PDA

View Full Version : Sharpening advice....



Zwiefel
02-17-2013, 09:23 PM
got a couple of knives in from a friend to sharpen/repair.....they're in rough shape....here's a sample:

http://farm9.staticflickr.com/8089/8484391028_1a7c9eddae.jpg

So I have a couple of questions...

1) last time I worked on a broken tip, everyone said to work from the spine down. How does one do that w/o creating a bevel on the spine? Grind the knife against the stone perpendicular to the stone? Would this be a good task for the steel flattening plate (#150)?

2) What's the best way to get those massive chips out? Something similar to the spine? (grind it perpendicularly on the flattening plate)

Any other thoughts? (I don't know the details of the abuse that led to this...)

I can't quite make out the brand....here's the best photo I could get of the maker's mark:

http://farm9.staticflickr.com/8225/8483296481_55ae58ec16_z.jpg

TIA!
Z

shaneg
02-17-2013, 09:32 PM
A chipped shun, who would've guessed.

ThEoRy
02-17-2013, 09:35 PM
It's a Shun, most likely vg-10. Just put tip of the spine down on a diamond plate and start pushing and pulling away and towards yourself until the spine reaches the edge or is about 1mm away. Then just start on a low grit stone and sharpen as usual until the chips are mostly gone. Move up to a 1k stone and just sharpen as regular up to 5k then strop.

You can even take a magic marker and draw on the knife the new curve down to the edge as a template to follow. You kind of have to start back a bit to keep the tip natural looking.

Benuser
02-17-2013, 09:42 PM
For both spine and edge I would use automotive sandpaper, grit P120, 90 degree with the spine. With the edge, I would suggest an edge trailing motion under some 80 degree.

vicv
02-17-2013, 10:02 PM
the problem with fixing the tip by grinding down the spine is are you not going to completely change the look of the knife with a very triangular tip? Or is that just something you have to accept if you break off a tip?

stevenStefano
02-17-2013, 10:03 PM
the problem with fixing the tip by grinding down the spine is are you not going to completely change the look of the knife with a very triangular tip? Or is that just something you have to accept if you break off a tip?

You gotta blend it in, which means grinding quite far back from the tip as well

ThEoRy
02-17-2013, 10:09 PM
the problem with fixing the tip by grinding down the spine is are you not going to completely change the look of the knife with a very triangular tip? Or is that just something you have to accept if you break off a tip?

My knives don't look like that and I've broken many a tip. You just have to start back far enough to make it blend naturally. In this particular case I would start about halfway back in the first image shown.

vicv
02-17-2013, 10:11 PM
That's what I thought. I did it once on a cheap knife with a belt grinder before. It worked and fast but looked funny afterwards. As far as the chips though I also used my grinder before perpendicular then thinned the edge back out. Worked quite well and put actual edge on with stones. That was easy. Fixing a tip takes a lot more skill.

ThEoRy
02-17-2013, 10:19 PM
Here's a little bit better idea of what needs removal. Still this is by no means exact but a basic guideline.

13383

It is a good bit of removal still but keeps the profile basically the same.

Zwiefel
02-17-2013, 10:22 PM
Thanks guys...I'll think on it and give it a go next weekend....will be interesting to use the diamond plate in this way.

Benuser
02-17-2013, 10:23 PM
Ever thought about a kiritsuke tip?

http://postimage.org/image/v7b5m14bj/

vicv
02-17-2013, 10:27 PM
That line actually helps a lot. I know it's not my thread but thanks. That's helpful when I have to do this eventually

Zwiefel
02-17-2013, 11:36 PM
Here's a little bit better idea of what needs removal. Still this is by no means exact but a basic guideline.

13383

It is a good bit of removal still but keeps the profile basically the same.

I didn't see these graphics before...very helpful, thanks Rick!

Any thoughts on the suggestion of a Kiritsuke tip?

vicv
02-18-2013, 07:56 AM
It would make it look different!

cwrightthruya
02-18-2013, 10:08 AM
I've done a few tips, but nothing nearly as bad as this. So, here is a question for you all. Would it be better to fix the bevel and take out the large chips before even trying to fix the tip by grinding the spine? It seems that it would make it easier, at least for me, to see what the final shape would end up as. Or would it be better to switch back and forth as you work, sort of making the 2 meet in the middle?

