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- Dec 20, 2012
The Razor Sharp Edgemaking System 8 Inch Deluxe Blade Sharpening Kit – a quick Review
Not too long ago, @mickri started a knife sharpening thread and after that discussion I pretty much resolved to find a way to sharpen knives, despite the fact that I totally suck at it. I wanted a knife sharp enough to produce a translucent tomato slice without holding the tomato down on the cutting board. To me, that is a sharp knife and I could not produce an edge that will cut a stupid tomato like that. What’s more, I needed to be able to sharpen my wife’s favorite serrated MAC knife without damaging it.
I did my due diligence and looked at many of the sharpening systems currently on the market. Some, like the Wicked Sharp system, were attractive but are way too expensive for my simple needs. Then I happened upon the Razor Sharp Edgemaking System and it looked really good – power driven, fast and many of the enthusiastic reviewers were knifemakers that said it produced good results. I figured if anyone would know what worked it would be a knifemaker so I jumped.
The system consists of two 8” diameter wheels about ¾” thick made of compressed paper that is intended for use on a 6” bench grinder without wheel guards and tool rests. One wheel comes coated with 180 grit Silicon Carbide particles; this is the cutting wheel. The other is a slotted wheel that is loaded with a white buffing compound by the user; this acts like a powered solid strop. The wheels will fit either a ½” shaft with the supplied bushing or a 5/8” shaft. The fit on the shafts is very good – no slop. The kit comes with some wax that is applied to the gritted wheel, some white buffing compound for the slotted wheel and a small tub of 180 grit carbide grit to renew the cutting wheel when needed.
Woodworkers have used similar set ups using shop made MDF wheels for years; this one differs in that it comes with a pre-charged cutting wheel. I think this is simple enough to make in your shop but by the time you buy the materials it might just be cheaper and easier to just buy the kit. I bought my set from Amazon. It is cheaper from Grizzly but with the free Prime shipping I think it’s a wash.
My old Craftsman bench grinder has two Norton wheels that run smooth and vibration free. It is used to sharpen my gravers and I was loathe to sacrifice this capability by touching the wheels so I decided to buy a new Jet JBG-6A, a 6”, 1/2HP bench grinder on Amazon. I bought this grinder instead of a cheaper one because I wanted a good machine right out of the gate and the Jet did not disappoint. Out of the box with the included stock wheels it ran smooth, quiet and without a hint of the vibration that seems to be included with cheaper grinders.
I removed the wheel guards and installed the Razor Sharp wheels one at a time, indexing each one 1/8 - ¼ turn at a time until I found a position where it ran smoothly. Jet hand grinds their wheel flanges so they are vertical when installed and I think this helps to reduce any wobbling at the wheels. Under power, both wheels run without a hint of vibration.
There was no need to dress or otherwise alter the Razor Sharp wheels before use. I applied a sparse coat of wax to the gritted wheel and some white buffing compound to the slotted wheel while turning the wheels by hand. Not much of either stuff is needed and the system was ready for use.
I should bring one thing to your attention right off the bat: any edge must face in the direction of rotation of the wheel. That is, with the wheels running in the normal direction, which is towards you, the edge of your knife must always face down. If you touch the wheel with an edge facing up it will catch and the knife will be forcefully thrown down and possibly out of your hands, and then probably into your foot or some vital organ. Please be mindful of this.
One thoughtful Youtube reviewer turned his grinder motor around on its base so the wheels rotated away from him and I thought that was a good idea because if he lost control of the knife it would be thrown away from him. Intuitively, this made sense so I decided to do that, too. For my first attempt, I chose to sacrifice my most used and abused Chinese folder that I got as a freebie from some forgotten mail order thing. The blade had this attractive multi-hued coating like the titanium blades get when heated; cheap but a nice touch and I sort of liked how it looked. I approximated a 22 degree angle and promptly ground the coating right off the hollow ground part of the blade instead of the edge! It turned out that running the grinder in the reverse direction made it difficult to sight and maintain the correct blade angle and I couldn’t see the point of contact well, at least in my newbie hands that were extended out in space with no support.
After much laughter and acknowledging my suckability, I quickly restored the motor to its normal direction of rotation and was then able to brace my arms against my body and sight down on the blade. This made it much easier to see the angle of the blade and the point of contact. THEN I was able to grind the edge much more accurately.
