After exhaustive testing of more than 15 of the top rated knife sharpeners on the market we've found the Apex knife sharpener from Edge Pro to be the best knife sharpener for the widest variety of knives.
With the capability to sharpen blades up to 3 inches wide at any angle between 10 and 30 degrees it offers a great deal of flexibility.
It is extremely well-made and solidly built. The operation is simple to use for even a novice, and it will quickly sharpen even your dullest knives back to a factory edge.
Stop Using Dull Knives!
Using a dull knife to cut your foods can be both frustrating and dangerous. A dull knife requires more pressure to cut and change directions, slowing you down and potentially causing serious injury.
After spending nearly 40 hours researching and testing various sharpeners in our kitchen, we've come to a couple conclusions:
- You need a tool that can sharpen a wide variety of knives with different blade angles.
- Your sharpener should operate in a manner that doesn't destroy the tempering of the steel blade.
This insures both a sharp blade and a long life for your knives. Keeping this in mind, here are our picks for the top 7 best knife sharpeners on the market.
7 Best Knife Sharpeners
1. Edge Pro's Apex Sharpening System (Best Knife Sharpener)
The top spot in our comparison goes to the Apex 1 knife sharpener. Here's what makes it the best.
- Infinite angle selection between 10 and 24 degrees
- Simple-to-use manual operation
- Small, lightweight, and easy to store
The first thing that you will notice is this is not an electric sharpener. The reason for this is simple.
While electric sharpeners do offer speed, they can very easily damage the temper of the blade of the knife by heating it too much.
This is due to the fact that all electric models use the same method for sharpening knives. A set of grinding wheels rapidly spins and removes material from the edge of the blade. This causes friction that heats the knife and weakens it so it will never truly be as sharp. So with one pass through an electric sharpener you can literally RUIN a knife.
In addition to damaging the blade there are other disadvantages to electric sharpeners. First and foremost they typically allow you to sharpen your knives to only one angle. Both the angle of the blade and the hardness of the steel are crucial design components of any knife. These should NOT be changed.
The manual operation of the Apex 1 means that it doesn't generate heat and will NOT impact the blade temper. This will extend the usable life of your knives. And since the blade angle can be set to anything between 10 and 24 degrees, you can precisely match the existing angle of your knives.
The build quality of the Apex System is extremely high quality and is designed to last. The operation of the knife sharpener is smooth and consistent, ensuring a razor sharp edge along the entire length of the blade.
The system can sharpen anything from a small paring knife to larger knives up to 3 inches wide.
Built-in stops insure that you won't cut yourself as you get used to the operation of the sharpener. With a little practice you can sharpen knives to a keener edge than what they had when they shipped from the factory.
- Flexibility to match any bevel angle
- Manual knife sharpener protects the tempering of your blades
- Can sharpen a wide variety of knives
- easily sharpens Japanese (one-sided), Western-style knives, and even serrated blades
- manual operation requires a bit of practice and is a deterrent to consumers
- longer slender knives such as filet knives are challenging
How it Works
The Apex system was designed to be extremely easy to use, quick to setup, and easy to store. As a professional knife sharpener, the inventor was looking for a way to speed up the process of using sharpening stones to restore a sharpe edge to his customers blades.
Suction cups on the bottom allow the sharpener to be anchored to any smooth surface. There's also an optional glass platform that can be used to create a base for the knife sharpener. If you want to permanently attach the sharpener to a work station the suction cups can quickly be removed.
Unlike the other knife sharpeners on the market, the Apex doesn't use a clamp to hold the knife in place. Instead they use a guide to hold the knife in place. This guide is what allows the sharpener to work on such a wide range of blade sizes. There are no real length restrictions, and it can accommodate blades of up to 3 1/2" tall.
There a markings to quickly allow you to set the sharpener to the most common blade angles, but you can set anywhere between 10 and 24 degrees to exactly match your knives.
Included with the Apex 1 Kit
- Apex Model Edge Pro Knife Sharpener
- 220 Grit Medium Fine water stone
- 400 Grit Fine water stone
- Micro-fiber Towel
- Water Bottle
- Instructional Manual
- Black Cordura Carrying Case
Additional accessories can be purchased for the Apex 1 system or you can opt for the 2, 3 or 4 kit. These differ based on the number of stones, stropping attachments, and other accessories.
