No edge retention due to burr?

awestib

awestib

Joined
Dec 29, 2008
Messages
1,647
Hi Guys:
I got my first Murray Carter knife that was on sale. It's a rather small neck knife, laminated steel with his blue steel as the edge-steel I assume. It came quite sharp. No I have used it quite a bit cutting cardboard and actually, I was quite disappointed about edge retention. In fact, it was worse than my Izula?! I sharpened the Carter knife on my sharpmaker at 30dgr with a Microbevel of 40 degr. I also stropped it afterwards. It cut paper very easily and shaved also quite ok. However, after only a few strokes through cardboard, it started to rather rip than cut it. So I wonder if I had rather a sharp burr/wired edge than an actual sharp real edge that caused this poor result? Is that material (Blue steel?) known to produce a burr quite a bit? Any suggestions?
Thanks, A.
 
Unsure on that knife, but a lot of factory edges the temper seems to be shot from the factory grind. After reprofiling as I go, I can actually feel the steel change as I remove the initial edge grind. Once down to that point the edge retention is much better.

The feeling of the steel goes from a very brittle feel to a smoother feel while honing. It's hard to describe. The feel on the stone becomes almost silky or slick.

Just something as a noob that I've noticed. Maybe the belt grinder edge that a lot of knives ship with ruins the temper of the immediate layer of steel? That's my theory at least.
 
I'm pretty sure Mr. Carter uses water cooled rotating Japanese water stones, so losing the temper due to heat should not be an issue.

Slicing cardboard is the way Murray Carter suggests removing a wire edge, so it seems odd that you cutting cardboard wouldn't remove a burr if you had one. Hopefully someone a lot more knowledgable will come along shortly.



kingsqueak said:
Unsure on that knife, but a lot of factory edges the temper seems to be shot from the factory grind. After reprofiling as I go, I can actually feel the steel change as I remove the initial edge grind. Once down to that point the edge retention is much better.

The feeling of the steel goes from a very brittle feel to a smoother feel while honing. It's hard to describe. The feel on the stone becomes almost silky or slick.

Just something as a noob that I've noticed. Maybe the belt grinder edge that a lot of knives ship with ruins the temper of the immediate layer of steel? That's my theory at least.
Click to expand...
 
There's a pretty good chance you have a burr or, as previously mentioned, some weakened steel near the edge. Either way, you can deal with it in much the same way as you would for a stubborn burr.

I've been in the habit, especially after sharpening on ceramics (like your sharpmaker rods), of making a few hard draw cuts into some hard wood, like oak. Ceramic hones are known to leave some significant burrs on edges, which won't necessarily be removed during stropping (in my experience, they're almost never completely removed this way). Make two or three aggressive cuts across the grain in the wood (I use the edge/corner of my oak strop block). If a burr or wire edge is there, this usually goes a long way toward breaking it off. Strop again afterwards, then cut into the edge of a sheet of thin paper, like newsprint or catalog/phonebook pages. If a burr is still there, it'll snag & tear the paper very easily. If you need to, make some VERY light passes on your ceramic again, then strop, then test again on the paper. Keep doing this until you can make very clean, smooth cuts through the paper repeatedly, along the full length of the cutting edge. Then test again on the cardboard.

A side note, some cardboard can have some pretty sticky binders/adhesives in it. That'll sometimes aggravate cutting, causing the blade to hang or stick. It's usually fairly obvious though, because the sticky stuff in the cardboard will deposit itself all over your blade. It's usually pretty easy to see it.

You might also check for burrs along the shoulder of the edge bevel. Sometimes those can create quite a bit of drag when cutting through tough material.
 
I had an M2 knife that did the same. I could slice TP, push cut newsprint a few inches from point of hold, shave easily, etc. Breaking down one box would take the edge down to where it was completely unable to even scrape arm hair. This was the only knife I've ever had this issue with, considering the alloying and advertised hardness of the steel.
 
awestib said:
Hi Guys:
I got my first Murray Carter knife that was on sale. It's a rather small neck knife, laminated steel with his blue steel as the edge-steel I assume. It came quite sharp. No I have used it quite a bit cutting cardboard and actually, I was quite disappointed about edge retention. In fact, it was worse than my Izula?! I sharpened the Carter knife on my sharpmaker at 30dgr with a Microbevel of 40 degr. I also stropped it afterwards. It cut paper very easily and shaved also quite ok. However, after only a few strokes through cardboard, it started to rather rip than cut it. So I wonder if I had rather a sharp burr/wired edge than an actual sharp real edge that caused this poor result? Is that material (Blue steel?) known to produce a burr quite a bit? Any suggestions?
Thanks, A.
Click to expand...

