Lance,

I have moved this discussion over here because I think it's important enough to need it's own thread.

While this has been touched upon numerous times, my own approach is not unique.

I used to sharpen knives with a series of finer and finer stones...starting with carborundum and moving on to and through a Washita, Black Arkansas and a clay stone.

The critical issue is first to hold the knife at a constant angle as you sharpen. What angle?...Well, a steep (short angle) on the blade will result in a longer lasting edge but perhaps not as sharp as a flatter angle. The shallow (flat) angle on an edge will result in a sharper edge but one that needs to be re-sharpened more often.

For most purposes I like a flat shallow angle as I a looking for extreme sharpness. But again it is vital that the blade always be held at the same angle while sharpening and honing. It should also be remembered that for either kind of edge, stropping may bring the keen sharpness back but it is a process of diminishing returns as stropping will eventually "round" the edge, destroying the angle you have worked so hard to achieve.

The process involves drawing the blade over a stone, again held at a very consistent angle, until a bevel is created. Then the knife is turned over and the same bevel applied on the opposite edge.

When the bevels are identical and begin to meet at the edge, the metal will become so thin that a "wire" of thinned metal will form on the edge opposite to that being drawn across the stone. This "wire" can be felt as a "burr" on one side of the edge of the knife. The blade is then turned over so that a "wire" is created on the opposite side. In reality, this "wire" of thin metal is just rolled over to the the other side each time the blade is flipped and drawn across the stone.

When the bevels are satisfactory, the blade may be transferred to a finer stone and the process of creating wires on each side of the edge is repeated. And repeated again on successively finer grained stones. Finally the wires are "stropped" off--literally thinned to the point they detach from the blade--on a leather belt or stick treated with Tripoli or rouge.

When a sharp blade is held in the light such that you are looking directly at the edge, the edge itself will be invisible. Any hint of that edge, any glint of light along that edge, is an indication of a dull spot. Additionally, a truly sharp blade will "catch" when the edge is gently "dropped" at a steep angle from about a height of about an eighth of an inch onto the thumbnail. That "catch" will require no pressure but be so definite that there will be no question that the blade is catching.

Depending on the leather, the more noise a blade makes while slicing through the leather, the greater chance it needs sharpening. In mellow leather, with little or no residual chrome, a truly sharp blade will be all but silent.

Having said all that, in later years I have moved to a RazorSharp sharpening system for all but the basic shaping (or re-shaping) of the bevels. That work I still do with the carborundum stone and the Washita (or soft Arkansas). I know this seems like a short cut and it really is, but it is also one of the most efficient methods of obtaining a "scary sharp" blade, that I know.

I hope this helps...there are sure to be numerous other methods and techniques for sharpening a knife out there and even minor variations may make more sense to one person or another.

Tight Stitches
DWFII--HCC Member

This is a topic I've been looking into for a while first as a collector and user of knives and now as an aspiring worker of leather and wood.

For a good understanding of what a sharp edge really is and what it takes to create one I would recommend delving into the woodworking world and some of the books published on the topic of sharpening tools for woodworking. Shoemakers may not have much call to sharpen a plane iron but the principles are all the same and understanding what you're trying to create in the way of a sharp edge is critical.

Leonard Lee's Complete Guide to Sharpening (Taunton Press, ISBN 1561581259) is a good place to start and covers knives as well as woodworking tools.

For light grinding and honing I'm a big fan of sheet abrasives on glass as a grinding surface, regular wet 'n dry sandpaper glued down with a thin spray of contact adhesive is cheap, dead flat and cuts quickly. For heavier grinding a belt grinder with a decent 3rd party tool rest such as Lee Valley sells, or a home made version are quick and easy. Belt grinders have an advantage over wheels of more easily changeable grits, and a flat rather than curved grinding surface. A belt grinder will also let you sharpen larger blades like the ones in skiving machines which can be tricky to do by hand.

For honing, modern sheet abrasives; specifically 3M "micro finishing abrasives" offer higher grit counts and a smoother finish than even buffing wheels and polishing compound albeit at rather higher cost.