Our Final Thoughts
Understandably the manual operation can be a turn off to some folks, but the EXTREMELY simple operation of the sharpener is very easy to master. The Apex system will sharpen knives to a level beyond how they ship from the factory. The smooth, manual operation of the sharpener protects the temper of the knife and creates a consistent edge along the entire length. It is far and away our pick for the best sharpener on the market.
2. Kitchen IQ Electric Knife Sharpener
If you're dead set on purchasing an electric model the best choice out there is the Kitchen IQ electric adjustable sharpener. Why does this sharpener get our nod for best electric knife sharpener? Three reasons
- Flexibility - angle adjustment allows you to maintain the factory bevel
- Consistency - pressure is evenly applied using a patented grinding wheel system
- Speed - the Edge Pro electric knife sharpener is as fast as any unit on the market today
The ability to set the sharpening angle is huge. Knife manufacturers choose their blade angles based on the strength of the steel. Changing this can shorten the life of the knife.
The KitchenIQ has a simple-to-use dial that allows you to quickly and easily set the bevel angle for each knife.
- Quick angle adjustment dial
- Can sharpen a wide variety of blades
- Quick and simple operation
- Still possible to damage the tempering of the steel
- Extended usage can lead to overheating necessitating a cool-down
What We Like
The angle knob allows for quick adjustments based on the type of knife you're using with the sharpener. It's clearly labeled for anything from paring knives to pocket and hunting knives.
Includes a serrated knife sharpener that pulls out from the side of the unit.
Superior flexibility and still competitively priced. Even with all it offers, it's still one of the best priced electric models out there.
This helped land it the #1 spot in our best electric knife sharpener comparison.
What We Don't Like
While we love the feature set of this knife sharpener, we still have one big complaint. The spinning discs generate friction which will heat the blade as it is sharpened. This will eventually cause a weakening of the steel and shorten the life of the knife. That said, we would consider this sharpener the lesser evil.
During heavy usage the Edge Pro tended to heat up. This only happened when we sharpened for 15 minutes or beyond and by that time we were well into our 6th or 7th knife. If you're only using the sharpener with a few knives at a time this shouldn't be a problem.
Our Final Thoughts
The Adjustable Edge Pro from Smith's has it all. You can sharpen your knives at any angle you like between 10 and 30 degrees. This reduces the amount of material removed by the knife sharpener and extends the life of your knives. In a matter of minutes you can restore all your knives to a razors edge.
3. KME Knife Sharpener
The KME is another fine sharpening stone based system. It differs in operation from the Apex in that the knife is held in place via a clamp system. This clamp rotates 180 degrees allowing you to quickly sharpen both sides of any knife.
The KME system includes a set of sharpening stones, but just about any standard 4" sharpening stone will work with this knife sharpener.
The angle can be adjusted to anywhere between 17 and 30 degrees. To change it, you raise or lower the sharpening rod to the desired position and then lock it into place.
A layer of neoprene is used on the clamps to ensure there is no damage to the finish of the knife while it is firmly held in place. There are two different settings on the clamp to allow for both larger and smaller blades. To lock the clamp on the knife you simply tighten the thumb nut to the desired level.
There are a couple different options for sharpening stones. The diamond series includes a coarse, fine, and extra fine set of stones. These will work for anything from minor repairs to damaged blades to finely honing a keen edge.
How it Operates
After locking the knife in place you will need to select the stone you wish to use and place it in the sharpening rod. To tighten the stone in place simply tighten the supplied thumb nut.
Next you'll slide the rod into the ball joint that is housed in the angle selector. The ball joint is an improvement that allows for smooth travel of the stone along the entire length of the blade.
After performing a few passes with the stone you'll want to flip the knife and perform a few passes on the opposite side. This is quickly done with the rotating knife clamp.
Once you've created a good bevel you can move on to the next higher grit stone. Repeat until you reach the desired sharpness.
For serrated blades KME offers a tapered rod attachment that can be purchased separately. This rod utilizes a diamond infused substrate insuring a long life.
Other accessories include a honing rod system for recurved blades as well as stropping stones for even more refined sharpening.
- flexible design that is easy to use
- knife clamp flips 180 degrees so no reclaiming
- compatible with most 4 inch stones
- clamp struggles with unusually shaped blades
- base should be more stable
The KME knife sharpener is a top notch product made with quality components. The instability of the base (for which you have to pay extra) is our biggest complaint. We'd like to see a lower setting than 17 degrees. Combined with the lower price and added stability the Apex just outperforms it.
