The Push Cut

I haven’t read anything about the Surgi-sharp Universal Angle Guide anywhere. But I have the item. So here’s what I know about it…

It’s a simple angle guide for making flat bevel grinds on a belt grinder. The ramp is only 1.5″ long from top to bottom. This works well for small blades and not so much for, say, a cleaver. The adjustments are a little shaky, but at least they are made with knurled thumb screws and not wing nuts, hex nuts, etc. There are angle marks on the side so you can ballpark your angle measurements fairly easily. For exact measurements, spend the $25 for an Angle Cube. The angle guide clips on top of the existing platen on your grinder. However, you need to make sure it fits. The inside of the clip measures 1-1/16″, so your platen can’t be any wider than that.

The irony of this product is that it doesn’t work out-of-the-box with the leather belts sold by the same company. The same holds true for any belt thicker than about 1/16″. There simply isn’t enough room for the belt to fit between the platen and the blade table.  This can be remedied by simply grinding the ramp back an 1/8″ or so on your grinder.

Most grinders are set up to run counter-clockwise. Since soft belts like the leather belts need to be run in an edge trailing (clockwise) direction, you will also need to have a reverse (DPDT) switch installed on your grinder if you want to use the leather belt with the angle guide. Otherwise, you can just freehand strop for that sharpening step.

While this is not a comprehensive review, hopefully my initial observations about these stones will still be helpful for some. The stones that I have been trying out are the Sigma Power Select II stones in 1K, 3K, 6K, and 10K grit (JIS). Also in the progression is the Sigma Power 3F Carbon #700 and the Sigma Power Ceramic 13K. These stones were cut and mounted for use with the Edge Pro sharpening system. They were tested for use on knives, not tools. The knives I tested were all about 60 HRC of various stainless steels.  All of the stones, aside from the 13K ceramic, were designed to sharpen high speed steel. So they will cut just about anything you can throw at them.  The Select II stones are all pure sintered abrasive.  That is to say that there is little to no binder, ceramic or otherwise, in the stone.  The stones are all heated and pressurized into a brick of pure SiC, like the 1K, or nearly pure Aluminum Oxide (AO), like the 3K, 6K, and 10K.  The 13K ceramic stone is just that, extremely fine blend of AO and natural stone silicates with a ceramic binder.

Sigma Power 3F Carbon #700: This stone is so large that when cut for the Edge Pro, the stone measures 2″ wide. The double width is really great for reprofiling a blade. It helps to minimize the amount of hollow areas that can develop along a blade edge. I love this stone. It’s my favorite of the coarser Sigma Power stones that I’ve tried. (Full disclosure – I personally favor the speed and quality of edge that a silicon carbide (SiC) based stone gives up to about 3000 JIS.)  This stone will grind a new edge bevel on a large kitchen knife that has no bevel in less than two minutes – easy.  To top it off it stays visibly flat after doing so.  Did I mention that I love this stone?  Removing and repairing chips in a blade edge calls for a coarser stone, but the 3F Carbon could still pull it off.  Unlike the Select II stones, this stone is not pure sintered abrasive.  There is just enough ceramic binder in it to keep it’s flatness and not slow it’s cutting ability.  In all honesty, I wish there was a 1K and 3K stone made in the same way this one is.  However, the Boride CS-HD 400-800 grit (FEPA) are the only stones that I’ve tried that come close to this level of performance in that range.  3F Carbon #700, where have you been all my life?

1000 Sigma Power Select II: After coming off the last review, I’d expect to be disappointed… and I’d be right. The width is nice, 1/4″ wider than a standard Edge Pro stone.  The 1K Select II is the only pure SiC sintered abrasive that I’ve ever tried.  It proved to be much too friable.  I can see why it would work well for wide straight bevels like chisels and plane blades.  With these tools you can justify the loss of abrasive for the amount of time it saves sharpening.  But it didn’t do well for knives.  The stone cuts quickly.  However, it looses flatness at an alarming rate when working on a knife tip or heel.  It gouges too easily.  After rebeveling a knife with the 3F Carbon,  the 1K Select II still sustained visible gouging and wear just to remove the scratches from the previous stone.  On one particular knife with a curved tip, I felt the need to flatten the stone twice on a diamond plate before finishing the edge.  Don’t get me wrong.  This stone is not Norton 220 terrible, but it’s not good, in my estimation, for knives.  I recommend skipping this stone altogether, going from the 3F Carbon to the 3K Select II stone.

