pull through sharpener?

J

jaydon

Joined
Aug 25, 2012
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34
i've heard that a pull through knife sharpener will put a brittle edge on a knife. just wondering if that is true
 
They tend to leave weak & tattered edges on blades. Not-so-much brittle (that's a function of the steel & heat treat), but the carbide pull-through sharpeners 'form' an edge basically by grabbing/pinching and ripping the steel, as opposed to simple abrasion. Resulting edges tend to be 'rippled' or waved in appearance, oftentimes with splits/tears in the edge. It stresses the thin steel at the edge and leaves it weak; it won't hold up under use. Take an index card, and 'pull' it through the 'V' formed by a pair of scissors, and look at how the edge of the card gets ripped & tattered in the process. That's essentially what a carbide pull-through will do to a steel knife edge.

Have a look at the following thread, for images of edges produced on them:

Long term carbide scraper use
 
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I've seen charter fishing mates sharpen filet knives with pull throughs prior to fileting for clients. I suppose that tattered edge did well on fresh fish flesh (say that 3 times fast!) but I'd hate to see what was left in the fish after he was done. I would never use any pull through on any knife I wanted to use.
 
The ceramic pull through I've seen leave a very thin, concave edge that performs well till the edge collapses - say after three cuts.
 
I usually try to sharpen my blades using sand paper. In the future I might buy myself a guided system such as a lansky, or maybe a rod-based system mile the Sharpmaker by Spyderco.

I've seen these pull through sharpeners in local camping shops. I think they might come in handy (when they're pocket-sized) for really dull blades when you're out in the field for a long time and you can't carry around a lot of tools. But even then, I think I'd rather have a small sharpening stone.

Anyway, my mom and dad use some other kind of pull-through in the kitchen. It's coated with diamonds and has two grits (medium and fine, but the fine is still quite abrasive). This sharpener has two diamond coated plates instead of rods and look's pretty much like this (it's even the same brand):
2cmoqh5.jpg


Is this kind of pull through any better in regard to the crossed ceramics pull through devices?
 
I can't really see how that works from the picture. It looks like it guides the edge past some abrasives. Most of what people are calling pull-throughs have either a ceramic or carbide rig crossing over...like a pair of open scissors...and they either scrape or abrade the edge lengthwise and they are pulled through. This thing seems a bit better conceived but you'd still be putting an lengthwise scratch pattern on the edge which is not desireable. There just is no real shortcut to knife sharpening. There are some ways that are easier than others but they all require skill.
 
zpavao said:
What about ceramic pull through systems?
Click to expand...

The ceramic pull-throughs won't likely rip or tear the steel at the edge like the carbide 'scraper' types. So, from that standpoint, they're OK. On the other hand, as with all fixed-angle pull-through sharpeners, results will vary widely if the set angle doesn't match the edge angle of your blade. Especially if the edge angle is wider (more obtuse) than the set angle of the sharpener. You'll only be grinding on the shoulders of the bevel, and the edge won't get touched. The flip-side to that is, if the blade's edge angle is much narrower than the sharpener's set angle. In that case, so long as it's done very, very lightly, it's possible to put a decent micro-bevel on the edge. But, if pressure is just a little too heavy, a lot of force is exerted on a very small portion of the edge, when it 'bottoms out' in the 'V' formed by the ceramic inserts. That makes it impossible to avoid dulling the edge.

The biggest problem I see with 'V' pull-through sharpeners, is the 'dead end' into which the blade edge is forced (at the bottom of the 'V'), combined with the 'scraping' done when it's there. The abrasion is applied directly against the cutting edge itself, as opposed to other sharpening methods which abrade the bevels only (if done properly). When you have that abrasion directly against the edge, it's easy to see why the blade can only get so sharp, and the really refined edges that other methods create are virtually impossible from a pull-through.

It's possible to put a 'functional right now' edge on a blade with pull-through sharpeners. But, there are much better ways to put excellent edges on a blade, which will also be durable.
 
