paracord and right into the surface beneath it with a minimum of pressure. The performance of the knife has been improved 1000%! I have now sent another knife to him for a similar job.

I feel some custom makers simply dont pay enough attention to sharpening their knives properly before sending them out. That is the exception though, most can do a very respectable job. I will qualify this by saying that my sharpening skills suck! But I would expect a knife maker to know how to put a proper edge on a knife.

The NEW edge:

 

[BluntCut MetalWorks]

Thick behind the edge is more a concern for me than obtuse factory angles. Most high end knives that are not marketed toward hard use are ok ... But once you get a couple utilitarians custom you see what a proper grind should be and even a caly or military seems thick ...

Totally agree. If just an obtuse angle on a thin-behind-the-edge, cutting performane wouldn't be so bad. Edge thinning usually not get done by the majority of users because it's time consuming and not easy for those new with sharpening. Knife maker keeps cost low by having a thick behind the edge to minimize HT warping (hence getting a higher yield) and more cost saving by not grind it thin afterward. Many custom knife makers do make a thin-edge knives with decent bevel angle.

 

[Indianbladenoob]

'Coarse' grinding generate less heat, this essentially the main reason why edge double-bevel knife must be thick. Thicker edge can take coarse grinding and able to disfuse heat better. The finishing grit (much finer than serrated wheel) will generate much more heat, which doesn't take much to de-temper the blade.

Understood the rest but how much heat would it take to de-temper the blade? because my blades tend to heat up when I try to freehand in the Murray Carter style.

 

[BluntCut MetalWorks]

Understood the rest but how much heat would it take to de-temper the blade? because my blades tend to heat up when I try to freehand in the Murray Carter style.

This post is a reference to another reference - not a confirmed but interesting how thermal from abrading could hit 2000C at the very edge
http://www.bladeforums.com/forums/s...d-water-stone-review)?p=11184875#post11184875

I guess, we probably can calculate how much heat/time taken to warm a blade where the abrasion area = bevel height * blade cutting length. If the blade gets warm in a few seconds, hey 'houston, we might have thermal problem!'

 

[Indianbladenoob]

This post is a reference to another reference - not a confirmed but interesting how thermal from abrading could hit 2000C at the very edge
http://www.bladeforums.com/forums/s...d-water-stone-review)?p=11184875#post11184875

I guess, we probably can calculate how much heat/time taken to warm a blade where the abrasion area = bevel height * blade cutting length. If the blade gets warm in a few seconds, hey 'houston, we might have thermal problem!'

It would be a function of the factors you have mentioned aaaaaand friction coefficient of both surfaces, velocity of the abrasive movement, pressure on the surface being abraded etc etc etc......................

 

[unit]

There are a lot of users and uses. Some may conject that modern knife geometry is a product of lessons learned in the warranty and repair departments.

People that are very serious about knife performance and responsible use that must accompany high performance cutlery, either purchase customs ground the way they like, or regrind their own as many in this thread seem to have done.