Help with 204 Sharpener

S

Steve Campbell

Joined
Jun 22, 1999
Messages
47
Sal (or anybody),

I recently purchased a 204 sharpener, and what a joy it is. I operate three Spydercos (a Military serrated, an older Endura with Black-T serrated blade that Spyderco recently re-fitted with a metal clip, and one of those composite-scale Pro-Venators). This 204 keeps them razor sharp, and I find myself doing a lot of my buddie's Spydercos with it. It has been one of the best investments I've ever made.

But I simply CANNOT put an edge on the wife's kitchen knives with it. I follow the directions to the letter, with absolutely no positive effect. These are RADA "High Carbon Stainless" knives, ranging from small paring blades all the way up to a mega-bread blade. The wife accuses me of ruining all of them; when I point out that they were dull as hell BEFORE I tried to sharpen them- well, you know women and reason (sorry, Danelle<G>). It has gotten to the point that I have to use my Military now to slice my daily ration of fresh garden tomatoes. Of course, when she sees the Military's big serrated blade gliding through the tomatoes, she goes berserk and thinks I'm trashing her knives on purpose! Not really, but she is really annoyed about this and so am I. I'm desperate to the point of getting a Ronco Sharp-A-Matic or some such gimmick.

Anyone know anything about these RADA knives? Is it really "high carbon stainless", or melted-down boxcars? I guess I should just buy the Spyderco kitchen knives and be done with it...

Any ideas? This is wearing me out...<G>

Steve

 
The only Rada kitchen knives I've seen are the ones listed here:

http://www.knifeworks.com/RADA-HOMEPAGE.html

This web-page lists the steel as being T420, which I suspect is another name for 420J2, a steel known more for extreme corrosion resistance than for edge-holding ability. With that said, you should still be able to get these knives sharp enough to cleanly cut tomatoes. I've found these mild steels to form burrs very easily (Read: easy to sharpen).

Normally, to sharpen a knife, you raise the burr on one side of the knife, flip the knife over and raise the burr on the other, and then go to a finer grit (smoother) stone to remove the burr. With these mild steels, staying with the coarser hone and double-grinding (raising the blade-hone angle to yield a thicker edge) breaks the burr off to leave a micro-serrated edge that breezes through tomatoes and other soft fruits.

For a far better description of the above, look for the Joe Talmadge Sharpening FAQ (frequently asked questions) accessible from the Bladeforums start-up page.

I suspect your problem is that you're simply not sharpening enough to create that burr. Dead-dull knives such as you mention are often caused by unaware people who repeatedly cut objects over a ceramic plate or counter-top. This flattens out the edge severely and requires that a fair amount of metal be removed from the knife to re-form the edge.

In this regard, the Sharpmaker is not the best instrument to use, as it removes metal from a knife relatively slowly, due to the ceramic nature, and small surface area of the hones. Joe has a suggestion that you buy an actual sharpening stone (diamond, carborundum, Silicon Carbide, your choice), and lean it against the Sharpmaker rods. When you sharpen against this stone, you maintain the same angle as with the ceramic hones, but the surface area is greatly increased, and the sharpening will go significantly faster.

Bottom line:

Sharpen until you raise that burr. Don't stop until you get there, and expect that just using the Sharpmaker, each knife may take an hour to do. That's my current record. Touch-ups afterwards will be very rapid, since you won't be re-forming any edges.

Ian
 
The website for J. Mark Cutlery (I don't anything else about them) at:
http://www.jmcutlery.com/radaknives8.htm

describes the RADA cutlery they sell as "420 Surgical high carbon stainless steel".
(Yes, the infamous "S" word).

The next page shows the sharpener they sell with it... looks like one of those with overlapping disks, tho I can't tell if they're metal or ceramic.

I don't know much about steels, but I didn't think 420 (if that's what it is) would pose any problem for the Spydies.
 
