RC-4 sharpening - something that helped

kgd

kgd

Joined
Feb 28, 2007
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The RC-4 is one of those knives that finds its way on my person pretty much wherever I go. Even for urban conditions, it has found a nice little home in my backpack/laptop/camera/PSK bag this is always on my person. This means it also gets a lot of sharpening because it is likely the only knife on my person at work when I have to do knife dulling things like upen up boxes and even pull apart shipping crates (yes done it many times when I'm too lazy to find a screw driver).

My regular touch up involves using the sharpmaker. Out of the box, the RC-4 mates perfectly with the 20o angle of the sharpmaker and this worked well to get that razor sharpness just as it came new. Until lately though.

It has been harder and harder to sharpen it. In part this had to do with some pretty rigorous dulling of the blade while I was on an extended field trip. I used Sal's video advice and tried sharpening the RC-4 on the 15o to knock some of the bevel down and then re-sharpened it at 20o. This did improve the knife, but it still wasn't nearly as sticky as it used to be. I think I was getting to the point where the bevel was starting to be affected by all the sharpening I keep applying.

This weekend, I pulled out my Lansky guided rod system which went into storage after getting the sharpmaker. I used the medium stone at 17o and really went at the edge on both sides for about 20 minutes. This widened the bevel a few more mm than the original by my guess. I followed this up with a full sharpening on the sharpmaker at 15o (okay I became greedy) + a microbevel at 20o (10 very fine strokes) and WOW. I'm impressed. It slices paper and makes nice paper curls very nicely. I finally realized the hair popping sharpness I keep reading about by other forumites.

I know that this is a bit weaker than the orginal geometry but the cutting performance is really improved. Never had success with convexing a blade myself yet but as a V-grind this combination of Lansky - knocking back the bevel, then sharpmaker to finish the edge and micro-bevel worked really well.

Just thought I'd share.
 
I have found that anytime a knife doesn't come back to at least factory sharpness it has everything to do with the bevels you are using. So, going to the Lansky almost always works for me to put a knife back to shaving sharp. The Sharpmaker is great for touch ups but not good enough, IMO, to bring exact angles back to the edge.
 
R.A.T. said:
I have found that anytime a knife doesn't come back to at least factory sharpness it has everything to do with the bevels you are using. So, going to the Lansky almost always works for me to put a knife back to shaving sharp. The Sharpmaker is great for touch ups but not good enough, IMO, to bring exact angles back to the edge.
Click to expand...

Do you find using the Lanski is enough.. or do you use the Lanski and the Sharpmaker as well?
 
Sorry to butt in..but would either of you mind posting a link to the specific Lansky piece you are talking about so I could take a look?

Much appreciated!
 
Could be just me but I just handled a rc4 on an passaround and had a hard time getting the clamp on the blade.
Seemed to be on the edge of being to thick for the length of screw that was available. I got it to work only one side at a time. Anyone else notice this?
Did I miss part of the instructions? I did find that the 17 degree angle was a good match for the bevel but didnt really take any steel off due to the restrictions of the knofe not being mine.
 
Oops sorry haven't checked this thread in a little while. I like to use the Lansky Delux guided rod kit (stones not diamond) in combination with the sharpmaker. I probably wouldn't recommend buying the two in combination, but it seems most people graduate from a Lansky to a sharpmaker so they end up having both. Other possible alternatives include the DMT aligner kit which gets pretty good reviews but I haven't tried it personally.

Regarding the clamp. I busted that little plastic screw about the third time I used the Lansky. So I just have an old fashioned metal screw that I use with a Phillips screw driver. The lets me slide the clamp a little deeper and tighten it down really securely. I found that putting a thin piece of cloth between the clamps keeps it from scratching the blade and coating also.

Grind the shoulders down until. You don't really have to use any technique at this stage. Grind in circular motions or a sawing motion or switch up. Just try not to cut your finger when not paying close attention. It takes a while and you want to switch sides about every 5 or ten minutes. Continue until you start to get a noticeable burr on one side and then sharpen the edge in sections until the bur feels pretty uniform. It may take you 30-40 min. depending on how steep an angle you choose. Repeat on the other side again until the bur is formed.

One other little trick is to keep wrap your pink finger around the end of the rod exiting the guide hole behind the clamp. This keeps the rod tighter to the hole as opposed to bouncing around and maintains the angle better.

Now once the bur is formed switched to a more consistent stroke. I like to start at the back edge and sweep it towards the front while sliding the stone in a downward motion. Do the same stroke for about 15-20 strokes until the burr re-forms on the edge. Repeat on the other side.

Repeat each side with fewer strokes (i.e. 5-10), just enough strokes to get the bur up again. Now switch to the medium stone. You will only need to do the 15-20 careful strokes to raise the burr. You will notice the burr is finer with the medium stone than course one. Again repeat on both sides about 3 times and move to the fine stone.

After the fine stone I go to the sharpmaker. You can use the 15o slots now starting with the grey corners/ gray flats/white corners/white flats for 20 strokes each. You should have a hair shaving, paper slicing knife at the end of this.
 
newknife said:
Do you find using the Lanski is enough.. or do you use the Lanski and the Sharpmaker as well?
Click to expand...

You can use the Lankski on its own. It is a pain in the ass though making sure that you fully remove the bur. Basically you want to perform a bunch of one or two strokes per side on the knife in succession. I.e. perform two strokes, flip the knife over, perform 2 strokes, flip the knife over...and repeat about 20 times. The sharpmaker is just very much optimized for doing this last part. I also find the sharpmaker gets the angle more precise than the Lanski.
 
Moving Target said:
Sorry to butt in..but would either of you mind posting a link to the specific Lansky piece you are talking about so I could take a look?

Much appreciated!
Click to expand...

I don't even own one anymore. I use an old Smith Bros. that does the same thing.
 
The only problem I have had with the Lansky is that unless you chuck the blade up EXACTLY THE SAME every time, you will cut different angles each time you sharpen, owing to the fact that the geometry is not the same. It is not a big deal if you are reprofiling, because you are redoing the bevels anyway. But if you are only doing a touchup you have to be careful to clamp the blade in at the same place and depth and the clamp screws have to be tightened the same as the first time you did it. Otherwise the angles will be slightly off and you end up wondering why the Sharpie is not coming off properly.
 
Yep, thats why the sharpmaker is so much better at touch ups. I hold off on using the Lansky until the sharpmaker starts running up against the bevels again. That amounts to about needing to rebevel about once every 8 mo or so.
 
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