Restoring a needle-sharp tip with the Sharpmaker?

[metaphoricalsimile]

Like a jackass I broke off the tip on my BD1N Manix 2 by hitting a plate with it. I've been working on re-sharpening the tip using a sharp maker with boron nitride rods, but can't quite seem to get there. I have done a *little* regrining the spine of the blade near the tip, but I don't want to change the geometry *too* much.

Thus far my method of tip refurbishment has been: sharpen as normal with the corners of the rods, being *exceptionally* careful not to ride the tip off the edge (I have rounded the tip sharpening with these rods before). When I switch to the flat sides I spend extra time removing material at the tip. The tip is definitely better than it was, but not as good as I want, and definitely worse than the factory tip.

Here's what the blade looks like right now:

Here is a close-up on the tip:

As you can see it looks ok from a distance, but it definitely is not anywhere near as sharp as it was out of the box, even though I have the edge of the blade sharper than the factor edge was.

Should I just keep doing what I'm doing? Are there any technique issues I'm possibly not paying attention to? Do I just need to use different tools to accomplish this job? Should I grind down the spine a little more? Any help or feedback is appreciated, thanks.

 

[Obsessed with Edges]

An EASY way to re-point the tip is to use an appropriately aggressive stone, or improvised 'stone' of SiC sandpaper over a hard backing (like glass or a very smooth/flat ceramic tile), to grind down the spine of the blade near the tip. Lay the spine flush to the abrasive, starting with contact somewhat behind the tip (by an inch or two). Then draw the blade in a tip-trailing direction over the stone/paper in a smooth pass, while gradually and smoothly lifting the handle end to carefully rotate the tip end into contact with the abrasive. Don't lift the handle end any further, once the very end of the spine is in contact. Done smoothly and carefully, the gentle arc of the spine will be preserved and the tip will sharpen up like the damage never happened in the first place. The advantage to doing it this way, from the spine side, is you won't have to regrind a new edge profile to fix it, when a good edge profile is already there. This is also a good method in general, for keeping the tips as pointy as they can be, even when they're not broken.

Something like 150-220 grit, in a stone or in the SiC sandpaper, will do the job very quickly. You didn't lose much tip on your blade, so the fix will be pretty quick. The tip will finish up more 'pointy' and crisp, the harder the abrasive surface is (stone = best; hard-backed sandpaper is adequate). A larger bench-type stone in 8" or longer, or a sheet of wet/dry SiC sandpaper also lend more abrasive working area to the job, which greatly speeds up the work.

 

[mendezj]

I’d send it to Josh, at Razor Edge, get the knife better than new and easier to keep sharp in the future. Been there, done that.

 

[c7m2p3]

Unfortunately there is basically only two ways to go here. Move the spine DOWN to where the new tip would be, or move the edge UP to where the spine is. Both methods will require some aggressive stock removal and thus probably need something a bit more deliberate than the sharpmaker rods.

 

[marchone]

It looks like you’re almost there. I’d keep on going.

I reprofiled a broken tip on a carbon Kramer Zwilling paring knife successfully. I chose to flatten the edge to a new tip before matching the geometry of the original edge.

It’s doable.

EDIT:

I have been using a Sharpmaker exclusively the last few years with good results overall. The harder steels are tedious to reprofile on it, but are achievable.

I have a Wicked Edge Pro Pack III coming tomorrow. I’m so ready.

 

[Obsessed with Edges]

That tip damage is small enough, it could likely be done (CAREFULLY) in the spine-down fashion I mentioned previously, using the flat of the SM's CBN rod. Lay the rod flat to do this (underside of the SM base has provision for this). Only down side is that the rod is very narrow; you'll need to be careful not to let the blade slip off the side of the rod. If doing it this way, take it slow & easy - no need to rush it.

But still, the tip damage isn't that bad. With the right materials, it's a pretty simple fix. It's much easier than it may first seem, if you've never done it before.

 

[bgentry]

That's a very small rounding of the tip. When you said you broke the tip off, I expected to see a broken area at least 1/8" wide if not more. That rounding you have there can be fixed simply by grinding the edge at the regular angle until you make the tip sharp again.

However, I see that you are forming a funky microbevel in the last part of the tip. You are probably slightly angling the knife away from the rods as you approach the tip. I'm just guessing at the method, but the secondary bevel sure seems to be there in the pictures.

