Work Sharp’s Ken Onion Knife & Tool Sharpener Review–maintaining the sharpest tools in the shed

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The first thing that popped into my mind after meeting Ken Onion is that he’s a man who has truly embraced his ikigai.  By my reckoning, a great deal of Ken’s life has been influenced by all things Japanese so I felt the best way to describe him is through a concept central to the Japanese culture. In Japan, finding your ikigai is akin finding your mission in life. In short, it’s the reason why you get up in the morning.

Ken Onion’s ikigai is all about creating and designing high quality, functional knives. His enthusiasm is infectious and his design acumen, iconic. He was inducted into the Blade Magazine Cutlery Hall of Fame at the 2008 as the 45th and youngest living member.

Ken in action
Ken Onion in action grinding away at his Oahu workshop

Thus when Ken Onion associates his name with a product, you know you’re going to get something of high quality. When I came across the Work Sharp Knife & Tool Sharpener–Ken Onion Editon, I knew this would be something I’d want to look at for my readers.

Darex is a family owned company out of Ashland, Oregon which produces high end industrial bit sharpeners and DIY drill bit sharpeners. They have been in the commercial sharpener business for decades and bring the same industrial strength class of products to the consumer. Its current CEO, Mathew Bernard, is the fourth generation family member to run the show.

I had the rare opportunity to do a test and evaluation of this product on Oahu with Ken as my instructor.  (Luckily we live on the same island).

Work Sharp Knife & Tool Sharpener

The feature I like best about this product is that it’s designed to sharpen every knife and tool that you own.

Think about that for a second.

I would suspect most people who are reading this article own kitchen knives, pocket knives, axes, scissors, and even a machete or two. With so many implements around the house and workshop that need ongoing attention, I would also suspect that many of these items may not have the best edge to them at any particular moment. The great thing about this product is that you can easily put an professionally sharp edge on any blade you own—including items such as garden shears or lawn mower blades.

ckise up
Placement of knife on the sharpening guide puts the blade at an angle that will produce a convex edge.

At the heart of the Ken Onion system is a handheld device that combines flexible belts, a variable speed motor and a precision guide to place the blade. The sharpening guide is fully adjustable in 1° increments from 15° to 30° which provides you with the option to sharpen your instrument – whether a pocket knife or butcher’s cleaver at the precise angle that will best suit your needs. (For example a pocket or outdoor knife is best sharpened at a 25° angle whereas a kitchen or fillet knife should be sharpened at 20°).

The motor has variable speed control (1200 SFM to 2800 SFM) so that you can readily keep the belts running at the optimal belt speed for the task at hand. It also has trigger-like button that will allow you to control the speed as if you were running a drill.

The 3/4 x 12-inch flexible belts provided for the unit are from a company called Norton Norax and are the same standard that you’d find in a machine shop. They come in five flavors–P120 Extra Coarse; X65 Coarse; X22 Medium; X4 Fine; 6000 Extra Fine. They are perfectly suited to take care of your sharpening needs.

Techniques and Controls

Ken says the flexible belts are preferable for sharpening because they create a convex edge which is both strong and sharp. This contrasts with most knife sharpeners which form a flat bevel on a blade. Essentially with a conventional sharpening tool the edge gets thicker when resharpened. Consequently, when the knife is used to cut meat or produce it creates more friction than with a thinner blade. What you want to do says Onion, is to emulate the type of convex edge you’d find on an axe which will last longer than a “flat ground” sharpened edge.

Kitchen knive
Ken shows how to place the knife on the blade belt. Keeping the edge perpendicular to belt is key.  

Using the unit does take a bit of practice but it’s not rocket science. Technique can be acquired after a few sessions and there is an excellent instructional video available.

There are several key components to familiarize yourself with. The motor’s speed can be manually regulated with a trigger type control or adjusted to run at a set speed with a variable speed dial.

You will want to use lower speeds for knives and higher speeds for tools such as mower blades. To set the cutting angle you simply turn a knob and adjust to the angle you want. The kit includes a tool chart to determine the right angle for the job.

When sharpening a blade, all you do is place the knife on the bottom, outside edge of the guide slot and use the edge guide to position the blade. The blade should be held in place with very light touch—the weight of the knife should provide enough pressure to do the job. This point can’t be over emphasized. (If you put too much pressure on the  edge, especially with a very coarse belt, you can do damage to your knife).

choosing the right belt
Choosing the right belt is part of the process. Five different belts are offered in the kit.

