How to sharpen a head knife

[bikermutt07]

On 3/14/2008 at 9:58 AM, Art said:

Hi Sharp,

The old Convex -- hollow ground -- straight bevel controversy again? Been there done that on the knife-list 10 or more years ago. Convex is great, I like meat behind my edge. However, that is not an easy edge for the average leatherworker to profile, and the newer head knives are getting thinner and thinner to the point that the Convex is getting darned near impossible, not quite, but darned near. While you and I probably have a Bader or a Burr-King where you can get a long run of belt to effectively produce the edge (although the Japanese used to do it with a rock) the average leatherworker doesn't and the hollow or straight is much easier with readily available tools, and very easy to maintain. I do agree that convex is better if you have a thick enough blade to pull it off, the J.Cook blades would be candidates for a convex edge, and even the CSO blades could be done to effect. The last .030-.060 of most convex edges are straight bevels anyway.

Art

Art. I'm a complete novice when it comes to sharpening. But I find the convex easier to maintain on my knives. Two years ago I watched a gazillion videos on sharpening. I just thought as a man, dangit, I should be able to sharpen a knife somehow someway.

It was really frustrating. The first video that stuck out was some kid with a cheap buck lockblade. That kid took a cinder block, a red brick, and a little water and had hairs jumping off his arm in a matter of minutes.

The second video was of a gentleman in Canada that sells fallkniven knives. One comment in the video went like this.....

The first time "you" sharpen a knife it will take longer than normal. Your hand does certain little things that other peoples hands and machines don't do. 

What he was saying was that all my life I had given up on sharpening too quickly. I didn't take the time to acclimate the blade to "my" sharpening.

That was a huge eyeopener for me. Since then I have been able to get my knives working sharp. Not sharp like you can accomplish, but sharp enough for my needs. 

I tend to lean more towards the sand paper mouse pad sharpening technique. I lay the blade flat and as I start to pull the blade across the paper I lift it up until I feel the edge grabbing the paper. This sets my angle. And it may not be right but it works for me.

Then comes leather. I had to raise the bar. In the last two weeks I have finally been able to get my leather tools just about as sharp as they need to be.

I have since abandoned the mouse pad and replaced it do The a piece of quartz (manmade granite) about 8x12.  This has helped me get my edges cleaner.

Two weeks ago I acquired a small Al Stohlman round knife. It was kind of sharp, but I hadn't played with it.

Thirty minutes ago I read through this tutorial. I have never sharpened a round knife. The whole time I was sharpening it I was thinking "Boy am I messing this thing up".

After stropping it, it cut a piece of Hermann Oak four ounce like it was paper. The I took it to some 8 ounce scrap. I can actually hold the piece up in the air and slice right through it. I was amazed. 

Now this is an Al Stohlman knife and I have heard bad things about those here. So, I don't know how easily it will keep that edge. But it's nice to think I can get it that sharp again.

I'm quite proud of myself.

[Art]

On 10/18/2016 at 2:46 PM, bikermutt07 said:

Art. I'm a complete novice when it comes to sharpening. But I find the convex easier to maintain on my knives. Two years ago I watched a gazillion videos on sharpening. I just thought as a man, dangit, I should be able to sharpen a knife somehow someway.

It was really frustrating. The first video that stuck out was some kid with a cheap buck lockblade. That kid took a cinder block, a red brick, and a little water and had hairs jumping off his arm in a matter of minutes.

The second video was of a gentleman in Canada that sells fallkniven knives. One comment in the video went like this.....

The first time "you" sharpen a knife it will take longer than normal. Your hand does certain little things that other peoples hands and machines don't do. 

What he was saying was that all my life I had given up on sharpening too quickly. I didn't take the time to acclimate the blade to "my" sharpening.

That was a huge eyeopener for me. Since then I have been able to get my knives working sharp. Not sharp like you can accomplish, but sharp enough for my needs. 

I tend to lean more towards the sand paper mouse pad sharpening technique. I lay the blade flat and as I start to pull the blade across the paper I lift it up until I feel the edge grabbing the paper. This sets my angle. And it may not be right but it works for me.

Then comes leather. I had to raise the bar. In the last two weeks I have finally been able to get my leather tools just about as sharp as they need to be.

I have since abandoned the mouse pad and replaced it do The a piece of quartz (manmade granite) about 8x12.  This has helped me get my edges cleaner.

Two weeks ago I acquired a small Al Stohlman round knife. It was kind of sharp, but I hadn't played with it.

Thirty minutes ago I read through this tutorial. I have never sharpened a round knife. The whole time I was sharpening it I was thinking "Boy am I messing this thing up".

After stropping it, it cut a piece of Hermann Oak four ounce like it was paper. The I took it to some 8 ounce scrap. I can actually hold the piece up in the air and slice right through it. I was amazed. 

Now this is an Al Stohlman knife and I have heard bad things about those here. So, I don't know how easily it will keep that edge. But it's nice to think I can get it that sharp again.

I'm quite proud of myself.

Well, I'm quite proud of yourself too.  If you can sharpen a head knife to that degree, to the point that it satisfies you, you have arrived.

Art

[bikermutt07]

Thanks.

[TinkerTailor]

There is one thing about hand sharpening that has not been mentioned (enough) is the pressure you use and when. There are 2 ways to control material removal, pressure and grit. Either a lesser grit or a lighter pressure will create a finer grind. Guys who do surface grinding and sharpening on machines get mirror finishes with crazy coarse stones just by varying the pressure. (if you are interested in this: https://www.youtube.com/user/shadonhkw/videos)

The particles sharpening stones are made of have sharp corners, and this is what does the cutting. When sharpening, the pressure that you use dictates how far the little corners dig in. More pressure=deeper scratches. Less pressure= shallower.