What you really want to do is grind the whole bevel evenly. THe sharpmaker's vertical setup isn't very good for that. A bench stone, guided system (edge pro or similar), belt sander, etc will all be better tools for getting a consistent bevel all the way to the tip.

I would probably start with my DMT Coarse and see if that did it. Or maybe a very coarse bench stone. It looks like you could fix it in a few minutes with the right stone. But your technique needs to be solid so you don't alter the tip bevel geometry even more. A loupe, checking often, and patience will all help.

Good luck!
Brian.

 

[metaphoricalsimile]

That's a very small rounding of the tip. When you said you broke the tip off, I expected to see a broken area at least 1/8" wide if not more. That rounding you have there can be fixed simply by grinding the edge at the regular angle until you make the tip sharp again.

However, I see that you are forming a funky microbevel in the last part of the tip. You are probably slightly angling the knife away from the rods as you approach the tip. I'm just guessing at the method, but the secondary bevel sure seems to be there in the pictures.

What you really want to do is grind the whole bevel evenly. THe sharpmaker's vertical setup isn't very good for that. A bench stone, guided system (edge pro or similar), belt sander, etc will all be better tools for getting a consistent bevel all the way to the tip.

I would probably start with my DMT Coarse and see if that did it. Or maybe a very coarse bench stone. It looks like you could fix it in a few minutes with the right stone. But your technique needs to be solid so you don't alter the tip bevel geometry even more. A loupe, checking often, and patience will all help.

Good luck!
Brian.

You misunderstand. The tip as it is now is the point I have repaired it back to, although the original break was probably closer to 1/16" rather than 1/8".

Also the microbevel is the result of how I created this edge by creating a 15 degree back bevel then 20 degree edge bevel with the sharpmaker.

 

[bgentry]

I see. Looks like you've done a really good job so far. You can probably make it needle sharp again with some more careful effort.

Murray Carter taught me the concept of "sneaking up on the tip". Grinding *right* to the tip, but not past it. Putting his advice to work, and using a sharpie to mark the edge, I found I was actually no where near the tip. There was a 1/8" wide area that I wasn't touching, even when I thought I was grinding right at the tip. Turns out that the angle, when you are grinding right at the tip, isn't nearly as obvious as when you are on the main part of the bevel. Using sharpie and getting right up to the tip.... and use a loupe to verify. I was able to make the sharpest tips I had ever made. It's very satisfying to do!

Best of luck.
Brian.

 

[metaphoricalsimile]

I see. Looks like you've done a really good job so far. You can probably make it needle sharp again with some more careful effort.

Murray Carter taught me the concept of "sneaking up on the tip". Grinding *right* to the tip, but not past it. Putting his advice to work, and using a sharpie to mark the edge, I found I was actually no where near the tip. There was a 1/8" wide area that I wasn't touching, even when I thought I was grinding right at the tip. Turns out that the angle, when you are grinding right at the tip, isn't nearly as obvious as when you are on the main part of the bevel. Using sharpie and getting right up to the tip.... and use a loupe to verify. I was able to make the sharpest tips I had ever made. It's very satisfying to do!

Best of luck.
Brian.

Yeah, thanks for the feedback. I think at this point just slowing down and being super careful about sharpening just to the tip is going to be my path forward.

 

[comis]

I see. Looks like you've done a really good job so far. You can probably make it needle sharp again with some more careful effort.

Murray Carter taught me the concept of "sneaking up on the tip". Grinding *right* to the tip, but not past it. Putting his advice to work, and using a sharpie to mark the edge, I found I was actually no where near the tip. There was a 1/8" wide area that I wasn't touching, even when I thought I was grinding right at the tip. Turns out that the angle, when you are grinding right at the tip, isn't nearly as obvious as when you are on the main part of the bevel. Using sharpie and getting right up to the tip.... and use a loupe to verify. I was able to make the sharpest tips I had ever made. It's very satisfying to do!

Best of luck.
Brian.

I think that's a great tip, especially using the marker to check. I find the vertical/angled setup of the rods on sharpmaker is the easiest to work with for tip sharpening/repair, but if you lay the rods horizontal at the back channels, maybe it's easier for tip repair/sharpening.