need advice on sharpening a thin, flexible Santoku

[Magnaminous_G]

Having a bear of a time with a friend's Wustof Grand Prix II Santoku, 6.5" blade. The blade is very thin and *very* flexible. I can't get it sharp off of the Arashiyama 6k, and I've actually dulled it trying ultra-feather-light edge-trailing strokes or moving to newsprint stropping. I went back to the Arashiyama 1k and started over. Same thing happened. Tried very carefully applying pressure at points of contact and got better results, but still not where I want it to be... oh, and *easily* re-dulling it with even the lightest edge-trailing pressure on either the 6K or the newsprint. In fact, not only dulling it, but creating new artifacts/burr on the edge!! Sitting here scratching my head. I'm guessing it's the soft steel and very flexible, thin blade, but not sure obviously. Gonna go to sleep and try this tomorrow. Advice?

 

[richard thurman]

you can make your own sharper like I did. I have a kershaw leek and I have been using this sharper for around 10 years on it. it shaves the hair off of my arm.

 

[Magnaminous_G]

That's not what I was looking for, at all...

But now I am curious. Where did you get those rods? Did you cut them yourself?

 

[Benuser]

These soft German steels haven't to be treated like hard Japanese ones. I use a J400 stone - or corresponding sandpaper - and strop very lightly on a 800. Done. You may add a few strokes on rough split leather.
No refinement. It won't hold a polished edge.
About the flex: annoying, but you will get used to it. Reduce pressure.

 

[pwet]

have you tried edge leading, very light pressure ?

anyway this is x50CrapMoV HT'd to the mid 50's hrc like 56... no need to polish it beyond 1k JIS. 1k plus a charged strop gives a good "hybrid" edge.

 

[lutejones]

I have had the same problem with an spanish ham knife, i don't know if you know what kind of knife It is, so imagine a filet knife but thinner and longer a nightmare on the stones because it flexes like mad.
I think you have to options:
- try guided style moving the stone instead of the knife could work
- what I did is modify a little bit the technique and create a leverage between your hands against the desire of the knife to bend(this is hard to explain in words, not being english my mother language), long strokes japanese style with the knife 45º on the stone and running the hand not holding the handle to the point while making the stroke to create that leverage which holds the knife flat on the stone and alouds you to create a nice edge. (not the rounded sh*t i'm supposing you're achieving now, like I did )

the problem with flexible blades is that the bending increases a lot the pressure on the edge by reducing the lenght that is in contact with the stone, and you have to try to increase it.

I really hope I've explained myself, if not feel free to ask:

Mateo

 

[richard thurman]

That's not what I was looking for, at all...

But now I am curious. Where did you get those rods? Did you cut them yourself?

I found a dealer that had the rods extra from her fathers knife shop. he died so she gave them to me.I am trying to find more of them but I dont have any good luck in doing so.

 

[HeavyHanded]

have you tried edge leading, very light pressure ?

anyway this is x50CrapMoV HT'd to the mid 50's hrc like 56... no need to polish it beyond 1k JIS. 1k plus a charged strop gives a good "hybrid" edge.

^ This!
You might even want to use a solid stone, like a DMT or India. A charged strop is what I was thinking - very light touch and a fairly aggressive abrasive. The steel is to low RC and an alloy to boot, JWS probably not the best choice, and trailing strokes tough to remove final burr/clean up edge. ANother option is use the 1K stone to grind fresh bevel, claim the swarf and slurry from stones surface and smear on newspaper - wrap around stone and strop with this. Either way, edge leading to finish on the stone and a loaded strop for a final clean/deburr.

 

[Magnaminous_G]

Alright, edge leading, light pressure, finish with edge leading and loaded strop for final deburr. Gonna try it now.

 

[Magnaminous_G]

[youtube]Y7QU6Mz_QBs[/youtube]


This knife gave me major problems while sharpening it. In fact, this may have been the most difficult knife I’ve ever sharpened. It's made of very soft Krupp X50, and the blade is very thin and is impossibly flexible. The slightest applied pressure on the stone made it bend like a rubber band. Due to the soft steel and flexible blade, I just couldn't get it sharp. The lightest edge-trailing strokes on the 6k Arashiyama stone (and even newsprint) would introduce new artifacts and burr on the edge. Thanks for all the advice from the guys who commented in this thread. I decided to try the advice to finish on the stones with edge-leading strokes and move on to a loaded strop to clean the edge up. That worked.

Sorry for the excessively-long video. In retrospect, I probably could have moved on to the strop sooner and spent more time lightly stropping before testing the edge. I was in unchartered territory and was very cautious about overdoing it on the strop and rounding/dulling my edge. I didn’t need to worry so much about that and could have stropped more confidently. I could have shaved 15-20 minutes out of this process if I knew then what I know now. But next time, I’ll be prepared. Still, I wanted to post this video for anyone who has had a similar experience. With the knowledge gained from this experiment, the next time I do a blade like this, I will finish up on the stones quickly, just after establishing my bevel and scratch-pattern, after which I’ll confidently let the Chromium Oxide on leather work its magic.

Cheers,

Mag

 

[Mark-60]

One of the first knives I ran thru my new Work Sharp was my (brand unknown at this time) santoku. It came out better than any other knife I've ever sharpend. It would go thru a sheet of paper like butter.