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View Full Version : How to sharpen a knife with the right tools?



Peter.
10-09-2011, 04:57 PM
I bought an EZlap off eBay and it came with two round sharpening rods. One is a light grey diamond grit tool in a pen style and the other is a finer dark grey rod in an aluminium tube with a screw cap.

The EZLap is great - I use it for dressing every HSS lathe tool and it gives great finishes.

I've had a couple of tries at sharpening knives with the two round rods and pretty much failed miserably compared to my expectations. One is a small kitchen vegetable knife and the other an old pocket knife. I did manage to improve the cutting edge on both but found that it was more by accident than anything, often I would just put a burr on the opposite face. The kitchen knife fared better but then the blade was harder so I guess that makes a difference,

Clearly I'm doing something wrong, so could someone run through the basics of using these round tools to sharpen blades? I'd also like to hear why there is a fine groove running down the sharpening rod.

gwilson
10-09-2011, 07:09 PM
The groove is for fish hooks.

You need to get a proper set of stones for sharpening. Diamonds are going to leave a sand papered,fairly rough edge.

I use a diamond bench home for the initial job of getting rid of grossly dull edges on knives. Then,I use a black Spyderco ceramic stone. Last,a fine white Spyderco ceramic stone. Then,a strop of leather with green chromium oxide buffing cxompound. Some use a strop made of MDF with the compound on it.

The white stones sometimes come with some ceramic fuzz left on them. I scrub them off with the diamond stone and water to frequently rinse.

This is the setup I have arrived at after trying many stones. It gives a truly razor sharp,polished edge. The initial diamond hone really speeds up the process of getting flat spots and little nicks off the blade to begin with.

armedandsafe
10-09-2011, 08:00 PM
If you are turning a burr, I suspect you are using too much pressure. Diamond shapers/sharpeners require a light touch, only. Knife sharpening is much easier with flat hones, although not impossible with a round hone.

There are many aids out on the 'net, most of which explain it very nicely. I like the Buck and the Bob Kramer how-to pages. There are many videos on youtube, also. I haven't vetted them all, but most are pretty good in explaining how.

http://www.buckknives.com/index.cfm?event=about.sharpening
http://www.buckknives.com/resources/pdf/Buck_Knives_Knife_Sharpening_Instructions.pdf
http://www.kramerknives.com/sharpening.htm

Note that almost all instructions talk about "turning a burr." While you can sharpen without turning the burr, it is much easier if you do turn the burr and finish by pulling just the burr off.

I use the Lansky and Smith kits most of the time, and fine tune the edge with the diamond hone in the field. I do have a two sided hone and a couple of Arkansas stones. My method, which is not common, is to put a fairly wide, shallow angle edge all the way down the blade, then run a fairly steep angle on the edge of that. That two-step edge works best for me but is not liked by everybody. The shallow angle slope is about .1" to .15" wide. The steep slope is about .04" to .05" wide.

This does not show exactly what I'm describing, but might give you the idea.
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To do a quick test on the edge, rest the edge lightly on your thumbnail, vertical to <10* from vertical. If it catches as you slide it sideways, that portion of the blade is sharp. If it scrapes but chatters, it is not yet sharp enough. If it slides smoothly, it is dull.

Some instructions will tell you to always run the edge of the blade into the hone. Others will tell you to always run the edge away from the hone. Either works, if you use a bit of care and attention. Running the edge into the hone is faster, eats more metal per stroke. Running the edge away from the hone is slower, eats less metal per stroke. In either case, you don't need nor want to put too much pressure on the hone. Pressure of 4 to 6 pounds is for creating a new edge. The weight of your hand is enough to fine finish the edge.

Pops

Peter.
10-10-2011, 01:50 PM
Great, cheers for the links. I'll have a read through them.