I collect samples of cutlery steel by buying kitchen knives at Goodwill stores. Almost universally the knives I get this way are extremely dull. For a large knife with a good grade of stainless steel it can take almost a half-hour to sharpen using medium and fine diamond hones (I lower the bevel to 20 degrees when I do this which takes extra time). I suspect that you need to do more material removal.

To test this theory I suggest you work on one of the smaller knives as follows:

Take your coarsest sharpening rods and scrub thoroughly with Comet or Ajax sink cleanser and water.

Mount the rods in their lower angle (more nearly vertical) positions.

Work on just the left side rod. Using rather strong force keep working on the left side until you can feel a burr on the full length of the right side of the edge. Periodically rotate the rod as it loads up and maybe even reclean the rod.

Work on just the right side for about 1/2 the time you spent on the left side. When I'm working on a really wrecked edge I like to make sure both sides of the edge have been profiled.

Switch to your fine rods. (Clean them first). Use about 30 alternating right/left strokes to remove burrs and smooth the edge. Make the last few strokes very light.

Put your rods in their more nearly horizontal positions. Do a few very light strokes at this lower angle.

If you can't shave at this point the steel is junk (has carbide particals that are too big or is soft like putty). To find out which try stropping on a leather belt. When you strop keep the blade almost flat on the belt and have the sharp edge trailing as you stroke.

If you can't get a razor edge after stropping install the medium grit rods in place of the fine rods and take a couple dozen light alternating strokes. This should leave a coarse edge that will serve any kitchen function.

If the above doesn't work post another comment. I've got a couple RADA's at home that I'll play with to see if I see anything unusual about the material. I got them new at a garage sale and haven't tried to sharpent them yet.
 
The method that Jeff Clark just outlined, and that I heartily endorse, is not quite the method that Spyderco tells you to use, but it *is* the way to do it.

The one thing I might change is this. Jeff has taken you through reprofiling the edge at 15 degrees to get a burr. This could take quite a while the first time you sharpen. You can sit down and do this all at once, or do it over the course of two sharpenings as follows:

- First time, do as Jeff outlines above, but on the 20-degree angles the whole time. This will get you 80% of the performance you're trying to get, and won't take quite as long.

- Next time, do exactly as Jeff outlines above, starting at the 15 degree angles and then finishing on the 20 degree angles. This will get you the rest of the performance.

From there on in, sharpening should progress much faster.

Or, you can just bite the bullet, and bring the edge down to 15 degrees the first time. Better plan on being there for a while though!

Joe
 
Steve,

Well now I know. I just spent 22 minutes to resharpen a 3 inch bladed RADA paring knife using more or less the method I described in my previous reply. Scaling upwards it would take me around an hour to do the same on a carving knife. I am very surprised by how hard the steel is in these knives. On the other hand I did get a very good shaving edge when I was done.

Details:

I took a brand new RADA paring knife (that I bought for $1.00 at a garage sale) and used it to carve on a coarse aluminum oxide hone, then on a steel, and then on a ceramic hone. Thereby I got the knife as dull as some of the worst neglected knives I have seen.

Then I used my V-style ceramic hone to sharpen the blade. This hone is not a Sharpsmaker, instead it uses round rods and is made by Colorado Ceramic Abrasives. The lower-angled rod position is at 19 degrees and the higher angle position is 25 degrees. I have two types of rods. Grey medium grit and white extra-fine grit.

I cleaned the rods using LOTS of Comet and water on a green Scotch Brite pad. I started with the medium grit rods in the 19 degree holes.

// note: in the following all my honing strokes were downwards and vertical unless otherwise noted.

When I started working hard on the left side of the edge I expected to raise a burr in less than 5 minutes. I try and work as efficiently as possible. I rotate the rods a few degrees every 10 or 20 strokes. When I've used most of the surface of a rod once I invert it and make another circuit. In 3 or 4 minutes I had loaded up my left hand rod to my limit and swapped the right-hand rod into the left hand hole to continue. I could still see a bright flat surface on the edge when looked at it in the light. Uh-oh! I'm not making much headway.