I have a Carter in Blue Super, I tested it breaking cardboard down and slivering them until there was practically nothing (I might still have the video...), so... I know that the steel isn't prone to just losing it's edge. Maybe it could be that you microbeveled it. Murray sharpens his knives at 15º, or at least in his video this is the angle that he recommends ("two nickels"). He also recommends pulling the blade through some wood to remove any burr.

On the phone he said not to strop on leather as this creates a rolled edge instead of an edge that meets at a fine point, as a side note. Which is probably why he strops in reverse on his waterstones.

Would you mind showing some pictures of your Carter? I'd love to see them.
 
You could also be fracturing the edge with the ceramics if the Rc is high enough. This is a very noticeable thing though and the resulting edge will be rough and dull.

The burr created by a ceramic is not usually of the "soft" type and if there is one the edge its usually dull. Running the edge through wood might help but I wouldn't expect much.

I'd try some fine sandpaper and a strop to help eliminate some factors first.
 
That's definitely hard enough and depending on the pressure used in sharpening and how ductile the steel is it could cause issue.

Ceramics are not my prefered tool for carbon steels either, they "work" but don't do the greatest job. When done correctly the edge will be sharp but edge quality tends to be low from the burnishing effect of the ceramic. To me it makes the edge feel over polished and lacking bite.
 
kingsqueak said:
Unsure on that knife, but a lot of factory edges the temper seems to be shot from the factory grind. After reprofiling as I go, I can actually feel the steel change as I remove the initial edge grind. Once down to that point the edge retention is much better.

The feeling of the steel goes from a very brittle feel to a smoother feel while honing. It's hard to describe. The feel on the stone becomes almost silky or slick.

Just something as a noob that I've noticed. Maybe the belt grinder edge that a lot of knives ship with ruins the temper of the immediate layer of steel? That's my theory at least.
Click to expand...

I think that feeling that your taking about is the steel telling you it's time to progress to the next grit.
 
knifenut1013 said:
That's definitely hard enough and depending on the pressure used in sharpening and how ductile the steel is it could cause issue.

Ceramics are not my prefered tool for carbon steels either, they "work" but don't do the greatest job. When done correctly the edge will be sharp but edge quality tends to be low from the burnishing effect of the ceramic. To me it makes the edge feel over polished and lacking bite.
Click to expand...
What would you use for this kind of steel? Diamonds?
A.
 
knifenut1013 said:
That's definitely hard enough and depending on the pressure used in sharpening and how ductile the steel is it could cause issue.

Ceramics are not my prefered tool for carbon steels either, they "work" but don't do the greatest job. When done correctly the edge will be sharp but edge quality tends to be low from the burnishing effect of the ceramic. To me it makes the edge feel over polished and lacking bite.
Click to expand...

When Wayne Goddard test edges on a brass/steel rod to test proper heat treat he flexes it and if stays flexed it is too soft and if it chips it is too hard for that particular steel/grind. It seems to me that the ceramic rod is acting as a de facto rod test and the steel is too hard for that steel/grind.
 
awestib said:
What would you use for this kind of steel? Diamonds?
A.
Click to expand...

My first choice would be waterstones followed closely by sandpaper, diamonds do well on high hardness carbon steels but not as well as the aformentioned.
 
somber said:
I have a Carter in Blue Super, I tested it breaking cardboard down and slivering them until there was practically nothing (I might still have the video...), so... I know that the steel isn't prone to just losing it's edge. Maybe it could be that you microbeveled it. Murray sharpens his knives at 15º, or at least in his video this is the angle that he recommends ("two nickels"). He also recommends pulling the blade through some wood to remove any burr.

On the phone he said not to strop on leather as this creates a rolled edge instead of an edge that meets at a fine point, as a side note. Which is probably why he strops in reverse on his waterstones.

Would you mind showing some pictures of your Carter? I'd love to see them.
Click to expand...
Here you go. Not a good picture, taken with my phone:

? Not sure, can't figure it out. How can I attach a picture? Via URL? What's that mean?
Sorry! A.
 
Host it, then just
.
 
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