A few questions that have been bugging me for years...

[shadowspawn]

First off, how would you fix the tip on a damaged clip point knife with only a stone?

Second, would there be a truly significant difference between a full convex knife vs. a multi-bevel (perhaps 4-5 bevels total) knife?

Thirdly, I've been thinking of getting a polishing compound (I'm thinking chromium oxide) but I've heard some stories of people who have gotten some pretty crappy CrOx in the past. All of the older threads I've seen seem to direct me to the same CrOx paste that is no longer available so if anyone has any reliable vendors of good CrOx, I would appreciate it.

Fourthly, what real advantage is there to sharpening on a wet stone than compared to a dry stone? It feels smoother when you're sharpening but honestly it's way too messy for me and almost feels as if it cuts slower. It may all be placebo though.

And finally, my grandpa just got a small bench grinder (without any safety equipment might I add) and I'm thinking of starting my journey into the world of power tools so his money doesn't go to waste. Anyone got any tips for someone who has never touched a grinder/sander in his life?

 

[Jason B.]

Fixing a broken/damaged tip with a stone is a advanced technique and will first be a question of your skill level. That is, unless you grind down the spine to fix it.

Convex is a multi angle bevel, if you have sharpened by hand than you have to a point convexed your edge.

Handamerican would be my choice but I would also opt for diamond compound instead of chromium oxide.

Their are hundreds of stones you will need to name the exact ones you are speaking of for a proper answer.

Some like power tools and some don't, IMO they take off too much metal.

 

[shadowspawn]

1. I don't see how you can elegantly fix a clip point by grinding the spine. I would imagine you simply sharpen as you normally would. It's just that it becomes even more important to maintain angle consistency as you near the tip. But if there are any alternatives, they'd be nice to hear since I don't have anything exceptionally coarse that could take off that much steel in only a few strokes.

2. True but I was always under the impression that a true convex edge was more round and parabolic in shape and that a multi-bevel knife was more polygonal in shape. But basically, there's no difference right?

3. Well from what I've read on this site, diamond compounds leave a more coarse edge and less of a polished finish. As far as I can see, the only reason to use a finishing compound is to have that nice polished finish. From what I've read, CrOx does the best job.

4. I don't have any specific brand names, but it's just a basic whetstone. Not a Japanese waterstone or an oil stone or anything. Feeling the whetstone's 2 sides, it feels like a 400/600 grit stone. Not sure though since it was a hand-me-down from my grandma's sister.

5. I don't like them because they just seem way too dangerous for my tastes.

 

[Jason B.]

1. The method will require at least a 320 grit stone. You start by raising your angle to 30-40 degrees Per side and grind until the shape is restored. You then move back to the bevel angle you want (15-20 per side) and grind until the bevel is ready for the next stone.

2. No difference just easier with sandpaper and a soft backing. Doing it well on a stone is very hard.

3. Diamond compounds are some of the finest available in grits greater than 200,000. Those that say diamonds leave a coarse edge need to do some reading. Also if your not running a 8-10 step sharpening progression of grits 0.5 micron compound will be a waste of time.

4. Likely a old oil stone, I like soapy water or dry works too. Doesn't really mater either way.

 

[shadowspawn]

1. Would you have to sharpen the whole blade at 40 degrees or could you stop at the end of the belly?

2. Alright just making sure. Haven't had the chance to try that mousepad technique or anything similar yet so I have yet to experiment with a "true" full convex blade.

3. Well quoting someone on the forums: "On most razors the .50 Cr is going to give the overall best, and smoothest results.... Some of us use a combonation on the razor, with a .50 Diamond followed by the .50 Cr
Now to be fair there are certain razors and certain steels that really shine from a .25 diamond paste, they will hold that fine of a edge, and not mircochip, or breakdown too fast.
But in general, and for most people, the .50 Cr is a perfect finish" It also seems that diamonds will leave a "mistier" finish than CrOx from what I've read (even diamonds <.25 grit in size).

 

[Jason B.]

What's good for a razor and a knife are two different things. You would need a well rounded set of stones before the strop and a razor to fully grasp what they are talking about. Stainless or carbon steel makes a difference but that's getting waaaaaaaaaaay beyond your experience level.

 

[HeavyHanded]

1. I don't see how you can elegantly fix a clip point by grinding the spine. I would imagine you simply sharpen as you normally would. It's just that it becomes even more important to maintain angle consistency as you near the tip. But if there are any alternatives, they'd be nice to hear since I don't have anything exceptionally coarse that could take off that much steel in only a few strokes.

