We have discussed serrated knives before, and using both Jeff's technique and a slightly modified Jeff's technique (buffing more on a true buffer, rather then the leather wheel), I feel pretty comfortable sharpening them now. What I realized this week, when sharpening about a dozen old ones ("recently found") from my friends restaurant, as well as a chef's knife, is what I am not happy with, is the way to test.
The Chef's knife, I wasn't 100% happy with, as I think that is just more practice needed (didn't quiet get the grind even on both sides for my taste). But it cut paper extremely well, didn't take long to do, and made the user very happy. It was testing with paper I realized that doesn't work well with serrated knives.
Serrated knives have points when new. As they get used quite a bit, the points wear away, and they become more of a scalloped (think bread) knife. Now granted, I don't go out and buy Tomato's and onions as test materials (what they are most used for in their place), and they seemed to like the way it cut them. Where my unhappiness lies, is I have been able to use a tapered diamond hone to effectively repair serrations towards the tips. but I can't make new points on a well used knife (now scalloped). Points tell me it is sharp. Since serrated knives can't really slice paper, but may do more of a tear cut, I never feel comfortable with my work.
In my thoughts, I am wondering if Stevebot, tells how he tests those in his video?
SADW, I have no simple solution, but can offer my idea for testing and further research and development. ;)
Prepare a paper roll by winding up a few turns of office paper around a tube of suitable diameter. Remove the tube and secure the paper roll to unwind. Attach two heavier magnets to the tip of the knife to be tested to simulate some constant cutting force.
Now try to perforate the paper roll by the tips of the serrations. If you've been successful unwind the paper roll and determine how many layers of paper were perforated. This figure could serve as a measure of tips performance. :)
The idea is provided without any guarantee because I do not have suitable knives for its more thorough testing.
Jan
@Witt Nothing on my video, alas. Today I would use my PT50 tester or its primitive predecessor, a loop of thread on a spring scale.
My video on sharpening serrated knives is not on-line
https://www.youtube.com/watch?v=059JiOcum84
Unfortunately it was made before I had F. Dick make a serrated knife sharpener to my design. The RS-75 SERR will sharpen all serrated knives with 8 or less serrations per inch, including CUTCO.
On youtube there is Richard Blaine video "How To Sharpen A Serrated Knife Blade", which mentions standard paper slice test also. (At min. 11:50)
https://www.youtube.com/watch?v=9dUb4z7JC8M (https://www.youtube.com/watch?v=9dUb4z7JC8M)
Jan
Jan, thanks for the video link. There is one of the knives that they sent, that I was able to sharpen, but IMHO, it was close enough that I considered converting it to a standard edge (the knife is nearly identical to the companies stiff blade fillet knife).
Points make it easy to tell, it is more the in between stages where the problems for me lie (and they tend to like to wait before buying a replacement.) Just a different technique with a serrated knife.
Now they have a pretty decent stock of sharp ones (around 30), of their most used utility knife (multiple people, some younger ones, and one owner who tends to abuse knives ). I guess I don't use that style knife as a "utility" knife much.
So different from what I consider a generic type restaurant, to the chef's I know, that have their own knives and if someone reaches for one of them, tends to get cut. I may have talked the restaurant into the T4.
Steve, I will be ordering your video's pretty quickly (getting some reimbursements from work). While work stabilized, (medical issue of owner, then some equipment issues), plumbing emergency took my fun money so I didn't hit emergency fund. I need to build that back up, while thinking do I really need another Tormek, verses just getting another stone.
The serrated knife I have is flat on one side. I reground that side & it works wonderfully.
Quote from: RichColvin on July 23, 2016, 12:11:14 AM
The serrated knife I have is flat on one side. I reground that side & it works wonderfully.
That, along with applying the scallops to the corner of the honing wheel, is the method recommended by Jeff Farris.
I did that so many times with mine that I finally had to take a round file to the scallops. They had just about disappeared. I then made a honing wheel out of a piece of quarter inch plywood and applied some valve grinding compound.
Hate the serrated knifes :)
OK I don't have any feelings for them.
Almost every client have dull serrated knifes. They ask for sharpening and I tell them it depends on the profile of serration. Some I do and some don't.
But to the profiles I do I give 2 alternatives. I either send them to a friend that do each tooth with Dremel. He got lots of patience for it, or I tell dem I can do it my way.
I sharpen the teeth half way making the blade with small straight edges combines with arches that make the knife very sharp and dangerous. I tell them that it can be done only once, sometimes twice. then they have to decide to either have a straight edge or reshape it to the former shape.
Sorry I don't have pictures of it but will do some next time and upload.
Quote from: Herman Trivilino on July 23, 2016, 02:00:30 AM
Quote from: RichColvin on July 23, 2016, 12:11:14 AM
The serrated knife I have is flat on one side. I reground that side & it works wonderfully.
That, along with applying the scallops to the corner of the honing wheel, is the method recommended by Jeff Farris.
I did that so many times with mine that I finally had to take a round file to the scallops. They had just about disappeared. I then made a honing wheel out of a piece of quarter inch plywood and applied some valve grinding compound.
That is where a couple of these are getting. (scallop still there, but the points are not mountains, but bumps)
They are also not that expensive (around $12), and made in the USA. But there really isn't point in spending money when there is life left with a little help.
Quote from: SharpenADullWitt on July 23, 2016, 03:38:49 PM
That is where a couple of these are getting. (scallop still there, but the points are not mountains, but bumps)
They are also not that expensive (around $12), and made in the USA. But there really isn't point in spending money when there is life left with a little help.
I know what you mean. Mine is a cheap Ekco. It's just that my wife remembers us having it since before we were married 34 years ago. So it's still in the knife drawer. Along with the Victorinox I bought a year or two ago.