Repairing a Botched Sharpening

[RickKrung]

When I first got my T8, I was so anxious to try it out, I didn't follow the sage advice here to practice on some junk or unimportant knives, such as can be had at thrift stores.  I did try out the DBS-22 Drill Bit Sharpener first, as that was my primary interest. But, I have two Leatherman Wave multi-tools.  One lives on my belt, the other should live on my nylon fishing fishing belt, but it has been hanging out on my workbench ever since I botched sharpening it and I've been procrastinating. I suspect I did not lift or pivot the blade as I got to the tip.

But, in the meantime, I've learned a ton reading the various posts about knife sharpening and feel that now might be a good time to try tro fix the botched job.  Basically the bevel at the curved tip is quite wide, a lot more so that on the main part of the blade.  I have not checked to see if the bevel angle at the tip is the same or not. I also managed to blunt the tip. 




I am wondering how repairing this should be approached.  I read one thread where a fellow named Magnus Sandquist put a new tip on a knife by drawing a new profile on the knife with a marker and sharpened it until that line was gone. 
https://forum.tormek.com/index.php?topic=3124.0

A am wondering if the front edge should be flattened and then sharpened, or if it should just be sharpened again using some of the techiques I've learned (perhaps Herman's free hand platform) until the bevel is the same from end to end.  The problem I have with using Herman's platform is that I felt it did not work so well with the shape of the sides of the Wave blade.  I am more inclined to use the regular knife jig where I have turned down and squared off the adjustable stop. 


I think before I tackle trying to fix the Wave, I'm going to practice some more on knives I've gotten from the thrift store and maybe some of my former father-in-law's that came my way after his passing.  I need to set up my laser and try out the turned-down/squared off adjustable stop and work out the degree of lifting and pivoting that is required to get a more uniform bevel width.

Rick

[Crusty]

Hi Rick
I reckon you should just resharpen on the SVM-45 knife jig, mount the knife in the jig on the top flat sides of the blade and use that nice new stop, work on reducing the angle grinds back to normal. 
Most of the uneven grinds appear to be near the tip so I would start from there and work back towards the heel, make sure the knife is not on the piss in the jig as it looks like it was the first time. Once the angles are getting close sharpen as normal.
As a note, I've found most leathermans to have uneven grinds on them, (strange as they are sharpened on cnc robotic grinders).

[RickKrung]

make sure the knife is not on the piss in the jig as it looks like it was the first time.

Thanks.  I don't understand what is meant in the quote above.  I'm thinking it is some kind of typo, or I need to be educated in some lingo.

Rick

[Ken S]

Rick,

Welcome to the club. For more years than I remember, I have always kept my Swiss Army Tinker Knife in my pocket. The blade is worn more than it should be, part of my tuition in Sharpening 101.

We are fortunate that the owners of these knives, while observant, will not make problems for us. You are wise to use this knife sharpening as a learning opportunity. What can we all learn from this? (By the way, my Henckel chef's knife has not been exempt from my learning process. The patient has survived and is still working.)

You noted the obvious first lesson; don't start out with an expensive knife.

The second mistake is very easy to make. The grinding wheel should be graded fine. It took years before I knew that what I thought was fine was actually a middle grit. When I used the stone grader for a full minute, I was amazed with how much finer the grit became. Stig told me he grades his grinding wheel to 600 grit. I am sure that "600" is approximate, however, it makes us aware that grading is not an all or nothing process; the experienced sharpener can benefit from middle grading. Tormek is very lean on stone grader recommendations. This should be corrected with more information.

Back on point, a wheel graded fine lets us make misgrinds slowly. Just like grinding a chisel out of square, it is not cheating to observe the process along the way and make course corrections.

If the knife was mine, I would not regrind it. I would keep it sharp and let it continue to be a quiet reminder to use good technique. Regular sharpening will gradually correct the grind.

