Switch to full style
We have a massive amount of Edge Pro products so we figured it would be good to have a whole section on how to use the machine and what to use on it.
Post a reply

GUIDE — Convex Sharpening with the Edge Pro Apex

Wed Jul 04, 2012 9:13 am

Hi everyone,

I had spoken to Mark a few months back about my plans on trying to use the Edge Pro Apex for convex sharpening,
when I ordered it from him. I promised I would post my findings on here.

Here goes:

It is very easy to use the EP for convex sharpening! I use mine primarily for just that!
Some people may ask why one would want to do this, but I think it's a no-brainer, since the EP allows for very exact bevels.

I rarely need to use the guide plate, since convex sharpening with a padded abrasive is more forgiving than when sharpening with a stone.
The reason for this is because the padding compensates for small errors, in that it curves to the bevel, whereas a stone does not.
Having said that, using the guide plate is always better and much more precise, but the lazy way out is to not use it (and risk getting poorer results).

So, basically all that is needed to do this at home is:

*A blank EP plate
*Double-sided tape (strong bond. If possible — not with water based glue)
*A cut-to-size padded backing, such as a mousepad (but harder backings work much better)
*Sandpaper which has been cut to size with an Exacto and a ruler (preferably wet sandpaper)

There are many different types of sandpaper, tapes and backings around and not all work very well, whereas some excel at the task.

I personally like a stronger double-sided tape, since it doesn't get loose when wet (regular office supply ones seem to do so, but work fine).
Remember that you will be applying force, so the paper may get loose, just as the regular 2000/3000/6000 EP-tapes do sometimes.
Fabric sandpaper seems to stick poorly to regular double-sided office tape. If the glue of the tape is too strong though and your sandpaper-backing is made of paper,
it may be difficult to remove the sandpaper and reuse the tape without tearing the paper, so be prepared to use a bunch of tape or experiment with different supplies.

I use several, which I've cut to size. Permanent Spray Mount (3M) bonded it to the blank plate, but double-sided tape works too.
You can probably find your backing at a rubber- and hose supply store. I use a softer one (stiffer than a mousepad though) for grinding and chopping tools.
The hardest one I could find was made of natural rubber, which is a bit expensive; but, it's almost like sharpening on hard leather.
I found another one which is sort of in between and it is just right for me (some sort of plastic rubber).
It is important to get the right amount of give in the backing, especially if you want to get hair-whittling sharp edges.
If the backing is too soft, such as most mousepad are, then it is very easy to round the edge and it becomes harder to get it scary sharp.
Remember that the backing should be easy to clean, unless you want to make new backings all the time.

I only use wet sandpaper and a toothbrush (to spread 2-5 water drops evenly), so as not to get metal dust in my lungs.
The sandpaper should not have a slick woven fabric backing, as it doesn't stick very well to the tape (but use it if you like).
Cut the sandpaper into strips which won't extend over the backing, since sandpaper edges cut just as well as a knife does, especially on higher grits.
The sandpaper can cut the support-hand index finger easily when working around the heel of the knife.

I try to wear breathing protection, as I've noticed that when the sandpaper becomes filled with metal and loosened particles,
that dust-buildup sometimes goes airborne when I remove the strips and so on. Eye protection (glasses) is a good idea too,
especially when grinding (particles may splash all over).

I've sharpened and honed a plethora of different knives with the convex method now and it works very well!
I'm talking folders and fixed blades, convex edges and full zero-grind convex blades of all shapes and sizes.
Full convex zero-grind blades require a raised triangular block on the guide (to get a lower angle), or balancing freehand on the edge of the EP.
The convex sharpening modification works!

Here are some pics of my setup. I figured I'd show you my Cold Steel Gurkha Kukri (SK-5) which I convexed on the EP Apex.
I chose to show you this one in order to illustrate that even the most difficult blades are easily sharpened with this method.
The grits I used were: 120/240/400/1200/3000/6000. It is extremely sharp now. The pic makes it look satin finished, but it is almost mirror polished.





