# Fixing wavy shinogi line



## abcd4653 (Jul 4, 2017)

Because of poor sharpening skills, My yanagiba's shinogi line is so wavy...
So, i'm trying to fix shinogi line, But i have no idea how to do it 

Is there anyone who can teach how to fix shinogi line to me???

Thanks.


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## chinacats (Jul 4, 2017)

Try Jon's single bevels playlist.


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## StonedEdge (Jul 4, 2017)

+1 for checking out Jon's single bevel playlist.

As for fixing the wavy shinogi line, you will have to work carefully to remove metal evenly across the entire blade road working uniformly from heel to tip. Always keep moving and don't focus on a single area for too long.

Wavy shinogi line occurs by spending too much time working on a single area of the blade road. It creates a low spot thus making the shinogi line uneven in that area compared to the surrounding higher spots. To fix this you will need to focus your efforts on the top of the blade road and not down by the cutting edge. You will want to "push into" the shinogi line with your fingers applying pressure inwards and up toward the spine of the knife, imagining that you're trying to literally push the line upwards (see Jon's YouTube single bevel vid for a much better explanation of this concept). The key is to remove metal consistently and evenly across the entire length of the blade until the high and low spots you inadvertently created are as close to even as possible.

Take your time and don't fuss too much. Not sure what stones you have on hand but you will need a coarse one for this. Remember that with every stroke on the stone you are either working toward making it straight again or working toward making it worse depending how focused your are and how much attention you're giving it. You may not get it 100% lazer straight but you should be able to get it close enough. 

You may want to spread this out over several sharpening sessions rather than a single marathon-like torture session. Have a few cold ones ready nearby.


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## Badgertooth (Jul 5, 2017)

Cheat.


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## erezj (Jul 5, 2017)

Badgertooth, I like the direction you are going, can you elaborate on the technique.
I see tape to show the straight line, and a finger stone?


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## LifeByA1000Cuts (Jul 5, 2017)

That cheat would still leave your edge profile in disorder unless you compensate by introducing some intentional, more obtuse facets in the blade road, no?


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## dwalker (Jul 5, 2017)

Badgertooth said:


> Cheat.
> 
> View attachment 36248



This is what many makers do. Use the masking tape to make a straight line and finger stone polish up to it.


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## tsuriru (Jul 5, 2017)

I understand the frustration associated with a wavy shinogi line. It takes a lot of practice to get proper geometry. What I dont understand is, if the path of the blade is properly set towards the ha (cutting edge) and an equally proper micro bevel is also in place, is the wavy shinogi line not a cosmetic problem to begin with? and if so, why would it be a cheat to finger polish and straighten things out a bit so they look nice?


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## LifeByA1000Cuts (Jul 5, 2017)

@tsuriru I was thinking of a pure zero grind (straight line from shinogi to apex, with at most a microbevel there), which sounds like something you would sometimes want on a yanagiba. And I guess even with hamaguriba you will run into a similar problem...


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## NotThinEnough (Jul 5, 2017)

Make sure the blade itself is straight. Take the handle off then flatten the hira. After that, keep your stones flat. Then you can have a straight shinogi line. If these conditions aren't met, you will not get a straight shinogi line no matter how good you are at sharpening. what Badgertooth suggests is the path of least resistance, which I often take. good luck!


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## zitangy (Jul 5, 2017)

You mentioned a yanigiba...

my method 

1. is to use a slack belt grinder with a used belt used so that i maintain the convex grind

2. Sandpaper sheet say 400 grit on a a phonebook backing.

all with long strokes. Practice strokes to see where you are hitting the shinogi line wld with featherlight strokes.

Also check the possibility of sanding down above the shinogi line from the top; wich most of the time is a slight hollow grind adn i normally do this with sandpaper 400 grit with an eraser ( pencil rubber) backing again to maintain the hollow grind and this cld be a start of polishing above the hollow grind.

hv fun...z


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## Badgertooth (Jul 6, 2017)

LifeByA1000Cuts said:


> That cheat would still leave your edge profile in disorder unless you compensate by introducing some intentional, more obtuse facets in the blade road, no?



Sort of but you have, at the beginning, a crisp straight shinogi relative to a blade road with dips etc so my mistake was working those areas too much in isolation so the shinogi lifts unevenly relative to the flattening of the blade road. You'd have to move the same amount again from all across the entire bevel and reflatten the shiny surface. What I forgot to add is that once the fingerstone work is done I tape the bevel and work on the shiny surface with silicon carbide


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## v647c (Jul 6, 2017)

If you only have access to bench stones, sharpening with the blade as parallel to the stone as possible should help make some corrections. I've ruined some shinogis before and this worked well for me although it took ages of course. Good luck!


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## brooksie967 (Jul 10, 2017)

Even the Japanese cheat as seen here shortly after 7:35: https://youtu.be/Hc6_61CMAOk


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## Badgertooth (Jul 10, 2017)

brooksie967 said:


> Even the Japanese cheat as seen here shortly after 7:35: https://youtu.be/Hc6_61CMAOk



Exactly!!


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## LifeByA1000Cuts (Jul 10, 2017)

One mistake I did in the beginning was disregarding uneven ura thickness and trying to fix it on the blade road.


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## zitangy (Jul 11, 2017)

Badgertooth said:


> Exactly!!



The bladesmith is Tanaka san. The sharpener... a modern guy.. he uses a belt grinder| . Having said that I hv seen a Belt grinder in Shiraki-san work-shop too..The green grinder in cant figure out but i hv seen for light grinding, quite ingenous i must add, they use a buffer wheel wch is then coated with a special type of glue adn some grit powder of 220 grit.. this way it remains flexible and follow the shape and not to mention a large wooden wheel of soft wood to wch they add some mud... and let it do its work.

working with wheels will give a concave/ ura .. if its a straight draw.... so i think.

whatever works..... efficiently..


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