3000 Sigma Power Select II: This is a great kid who might feel bad because he’s not as awesome as his older brother, the 3F Carbon.  I wish the stone were SiC but it’s AO instead.  However, the AO making up the stone sinters amazingly well.  It cuts amazingly well too.  If I wasn’t wanting SiC so badly at this grit level, I would say that this is my favorite 3K stone.  The stone is fast.  Beautifully fast.  It holds together well on curved edge bevels too, something a sintered SiC stone couldn’t do.  While the 3K Select II can be gouged and does release abrasive quicker than some other stones, the speed of sharpening makes it worth it.  I suspect, but can’t verify, that the sintered AO stones at the higher grit levels cut quicker and release close to the same amount of abrasive through the sharpening process that ceramic Sigma Power, Shapton, and Chosera stones would. This stone can be gouged, but not gouged as easily as say a Naniwa Superstone or the 1K Select II.  Overall, I really enjoy using the 3K Select II and it is now my favorite 3K AO based stone.  Yep, I like it better than the Shaptons for knives.

6000 and 10000 Sigma Power Select II: This is where the Select II series shines the brightest.  There aren’t many stones available in these upper grit ranges and most of the ones that are available are slow to cut.  The Select II stones are designed to cut, not polish.  But they will begin to polish somewhat if only due to the way AO cuts steel and the decreasing size of the abrasive through stone progression.  Basically, don’t expect too much shine from these stones.  Again, like the 3K, these stones are fast.  I wouldn’t trade them for anything.  In fact, I’d dare to say they are the fastest I’ve ever used in this grit range.  Ever.

13000 Sigma Power Tamago-iro Ceramic: This stone hails from the main line of Sigma Power stones.  The Select II series doesn’t have a stone this fine.  I wasn’t expecting much when I tried the 13K.  I have Shapton glass stones up to 30K (different grit standard here) and have SuperStones up to 12K.  I have to say that my initial impression is that the Sigma Power 13K leaves a mirror finish that is, to the naked eye, on par with the Shapton 30K and it puts the SuperStone 12K to absolute shame in terms of cutting speed.  I need microscope comparisons to check scratch patterns between the Shapton and Tamago-iro.  The Tamago-iro has a more organic cut to it than the Shapton, but, dang, they finish pretty.  With the price point of the Shapton being astronomically high, I can’t be anything but impressed with the Sigma power.  First, it was fast.  I couldn’t believe how much metal was floating on the stone after just a couple passes.  The 12K SuperStone is not even in the same league with the Sigma.  Finally, the finish it left was a perfect mirror.  The perfect mirror was left by cutting and not just glazing over the tops of the edges scratch pattern.  More on this later, but for now, the Sigma Power 13000 is now my favorite finishing stone.

A forum friend of mine was kind enough to send me these Boride CS-HD stones to try out.

 

 

They are a Silicon Carbide (SiC) based stone.  Edge pro users are familiar with the 120 grit CS-HD as it is the stone sold by Edge Pro for edge creation and reprofiling.  However, this is one stone in a series of stones that  Boride Engineered Abrasives markets as polishing stones.  They are designed by Boride to be used on harder modern steels (HRC 60+).

At first blush, marketing a SiC stone as a polishing stone might seem a bit odd.  Especially since, due to the way SiC cuts steel, it does not produce much luster if any.  Knife people tend to think of “polish” as luster.  In other words, The more polish there is the more like a mirror the edge becomes.  However, smoothness of finish is what I think Boride is trying for here.

Here is a photo of the test setup with the test knife.

 

 

The edge angle on this knife was about 40 degrees inclusive before the test.  There were two small chips in the edge as well.  The chips were no deeper than half of the edge bevel.  I began testing the CS-HD stones by reprofiling the blade edge to 30 degrees inclusive.