Re: GUIDE — Convex Sharpening with the Edge Pro Apex

Wed Jul 04, 2012 2:02 pm


I documented my setup a few years ago. i kind of like leather as a backing or neoprene for heavier convex edges.

Re: GUIDE — Convex Sharpening with the Edge Pro Apex

Wed Jul 04, 2012 3:09 pm

—Cool! I'd love to see your setup! I'm always looking for new ideas.

Re: GUIDE — Convex Sharpening with the Edge Pro Apex

Thu Jul 05, 2012 2:19 am

Here's the initial review I did when I received my Apex with a convex set from Ken. It was written 2 years ago.


In June 2010 I first met Ken when asking about stones, compounds and sprays. Over the next half year, we’ve exchanged PT’s, mails, Skype chats and we’ve spend numerous hours on the phone. After ordering Keith de’ Grau his products from Hand American I posted a review on the compounds I had and how I use them. After this Ken started producing compounds that work with Keith’s products instead of competing with them.

Ken explained this:
“I specifically designed my custom formulations used in my product lines for compatibility with Keith's products, using the highest standards in the industry. My products have a consistent 'highest level of quality' and I thank Keith for instilling in me the value of producing a quality product.

As Isaac Newton said, “If I have seen further it is by standing on the shoulders of giants”.”

There is no point in competing with Keith’s products as they are by far the best I’ve ever used for knives and razors.

On the 21st of December, Ken sent me a package with an EP with following products:

EP itself
220 grit EP stone
320 grit EP stone
400 Chosera
1k Chosera
3k Chosera
5k Chosera
2µ CBN (no longer available)
1.5µ CBN (no longer available)
2 aluminum blanks. I glued HA bovine leather on it. Thank you Keith!
1 1x6 neoprene blank for convex edges.
1 2x6 neoprene blank.

Sadly I did not get lucky… The package arrived after 3.5 weeks. Customs decided they had to “test” the CBN and half the bottle of the 2.0µ is gone. So while waiting for my products I was the laughing stock of Madrookie and Tom Blodgett… All in good fun of course.

A video of me unpacking the box and cursing can be found here:

I got home and started sharpening right away. These are MY impressions. They are in no way scientific tests and are subject to my skill and the lack of it.

I am not affiliated with Ken, Keith, Tom or their distributers. Just a very happy customer.

I also apologize for my English. This will not be the best written review out there, but hey… This is not about my English, but about the products.


Part I: Convex edges

Starting an EP review with convex edges won’t make any sense to a lot of you guys. However, it does for me. I’ve been doing convex edges for the last 5 years free handed and it has taken me 2 years to get good results to begin with. If I had the EP with neoprene to start with, it would have taken me DAYS. The same key concepts apply to convexing on the EP:

1. Keep light pressure: With the EP you don’t want to apply pressure. The weight of the arm is perfect and is consistent. A lot of times you read: The weight of the knife is enough.
Well,… Every knife has a different weight! You cannot get results as consistent free handed as with the EP. Unless you are very experienced with it. You’ll want to put your index and middle finger below the arm and just pull. That way you cannot put any more pressure on it.
2. Convexing is slower: You do half of the work you would on a stone because you are just doing pull strokes. Keep that in mind.

I tested 3 convex ground knives in 2 different steels:

• BRKT Manitou 52-100
• BRKT Bravo 1 A2

All 3 knives got as sharp as I could get them free handed, but the Manitou did get even sharper, which was a surprise as it is full convex ground, while the other 2 still have a small flat portion and are easier to keep flat on the EP.

I glued the abrasive paper to the neoprene blanks with a glue stick and put a drop of water on the paper. I finished these knives up to 16k and then stropped them on CBN, boron, CrO and 0.25 micron Diamond spray.