A good website detailing sharpening using sheet abrasives on glass including microscope pictures of the edges showing the scratch patterns can be found at http://www3.telus.net/BrentBeach/Sharpen/ it's aimed specifically at woodworking tools but as I say, the principles are the same. A tina knife for example is fairly analogous to a skew chisel when it comes to sharpening them.

The questions of whether or not to use a jig is open in my opinion. While learning to sharpen I think they're useful because they can tell you what a truly sharp edge feels like to use and show you what you're aiming for.

The argument against using jigs is that sharpening freehand teaches you to hold the tool consistently, and that if you can't hold it consistently when sharpening you can't hold it consistently while cutting. Perhaps owing to my relative lack of skill I'm a bit unconvinced. As I see it, sharpening doesn't offer the same feedback as cutting, and the tolerances involved in sharpening are so small that you need perfect technique to get them right.

If I may venture my opinion.

I am glad this thread was opened because this is a major issue working with leather. My skiving knife is a 7" filleting knife with a very thin blade. It is about 3/4" wide and is made from 440-C steel. It was quenched in liquid nitrogen, minus 305 degrees, and then tempored to a 58 Rockwell. I sharpen with a 12 inch long three inch wide, medium and fine stone and then condition with a 16 inch steel. I don't care for the diamond hones.

In my opinion, this knife is less than ideal. I must condition the blade quite often on the steel and too often on the stones.

I have been making knives for many years and the blades made of non-stainless or just carbon steel hold a much better edge than those with the chromium. I finished a run of blades made of ATS34 and I find them no better than 440-C for holding an edge. I do like the flex with the thin blade and a highly hardened carbon steel has a propensity to be a bit brittle.

During the hardening process most steel should be heated to a dull cherry red or until a magnet will no longer have any attraction and then quenched. If the steel is heated over that level or if it is quenched before reaching that level, the steel will have large grain structure. The last awls I made were from A-2 steel which has .04% chromiun and about .95% carbon. These are air hardening and so far, have been the best ones I have made.

My wife ask, "if you know haw to make a better skiving knife, why don't you do it?" I told her that I will just as soon as I get a "round-to-it."

I am anxious to hear what every else has to say on the subject.

Respectfully, Larry Peterson

For my christening of this new thread (thanks Admin.), for general work knives (clicking and edge trimming) I use a tan colored "medium" India stone, with oil, for cutting that quick edge/bevel, then strop it on a stick surfaced with leather and rubbed well with red jewelers rouge. For my finest edges on skiving (uppers) knives, I have an old (1940s) natural stone of some sort I inherited from my dad. It takes longer to cut the steel, but leaves a finer polished edge.

My dad always chided me that I could sharpen a knife better than him, so he had me sharpen all his knives. It's a knack I guess, and whatever method you use to test the edge: shaving your arm bald; dragging across your fingernail; slicing a sheet of paper, etc. the "proof is in the pudding".

I made a stick up with 600 grit wet/dry emery paper on two sides (one flat, one convex), and leather rubbed with jewelers rouge on the other two sides. I use that for quick touch-ups to knives, but stones to put the actual bevel-edge on new knives. BTW, I find that chrome leather dulls the skiving knives fast--veg-tanned is not so hard on them.

Jenny,

It sounds like you have a good system worked out. And the stones on the JapanWoodWorker site look to be both good quality and reasonably priced.

That said, what it all comes down to, in my opinion, is that if one understands the principles of sharpening--the bevels, the consistent angles (steady wrist), the concept and utility of the "wires," and the various ways of determining if the knife is really sharp.

Once you understand those principles you can dern near get a satisfactory edge with any set of stones or any system.

When I first got into this business I sharpened my knives on a finisher and naumkeg. They were cheap knives and they wore away pretty fast under the onslaught of all that carborundum but I got a pretty good edge, all that not withstanding.

Ultimately, it doesn't really much matter how we get there so much as what the final result is.