I worked hard for 16 minutes before I got a burr raised on the right side of the blade (not even as much of a burr as I expected). In the process I had used, inverted, and cleaned each one of my medium rods twice.

I then recleaned the rods and started on the right side of the blade. By my original directions I would have honed the right side for 8 minutes, but the process was taking so long I decided to compromise. I worked on the right side for about 4 minutes.

Then I started to use alternating strokes on the left and right rods. I could feel a burr on the left side so I worked that side a dozen strokes to make things more even. Then I alternated strokes for about 30 strokes.

Then I switched to the white extra-fine grit rods in the 19 degree holes. I used alternating left/right strokes for 30 or 40 medium strength strokes. Then I did a few light strokes.

Then I moved the rods into the 25 degree holes and did a few light down strokes and maybe 6 light upstrokes. At this point I could easily shave with the edge. Total elapsed time was about 22 minutes.

Just to learn a little more I stropped the edge on plain leather which made the edge a little sharper. As a finishing touch I stropped the blade on a real razor strop coated with green chromium buffing compound. The knife is now one of my sharpest, but gee it was a hard job for such a short and very thin knife!

In conclusion I would suggest you take your wive's knives to a professional sharpening service who will use power equipment to reprofile the edges. Subsequently you should be able to maintain the edges via periodic honing with your Sharpsmaker.

If you want to do it yourself I would buy a long medium-coarse diamond bench hone. With a hone like that for reprofiling you should be able to rough sharpen the knives in under 1/2 hour each. Then finish the job using your Sharpsmaker. That is the type of thing I do for fun. It's the sort of thing that other people avoid like the plague.

I haven't actually used the RADA knife yet, but I have high hopes for it.

Thanks for raising your question. I found it very educational.

PS. Joe is right about not using a 15 degree bevel--19 degrees was tough enough. Use the 20 degree holes until the point where I switched to 25 degrees. At that point just tilt the top side of the blade slightly further away from each rod as you stroke on it (to create a slightly increased finish bevel).

Good luck
 
Thanks to all who answered; particularly Jeff, who bothered to make extra effort.

Jeff, after reading that fantastically detailed description of how to do it, I am smart enough to realize I am in way over my head with these blades. While I no doubt could learn the techniques, I simply have too many irons in the fire right now to take up yet another detailed, demanding exercise.

So, having said that, what is, in your opinion, the optimum power sharpener extant? I remember seeing one advertised i a knife magazine awhile back, but the rag is at the office and I'm on vacation right now.

And the only knife sharpening services available where I live (at least, that I've found so far) do not give off an aura of competence, if you know what I mean.

Thanks again for all of the detailed replies; you guys may yet save my marriage!!!

Steve
 
For these particular knives I would not use any commercial sharpener that I have seen. The issue is the abrupt start of the flat uncontoured blade area between the edge grind and the handle (as I recall you call an area like this a ricasso). Most inexpensive sharpening rigs would not let you sharpen right up to the ricasso. You would either grind into this area or you would leave a conspicuous unground transition area between your sharpening and the ricasso.

I would use the internet or the yellow pages to search "the big city" nearest you for a good professional. A little traveling would be worthwhile. On the phone discuss your desire to preserve the look of the knife and check that they have the right equipment. The equipment is probably a form of belt sander.

PS. As a point of reference--if you did go with a diamond plate it would cut 2x to 4x faster than ceramic rods.

[This message has been edited by Jeff Clark (edited 21 July 1999).]
 
Wow Jeff!

I'm honestly impressed that you went out there to do those tests. You're quite right that diamond plate will go significantly faster than ceramic rods for re-profiling the edge, but a good artificial stone (carborundum, silicon carbide, whatever) will do the job orders of magnitude even faster. Note: I'm referring to benchstones now, not the ceramic rod-type sharpeners. This may seem counter-intuitive, as diamond is the hardest substance on Earth, but unfortunately, if you really bear down, and apply hard pressure when sharpening, you will quickly strip the diamonds out of the matrix, leaving you with poor sharpening performance and longevity.