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Theyre ok for slight touch ups when youre out... but not my preferred way of sharpening. I use one for my stainless fishing knives, or sometimes my mini griptilian if I have to. When I first bought my TOPS survival knife in 1095, my dumbass tried to put a new grind on it using a ceramic pull through sharpener... I learned what micro chipping was that day.
 
jaydon said:
i've heard that a pull through knife sharpener will put a brittle edge on a knife. just wondering if that is true
Click to expand...

Possibly. They are quick and dirty devices that generally get no love from knife nuts. But they do work. I've played with them, and they seem to work better/easier to use on softer steels. Harder steels/large carbide steels present greater challenge, with a tendency toward chipping.

Best results can be had if one understands precisely what is occurring during the process, and the sharpener is used with a subtle hand, so as to avoid excessive wear, chipping, burring, etc. IOW, prime results take some practice and skill, just like with a stone, or any other method.
 
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Use a Spyderco Sharpmaker, wet/dry sandpaper or regular stones instead. Pull through "sharpeners" are bad.
 
Carbide PTS's (pull through sharpeners) . . . yeah . . . best only to use those for things like a lawnmower blade. the ceramic are okay. some of the cheaper ceramic PTS's are complete garbage. your knife will actually break them, and by break, I mean wear away the so-called ceramic! something like Smith's is just fine. I keep one in my backpack for backpacking (if I actually need it) and it works like a charm. of course sharpening the 'right' way is always better but it would suck to have to carry around a sharpening system with you for backpacking and then of course they cost quite a bit more too if that is an object. Only two bad thing about the PTS's is the only offer one angle. which is okay for emergency, but really knives should be sharpened according to their use. not just one angle for all knives. and the second is that it is they can mess up a blade a bit if used wrong. Dont press hard on them even though it feels like its working better. It causes the blade to look like CRKT did micro veff serrations along the whole blade and then sanded them down half way on the sides.

Overall, good bang for the buck if you need it, but beware the downsides.
 
HoosierQ said:
I can't really see how that works from the picture. It looks like it guides the edge past some abrasives. Most of what people are calling pull-throughs have either a ceramic or carbide rig crossing over...like a pair of open scissors...and they either scrape or abrade the edge lengthwise and they are pulled through. This thing seems a bit better conceived but you'd still be putting an lengthwise scratch pattern on the edge which is not desireable. There just is no real shortcut to knife sharpening. There are some ways that are easier than others but they all require skill.
Click to expand...

It does exactly what you say. Instead of a V created by two rods, it creates a very long three-dimensional V shape. The red guides in the middle keep your knife levelled and they roll along with the blade while you pull the knife through. It does create grindlines opposite to the original factory grind, indeed. That's why I don't use it on my nices blades. I do tend to use it from time to time on one of my cheaper knives, and after only a few pulls, they can shave hair right off (8Cr steels).
 
Pull through type sharpeners are the enemy of all knives and if you believe them to be a usefully item then you edge-u-cation is in its primal stages. Regardless of the abrasive used in these type sharpeners you will always end up with a heavy burr formation to one side of the blade due to the orientation of the abrasive rods/plates/scrappers in the device.

The simple fact is they are awful for sharpening a edge and should be well known as such by knife enthusiasts that are part of a internet forum devoted to knives.
 
Throw that away and buy a Spyderco doublestuff for field use, its all you will need and it will help you learn freehand. The scissor analogy that Obseed with edges gave you is spot on, exactly what is happening to the edge. I would rather use a rock than a pull through
 
knifenut1013 said:
Pull through type sharpeners are the enemy of all knives and if you believe them to be a usefully item then you edge-u-cation is in its primal stages. Regardless of the abrasive used in these type sharpeners you will always end up with a heavy burr formation to one side of the blade due to the orientation of the abrasive rods/plates/scrappers in the device.

The simple fact is they are awful for sharpening a edge and should be well known as such by knife enthusiasts that are part of a internet forum devoted to knives.
Click to expand...

agree 100%. i found out the hard way, by buying some and trying to use them years ago. i realized very quickly they are pretty much useless....but someone should tell benchmade......;)

http://www.benchmade.com/products/983902X
 
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