Tight Stitches
DWFII--HCC Member

I have been sharpening my Tina 270 knife on my bench grinder, I am getting better at keeping the bevel consistant but can only seem to get a real narrow cutting edge. It seems that alot of the sharpening tips I have read make sense but dont readily translate to sharpening a concave surface. If someone was willing to post a video of sharpening a skiving knife I know I would be excited and gratefull!

O.K., I got a wider edge but would still like to see how others do it.

Courtney, Don't have a video, but there are books available on tool sharpening. Look in the wood working section at the library. To each his own, but would not touch my knives on a bench grinder, except maybe to reshape. One blue spot and it is ruined. Six inch aluminum oxide stone (coarse on one side, fine on the other) for initial shaping. Worn cheap diamond stone for next step, ceramic rod then leather strop with rouge to finish. Seldom have to go past ceramic rod to resharpen. Wet or dry sandpaper will work, also a firm buffer with rouge, if very careful. Sharpening is one of the most important, yet harder skills to learn.

Courtney,

I agree with Chuck above, about pretty much every thing he said. I am very careful with the bench grinder and only use it for regrinding at a very basic level.

Lee Valley Tools has great book about sharpening everything, it's a little technical at times, but I learn something new every time I open it. There is also a video version, I haven't seen it except in the catalogue, they have an extensive web site.

Jon

Courtney:

There are a number of videos on youtube on sharpening. In general, these are by folks who are sharpening kitchen knives or woodworking tools, but the general concepts still apply. Also, many of these people use Japanese wetstones/water stones, which cut much faster than do oilstones; I've started using them as well, and they really are capable of putting an awesome edge on the blade. But be forewarned, sharpening can be addictive, always searching for an even sharper edge.

Check out these sites for information on water stones and sharpening.

http://www.knifeforums.com/forums/showforum.php?fid/26/fp/2/

http://knifeforums.com/forum/showforum.php?fid/48/

http://www.foodieforums.com/vbulletin/forumdisplay.php?f=6

Lance

Chuck, Jon, Lance, Thanks for the tips.
I made a curved stick with sandpaper that has made a big difference. How would you sharpen a curved skiving knife on a flat stone? I have been doing it but not with very great results.

Courtney:

Curved knives can be sharpened using the edge of the stone; it is a bit more challenging, but it can be done.

BTW, skiving knives are often ground/sharpened on only one side. The back side is kept flat and simply deburred when sharpening.

Lance

Courtney,

Any chance you could post pictures of the knife you're trying to sharpen? I'm having difficulty visualising the blade and the issue you're having.

In terms of sharpening gear, I am a huge fan of high-grit sandpaper glued to sheets of glass. It's cheap, easy and incredibly effective.

Originally introduced to the Internet as the "Scary Sharp" system, the idea has been around for a while before that. The wikipedia page has some links to resources.
http://en.wikipedia.org/wiki/Scary_sharp

A chap by the name of Brent Beach has one of the better websites dealing with sharpning woodworking tools, including curved blades. He concentrates on chisels and plane irons, but the principles are the same for any blade.

http://www3.telus.net/BrentBeach/Sharpen/sharpen.html

He uses ultra-fine 3m abrasives which negate the need for a honing step, but regular wet 'n' dry sandpaper followed by honing on a buff, or on a piece of MDF impregnated with honing compound works pretty well.

Admittedly for some blades, building a jig isn't possible for all tools, but I imagine it should be possible for a skiving knife. I built jigs for my chisels and plane irons and got very, very good results with little effort.

I'm not a big fan of bench grinders for tool sharpening. Belt grinders are a lot more flexible in what you can do with them and you can get much finer grit belts than you can grinder wheels.

Personally I use a cheap 1" belt grinder for grinding and sandpaper on glass for honing woodworking tools and I get pretty good results. Leatherworking knives I do freehand on sandpaper & glass, then strop.