4. Chef's Choice Angle Select
The folks at Chef's Choice have been a mainstay in the knife sharpener world for quite a few years now. While the Angle Select is a solidly built knife sharpener, it doesn't offer the same options as the Edge Pro when it comes to choosing a sharpening angle.
Instead it offers 2 different sharpening angles: 15 degrees and 20 degrees. Like many sharpeners in this category it uses diamond impregnated abrasive wheels to accomplish sharpening and honing.
One nice feature of this sharpener is that it only sharpens one side of the knife at a time. For that reason it can be used on both Western and Easter (Japanese) style knives.
While it has three slots, it is technically a 2 stage sharpener. Slot #1 is for sharpening blades at 15 degrees. For single sided blades you'll only need to use one side of the first slot.
Slot #2 is set for 20 degrees and can be used on chef's knives and most utility type knives. The final slot is for honing.
There is nothing complicated about using this knife sharpener from Chef's Choice, but you'll want to carefully review the instructions before using it on your knives.
How Does it Perform?
Operation is very simple. Each of the slots are magnetized so that the knife is held in a consistent position as it's pulled through.
As with the Edge Pro it's difficult to sharpen knives with a large bolster as the guides inhibit the entire length of the blade from entering the slot.
You can also check out our full Angle Select review.
- option to choose 2 different angles
- slots are magnetized for consistency while sharpening
- operation is simple and painless
- the sharpener's wheels spin fast enough to damage the temper of the knife
- only a couple of angles to choose from
Chef's Choice is a name that has a strong reputation for quality. But the lack of flexibility when setting your sharpening angle is a serious shortcoming when compared with the Smith's knife sharpener. Unless you're just dead set on the Chef's Choice name we recommend the Edge Pro.
5. Chef's Choice Trizor XV
Our third choice in our electric sharpener comparison is the Trizor XV Edgeselect. Also from Chef's Choice the Trizor XV uses a different strategy than other sharpeners in this category.
The Trizor sharpens to a 15 degree blade angle. This is significantly sharper than most Western or European blades.
Trizor is actually the name given to the proprietary bevel shape created by this knife sharpener. The idea is to create a blade that is both extremely sharp and very durable.
It's important to know that the first time you use this sharpener on one of your knives it's going to remove a SIGNIFICANT amount of steel to achieve this shape.
As you might've guessed we're not big fans of any sharpener that changes the factory blade angle. We're equally suspicious of changing the shape of the bevel. When manufacturers forge their knives the hardness of the steel and bevel are important factors in the blades performance and usable life. Changing these after the fact rarely works out well.
Using the Trizor
The XV utilizes 3 stages. The first stage uses a strong abrasive to reprofile the blade down to a 15 degree bevel. It's at this point in the sharpening process where you'll see the most material removed.
The bevel of the blade is created while using the second stage. The third and final stage stripes the blade to a smooth and razor sharp edge. The final stage can also be used on serrated knives to restore their edge.
Check out our full Trizor review.
- very sharp edge
- simple operation
- works very quickly
- all blades sharpened to 15 degrees
- unusual bevel shape may not be compatible with all blades
- first use of the knife sharpener removes a great deal of steel
- temper of the knife may be damaged during sharpening
The Trizor's biggest selling point is that it creates an extremely sharp blade with a proprietary bevel angle. Unfortunately you end up sharpening ALL your knives to the same angle. Sometimes it's not about being razor sharp. Durability should also be a consideration and we're not convinced the Trizor shape is the way to go. Couple that with the high speed spinning discs and you could end up with a very sharp and very brittle blade.
6. Wicked Edge Precision Knife Sharpener
The final knife sharpener we've reviewed in this category is the Wicked Edge Precision Sharpener. Wicked Edge is the brainchild of Clay Allison and Devin Kennemore. The sharpener is is geared more towards outdoor enthusiasts, but works very well for kitchen knives as well.
A unique feature of the Wicked Edge is the dual rod system that allows you to sharpen both sides of the blade at the same time. This can be the best way to increase the speed of the work, without overheating.
It offers the widest angle selection of any of the sharpeners with a range of 15 to 30 degrees.
