Edge retention

[Scotty]

I have been using my T4 almost exclusively for knife (kitchen, work, edc, etc) and have become what I thought was fairly proficient at creating a very sharp edge - paper cut, fingernail test, arm hair shaving.
I almost always use a 20 deg/side bevel for simplicity sake (and my forgetfulness).
Most (if not all) the knives have high quality steel.
When I touch up the blades, depending on the shape, I usually just polish them on the leather wheel, separate paper wheel or razor strop (lightly) - if needed, I will lightly touch them up on the 1000 SG200 followed by polishing to remove the burr..
I have tried to religiously follow the guide and the several videos.
Problem is, the blades do not seem to retain that fine edge for long.
I hand wash/dry and keep them on magnetic holders.
Any advice and or thoughts would be appreciated.

[John_B]

I sharpen my personal knives at 13 degrees and hone at 15 degrees. While it is possible to  obtain a sharp edge at the higher it will take more force to cut due I believe to the wedge angle going through the material. As a knife dulls this worsens. Most manufacturers have gone to a 15 degree edge for kitchen knives.

To maintain the edge I use a steel before each use. The steel works by aligning the edge at a level that can't be seen with your naked eye.  On knives that are prone to corrosion steeling also remove the imperceptible amount from the edge. Steels come in 3 grades smooth, fine and coarse. Smooth is the least aggressive. Ceramic rods are also used for this purpose. They remove a small amount of material from the edge and many people like them. Diamond rods which are the most aggressive in terms of material removal are also available. I use smooth and fine steels and go to the Tormek when the edge needs it. I am going to get a ceramic rod to try out.

Another tip is to never use your knife edge to scrape the board. There are good threads in this forum on board material and  knife usage.

[RickKrung]

Scotty,

The information and help on this forum is so deep and thorough, it is like no other.  You really need to look beyond "the guide" (if you mean the Tormek manual) and read as much as you can of the posts here. 

But...  the single best resource/reference on sharpening for edge retention, in my opinion, is the book by Wootz of Knife Grinders:
http://knifegrinders.com.au/11Shop.htm

Wootz participated a lot in the past and contributed so much to the knowledge and advancement of knife sharpening and edge retention (deburring).

Rick

[Josu V]

I think that High Quality steels need other wheel to sharpening well.
This steels contain elements that SG-200 can not sharpening effectively.

Try to use Diamond, CBN or Silicon Carbide honing wheels.

Regards

[Scotty]

Good advice.
Thanks to all.
I just ordered  Dr. Vadim Kraichuk's book
I like the 15 deg idea.
I sometimes have a hard time using the guide tool on the blades with a thinner width.
I might try free handing the smaller blades.
I have been using the steel after washing before I put them away. I will give the pre-cut option a try.

[RickKrung]

I think that High Quality steels need other wheel to sharpening well.
This steels contain elements that SG-200 can not sharpening effectively.

Try to use Diamond, CBN or Silicon Carbide honing wheels.

Regards

Josh,

Do you use those wheels for honing?  I only use them for establishing the bevels (grinding) and use the Tormke SJ wheel, leather honing wheel and/or diamond pastes on paper/felt wheels for honing.  I agree that successively finer grits on the wheels you mention are very useful for refining the edges, but they still require honing in the manner I mention. 

Rick

[Josu V]

Josh,

Do you use those wheels for honing?  I only use them for establishing the bevels (grinding) and use the Tormke SJ wheel, leather honing wheel and/or diamond pastes on paper/felt wheels for honing.  I agree that successively finer grits on the wheels you mention are very useful for refining the edges, but they still require honing in the manner I mention. 

Rick

Sorry... It is a mistake. When I said "honing", I wanted to say "grinding"

I´m  absolutely agree with your comment.

Regards

[Stickan]

Hi,
For personal use, all my knives are sharpened at 30 degree (15 each side)
They stay sharp for a year if I hone them 2-4 times a year.
I see no reason to use a diamond wheel on them, exept one knife I have, Vmatter that uses Amorphous Metal, as they call it. This specific metal get better removal and edge with dimanond.

My experience during the last years shows me that most times the issue to get really sharp tools is the lack of proper honing. On page 127 in the latest handbook, or in the straight edge jig chapter, the correct techniqe is shown.  I hope this can be of help.

Best,
Stig

[Josu V]

I have talked about diamond wheels for grinding high-end steels because these steels generally have a high vanadium and / or molybdenum content.
Sg-250 has difficulties with these metals. In this case, Diamond runs better (in my humble opinion).

About your comment on polishing, I think  that is as important as grinding. Absolutly agree.

Regards

[Jan]

Stig, thanks for sharing your experience with the VMatter knife. Its edge hardness is exceptional and should be HRC 70 or even more. The blade of VMatter knife is stainless steel and only the edge, some lower 3 mm, are made of the LiquidMetal. The bonding between the blade and edge can be fragile.

Jan

[Stickan]

Thats is one ruined knife, Jan!

When it comes to knives that have a have a high vanadium and / or molybdenum content, I have never had an issue with the SG stones. For instance, the knife Brand Global have knives with cromova 18 steel which are great to sharpen with the SG stones. I have had experiences with cheaper knifes that the burr is hard to remove under 40 degree angle. With the SG stones i find that the better quality it has, the better it work.
Regarding steel, I have a favourit powder metal which works extrmely well on the SG stones and that is PMV-11, a steel that Veritas uses in plane blades and chisels. Some facts here : http://www.pm-v11.com/Story.aspx

Best,
Stig

[Jan]

In my understanding the PM-V11 is a stainless steel. If this assumption is correct than it contains a lot of chromium. Chromium carbides are not as hard as alumina abrasive in the SG stone. This would explain why the SG stone sharpens the PM-V11 steel well.

Jan

[Stickan]

Jan,
I had a chat with a friend of mine who works for Veritas and his response was that it has properties of stainless steel but not considered as a stainless steel alloy.

Best,
Stig

[Jan]

Yes, Stig, you are correct. The composition of PMV-11 steel is not known and so only its properties can tell us something about the alloy constituents. Because the steel does not rust I think it contains quite large amount of chromium or nickel or both.

On the other hand your experience with good grindability of PMV-11 steel with SG stone may indicate that only limited amount of vanadium is present because vanadium carbides are harder than alumina. 

Jan