If you want to go the buy rather than build route, Lee Valley Tools sells a 1" belt grinder and a nice highly adjustable tool rest if you want to go that route. They also sell extremely high grit 3m belts that would allow you to do all sharpening steps on the one machine, though I imagine you'd want to gear it down and run it backwards for honing. I'm kicking myself for not bying a pair when the exchange rates were good, one for grinding and one for honing.

Grinder:
http://www.leevalley.com/wood/page.aspx?c=2&p=44884&cat=1,43072
Tool rest:
http://www.leevalley.com/wood/page.aspx?c=2&p=45938&cat=1,43072

All

Some 600 waterproof glass paper on the long sanding wheel and a gentle touch produces wonders. Then a few passes on a well oiled fine stone and you can shave with a knife.

JesseLee

I am still confused about how to sharpen a tina skiving knife, which has the bevel on the inside of the curve, on flat stones or abrasives glued to a piece of glass, etc? There should be no bevel on the downward side of the blade, right?

I saw that you could sharpen it "on the edge" of the stone but that doesn't seem like a common practice or a proper use of a stone...i.e., you should be using a different tool if it's a curved skiving knife?

I know the knives must be beveled and sharpened when they arrive from the factory because they are not sharp right away. Is the blade straightened when you sharpen it, or should you still maintain the curve?

EDIT : so it sounds like after reading everyone talk about regular sharpening methods, while the overall length of the knife is curved, the blade edge will still be flat, and thus you can grind it on flat stones and glued abrasive sheets?

(Message edited by producthaus on April 30, 2010)

Nick
Tina knives are great, You can do the initial grind with fine sandpaper on your finisher, cool the blade every few seconds in water. I try to made a bit of a hollow on the upside of the edge.

This may take some time or if you feel confident you can do this with a grinding stone but it takes a steady hand.

Once you have the hollow about 1/8 from the leading edge, start to work on the edge with what ever stones you use. Yes it is not like a wood chisel. You can take a piece of wood about 1 1/2 inches wide and glue wet/dry emery paper to 3 sides, 100 grit. 320, then 600. on the last side glue on some veg tan and rub red rouge on it and use it as a strop. This way you can hold the angle against the abrasive, and keep a flat sharpening surface, not worrying about making a dip in a traditional stone.

Now I will diverge. I do not use water/oil stones anymore. I got some diamond hones from Lee Valley tools. they had a sale on and I got from coarse to very fine. The go to is a narrow 600 grit and 1200 grit. once you have a good hollow grind get out the diamonds and have at it. It will take a while to get an edge, but once you have it, a quick swipe with the 1200 and a few licks over the strop and you have a very good edge.

I use the same with my woodworking tools and it is fast.

The big thing is once you have a good edge protect it from damage. Do not use it as a screwdriver etc.

I know many will laugh at my ways but I can sharpen tools so you may cut yourself and not know it till the blood flows. I try to avoid this!!!!.
Those diamond hones have saved me from many trips to the city. I have touched up carbide saw blades, router bits, fish hooks and Dear wifes kitchen knives.

I was wondering if someone could clarify these Gotz knives. I am speaking about items #1 and #4. #4 is labeled as a "skiving" knife, but I feel like I have seen #1 in pictures referred to "more often" for skiving. They may both be used for the same purpose I am assuming, as well as cutting out sole leather....a knife for many applications. However, I see that #4 has a curved edge, so I was wondering about that?

Nick

#1 looks like the Don Carlos knife I use for skiving but it can also be used as a general purpose trimming/clicking knife too.

Make sure you get the right knife for you, whether left or right handed.

I don't think #2 is much different.

Tim

Nick,

I've got several Tina knives of this type. The one's you posted are all about an inch wide so whether they would be good for clicking, I don't know...I suppose it depends on the maker. Personally, I like a much narrower blade and usually mounted in a handle for clicking. But I have seen highly respected makers using blades like these for clicking.

I believe these are all flat blades. One of the Tinas I have is both curved along its length and also bowed side to side. I don't think they offer that knife anymore, but the sharpening pattern on #2 suggests it too might be bowed side to side, at least.