Thanks,
Chris

cwrightthruya
02-18-2013, 10:12 AM
I didn't see these graphics before...very helpful, thanks Rick!

Any thoughts on the suggestion of a Kiritsuke tip?


My old shun is fairly thick toward the spine, affording it quite a small amount of tip flex and a large amount of toughness. Turning this into a kiritsuke tip would require you to take all the stability away from the new formed tip by grinding the spine down to meet the thin bevel. If this person already broke off the "thicker" tip, imagine what he would do to a kiritsuke tip.
Just my thought, but I will defer to those with more knowledge than myself.

Regards,
Chris

daveb
02-18-2013, 11:00 AM
Z,

The 0701 pictured is shun's version of a petty, 150mm. I own one just like it - without the chips. The only thing mine does well is trim silverskin from beef and pork loins. Being stainless I also use it on citrus and tomatoes if I don't have a knife handy. A new one is 100 bucks from amazon.

That said I would pass on the repair unless you're looking for a project. It would require way too much time and stone wear for a knife that at best would have limited application.

Regards,

Dave

Benuser
02-18-2013, 11:46 AM
Turning this into a kiritsuke tip would require you to take all the stability away from the new formed tip by grinding the spine down to meet the thin bevel. If this person already broke off the "thicker" tip, imagine what he would do to a kiritsuke tip.

One of the advantages of a kiritsuke tip - beside simplicity and edge saving - is its strength. It's a easy way to at least double the angle between spine and edge. The old angle was probably some 20-30 degree, I would put a 60 degree kiritsuke tip on it.

cwrightthruya
02-18-2013, 11:55 AM
Can you explain the logic/geometry to me? The only kiritsuke style gyuto I have is a Yoshikane. It has a much thinner tip than its "Standard" Shaped counterpart.

Thanks in advance

Chris

Benuser
02-18-2013, 12:51 PM
As always, it depends. You may have a kiritsuke tip of 30 degree, or one of 70 degree. A kiritsuke tip is not stronger or weaker than another one. I gave a few other reasons, but I can't agree, if one states a kiritsuke tip is weaker in se.

Notaskinnychef
02-18-2013, 01:47 PM
I want to know what the heck he used it for. Was he cutting rocks? I know the shun knives are fragile with regards to this but I've never seen such a mess

ThEoRy
02-18-2013, 02:17 PM
I've done a few tips, but nothing nearly as bad as this. So, here is a question for you all. Would it be better to fix the bevel and take out the large chips before even trying to fix the tip by grinding the spine? It seems that it would make it easier, at least for me, to see what the final shape would end up as. Or would it be better to switch back and forth as you work, sort of making the 2 meet in the middle?

Thanks,
Chris


Grind the spine down till it almost hits the edge that way when you start removing from the edge you can make the two meet. This way you lose less steel from the spine. Barely. But it's a bit easier since you don't have to take the thicker spine all the way down.

ThEoRy
02-18-2013, 02:18 PM
It would require way too much time and stone wear for a knife that at best would have limited application.


Not with a diamond plate or belt grinder. :biggrin:

Benuser
02-18-2013, 02:25 PM
...or with coarse sandpaper.

franzb69
02-18-2013, 02:27 PM
i would use a dremel tool. cut it down to the desired shape. would only take 15 minutes to cut it down. then just sharpening it up and rounding down the edges on the new spine.

berko
02-18-2013, 02:48 PM
ive done this twice. once with dmt 325 and shapton pro 220 and 320, which took like 5 hours. once with a belt sander, took like 30 mins. shaptons were ruined 4-5 mm and needed serious lapping afterwards, which took at least another hour with 400 grit silicon carbid. even with dmt coarse its a pain in the ass. i wouldnt do it again, especially not if i wouldnt get paid for it...

franzb69
02-18-2013, 02:52 PM
even an angle grinder, a vice and water to cool the blade down would work faster.