 

 

Prior to testing, all the stones were flattened.  The 120 and 220 CS-HD stones were flattened on a DMT8XXC.  The remaining stones were flattened with a Shapton Diamond Lapping Plate.

Reprofiling the edge of the blade and removing the chips tooks about 20 minutes, which was about 15 minutes way too long.  Although Edge Pro markets the 120 CD-HD stone for stock removal, the stone does not perform well for this function.  The binder in the stone is too hard for roughing. The stone slid over the surface of the edge while removing minimal amounts of steel.  Not surprisingly, this really is a polishing stone designed to remove the scratch pattern from a previous stone.  The 120 CS-HD is no substitute for a good roughing stone.

 

After the new edge bevel was created and repair completed,  the edge appears even and the scratch pattern on the edge bevel looks uniform.  Push cutting newspaper was difficult but achievable 3 inches from the hand.

The 220 CS-HD stone was similar to the 120 CS-HD stone.  It’s very hard, does not remove steel quickly, and the scratch pattern on the blade is fairly uniform.  Push cutting newspaper was much easier up to 3 inches from the hand.

The first thing you notice about the CS-HD stones labeled as 400 grit and higher is that they are lighter in color than the 120 and 220 stones.  So far there have been no surprises since most every Edge Pro user has experienced the 120 grit stone.  The 400+ stones are formulated differently.  As soon as I started to sharpen with the 400 CS-HD stone, my expectations were shattered. The stone didn’t merely slide over the edge bevel. It gripped the steel and abraded it perfectly. I was ready to move to the next stone after just a few swipes. The swarf on the stone was almost all steel. Unnoticeable amounts of stone was removed while sharpening. This stone reminded me how much a stone’s “feel” is important, even when using a guided system.

The scratch pattern is very uniform.  There are no noticeable scratches from the previous stone and the scratch pattern is uniform.  Push cutting newspaper was extremely easy.  The paper would slice fairly cleanly at about 4 1/2″ from the hand.

The 600 CS-HD stone had the same feel and sharpened just as fast as the 400.

The scratch pattern was still very uniform.  There were no noticeable scratches from the previous stone.  Push cutting newspaper was extremely easy.  The paper would slice cleanly at about 5″ to 6″ from the hand.

The 1000 grit stone fell in line with the previous two stones.  Excellent feel and finish.  As was expected, the edge appearance was still matte, even at that high of a grit.

While the edge appears much cleaner, the knife’s cutting performance did not improve.  Push cutting newspaper was no easier than with the 600 grit edge.  As far as utility is concerned, the 600 edge may have been slightly better.  This concludes testing the CS-HD stones.

To see if the edge could be further refined with stock Edge Pro finishing stones, I soaked and flattened the Boride AS-9 1000 grit and 1200 grit stones.  These are Aluminum Oxide (AO) based stones.  Here is the resulting scratch pattern from the AS-9 1000 following the CS-HD 1000.

This is also where the photo doesn’t tell the whole story about what is actually going on.  While fine scratches are clearly visible here, they are not visible to the naked eye. I primarily used a circular sharpening motion and I really worked the edge with the stone.  I finished with light edge leading strokes.  The polish the AS-9 1000 stone gave this edge is the best I’ve seen from this stone yet.  It was truly a near mirror finish with very little cloudiness.  This AO finish also greatly increased cutting performance.  Pieces of newspaper were flying everywhere.

The same held true for the AS-9 1200 stone…

…better near perfect mirror.  Push cutting couldn’t get any better.

I finished polishing the blade with a leather strop (no tapes) which erased all but very few of the microscopic scratches.  Unfortunately, the light on my USB scope is always on.  The reflection of the light from the scope kept me from getting a useful picture.

Concluding Summary and Opinions:
The Boride CS-HD stones are good hard polishing stones.  For knives, there are many better stone choices for roughing, reprofiling, and edge repair.  The mid range (400 and 600 grit stones) is where the stones really shine.  To bad Edge Pro doesn’t sell these instead of their regular mid-range stones. The CS-HD stones cut quicker, more evenly, and prepare the edge for finishing better than their AS-9 counterparts. The price of the stones from Boride reflect this too, as they are more expensive