'

Grind the spine, or mark your new profile with a Sharpie and start grinding a new bevel at the tip. Grind the blade to create the new radius and then grind in a new bevel. Its a lot of work and even when done well (depending on how big the loss was) will never look quite right. Much easier to grind the spine if the blade shape allows. If the clip has no false edge then its the better way to go IMO.

2. True but I was always under the impression that a true convex edge was more round and parabolic in shape and that a multi-bevel knife was more polygonal in shape. But basically, there's no difference right?

True convex is parabolic. I've been getting good results doing these on a hard stone recently. It may require a bit of extra work with a strop on the face of the blade (just for looks) to blend the grind layers, but with a bit of practice its easier than you might think. The biggest diff between muti bevel and parabolic is going to be how much of a shoulder is developed where the bevels meet - this will determine amount of resistance relative to the smooth transition of a convex. In all reality it will only make a big difference on thicker bladed knives. At the cutting edge itself, all hand-sharpened knives will be convex, esp after they've been stropped, so it comes into play only after the initial bevel has begun cutting and the rest of the blade is making its way into the cut. I don't believe I've ever seen a knife with 4-5 bevels. You'd need a pretty fancy jig to do that with any consistency.

3. Well from what I've read on this site, diamond compounds leave a more coarse edge and less of a polished finish. As far as I can see, the only reason to use a finishing compound is to have that nice polished finish. From what I've read, CrOx does the best job.

Finishing compounds do a lot more than leave a polished finish, they profoundly affect the apex of the cutting edge. Its possible to sharpen the same knife to, for example 600 grit, strop it on a number of different compounds/grit sizes, and get very different cutting characteristics each time. Stropping is also a great way to maintain the edge with the least amount of steel removal - stropping surfaces and different compounds, I have come to realize, are an art of their own.

4. I don't have any specific brand names, but it's just a basic whetstone. Not a Japanese waterstone or an oil stone or anything. Feeling the whetstone's 2 sides, it feels like a 400/600 grit stone. Not sure though since it was a hand-me-down from my grandma's sister.

Very accomplished folk have differing views on this, you'll have to experiment to see where you fall. The main issue doesn't change - any grinding operation produces waste and that will have to be dealt with or your cutting tool will stop working efficiently. Generally I use a lube (dish soap and water) and only go dry when I'm down to the last few passes for burr removal. On a dry stone I use a block of rubber to clean it out frequently.

5. I don't like them because they just seem way too dangerous for my tastes.

Too fast, too noisy. They can get a lot done in a short amount of time. If you have physical limitations, or are sharpening for a living, they make a lot of sense.

 

[eccvets]

dont be afraid of power tools. just pratice, pratice makes perfect and its so much faster. since you got a grinder, take off those stones and slap on a set of paper wheels. The grit wheel with wax on it actually cuts quite slowly and even without any wax, it really doesnt cuz that fast. It's not like an 80 grit belt sander or anything like that. either way, if you use power tools, get yourself at least saftey glasses!!!

 

[richard j]

shadowspawn, eccvets suggested the paper wheels. i have been using them for the past 20 years and they work great and do not take off too much metal like some people say . i only take off just enough to work up a burr. (they work so well i was even sent hate mail ).

here is a link to my paper wheel thread and a post by a member that i sharpened a knife for which sold him on the wheels. http://www.bladeforums.com/forums/showpost.php?p=9207988&postcount=710

 

[David Martin]

I've done them on both, hand stones and with power tools. Both means are easily done to correct a broke tip. Don't fret over this for years just do it. By now you could have already done it and learned something instead of still looking for 'walk me through it advise.' I think the stone you have is good enough to accomplish the task. Use the edge of the stone and work slowly. You'll learn something then report back on your results. It was already a knife you didn't use. DM

 

[Ben Dover]

dont be afraid of power tools. just pratice, pratice makes perfect and its so much faster. since you got a grinder, take off those stones and slap on a set of paper wheels. The grit wheel with wax on it actually cuts quite slowly and even without any wax, it really doesnt cuz that fast. It's not like an 80 grit belt sander or anything like that. either way, if you use power tools, get yourself at least saftey glasses!!!

I would respectfuly disagree with the safety glasses. If using any kind of powered sharpening tool., i.e. grinder, sander, paper wheels, etc, get a full face shied, a heavy leather shop apron, and heavy leather gloves. These are minimum requirements for commercial workers using such tools.