Here are some pictures:



BRKT Bravo 1:



As you can see the edges are very even and well polished. These edges now whittle hair, including the 5mm thick Bravo.

Conclusion: Convex edges have never been easier or more precise. The compounds from Keith and Ken gives these edges just that little bit extra.

Part II: V-bevels

I’m very new at V-bevels. I have experience with the Scandinavian grinds on carving knives. They are so easy, that there is no challenge in that. So after looking into Japanese kitchen knives, I found out that most of them are V-beveled. So since I had the stones for my Scandinavian knives, I thought I’d try my hand at v-bevels. Well… I wound up with a bad convex edge the first time… and the second… and the third… and the… well you get my point.
After 4 months I could get edges that are almost on par with my convex edges, but I felt like improvement would come slow. So I invested in an EP… and the waiting began.

When it arrived, the first thing I sharpened was a VG-10 santoku by Eden. A cheap knife, that holds its edge reasonably well, and is easy to sharpen and re-profile if I screw it up. I started with the basic 220 grit stone and marked the edge with marker. I instantly hit the bevel at 15°. I always thought that I was sharpening at 15°, but turns out my angle was much lower. I did NOT like the 220 stock stone. When the bevel was set, I switched to my Choseras. Starting with the 400 I reset the arm with Madrookie’s trick and marked the blade just to be sure. The angle was spot on and I progressed up to 5k. The stones Ken sent me were absolutely flat out of the box and all equally thick. When I told him how impressed by that, he told me he cuts these stones by hand and said it was “not bad for an old man”…

Here’s the bevel after the 5k stone. The scratches above the bevel are from sharpening the knife on a belt grinder before.



After the stones I glued 2 pieces of HA bovine leather to the blanks Ken sent me. I sprayed them with the CBN and let them dry. In meantime I readjusted the arm. Switching to stropping on the EP took a while to adjust to. I used no pressure and just pulled the arm. The CBN cuts FAST! It left a great finish and when I was done with the 1.5µ I thought this knife could not get any sharper. I don’t have a stone in a higher grit then 5k. So these high grit CBN sprays were perfect for me. Since I ordered it, Ken does not offer this anymore. And frankly I don’t see the problem. I’ve used Keith’s 2µ silicon carbide paste and have been equally impressed with it. A 2µ or 1.5µ CBN is therefore redundant. If you want a 2µ compound, Keith is the guy to talk to.

I continued with 1µ boron carbide, 0.5 CrO and 0.25µ diamond spray from HA. The results were stunning to say the least. I have never seen a knife pierce a tomato so fast in real life. I’ve seen video’s of it, but I never thought I was able to produce that kind of sharpness. With Ken’s and Keith’s products, this IS possible.

Best regards,


Re: GUIDE — Convex Sharpening with the Edge Pro Apex

Thu Jul 05, 2012 2:41 am

I've gotta try neoprene (isn't that like wetsuit material?). Sounds spot on!

Re: GUIDE — Convex Sharpening with the Edge Pro Apex

Thu Jul 05, 2012 3:43 am

Don't know, but it's a thick rubber. I now prefer leather, but for heavy convex edges it's very good.

Here's another article I wrote around the same time:

https://docs.google.com/open?id=0B5kR3p ... 0lfVTlKeU0

Re: GUIDE — Convex Sharpening with the Edge Pro Apex

Tue Jul 10, 2012 10:54 pm

Michiel, thanks for reposting this here.

I can add to this that you can control the degree of convexity by the selection of neoprene used from thicker mouse pads to thinner formulations.

And now the 1.5 and 2 micron CBN IS available over on Ken's corner.

I can now use diamond films on the flexible backing for doing convex edges over the entire range of films from 165 microns to tenth micron. PM me for details.

And if anyone is interested in using nanocloth for their convex edges, well, just ask.

All of this is available for the EP, bench hones, or Wicked edge. Again just ask. If I get enough requests for a particular solution, I'll ask Mark to put it up on Ken's corner.

Post a reply