Is uneven blade edge grind normal??

A

Applejacks

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Sorry if I used the wrong terminology. Basically, I was curious if it is normal for a new knife to have such an uneven blade grind. Here are some photos, hopefully they reflect what I am asking. Oh, and this is a new SOG Mini X-Ray. Thanks.



 
Applejacks said:
Do you think its possible, that this is in fact not a new knife??
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I don't think it's been resharpened, from what I can see. The actual grinding marks in the edge itself are too perfectly perpendicular for this to be a hand sharpening job, and I can't think of a sharpening system that would shape an edge like that. Looks like a factory job to me. I would post about this over in the SOG forum and see what they say about it.
 
Can you compare it to some others?

Sometimes our aesthetic expectations of knife grinds run counter to the difficulty the maker has in producing thousands of the same blade, or even his view of what he was trying to do.

It's his call, and if it doesn't suit you, he will probably exchange it happily. But it may be exactly what he settled on to distribute.
 
I've seen similar problems with spyderco knives and queen/Schatt&Morgan. It's a factory knife, if the edge is sharp, what's your complaint?
 
The real question I have on this one is this:

Is the sharpening angle different across that edge? If not, that different height sharpening bevel tells me that the actual primary bevel grind is uneven.

The edge is straight, so an uneven sharpening bevel either means more metal was taken off in one spot than the other, or the primary bevel varies so that the same sharpening angle takes off less metal in one spot than the rest.
 
David Schott said:
The real question I have on this one is this:

Is the sharpening angle different across that edge? If not, that different height sharpening bevel tells me that the actual primary bevel grind is uneven.

The edge is straight, so an uneven sharpening bevel either means more metal was taken off in one spot than the other, or the primary bevel varies so that the same sharpening angle takes off less metal in one spot than the rest.
Click to expand...

I'm just going to see if I know what you mean: (I just baught an SOG knife, so I want to know everything I can about the problems their knives have) So if the angle is the same on the tip and around the blade, then it could mean that the knife is simply thicker at the top near the point than it is at the edge of the blade? so the different widths of the actual cutting edge could be normal and not a defect?
 
Think of it this way for simplicity (numbers greatly exagerated). If you have a long straight edge and prior to sharpening it varies in edge thickness at the cutting edge from 1/4" wide to 1/8" wide, and you set a sharpening angle of 22 degrees, to get a sharp edge all the way across, youll need to take off more from the 1/4" thick part than the 1/8" thick part. You end up with the same secondary bevel angle, but that angle bites higher into the thicker steel then the thinner steel.

its easier than this sounds....think of it this way:

If you put a cutting edge on a piece of steel that was as thin as paper, you wouldnt even be able to see the cutting edge bevel. If you put the same angle edge on a 1" thick bar of steel, the edge bevel would be very wide.

My guess? Its uneven sharpening rather than uneven blade thickness. They pushed a bit harder at the tip than everywhere else and brought back the bevel a bit more. It may even be intended that way....sharper thinner front edge, thicker stronger primary edge...
 
David Schott said:
Is the sharpening angle different across that edge? If not, that different height sharpening bevel tells me that the actual primary bevel grind is uneven.
Click to expand...

That's the first thing that occurred to me when I saw the photos, though it's difficult to tell without seeing the knife in person.
 
I was looking at this pic closer:
dsc00911ba0.jpg


I noticed something i did not before....this blade has a americanized tanto tip, but look at the primary grind line...it does not appear to follow the edge shape. For instance, on a curved tip, usually you want the grind line to follow the shape of the blade which then creates the front of your distal taper as that grind line passes the spine....it appears here that the primary bevel was ground straight to the tip regardless of if the edge turned upwards. If that is true, then the edge thickness at the tip may indeed be thicker before sharpening than the primary cutting edge....

Picture taking a square bar of steel and grinding a long straight bevel in it with no tip. Then take a saw and cut an angle to form a tip. Obviously the steel thickness along that angled cut will be thicker towards your new tip than the steel along your ground edge...now sharpen that tip, and youd end up with the same grind you see here.....just a hunch....
 
t1mpani said:
I don't think it's been resharpened, from what I can see. The actual grinding marks in the edge itself are too perfectly perpendicular for this to be a hand sharpening job, and I can't think of a sharpening system that would shape an edge like that. Looks like a factory job to me. I would post about this over in the SOG forum and see what they say about it.
Click to expand...

Thanks. I did just that.
 
tirod3 said:
Can you compare it to some others?

Sometimes our aesthetic expectations of knife grinds run counter to the difficulty the maker has in producing thousands of the same blade, or even his view of what he was trying to do.

It's his call, and if it doesn't suit you, he will probably exchange it happily. But it may be exactly what he settled on to distribute.
Click to expand...

I bought it online, from a store in Massachusetts. I bought having owned a Vision Titanium, and having loved it. But this blade out the box just seemed wrong.

I contacted the shop via email, three times today, no responses. I am going to call tomorrow. Its too bad they don't care about customer service.
 
brownshoe said:
I've seen similar problems with spyderco knives and queen/Schatt&Morgan. It's a factory knife, if the edge is sharp, what's your complaint?
Click to expand...

I am not even close to an expert.. but I own several knives. What I consider good, all the way down to dirt cheap twenty five year old freebies. Not one has ever had an edge like this. It looks ridiculous in person.
 
David Schott said:
The real question I have on this one is this:

Is the sharpening angle different across that edge? If not, that different height sharpening bevel tells me that the actual primary bevel grind is uneven.

The edge is straight, so an uneven sharpening bevel either means more metal was taken off in one spot than the other, or the primary bevel varies so that the same sharpening angle takes off less metal in one spot than the rest.
Click to expand...

I am not sure what this means sir. Sorry.

The point where the sharpened area and the bulk of the blade meet.. that line is not straight. But the angle of the sharpening itself seems even.
 
David Schott said:
My guess? Its uneven sharpening rather than uneven blade thickness. They pushed a bit harder at the tip than everywhere else and brought back the bevel a bit more. It may even be intended that way....sharper thinner front edge, thicker stronger primary edge...
Click to expand...

Ahh, now I got what you mean. Thanks, I agree on your assessment after talking to SOG directly.

But you think it came from the factory this way, or was resharpened?
 
David Schott said:
I was looking at this pic closer:


I noticed something i did not before....this blade has a americanized tanto tip, but look at the primary grind line...it does not appear to follow the edge shape. For instance, on a curved tip, usually you want the grind line to follow the shape of the blade which then creates the front of your distal taper as that grind line passes the spine....it appears here that the primary bevel was ground straight to the tip regardless of if the edge turned upwards. If that is true, then the edge thickness at the tip may indeed be thicker before sharpening than the primary cutting edge....

Picture taking a square bar of steel and grinding a long straight bevel in it with no tip. Then take a saw and cut an angle to form a tip. Obviously the steel thickness along that angled cut will be thicker towards your new tip than the steel along your ground edge...now sharpen that tip, and youd end up with the same grind you see here.....just a hunch....
Click to expand...
That was so over my head.

In conclusion, not normal?
 
I think in either case, its not a huge deal. Either be it from a bit too much pressure sharpening or based on the geometry of the blade. Whip out a sharpmaker and you would be able to clean it up with little problem.
 
Applejacks said:
I have no experience with knife sharpening sir. I fear messing up the blade even more. hahaha
Click to expand...

All knives get dull unless they are safe-queens. You need to be able to sharpen. It doesn't get much easier than a Sharpmaker. Well worth the investment.
 
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