Patatas Bravas
02-18-2013, 03:22 PM
I also this you should use sandpaper for fixing this knife. Maybe so much work will wear on your expensive diamond plate and also I agree about it is not the best knife to wear your equipment with. Tell us after how this goes!

daveb
02-18-2013, 03:47 PM
That said I would pass on the repair unless you're looking for a project. It would require way too much time and stone wear for a knife that at best would have limited application.




Not with a diamond plate or belt grinder. :biggrin:


I know this anathema to some here but the best possible outcome of such a repair (on this knife) is a well polished turd. :biggrin:

Wrap it and round file it.

Regards,

mkmk
02-18-2013, 03:59 PM
Yeah, I'd have a hard time investing much sweat, time, or wear on my sharpening equipment on this one.

ThEoRy
02-18-2013, 04:34 PM
By hand it's really only about 45 minutes of work. Not a big deal.

joels747
02-18-2013, 04:56 PM
My logic tells me i would put the blade on a page and continue the original lines to find out the place of the original tip. I would then mark the place of the new tip on the blade keeping it at the same height as the original one.
I would then blend the lines from the new tip to the blade. (both on the height and the width of the blade).

Whichever way you choose to do it - good luck.

Chefdog
02-19-2013, 11:11 AM
Someone might have said it allready, but use the side of your coarsest stone so it doesn't ruin the sharpening surface. This obviously won't work if you're using a diamond plate. I use an old "peacock" stone flattener for tip repairs to get the shape 95% and then smooth it out on the side of regular stones.

Justin0505
02-19-2013, 12:51 PM
Use your sidewalk or piece of cement curb. As others have mentioned, it would be murder on your stones or plate and painfully slow.

Not only is the sidewalk coarser, but the extra real estate allows for longer strokes and much faster progress.
-draw the new shape out on the blade w/ sharpie and color in the metal you plan to remove
-dont press too hard when grinding
-move parallel to the blade, this makes getting a smooth curve easier and is less prone to chipping
-you can generate a surprising amount of heat: check the temp and use water if needed.
-after the coarse grinding is done, clamp the blade spine-up. If using a metal camp or vise, use wood or a few layers of cardboard on either side of the blade to protect it
-use sandpaper perpendicular to the spine in a "shoe shine" motion to even out the grinding and round the spine. Tape on the back of the sandpaper helps to extend its life before ripping. They a little more $, but you can also use belt-sander belts and cut them

zitangy
02-19-2013, 01:28 PM
I wld look for the cheapest belt sander as it may cost more if your stones adn plates becomes really, really uneven.

besides.. its a new toy to play with. I believe that there are some available under USD 50.

After the session on belt sander, sandpaper say 600 grit wld be ideal for the clean up . Do be aware that teh real estate of the tip is so thin and tiny that it literally disappears and leaves a fresh blackened tip. Thus the last bit I wld prefer sandpaper..

whilst t it have fun..

d

Zwiefel
02-21-2013, 11:56 AM
Lots of good ideas, thanks guys!

I was thinking about using a cinder block to do a lot of the steel removal, and I have a few floating around...any reason that shouldn't work as well as concrete?

Justin0505
02-21-2013, 12:09 PM
A cinder block should work well and will be more comfortable both interms of ergonomics and explanations to neighbors.

I vaguely remember some video of Carter from back when he was more interested in unorthodox grooming practices than flying helicopters where he sharpens an ax on a cinder block and then shaves with it.

Zwiefel
02-21-2013, 12:24 PM
Thanks! I'm planning to work this over the weekend...I'll take copious photos so you guys can make fun of me.

Zwiefel
02-21-2013, 03:23 PM
Oh, another couple of questions...do you try to keep the cinderblock wet? does that make any difference for this task + material? Also, assuming that grinding the spine down works, would it make sense to also use the cinderblock to remove most/all of the chipping?