You begin the sharpening process by powering on the machine and with light pressure, steadily pulling the blade through the guide at roughly a one inch per second. You’ll want the edge of the blade to be perpendicular to the belt. The idea is to raise a burr, which you can feel by stroking the blade from the top side to the business edge—side to side. Generally with four to five passes with the reddish (coarse) belt you’ll be able to raise the burr.

Once you’ve created a burr you’ll want to repeat the process on the other side to create a second burr. After creating the burrs you can strop it with a finer belt. At the shop, Ken used a honing compound on the belt but this isn’t obligatory. Note that it’s simple to change the belts—just rock a small lever on the belt drive and slide the new belt into place.

You can also sharpen serrated knives with a very fine belt by placing the flat side along the belt. Note that you’ll do the opposite with scissors—you’ll want to place the flat side of the scissors on the guide, rather than the belt.

For tools, such as axe heads, you’ll need to remove the guide. It’s made from a strong polymer and snaps in and out of a small housing. Once removed, twist the edge guide out of the way and swivel the cassette that houses the belt to a horizontal position. You’ll want to use a higher speed for tools.

Upgrading to the Blade Grinder Attachment

For most folks’ needs Ken said his standard Tool Sharpener will be fine. However he was insistent that those who want to “up their game” should seriously consider getting the additional Blade Grinder Attachment.

KO grinder in action
Ken believes the best upgrade to his system that you can possibly get is the Blade Grinder.

Why upgrade?

Mr. Onion flat out says that this attachment is the closest thing you’ll find to the belt grinders that professional blade makers use. This is a four-pulley attachment which is adjustable from 10 to 35°, thus providing more options for the end user. The belt size (1″ x 18″) is larger and wider which makes it more efficient to do the job. Four different belts are available with the Blade Grinder device.

Practically all the time I spent with Ken at his shop was in front of this attachment. The Blade Grinder has a large base with makes it quite stable. Thus you can adjust the grinder to run at a steady speed and use both hands to manipulate the blade, as you would on a professional unit. Ken demonstrated how quickly one can sharpen tools with this attachment. Like a production line, he had a number of my kitchen knives on the bench and proceeded to dispatch the lot of them in no time.

He illustrated this by holding the one end of the knife as if grasping a rail and, with the other hand, gently placing the tips of his fingers on the blade. He placed the blade on the horizontal edge guide to ascertain the correct angle. He then positioned the blade at the same angle on the belt, between the two upper pulleys, where the grinding takes place. The next step was to slowly and steadily glide the blade’s edge along the belt at one inch per second.

The upshot: This attachment provides an even wider range of flexibility to custom shape, sharpen and hone your blades than the stock Ken Onion Tool Sharpener. You’ll need to establish a bit more technique to use it but I think the rewards are well worth it. Ken said that he knows of several people, who with the benefit of this attachment, have begun their own knife sharpening businesses.


It takes an effort to keep your utensils in working order but I discovered how much easier (and even fun) this is when you have the right sharpening tool at hand. This system, especially with the blade grinder attachment, is a no-brainer for anyone with a large array of tools.

I could well imagine that in addition a home or shop use, this system would also be invaluable for a restaurant or even a surgeon’s who needs to keep in scalpels razor-sharp.

The only downside for a non-workshop setting, such as a kitchen, is that a grinder by definition will create dust, so when sharpening the sous chef’s arsenal of kitchen knives you’ll need to work in an appropriate spot.

The Work Sharp Ken Onion Edition is available on Amazon for just under $130. The Blade Grinder sells separately for $80. And yes…this would be a great holiday gift.

One last comment. The customer service at this company is first class. You’ll not be kept on hold for long (if at all) and any questions you have will be deftly answered. Maybe I’m bias because I used to work near Ashland while in college, but there is something very positive about the corporate culture of Darex and it’s reflected in the attitude of the employees.


I’ve had this product going on seven years. It’s all it’s cracked up to be. For the most part, the only thing I had to even do was replace sanding belts after they were worn out. I have nearly two acres of garden that needs constant attention so tools, such as my bush knife (as we call them in Fiji) need to be sharpened on a regular basis.

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My trusty Fijian bush knife and my garden always need attention. Time for a sharpening is long overdue.

Of course the knives in the kitchen also need constant care.

This has been a wonderful tool. However there was an issue recently. The flange on the powerbase that connected to the blade grinder cracked a few weeks ago. That meant my trusty tool sharpener was out of commission. It was also out of warranty. I contacted customer service at Work Sharp Tools and they replaced the entire powerbase. I wasn’t really expecting that and suffice it to say, I was very pleased. In short, a great product and great service.

Rob Kay, a Hawaii-based author is the creator of FijiGuide.  

Photos courtesy of On Target staff and Darex.

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