Because this, angle is set independently on both sides of the sharpener care must be taken that both sides are set precisely the same.
Once you've learned the proper operation of the Wicked Edge the dual rod functionality significantly reduces the time spent on each knife. The motion is also very natural as it allows you to extend your arms forward with each pass of the stone vs sliding your arm across your body with the KME and Apex.
In the beginning you'll want to start slowly to ensure consistent contact with the bevel of the blade. Once you're confident that each pass is properly raising a burr you can speed up the operation.
The base system comes with the clamp and eight sharpening stones. They range in coarseness from 100 to 600. While there is a granite base shown in many of the images, this is purchase separately. While it is expensive, the stability of the base is excellent and provides a very solid platform from which to work.
- dual rod system sharpens both sides simultaneously
- operation is simple to learn
- works with a wide variety of knives and blade angles
- settings are clear and easily adjusted
- doesn't work well on filet knives
- mounting the knives in the vice can be challenging
- high price
While the Wicked Edge is a high quality product, the high price tag compared to the other units in this comparison is a bit of a deterrent. At nearly twice the price of the Apex you'll be paying a serious premium. Since you can sharpen both sides of a blade simultaneously it can speed up the process, but you'd need to be doing a lot of knives to notice the difference.
7. Spyderco Tri Angle Knife Sharpener
Since all of the options listed above come in over $100 we decided to include a more budget friendly option.
The operation of this knife sharpener isn't quite as automated as the other solutions, but you can still achieve excellent results at a much lower price. The Tri Angle sharpener should be placed on a flat surface.
Then you simply hold the knife blade level to the surface and drag the blade across the stones. There is some flexibility offered by changing how the stones are installed in the base.
Once you learn the motion you can quickly sharpen all your knives in a relatively short amount of time.
Features to Look for in an Electric Knife Sharpener
The best kitchen knife sharpener for your needs should give you the features you want at a price that makes sense. Here are some of the features you should look for in any sharpener you're considering.
Angle Selection Capability
Knife makers have to take several factors into consideration when designing their products. Two of the most important are the strength of the steel and the sharpness of the knife. Hard steels can be brittle and break. Soft steels can dull too quickly.
An extremely hard and sharp knife (such as Japanes knives) will be more brittle than a softer knife with a higher (less steep) blade angle. In fact, just using a hard steel knife on hard vegetables such as carrots can cause chipping of the steel. Dropping it on hard surfaces can also cause significant damage.
The point of all this is that the hardness and blade angle are EXTREMELY important factors in the performance and life of your knife.
Many electric sharpeners only allow you to sharpen to one pre-determined angle. This can be OK if the bevel angle of your sharpener happens to match that of your knives, but if not…you could considerably shorten the useful life of your knives.
A sharpener that allows you to match this factory angle as closely as possible ends up extending the life of your blades. It also enhances it's performance.
While this particular feature doesn't get a lot of attention (possibly because very few units have this capability?) it is one of the most important considerations when buying a knife sharpener.
The Edge Pro includes this capability in both it's electric and manual models, and was a significant factor in it winning the best electric sharpener competition. This flexibility allows it to sharpen paring knives, pocket knives, chef's knives, whatever you like.
The methodology behind properly sharpening a knife is very simple. The first step (and corresponding first stage for knife sharpener products) is to grind out any nicks or imperfections along the bevel of the blade. This is achieved with a low grit stone or grinding wheel. This is about creating a solid and consistent base from which to form a durable and sharp edge.
Many models do NOT include this stage as they are designed to sharpen and hone not repair. Be aware of this when shopping if many of your blades are badly damaged.
Step two, and stage 2, is a higher grit stone that is used to raise a burr along the bevel of the blade. The burr is the small amount of material at the very edge of the blade. It folds over to the opposite side you are sharpening.
A consistent burr along the entire length of the blade is important to a smooth, strong edge.
Step three is known as honing or stropping. Essentially you are polishing the burr down to an extremely fine point known as the cutting edge. This is achieved with still higher grit friction. The higher the grit, the smoother and cleaner the edge. Using the right materials it's possible to achieve a "mirror finish".
Knife Sharpener Materials
There are a great many options available when it comes to which materials to use for sharpening steel. It ranges from natural materials such as Arkansas stones to manmade composites such as substrates impregnated with diamond abrasives.