In the end I think, if it were me I would go for a couple of #4...you can use them as an all purpose shoe knife and they skive nicely. They may be harder to sharpen if you're a little uncertain about sharpening but are easier to control in my opinion.

Bottom line they may all be interchangeable.

Tight Stitches
DWFII--HCC Member

Here is a better view of knife examples from Marcell, it's not clear from the Gotz picture that #2 Gotz is very curved.

#1 Marcell has a straight edge, while the others have a curved profile. Can someone explain the differences, i.e., purpose, size differences, arched forms.

BTW - its a little hard to see, but you can tell that the bevel on the Gotz knives are very small/short, the bevel on #1 Marcell looks wicked-sharp....can't wait to put something silly like a 7 degree bevel on mine.

Thanks for the other replies, too!



(Message edited by producthaus on May 21, 2010)

I picked up an old Sears motorized home sharpening stone for a couple of bucks at the thrift store for my sharpening/shaping needs. It has a water reservoir which keeps the stone and blade cool and wet, as well as a plate that allows you to set the angle that you're grinding. The stone is a very fine stone, so it doesn't get too hot nor does it take off excessive amounts of blade material. In other words, it works very slow. On top of that, I have my tri-stone and steel from when I was a butcher, (I have only the coarse and fine stones left), and I made a sharpening stick so I can strop on the stick using coarse and fine valve-grinding paste (one on each side, of course). This will work for me, I think. I will probably very seldom have to use the motorized stone, right now I mostly use the fine tri-stone and the sharpening stick. I've found by reading a lot on the various knife and woodworking forums that valve grinding paste and jeweller's rouge are virtually the same thing (you could match up the grits, I suppose) but the valve grinding paste is significantly less money in my neck of the woods.

My step-dad used to sharpen his safety-razor blades on a piece of what looked to be sandblasted glass (kinda almost looked like an ashtray but was shaped correctly for the blades), so I wonder how sand-blasted or acid-etched sheet glass would work for that.

Most of my knives are ebay and thrift-store buys, so for the most part, they aren't meant for leather work, but so far I'm getting the hang of clicking and skiving <|;^). It will take me a few months, I reckon, but eventually I'll be able to start making some footwear to get started.

Thanks to the various forums and the generosity of some on the forums, I'm getting in a position to maybe start posting with some of my trials and tribulations lol!

Since this thread is about tools, I've got a couple of questions. I bought a heel shaver on ebay the other day, and along with it came a couple of tools that seemed kind of weird. They were purported to be leather working tools, and one of them is for sure, I think ... it's a pair of lasting pliers that are very heavy, the jaws and hammer are about 1" wide and it says Thomas Adams - Warranted on it. They are pretty beat up, so I think they've been used for other than shoemaking, but I'm curious how old they might be.They are considerably wider than the lasting pliers that I have already got.
The other item was a small pair of scissors - with a square notch cut out of each blade down toward the screw where they swivel. I don't understand why they would have that notch cut out of the blade, because when the scissors are closed, they can't cut anything there!
Any suggestions on these two tools?

@ Nick Hausman - those are fine looking Koronya knives, thanks for showing them to us. Some of us newbies don't know what you guys are talking about with the different tools, so it's nice to have pix!

Jim,

Those scissors you describe are probably for cutting a slit a defined distance in from the edge of an object without cutting all the way to the edge. My guess would be for button holes.

Nick,
I am using a Tina knife that looks pretty much as Marcels no 1. Thean I am using a Berg knife bended about the same as Marcels no 2. That is all the knifes I am using.

I use the Tina as a all purpose knife i.e. everything from cutting patterns, upper leather and heavy work. That is why I have the same angle as on Marcels knife. On back side I realy don't sharp the knife I just take away the stuff that fall over from the inside.

The Berg is a skiver and will be sharpend mostly from the backside.

The imortant thing when it is about knifes is not the way the grindstone goes as long as the knife ends sharp anything goes. Find your own way and stick to that.