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Keeping the knife bevel straight

Started by Brosenfeld86, August 30, 2013, 09:29:25 PM

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Brosenfeld86

I've been sharpening knives on the tormek for a while now, and sometimes I have a difficult time keeping the bevel perfectly straight. I've messed up the geometry a few times, I've been able to re-straighten the bevel but only after taking off a lot of material. Any suggestions on how to keep it perfectly straight during sharpening as to avoid having to take off a lot of material? Thanks!

Herman Trivilino

Origin: Big Bang

mike40

Looks very good Herman, but I have already purchased the small knife jig that. It will be interesting to see how well it works for small knives (I haven't tried it yet). I don't have a machete so I'm not too worried about really big stuff. Have you tried the small knife jig?
Mike

Brosenfeld86

Perhaps some advice using the regular knife jig? Any advice on reshaping? It seems that it's very easy to be left with an uneven edge while sharpening knives, especially kitchen knives.

Ken S

Make sure you use the fine side of the stone grader thoroughly before you begin.  Then go lightly.  Spend more time where you need to grind more.

Stig had a good post recently; you  might want to find it.

Ken

Herman Trivilino

#5
Quote from: mike40 on August 30, 2013, 10:44:33 PM
Looks very good Herman, but I have already purchased the small knife jig that. It will be interesting to see how well it works for small knives (I haven't tried it yet). I don't have a machete so I'm not too worried about really big stuff. Have you tried the small knife jig?

No, Mike, I haven't tried the SVM-00 small knife holder.  It came out just after I made that video.

Origin: Big Bang

Herman Trivilino

#6
Quote from: Brosenfeld86 on August 31, 2013, 12:52:41 AM
Perhaps some advice using the regular knife jig? Any advice on reshaping? It seems that it's very easy to be left with an uneven edge while sharpening knives, especially kitchen knives.

It takes practice to be able to use the SVM-45 knife jig.  I recommend that you watch the videos made by Jeff and the other pros at Tormek.  Practice on cheap knives.  Keep the knife moving from side to side and feel for the burr.  On some steels it's very difficult to detect the burr by feeling, so good light is a must, and magnification helps.  I wipe the knife across a rag and check to see that the burr has snagged threads from the rag along its entire length.

If you do mess up and the knife requires reshaping I recommend that you clamp it in a bench vise with the edge facing upwards and run a file along it until its concave everywhere along the edge.  Then go back to the Tormek and try again.

Make sure the stone is graded fine.

I don't like to sharpen knives on the Tormek that have a grind, or secondary bevel.  Whenever I buy new knives I make sure the blade is flat all the way to the edge. 

In my opinion, the jig I demonstrate in the video is very much easier to use, but that's just my opinion.


Origin: Big Bang

Stickan

I have been sharpening a lot of knives on  the Tormek and the first times this happened to me too.
The thing is, even if the knife is "scary" sharp, you want it to look good. You want that bevel line to be perfect.
On some knives this is tricky but in general, you can sharpen almost any knife with the right technique. 
Jeff Farris shows his technique in this old video, (old because now the jigs are modified and the SVM-100 is now a SVM-140)

http://www.youtube.com/watch?v=fYURcwkKGPs

and if you watch 5 minutes in this movie you will see that he lifts up the knife instead of follows the knivesĀ“s curve on the stone.
Doing this you will have a perfect edge bevel.



Herman Trivilino

#8
That video is great, and is still up to date despite the fact that he's using the older green-colored Tormek machine.  The knife jigs shown still have the same names (SVM-45 and SVM-140) despite the fact that their design has been modified slightly (they no longer have the lock-down screw).

I find that I can get the fine adjustment of the bevel angle by simply using the micro adjust on the Universal Support instead of the micro adjust on the handle of the SVM-45, anyway.

The knife used in that video is a Victorinox knife, makers of the famous Swiss army knife.  I have one just like the one shown in the video, they are inexpensive and of good quality.  Jeff recommended the purchase, and so do the folks at Cook's Country (a PBS show).

A few things about the geometry of that knife that make it ideal for Tormek sharpening.  It has no secondary bevel (also known as a grind, taper, or wedge).  This means that the sides of the knife are parallel all the way across the blade, until you get to the place where the cutting edge is ground.  This makes it easier to measure the bevel angle.  Secondly, that knife has no bolster, which makes it easy to grind all the way to the heel.  And finally, the edge is convex along its entire length, making it easier to avoid the mistake of grinding the edge to a concave shape.

When I shop for knives I look for all of these features.
Origin: Big Bang

Ken S

Most of my knives have bolsters.  I'm a reader, and read that the bolster was a sign of a well made knife.  I still believe that, however, I have come to the conclusion that the guys who like the bolsters are those who use the knives, rather than sharpen them.  If I were buying a knife today, I would be very tempted to buy one without the bolster.

Stig is right on about the importance of a knife bevel looking right.  Jeff is correct in lifting the knife to keep the bevel consistent. Jeff's videos are an excellent training aid.  I wish you would continue making them, Jeff.  As much as I enjoy books, the videos are very effective learning tools.

Ken