Natural stones were of course the original method of sharpening tools and weaponry. Traditionally some of the best natural stones in the world come from Arkansas. There are several different varieties from this region of the U.S., but they are all generally referred to as Arkansas stones.
Man-made or composite stones are engineered to have a longer life than natural stones. They use a variety of abrasives and are highly effective. It often comes down to personal preference when selecting between the two.
Electric knife sharpeners generally use diamond abrasives as they offer the longest life. These abrasives are impregnated into the sharpening wheels within the knife sharpener itself. Each stage contains progressively smaller abrasives.
Some models will also use ceramics as they too have a long usable life.
While man-made materials function well, many sharpening pros will tell you that natural stones work best. This is due to the consistency with which they work.
The Advantages of Knife Sharpening Systems
Many sharpeners on the market label themselves as "sharpening systems" and utilize what is called a rod and stone operation. Let's take a look at how they differ from a traditional knife sharpener.
So how are these different?
When using a sharpening stone you're required to move the blade of the knife along the stone at a consistent angle. Maintaining this position while moving the knife can be quite challenging and generally requires a great deal of practice to perfect.
By reversing this process, these knife sharpeners have created a method that is much easier for amateurs to master very quickly.
To start, the knife is held or locked into the knife sharpener at the required position. This position is controlled by the user and won't change once it's set.
Next the stones are slid across the blade. Since everything is locked in place, the position won't change during this process, allowing for a very consistent edge. This simple operation means that even complete novices can achieve the same results as a pro that has been working with knives for years.
Other than their simple operation these units offer two very important features.
First and foremost they are manually operated. This means they won't heat the steel to a point that affects the tempering. This insures the strength and hardness of the steel remains consistent with the manufacturers design specifications.
The second benefit is that they offer a very wide variety of angles at which to sharpen. This means you can use one knife sharpener to PROPERLY sharpen all of your knives. And because these units offer a wide variety of higher grit stones, you can achieve a level of sharpness beyond how they ship from the factory.
The Pros of Knife Sharpening Systems
The process of sharpening a knife removes small amount of metal from the surface of the blade. As you can imagine, the less material you can remove during each sharpening the longer the knife will last. In fact this is one of the reasons that professionals prefer manual sharpening methods as they can control the amount of material removed.
Additionally electric models typically utilize spinning discs that generate enough heat to impact the tempering of the steel. This causes it to become weak along the edge of the cutting surface. Obviously this is bad.
Electric knife sharpeners also tend to only allow you to choose between a couple of sharpening angles. As a result the first time you use an electric sharpener they tend to remove a great deal of material from the blade.
The Edge Pro Electric (our top pick for in the electric category) is one model in particular that allows you to choose from a wide variety of angles. But even the Edge Pro can't match the flexibility of the systems we've highlighted above.
Creating a consistent bevel along the entire length of the blade is crucial to a durable and sharp edge. The more consistent the edge the longer your life will last. This also translates into less sharpening, again helping to extend the life of the knife.
This is where this type of knife sharpener separates itself from electric and most manual models on the market.
Choosing Your Angle
Because of the way these products are designed you can literally choose any angle you want for your knife. If you've got a paring knife that's sharpened to 15 degrees you can match it, or if your best kitchen knife is sharpened to 25 degrees, no worries.
Sharpening systems offer the best solution for maintaining (and improving on) your factory edge.
Sharpening Stone Selection
While an electric sharpener will have at most 3 stages with which to work, the best knife sharpeners offer the flexibility of dozens of different stone grits with which to work. They can literally polish a blade to a mirror finish if that's what you're after.
While the knife sharpeners covered in our comparison come with a pre-set number of stones, each has expansion packs that allow you to hone, strop, and polish your kitchen knives to perfection.
Simple to Use
Learning how to use a traditional stone can be both time consuming and frustrating. They are bulky, generally require oil or water as a lubricant, and can be quite messy. On top of all that, not keeping a consistent position can put you right back at square one in the process.
Sharpening systems simplify this entire process allowing you to master the sharpening and honing process in a very short amount of time. By allowing you to keep the stone angle consistent along the entire length of the blade you can create razor sharp and DURABLE edge.
Beginners can literally achieve the same results as professional who have been practicing for years.
As you might've guessed we're pretty enthusiastic about sharpening systems. But there are other options for sharpening your knives other than those that we've discussed above. Here are just a few.