Zwiefel
02-21-2013, 05:22 PM
It's a little grainy, lighting was tricky today, how does this line look to you guys?
http://farm9.staticflickr.com/8093/8495224927_efb58e793a_z.jpg

GlassEye
02-21-2013, 07:20 PM
Last time I did such heavy work, it was sidewalk and wet cinder block with brick slurry. I just walked backwards down the sidewalk dragging the spine, then used a sawing motion on the cinder block to remove chips, cut in a new bevel, then go to the water stones to polish everything out.

Zwiefel
02-22-2013, 06:38 PM
Thanks to everyone for the suggestions, observations, and ideas. Here is a side-by-side with my results:
http://farm9.staticflickr.com/8104/8499155354_b6722122c3.jpg

I'm quite pleased with the outcome. It could be a little flatter along the spine...but this is not bad at all. And that damn chip in the edge almost gave me a fit. These things are damned chippy...I wasn't about to start back over at 400 just to get that out.

If anyone is interested in the complete photo set, it's here:

https://www.facebook.com/media/set/?set=a.10151494041779415.510469.144012669414&type=1

This petty was 1 of 3 shuns I did, along with a Calphalon Katana, and some mid-range wusthoff/henckel's knock off. The Katana has a fracture in it about 1" from the heel, about 3/4" long, is that typical for these knives? It took a pretty darn good edge, as did the shuns.

stevenStefano
02-22-2013, 06:44 PM
Looks great

Zwiefel
02-22-2013, 06:59 PM
Oh, and kudos to ThEoRy, he guessed the time nearly exactly: guess=45 min, actual=40min.

Benuser
02-22-2013, 07:00 PM
Excellent!

ThEoRy
02-22-2013, 08:58 PM
Looking sharp!! Told ya it wasn't that bad. Nice job!

franzb69
02-23-2013, 12:04 AM
that looks awesome! good job!

Justin0505
02-23-2013, 06:43 AM
Nice work! I personally think that these kinda restorations are enjoyable... there's something about restoring function to a broken tool, even if it's "just" a humble shun, that's very satisfying.
And sharpening on a cinder block is just goofy fun.

Zwiefel
02-23-2013, 11:41 AM
I personally think that these kinda restorations are enjoyable... there's something about restoring function to a broken tool, even if it's "just" a humble shun, that's very satisfying.
And sharpening on a cinder block is just goofy fun.

Exactly! Both a good chance to learn something, and a good chance to confirm something I've learned. And yeah, the cinderblock was a bit of slapstick....rather effective slapstick mind you. I know the owner will be pleased, these were previously considered, "beyond help."

ThEoRy
02-23-2013, 02:05 PM
I fully restored one of those kalphalon katana vg1 blades last year for an employee. Tip was broken off and there was a HUGE overgrind about an inch up from the heel right through the sweet spot from improperly honing on a diamond rod for years. Told him I could fix it for him and he just laughed and was like "no way". Took it home and reprofiled it on the plate, fixed the overgrind, I even buffed it and etched the damascus just for fun. He was like, "I thought it was unfixable this is like a totally different knife!" Then I told him it was all done by hand... lololol It is a pretty satisfying experience.

Chefdog
02-23-2013, 09:35 PM
Alright, this thread has inspired me guys. I'm going to attempt to grind down my old masahiro gyuto into something more suji/petty shaped. Ill probably use the concrete patio out back to reshape the blade. Any reason I shouldn't use the concrete to do the initial thinning as well? And will it be worth the time to go pick up a cinderblock vs just using the patio or a curb?

Zweifel,
Nice work, the new spine looks nicely shaped.

Benuser
02-23-2013, 11:20 PM
Pix please from that Masahiro. Does it need such a harsh treatment?

Zwiefel
02-23-2013, 11:23 PM
Alright, this thread has inspired me guys. I'm going to attempt to grind down my old masahiro gyuto into something more suji/petty shaped. Ill probably use the concrete patio out back to reshape the blade. Any reason I shouldn't use the concrete to do the initial thinning as well? And will it be worth the time to go pick up a cinderblock vs just using the patio or a curb?

Zweifel,
Nice work, the new spine looks nicely shaped.

Glad to have inspired something other than laughter! Very pleased with my second tip repair. Good luck with your repairs/fixes.