Harpsichord builders traditionally scallop the ends of the wood keys. (work semi circles into the ends for decoration). A centuries old tradition is to intentionally leave one key unscalloped, noting as a sign of humility, "SDG" (Soli Deo Gloria, Latin for to God alone be the glory). My pocket knife is a reminder that I am continually growing. It keep me humble, and it keeps me learning. Use the gift your Leatherman knife has given you.

Ken

[cbwx34]

Rick,

First, I'd be curious how that was done... on the Tormek with a jig, that's kinda hard (but not impossible) to do.  That's usually seen freehand, where the knife is improperly rotated, and tipped "back" (for lack of a better term).  The Tormek setup usually prevents this, and on a shorter knife, it's hard to 'flatten out' the tip.

...
If the knife was mine, I would not regrind it. I would keep it sharp and let it continue to be a quiet reminder to use good technique. Regular sharpening will gradually correct the grind.
...
Ken

I'll 2nd this.  I would simply add a good bevel to the knife, and leave the "unevenness" alone.  For example, in this practice knife...



... you can see many uneven bevels, however it now has a decent, "even" edge on it, and cuts well.  (The black part that looks like it was colored with a marker, is the current edge).  May not look the greatest, but actually performs well, since it was thinned a bit. 

If you do decide to try and repair it, keep in mind a few things (you may already know):

• Making tip repairs requires removing a fair amount of metal away from the tip.  In this case, you'd probably have to start around 1/3 of the way back from the tip, and work your way toward it.  (You'll also be making the tip area thicker, and may not cut as well).
• Make sure you don't end up with a tip that sticks out when the knife is closed, which can happen if you do all the work from the bevel side.
• If you do decide to repair or reshape the tip area, I would not do it as shown in the link you referenced.  I would mark it with a Sharpie as you suggested, but then grind 90° to the stone to reshape the knife, then grind in a new edge.  Much easier approach.

But, like I said, on this knife, I would just sharpen a good edge on it.  You can spend a bit more time in the "belly to tip" area, and over time it might create a bit better tip, but I think a good sharpening will give you a decent tip, and a knife that will cut well.

make sure the knife is not on the piss in the jig as it looks like it was the first time.

Thanks.  I don't understand what is meant in the quote above.  I'm thinking it is some kind of typo, or I need to be educated in some lingo.

Rick

I'm hoping typo.      (I think "place" may make it make sense?) 

p.s.  I think this knife is a good candidate for your "squared off" jig stop.  (And as always, Sharpie is your friend). 

[cbwx34]

Just for (hopefully) a little better idea, I did a quick resharpening in the jig (similar to your setup), at a little lower angle... to give a better example...

[Crusty]

make sure the knife is not on the piss in the jig as it looks like it was the first time.

Thanks.  I don't understand what is meant in the quote above.  I'm thinking it is some kind of typo, or I need to be educated in some lingo.

Rick

No typo, ozzy slang. Basically translates to not "straight or true", To me it looks like the knife was on a slant in the jig, more grind on one side than the other.

[RickKrung]

Rick,

First, I'd be curious how that was done... on the Tormek with a jig, that's kinda hard (but not impossible) to do.  That's usually seen freehand, where the knife is improperly rotated, and tipped "back" (for lack of a better term).  The Tormek setup usually prevents this, and on a shorter knife, it's hard to 'flatten out' the tip.

...
If the knife was mine, I would not regrind it. I would keep it sharp and let it continue to be a quiet reminder to use good technique. Regular sharpening will gradually correct the grind.
...
Ken

I'll 2nd this.  I would simply add a good bevel to the knife, and leave the "unevenness" alone.  For example, in this practice knife...

p.s.  I think this knife is a good candidate for your "squared off" jig stop.  (And as always, Sharpie is your friend). 

First, it was done in a knife jig, SVM-45.  I don't really recall what I did so I can't help there.

Second, thanks for the feedback.  I will not regrind it, and will just grind a good bevel, as suggested.  And I will probably use the squared off stop.  After practicing a bit more.

Third, I don't recall that the knife was anything but straight, but I'll make sure this time.