Best Method of Sharpening Your Kitchen Knives
There are four basic types of knife sharpeners out there.
- Electric - these are by far the most popular. They are small, fast, and relatively easy to use.
- Manual - next to electric these are the most popular. Generally much less expensive, they are great for those on a budget. Some units take up almost no space. Slower than electric models.
- Sharpening Systems - professional knife sharpeners prefer stones. They offer the best "feel", flexibility, and they won't destroy the temper of the steel. These are our favorites too. Slower than electric, but less prone to damaging the knife you're trying to sharpen.
- Sharpening Stones - the old school way to sharpen knives. Stones require a great deal of patience and practice to use properly. Much slower than the other methods.
What's Best for You?
The easiest way to determine what you should purchase is to answer the following questions:
- What kind of knives are you going to sharpen?
- What kind of budget are you working with?
- What's more important, speed or accuracy?
If speed is your highest priority then you'll want to start your search with electric models. They aren't as good for smaller knives like paring or pocket knives, but they work well with larger blades such as chefs knives.
Some knives such as Wüsthofs can be challenging as well as they have a large bolster. This makes it tough to sharpen all the way to the heel of the blade.
Sharpening systems come in second place in terms of speed. They have the added advantage of not damaging the temper of the steel during the sharpening process.
If you're on a tighter budge you'll want to look at less expensive manual options. These require more time and patience but are perfectly capable of getting the job done. They offer a wide range of flexibility in terms of the size and types of knives they can sharpen. Like sharpening systems they won't damage the steel tempering.
If you're looking for flexibility and accuracy then you'll want to shop for the best sharpening systems. They utilize sharpening stones so they very accurate, will sharpen the entire length of just about any knife, and as we mentioned won't affect the steel tempering.
Sharpening Pocket Knives
Pocket knives offer a unique challenge when it comes to sharpening. The blades are generally shorter than kitchen knives and are sometimes comprised of unusual geometric shapes. For this reason it's difficult to use an electric model to sharpen them. Oftentimes you'll end up with a dull spot at the heel of the blade as the handle won't fit into the slots of the sharpener.
Thankfully there are some budget friendly options when it comes to caring for your precious pocket knives. We cover a few good options for under $30 in this post.
An added bonus on most of these units is that they're lightweight and small enough to fit into a pack when you head out into the woods.
The Blade Medic by Smith's is a perfect example. It is small enough to fit just about anywhere and can work on a wide range of knives.
The knife sharpeners we covered earlier are also great when it comes to pocket knives. They can handle a wide variety of knife lengths, widths, and angles.
Sharpening Hunting Knives
For hunting knives it almost always makes sense to go with some sort of stone based system. Many hunters treasure their knives and would never think of dragging them through an electric model that would chew off a bunch of steel or scratch the face of the blade.
Products like the Apex, KME, and especially the Wicked Edge are perfect for high end knives of any kind. They allow you to precisely match the blade angle, protect the face of the blade, and polish it to a mirror finish.
All of this will help extend the life of your knives.
Sharpening Serrated Knives
Serrated knives require a different approach from other knives. They are generally pretty durable and don't often require sharpening. But some maintenance is required to insure you don't destroy a loaf of bread when trying to cut into it.
Most electric models are NOT designed to handle serrated blades. The Edge Pro mentioned earlier does have a slide out serrated slot that is manually operated. This works fairly well.
There are products out there that are specifically designed for serrated knives. One such product is the manual serrated sharpener from Chef's Choice. It's operation is similar to that of an electric model where the blade is pulled through a slot. It's inexpensive and works pretty well.
The Apex system also allows for working on serrated knives when you purchase the honing attachment.
Sharpening Ceramic Knives
Ceramic knives have become somewhat popular in recent years. Since they cost significantly less than steel they are often a good budget choice.
Because of how hard ceramic is, you can't sharpen them with traditional sharpeners. You'll end up with a chipped and cracked knife that is completely ruined.
There are a few products out there that are designed to sharpen ceramic knives. One of these is the Precisharp. It can actually sharpen both steel and ceramic knives
Using a Knife Sharpening Service
While having someone else sharpen your knives can seem easier, it can sometimes be a hassle when you have to send them away for periods of time. On top of that they can be pretty expensive. Oftentimes a service will charge between $8 and $12 per knife. This can quickly add up over the course of the life of a knife.