Sharpening Hell

[pecanbery]

So yesterday I helped a family member sharpen their set of VG-10 Shun knives. After taking a closer look I realised they'd never actually been sharpened other than a honing steel (10 years). They didn't really have a secondary bevel, just a deeply chipped edge. Any cutting ability they had left was entirely due to the serrated effect the chips caused.

I spent over an hour with an SG 500 and a King Hyper 1000 trying to get three of the knives back into working condition but couldn't remove all of the chips towards the tip. Thinking I might need something faster than an SG 500 in the future for this kind of work. I finally appreciate why some people here avoid hard wear resistant steels, I'd hate to try to repair a knife made from ZDP-189 or HAP40.

[Ourorboros]

You need something coarser, like a 220 or maybe 120. Depends on the chips.

[Radar53]

^^^^^ +1 I use a Nubatama 150 and find that pretty good.

Thankfully I've never had to repair chips in ZDP189 or HAP40, but I think that I would be breaking out the diamonds

[Bensbites]

I agree, I would have thrown in the towel and either bought a courser stone or sent it out.

Shun does have free lifetime sharpening.

What do you use to flatten your 500? Would that have cut faster?

[pecanbery]

What do you use to flatten your 500? Would that have cut faster?

I have an Atoma 140 for flattening but it's mounted to a handle so I can't use it for sharpening. Also just based on the feel I don't think I'd want to put a knife on it.

Might get an Atoma 400 or a fast 320.

[nakneker]

Nubatama 150, SG 320 are two that handle that job well. The SG being much smaller and easier to travel with.

[lsboogy]

I took two very small chips out of a HAP40 blade last winter (brother lacks knife skills - he now uses the suisin 52100 when he cuts here) - until recently my coarsed stone was a 1K red monster - it took out the chips but was a good 20 minutes on the red 1K before I went on. VG10 should be much easier to sharpen, and I am now the proud owner of a basement stone - get a coarse stone and go to town. I've done my brothers wusthof knives that had not been sharpened for 10 years with a 1K stone to start with - I feel for ya.

[Ourorboros]

Also just based on the feel I don't think I'd want to put a knife on it.

Coarse is the way to go, not finer. You are reducing the problem from chips to coarse scratches, then polishing out (or down) the scratches. Going finer costs you time and effort, as you as with the SG 500.
As you get closer to getting out the chips, check often to know when to stop.

[ken123]

Depending on severity, a 150 bamboo or either the 60 grit or 24 grit Nubatamas are the way to go. I also have the 60 and 46 grit diamond plates too but for most work the 150 gets it done. There is also a 120 grit brick too.

Im always amazed at the hesitancy to employ a coarse stone or plate when needed. Spending a large amount of time on a higher grit stone is just an exercise in frustration. With the right stone this should be done in minutes. Same principles apply to more abrasion resistant steels.

---
Ken

[Wjhunt]

My coarse stone is a 320 grit diamond. I am hesitant to use it. My exercise in frustration is getting rid of the huge floppy burr it creates. I only do a few strokes on a side before flipping the knife. Sorry if this is off topic but I could really use some good advice.

[old onion]

My coarse stone is a 320 grit diamond. I am hesitant to use it. My exercise in frustration is getting rid of the huge floppy burr it creates. I only do a few strokes on a side before flipping the knife. Sorry if this is off topic but I could really use some good advice.

Don't create such a big burr.

[Wjhunt]

I try not to create a burr at all during normal sharpening. I check the knife frequently and stop just before or at the first sign of a burr. My problem is trying to get rid of a chip. The burr is there before the chip is gone. Always trying to learn. I appreciate all the wisdom and generosity from the members of this forum.

[old onion]

I try not to create a burr at all during normal sharpening. I check the knife frequently and stop just before or at the first sign of a burr. My problem is trying to get rid of a chip. The burr is there before the chip is gone. Always trying to learn. I appreciate all the wisdom and generosity from the members of this forum.

This is a common problem but requires a thread of it's own so that you can get more feedback and help when they read your
topic title. Just trying to help you out here.

[Wjhunt]

Thank you old onion. I didn’t mean to de-rail this thread. I apologize for that.

[old onion]

Thank you old onion. I didn’t mean to de-rail this thread. I apologize for that.

Oh,no problem on de-railing.I don't think anybody cares about that at all and that wasn't on my mind at all.I just thought to better serve you and get more people involved with repairing your chip or any other concerns you may have,it would generate more response to create your own thread.

[Jason H]

How large of chips are we talking about? I just sharpened my Shun that was full of micro chips and Chosera 400 handled it very well.

[Seattle_Ben]

My sharpening life's been so greatly improved with the encouragement to use the coarse stones. Especially when you are going after poorly treated and maintained knives. My knives rarely see those stones but when I get my mom's friend's knives in it's been straight to the SP320 and now they'll probably see the basement stone. The amount of time and wear on the higher grit stones that is saved is well worth the investment in some really coarse stones.

[ken123]

WJ, while it may be worth a separate thread of its own, it is a fair question..

So sometimes you have BIG chips. You bring the two sides of the knife together and still have large chips so now you are generating burr.Frustration begins.

So aside from generating only tiny burrs - a good idea but you have metal to remove. you need to get to the bottom of those chips.

Note that you will generate less burr with light pressure, but that's another topic.

If you focus on just the chips you remove too much metal in one spot and now you have a wavy edge which is a major PITA to fix. The easiest approach is to grind the edge perpendicular to the blade - holding the blade at right angles to the stone (video coming using a 24 grit stone). Then after removing the metal, recreate a new edge selecting the profile you wish. Note that here you can actually create TWO burrs - one on each side of the knife.

Try to maintain a balance between the two sides of the knife, grinding approximately the same amount from both sides. As you generate burr remove it using gentle lateral strokes on the burr formed rather than flipping the burr back and forth.

This video demonstrates removing excessive knife belly from a cleaver, but the principles for removing large chips are the same.



---
Ken

[Wjhunt]

Thank you Ken. That video was painful.

[jacko9]

I just sharpened my friends Doi B#2 Gyuto (his first J Knife) and it had several 1-2 mm deep chips. I took them out with my Shapton Pro 320 and while I wished it went faster i did like the control I had with that stone. I think for me I want a Shapton pro 220 or if Ken get's one in a Nubatama Black 220. I do have the Nubatama 150 but for this application I think that stone is too course for me to control properly (my lack of experience here).