Regarding  Herman's free-hand platform, it definitely puts scratches on the side of the blade.  I am thinking of putting some blue painters tape on both sides, down close to the bevel but far enough back to not impinge on the stone.  I'll try it on a practice knife first. 

Rick

[Nico]

What a great topic, I'm glad I found it before posting a new one of my own. Well, I am in the embarrassing situation of having totally botched the sharpening of a nice kitchen knife with a common Santoku profile. What makes it even more embarrassing is that the knife belongs to one of my best friends. Of course I have offered to replace the knife for my friend, but at this stage, I am wondering if there is any hope left for the edge?

To make matters worse, I am not sure exactly how things got so pear-shaped. I have sharpened dozens of knives on my T-8 by now, and I did set out to put a brand new bevel on it (12 DPS) and so I was expecting a decent amount of steel removal from the start. And I try to follow all the best Tormek practices (eg. 1 or 2 passes per side, always going unidirectionally from heel to tip, etc.), But at some point I started losing the profile near the heel, and the more I tried to fix it the worse it got. Oops.

Does anyone know whether this knife edge can be restored now, and if so, how?

For the record: sharpening was done with a T-8 with the SG-250 wheel first at #220 then at #1000. The jig was the KJ-45.

[tgbto]

Hey Nico.

Your friend's knife can still be fixed...


I think wolfgang covers it in the knife repair video starting 6 minutes in. If you have diamond wheels, sharpening on the side will be easy, and it is still doable with the side of a SG stone.

If you have access to a belt sander, it will be the most efficient way to go IMO.

Good luck.

[Nico]

Thanks a ton for that link. Checking it out now. This could be the justification I've needed to get one of the diamond wheels 

[tgbto]

Glad it helps. As for the diamond wheels, you probably want to make sure you have the need for them : to reshape the knife you'll need the DC, but common resharpening of carbide tools is more of a DF/DE job.

Even one diamond wheel will moreorless pay for a small versatile belt sander that will be more efficient for reshaping, but also for knifes with odd shapes, lawnmower blades, etc.

[Thread Killer]

Just a nugget My first knife was a Randall Made 19-5 and I totally messed up the grind line. See YOU'RE not the biggest idiot; I'm at the head of that queue for a while.  I too am afraid to work on fixing it. But some day........  So all your responses help.

[Nico]

Glad it helps. As for the diamond wheels, you probably want to make sure you have the need for them : to reshape the knife you'll need the DC, but common resharpening of carbide tools is more of a DF/DE job.

Even one diamond wheel will moreorless pay for a small versatile belt sander that will be more efficient for reshaping, but also for knifes with odd shapes, lawnmower blades, etc.

Thanks for the advice.

I watched Wolfgang's analysis of how unintended recurve mistakes happen. In my case, using too much pressure probably and overgrinding the heel was the problem. Perhaps I've been overly influenced by a tip I saw in one of Wootz' videos (below) where he emphasizes more time on the stone (in general) should be spent on the heel of a blade rather than the belly or tip. More practice required and a lighter touch!

https://youtu.be/kRZTiv6XVgA?si=Qk-cewiXPRCIQhIY&t=110

If I have any success at reshaping the profile I will post the results!

[Nico]

I had a go resetting the profile by grinding flat against the side of the SG-250 stone. I don't have a multi-base so I did it kind of freehand, but I was able to set a stop on the USB which the KJ-45 stop could rest against to give me a consistent angle from side to side. I found the approximate edge angle using the marker method.

After gently grinding on the side of the stone a few times, keeping the blade perfectly flat, the profile became dead straight as expected. No light could be seen shining through from the other side. Yay! Then I switched to regular grinding using the KS-123 angle setter at the 12 DPS I used originally, and cleaned up & polished the edge.

Results are below. It is a lot better than it was! But I detected a hair of recurve creeping back again into the profile from the final sharpening. I must be making the same mistake as before.

Thanks for the tips everyone. Now I can return the knife to my friend without so much egg on my face 

BTW I was horrified to see how much material I had inadvertently removed from the heel as witnessed by how close the edge has become to the grantons