Serrated knife sharpening wheel

[Garrett47]

I saw an announcement earlier today about new Tormek wheels for sharpening serrated knives. Where can I get more info? I looked at the website and did a search but couldn't find anything. Any guidance appreciated.

[tgbto]

Wow, a triangular wheel ? With a dual-MB102 "spaceship" contraption for truing it ? Or with a diamond-coated apex ?

[Ken S]

Garrett,

I saw what I believe is the same wheel for sharpening serrated wheels on facebook. It is actually a Slipakniven product, not Tormek. I don't know anything about it, although I have had success with the few peoducts I have ordered from ẞlipakniven.com.

Ken

[tgbto]

So this is actually a thing, even though not a Tormek thing...

Still, there are two fundamental issues with such wheels :
- If the wheel is noticeably wider than the serrations of the knife (as seems to be the case in the pictures on their website), then the result will be rounded out teeth and untouched "valleys". If the wheel is noticeably narrower than the serrations, it will be fragile *and* will cut aggressively.
- How do you restore them when they wear down ? I guess one could use diamond plates and aim for a triangular shape, but it will be fidgety.

IMO, a thin triangular or cylindrical rod used either freehand or on an edgepro-like system will make for a much more controlled process and repeatable results. Along with a flat benchstone for the backside.

[sharpening_weasel]

Is that a tormek subsidiary? How is that site and manufacturer up and running? Don't get me wrong it looks like they sell great tools, but it seems a little more officially making use of tormek intellectual property than, say, the late and great Wootz/Knife grinders AU.

[Thread Killer]

It is out of stock (too popular?)........ Waiting for an email. It beats using the edge of the wheel, I would think. BTW It is slipakniven,com not blip.
https://slipakniven.com/product/grinding-wheel-set-for-serrations/

[3D Anvil]

Interesting product!  I think these would also be quite useful for sharpening recurve knives.

[tgbto]

I hope I got that kind of basic math right, but I'll wager "R7" means a diameter of 14mm.

So for all knives with serrations spaced less than 14mm apart (which incidentally means all of my bread and frozen food knives), this wheel will grind the apex of the teeth and not the space in between the teeth.

[3D Anvil]

I hope I got that kind of basic math right, but I'll wager "R7" means a diameter of 14mm.

So for all knives with serrations spaced less than 14mm apart (which incidentally means all of my bread and frozen food knives), this wheel will grind the apex of the teeth and not the space in between the teeth.

14mm is .55", which seems about right for most bread knives.  I know that Cliff Curry sells a 6" by .5" CBN wheel for bench grinders that he recommends for bread knives.  Of course that's going to be more for cutting in new serrations as opposed to touching up existing ones.

Anyway, I'm going to order a pair of the SlipaKniven wheels when they come back in stock and will report back.

[tgbto]

14mm is .55", which seems about right for most bread knives

Well my typical bread knife is akin to this one.

It has 35 serrations in less than 8.25", which is at most a .24" pitch.

On this other one, it looks like a .25" pitch at best (31 serrations in less than 8").

For both, the wheel will ride on the teeth.

Wolfgang demonstrates using the edge of the wheel with what looks like a 3-ish mm corner radius, which seems more like it. Typical triangular ceramic rods have an even higher curvature.

[RichColvin]

I recently got a grinder used to sharpen a chainsaw's saw chains.  The grinding wheels used to sharpen the cutters are thin and rounded on the edge.



The two sizes most typically used are 1/8" and 3/16" wide.  They are only 5" in diameter, so I don't think they would work on the Tormek, but possibly they would work on a different style grinder and grind them by hand.

These are available as traditional grindstones (many types), CBN, & diamond.

[3D Anvil]

14mm is .55", which seems about right for most bread knives

Well my typical bread knife is akin to this one.

It has 35 serrations in less than 8.25", which is at most a .24" pitch.

On this other one, it looks like a .25" pitch at best (31 serrations in less than 8").

For both, the wheel will ride on the teeth.

Wolfgang demonstrates using the edge of the wheel with what looks like a 3-ish mm corner radius, which seems more like it. Typical triangular ceramic rods have an even higher curvature.

Yeah, those are smaller serrations than the ones on the Mercer bread knife I'm using.  I looked at a couple others we have and they are smaller.  I guess you'd need at least two sizes to cover all the bases.

[tgbto]

Plus I realized afterwards that a serration is not a half-circle, but rather a portion of it, so the diameter can be wider than the pitch.

I measured my ceramic rod that just barely fits inside the serrations of a Wüsthof bread knife. It is 8mm in diameter.

[RickKrung]

Plus I realized afterwards that a serration is not a half-circle, but rather a portion of it, so the diameter can be wider than the pitch.
...snip...

A radius gauge set, like below, is the right tool to measure the serrations. Match the curvature of the gauge to any portion of a internal or external radius and read the measurement from the stamped markings. 

[Ken S]

I have problems seeing the practicality of a specially shaped wheel for serrated knives.

With chisels and plane irons, the same grinding wheel can be used to sharpen the entire range of these. This is not the case with serrated knives. Even with bread knives, where  a given knife will have uniform size and shape of the serrations, I know of no standards for bread knives. This is even more problematic with more tactical knives which may have more than one  size serration on the single blade.

How many grinding wheels would be necessary to "cover the waterfront? Unless these wheels were diamond or CBN, each wheel would require its own dressing tool. How much total cost would be involved? How many serrated edge knives would be a realistic expected volume? What would be a realistic surcharge for serrated knives?

I have a Henckels bread knife which I have sharpened. My tapered DMT round diamond file can sharpen it, although my results have been very uneven. I only used it once for that purpose. My best results have been with using a wooden dowel wrapped in wet and dry abrasive paper. I have used both self adhesive and regular abrasive paper held in place with Scotch tape. Both seem to work equally well.

With the knife resting against a table, sharpening knives one serration time does not require much time and the "tooling cost" will be minimal. if an in between diameter dowel size is needed, a little sanding is all that is necessary for a custom size.

Ken