I look at it as a system of define-refine-finish. 

When starting out with a dull tool, heavily removing material,  and I am defining the angle and geometry, I use lots of pressure. I want maximum digging from the particles. I want to feel vibrations of the metal coming off through my fingers. This is the define stage

As I get closer to shape, I switch to a medium pressure. I call this refining stage. This keeps the particles from digging in as far. Less material is removed and the scratches are shallower. I am perfecting the geometry and bringing the surfaces smooth, clean, and ready for a polish. I also put in secondary bevels at this stage and get it to a reasonably sharp edge. This is the same effect as going up in grit. In addition, the particles in your slurry will break down smaller over time as you sharpen, adding to the effect.

The final stone step for me is the finishing stage, where I polish and sharpen the blade. In this step, very little pressure is used. The blade is floating on the slurry and you can just hear it touch the stone.

From there I have a strop stick loaded with some random white rouge I have a bunch of. I think it came in old Tandy kits. I vary the pressure here the same way.  I strop it till its awesome and then a couple times more and also before each session, sometimes during.

I do this all on the same stone. My grumpy-gramps taught me about pressure on an old Norton. This is how guys can use a brick to make a sharp edge. Pressure control. Angle is one thing, pressure control is the real skill for the expert sharpener. This way is fast once you get good because you are not wasting time switching stones, and removing material unnecessarily slow due to following arbitrary steps.

Now the downfall, and the reason why guys use 5 grit sharpening systems: One screw up at the later stages puts you right back at the beginning. One stroke too hard or with the wrong angle and you go back to start. It is pretty hard to put deep scratches, and have to start again, if you are on a 2000 grit diamond stone.

If you are new  to sharpening and don't know what 20 degrees looks like, get a few grits of stones and work up. As you get better with the pressure control, start to take away stones in the sequence. The reality is, in practice, it is a gradual reduction in pressure not 3 steps. The steps are a mental trick to "Pace the pressure". Also, pressure will need to be adjusted for harder and softer steels. This is also an experience thing. You get a feel for it.

Edited October 20, 2016 by TinkerTailor

[gmace99]

 

 

 

[Bobby hdflame]

Good explanation Rawhide!

I realize some people have problems maintaining the correct angle.  I don't really need or use it anymore, but here's an excellent manual sharpener that's also affordable.  I used one for years.  It is easy to maintain the correct angle and with just a little practice anyone can put a perfect shaving edge on anything from a small paring knife to a machete!  Guys at the fire station would line up with their pocket knives when I brought it out to sharpen mine!  It got to the point that I had to go into hiding when sharpening mine to keep from sharpening everybody's knives.

When I first bought my round knife it was not as sharp as I wanted, so I used this sharpener to put the initial edge on it.  Since then, all I need to do is strop it on leather with some fine rouge.  If you have a buffing wheel with some rouge, it's quick and easy to keep it sharp.

When using it, start with the coarse stone until you get the same angle from one end to the other.  Then gradually work your way down to the finest stone to get a polished razor edge.  If you use it to maintain your round knife you'll only need to use the finest stone to bring it back.  The secret is after every few cuts, strop the edge on leather with some rouge.  Maintaining a perfect good cutting edge on your round knife is a constant thing WHILE YOU'RE USING IT!

https://www.amazon.com/Lansky-Professional-Sharpening-System-Serrated/dp/B001KN3OKO/ref=sr_1_3?ie=UTF8&qid=1487792044&sr=8-3&keywords=lansky+knife+sharpener

https://www.youtube.com/results?search_query=Lansky+Professional+Sharpening+System 

BTW, I bought a sapphire and a diamond stone for mine.  I use them after using the fine stone that comes with the basic kits.

 

Hope this helps.

Edited February 22, 2017 by Bobby hdflame

[Sangrati]

On 3/12/2008 at 6:56 AM, Rawhide said:

To all:

I have had several requests to explain how I sharpen my head knives. I am by far not an expert, but here is how I do it, and it works for me. There was a thread where I addressed this before the crash of 07.

Below is a link to the tutorial that most gracious Johanna has created.

Please feel free to contact me if you have questions. I hope this is something useful.

Tool on!

Marlon

How to sharpen a head knife

The link is not working.

Regards

Sangrati

[Northmount]

8 hours ago, Sangrati said:

The link is not working.

Regards

Sangrati

LWN has changed to a secure webserver so all previous URLs that were http://leatherworker.net ... etc. now need to be https://leatherworker.net ... etc.

So the URL becomes https://leatherworker.net/sharpenheadknife.htm

Tom

 

[Sangrati]

1 hour ago, Northmount said:

LWN has changed to a secure webserver so all previous URLs that were http://leatherworker.net ... etc. now need to be https://leatherworker.net ... etc.

So the URL becomes https://leatherworker.net/sharpenheadknife.htm

Tom

 

Thanks. Got it.

Regards

 

[hiloper]

On 3/13/2008 at 12:28 PM, cjbleather said:

Marion, Off hand or easily available to you, what is the tan of 20 degrees? Thanks Carlb

PS I haven't found my engineering formula/table book yet. I can't even remember what we used to call this book as we went through school. yach for my memory.

Peter"s Book