It turns out that the bevel of a blade is a compromise, like most things in life. The sharper the bevel, the sharper the knife but the more fragile the edge becomes. A fine sashimi or vegetable knife might do well with a 10 degree bevel but it won’t last long chopping through the backbone of a fish. Similarly, the 22.5 degree bevel of a general purpose knife may work well for most kitchen jobs but won’t last chopping wood like that 40 degree axe will. So, the bevel is a compromise and I decided that most knives in my house will work just fine with a 20-25 degree edge angle. My sashimi knife will have a 10 degree bevel.
So, how do you get this edge angle without a tool rest? That was my big question and it turns out that you can do a fairly good job of it by eye. The Razor Sharp guy tell you to do it by halves: half of 90 degrees is 45; half of 45 is 22.5, and you can eyeball these angles surprisingly well. With a bit of practice, you can even do it pretty consistently and this is made much easier when you can brace your arms against your body and look down on the blade to see your blade angle. This sight picture also allows you to keep the edge parallel to the face of the wheel, even when you raise the handle of the knife as you follow the curve at the tip of your knife.
It takes very little pressure to grind knife steel, especially when an edge already exists. I found that I simply needed to put just enough pressure on the blade to keep it in contact with the wheel and it cut quickly. This allowed me to relax my hands and that helped me to work more accurately. The light pressure also generates very little heat so losing the temper on a fine knife is a very low probability. In most cases, the blade doesn’t even get warm unless you’re grinding out a nick; then it only gets slightly warm.
Grinding out minor nicks and edge defects is very quick and easy but for a serious nick I think I would use a 120 grit belt on a belt sander instead. I had one kitchen knife that had a small nick and it came out in 6 passes over maybe 90 seconds on the carbide wheel.
When sharpening a knife on these wheels, you grind one side until you create a continuous bevel, then you flip the knife and grind a matching bevel on the other side until you raise a burr along the entire edge; this tells you that the two bevels are meeting at the middle to create a sharp edge. On most of my knives, this took maybe 2-3 passes on each side. Once you get that burr, you switch to the buffing wheel where the process is repeated but this time you are just looking to remove the burr. When that is gone, the knife is sharp enough to be suitable for most purposes, including shaving hair; I have the bald arms and legs to prove it.
This system is also very effective for serrated knives. My serrated knife is beveled on one side and is flat on the other. You sharpen the beveled serrations with the corner of the wheels and remove the burr on the flat side by running it on the center of the buffing wheel with the blade held vertically; this stays dead flat if you hit the center of the wheel. Or you can hone that flat side on a stone if you prefer. The resulting edge is scary sharp but it took less than two minutes to do … a very pleasant surprise.
I wanted my kitchen knives sharper than they are coming off the wheels, sharp enough to scare a tomato. For this, I needed a strop and I didn’t have one. When I looked into it, it seems that the guys most knowledgeable about them are the straight razor guys and the chef knife sharpening guys. If you read their forums it is almost as entertaining as a machining forum, complete with competing opinions from folks who know they are dead right. Anyway, I ended up making a two-sided strop using vegetable tanned cowhide contact-cemented to a 2” thick X 3” wide X 10” long block of MDF. I worked in a layer of MAAS metal polish on one side of the strop and left the other side clear. An edge stropped on the MAAS side comes off with a mirror finish that is then refined on the clear side of the strop. It takes only a few ounces of pressure and the correct blade angle to strop a knife and THAT edge is tomato-scaring sharp!
So, my knife sharpening search is over. I own some of the finest Japanese Waterstones sold and I own enough diamond stones to sharpen most anything but from now on the only system that will sharpen a knife in my shop will be this Razor Sharp system. It is very fast, cuts very cool, works better than anything else I’ve tried and it also sharpens serrated knives quickly and well. A strop helps to refine the edges and will delay the need for regrinding on the wheels; I now consider it an essential part of the kit. MAAS metal polish cuts very fast and produces a mirror finish in just a few passes; just one thin application to my strop finished the edges on every knife in my house and it’s still going strong.
If you are looking for a simple, cheap knife sharpening system, have a look at the Razor Sharp system. If I can use this system to sharpen a knife then anyone can do it.
Tomatoes and cabbage cores now fear me and I look forward to seeing how my knife carves a turkey. Don’t think too much about it – go buy this thing!