Using a cheap $2 sharpening stone bought from Chinatown, you can really apply hard pressure, and go very fast sharpening on both the forwards, and backwards strokes. This removes metal like there's no tomorrow! Best of all, you can go through 15-20 of these stones before you approach the cost of one DMT 2x6 diamond stone.

Using the above method of free-handing the stone, I can re-profile a flattened-out Forschner 8" Chef's knife in approx 5-10 minutes of hard work. Re-profiling that same make of knife took about an hour on a 203 Sharpmaker using the medium grit rods. Never again!

What you might be thinking at this point is:
"Well, if you're going so fast, how do you hold the correct angle?" My answer to this is that keeping a relatively constant angle is this point is not important. All you are trying to accomplish here is to cut a more acute edge bevel into the knife, in order to lessen the drag felt as the knife wedges through a cutting medium. A slight discrepancy in the relief bevels does nothing to hinder cutting performance.

What is important with this method, is to remove the burr formed from the above using a Sharpmaker, or other angle guide that allows you to keep the final sharpening angle constant. I believe Joe has said as much in his treatise on the 15/20 Sharpmaker 204 sharpening technique. Using the acute 15 degrees, he states that you don't even have to sharpen all the way to the edge (and form a burr), all you really want to do is thin out the shoulders of the edge to improve penetration performance by reducing drag.
I agree wholeheartedly.

Therefore, I think a Razor-Edge guide might not be a bad investment. With it, you can sharpen on a benchstone, and remove lots of metal rapidly (which you'll need to do if the RADA knives are as dull as you suggest), and then once you've formed the burrs, remove them quickly using a Sharpmaker. You'll save a CONSIDERABLE amount of time versus just using the Sharpmaker.

Finally, this is the reason why all your Spyderco knives can be easily resharpened. First, Spyderco knives already have great edge geometry (nice and thin at the edge). Secondly, the fact that the models are serrated means that the inside arc of the edge doesn't hit ceramic plates or anything else hard, and flatten out. Therefore, the Sharpmaker is just straightening out burrs and rolled-over edges, for which it works great.

Just my thoughts,

Ian
 
Ian,

The Forschners are made of an easier to sharpen alloy than the RADA's. I do just what you suggest when I'm working on nice steel like in the Forschners (my 8" Forschner Chefs knife is my number one kitchen tool). With one slight variation if I'm doing heavy reprofiling. First I use the 1/2"-wide "side" of a medium-coarse hone rather than the wider "normal" surface and I grip the hone in my left hand while I hone under running water from my sink faucet. With this high pounds-per-square-inch zero-hone-loading approach I can really hog down material. I also use a back and forth stroke with minimal regard for precise angle when I start (of course I've done this long enough I probably don't waver more than a couple degrees). I particularly like to work under running water when I'm using a back-and-forth stroke because I figure my back stroke tends to pack metal into the stone.

On select harder alloys the diamond plates seem to work much better. Sometimes I use them under running water to avoid loose diamonds from wearing on diamonds that are still bonded down. I probably wear down my diamond hones faster than most since I often use two-handed pressure to get the job done. Lately I've used the diamond plates a lot more than my aluminum oxide stone. I've completely retired my arkansas stones as just being too slow.

I'm interested in finding some good silicon carbide stones to try. Borazon sounds interesting too.
 
The combination of Razor Edge Systems and Sharpmaker works very well for me as well.

------------------
Knowledge without understanding is knowledge wasted.
Understanding without knowledge is a rare gift - but not an impossibility.
For the impossible is always possible through faith. - Bathroom graffiti, gas station, Grey, TN, Dec, 1988

 
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