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Sharpening Wisdom

3K views 31 replies 14 participants last post by  redeared 
#1 ·
I have the Wolverine Lathe jigs for my 8" grinder with a 180 CBN wheel. I also have the jig that sharpens chisels and plane irons (see pic below). The CBN wheel leaves a pretty nice finish ands more than adequate for lathe tools, but for chisels and planes, I'd like to get a mirror finish. I was thinking of adding a 8" leather stropping wheel. Is this a workable idea?


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#3 ·
You're asking for a polished mirror finish. I'll assume you get edges as sharp as you need already.
Certainly. Use some honing compound on the leather wheel if you need to.
Autosol, Chromium Oxide green, Aluminum Oxide white.
And GO EASY. Such fine, sub-micron abrasives can raise the friction heating very quickly at edges.
 
#5 ·
I replaced the one grinding wheel on my variable speed grinder with a stack of cotton wheels for use with the compound sticks. I completely filled the shaft with cotton wheels and ended up with a 2" wide wheel.
 
#6 ·
I prefer to hand sharpen chisels and planes with a diamond plates and a veritas jig. For a final mirror finish I do a few passes on a 6000 grit plate. Once you get the face and edge you want it only takes a few minutes to touch it up. People have asked me to fix their chisels that they sharpened, I decline because I know it takes a lot of work to fix the wrong angle on the entire face by hand.
 
#7 ·
Can you be specific? How much time does it take for you to "fix' the wrong angle of an entire chisel face by hand on diamond stones? Say, with a 1/2 inch or 3/4 inch or 1 inch chisel?

I am trying to gauge my own work, and it would be helpful to know what it takes others to do the same. Do you have a sense that you can wear out your diamond stones doing that?
 
#8 ·
I am happy for you fellows who can sharpen a blade, knife or iron freehand, that is one thing in all my years I have yet to master. I have tried repeatedly with no luck, it is either a guide or it isn't sharp enough for me. I have leather and hard felt wheels as well as a couple of hand strops. I can strop freehand with good results.

Carving knives on the other hand I can sharpen well freehand. My carving knives (not gouges) are of a very steep angle. I don't use soft wheels as they will roll the edge of the blade or iron and I always keep my finger right at the edge of the blade when sharpening, that way if it is too hot for my finger, it is too hot for the blade.
 
#9 ·
Essentially you are rough grinding a hollow bevel. You need to take the honing much further from there. For me 8000 grit is the minimum (16K on plane irons). You can’t get there without stones. The exception might be a Tormek or Worksharp,

A leather strop is not going to make up for an inadequately honed edge.

I also leaned to sharpen freehand and never looked back. If a damaged edge needs fixing I go to the grinder, but for normal re-hones, it’s a 2 minute process.

My thinking is it’s just another skill we have to learn in ww’ing.
 
#13 ·
Essentially you are rough grinding a hollow bevel. You need to take the honing much further from there. For me 8000 grit is the minimum (16K on plane irons). You can’t get there without stones. The exception might be a Tormek or Worksharp,

A leather strop is not going to make up for an inadequately honed edge.

I also leaned to sharpen freehand and never looked back. If a damaged edge needs fixing I go to the grinder, but for normal re-hones, it’s a 2 minute process.

My thinking is it’s just another skill we have to learn in ww’ing.
I just recently learned from watching some of Rob Cosman's Youtube video's that you learn to sharpen by hand to maintain sharp. I don't have super quality hand tools so I generally sharpening planes and chisels before most uses. It only takes a couple of minutes to restore the edge to what I find reasonably/serviceable sharp.

I'm pretty new to the "pride in sharpening" thing, I'm more of a machine woodworker so I have yet to invest or found the need to buy 8000 grit + equipment. Most times, I've found my Stanley chisels sharpened with 3000 grid wet/dry sandpaper on a piece of glass works for me.

I find Rob can be a little annoying (OCD kind of guy) but has tons of knowledge. Sharpening video:
 
#10 ·
I hone molding knives on leather faced wheels charged with Clover Compound. These are made in pairs and sometimes left/right matched sets, so hand guiding them isn't accurate enough. The tool rest transfers from the grinder to the honing setup. I grind with an 80 grit wheel, and I've found that really fine polishing abrasives like Tripoli or rouge aren't aggressive enough to take out the grinding scratches. I think this is 600 grit Clover Compound. There is a bullnose wheel on the left for concave edges and a straight wheel on the right for convex edges.
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It's hard to compare machine knives with hand tools edges. I much prefer plane irons sharpened freehand on Arkansas stones.
 
#14 ·
Read the late Leonard Lee's book on sharpening. Available through the company he set up. Lee Valley.
You will find two pages of photographs made with a scanning electron microscope (SEM). There is no better way to examine a metal edge at any magnification.

I'm always carving in very softwoods (red & yellow cedar) so "carving sharp" can't be pounded in with a mallet.

What I learned is that steels are so soft and plastic when thinned to an edge that 1,500 grit (3 micron nominal particle size) is as far as you need to go. Then hone on some sort of a strop with CrOx (0.5 micron) mixed with AlOx (0.25 micron) to finish with a nicely polished surface. I put all my water stones and expensive diamond plates away. I use 3m fine finishing wet&dry silicon carbide sandpapers. The strop is an office file card with honing compound scribbled on it.
For my carving adzes, I use a tennis ball as a mandrel.

Don't forget to always paint the bevel with black felt marker to follow your progress.
 
#26 ·
I've been using the black felt tip trick for plane irons and chisels for many years and as my eyes have grown old with me it makes more and more sense to use it.
I also do not believe you need to use any grit beyond 12 to 1500 grit, especially if you use a two step stropping process of a Green polish proceeded with a stropping of White or Red. As you said any finer a grit your edge will roll over or fracture off. I've tried using a finish with 20K and end up having to sharpen again in the quarter of the time than with 1500 grit.
 
#17 ·
Part of what lead me to a machine based solution was my frustration with wet stones. I have a set of Norton wet stones - 220, 1000, 4000, 8000. The 220 obviously cuts pretty quickly and the 1000 isn't bad, but the 1000 can take a while to remove the scratches from the 220. The 4000 and 8000 clog like nuts. All of them tend to dish, requiring frequent flattening. Sometimes I use the flattening stone to remove the clogging. I spend more time futzing with the flattening stone than I spend sharpening.

I was trying to see what I can do with what I have before spending on diamond stones or something like a Tormek.

I mostly do machine work, but when I do use a hand tool, it would be really nice for it to work. I've never developed the skill to sharpen by hand.
 
#18 ·
Part of what lead me to a machine based solution was my frustration with wet stones. I have a set of Norton wet stones - 220, 1000, 4000, 8000. The 220 obviously cuts pretty quickly and the 1000 isn't bad, but the 1000 can take a while to remove the scratches from the 220. The 4000 and 8000 clog like nuts. All of them tend to dish, requiring frequent flattening. Sometimes I use the flattening stone to remove the clogging. I spend more time futzing with the flattening stone than I spend sharpening.

I was trying to see what I can do with what I have before spending on diamond stones or something like a Tormek.

I mostly do machine work, but when I do use a hand tool, it would be really nice for it to work. I've never developed the skill to sharpen by hand.
I'm just beginning to learn "real" sharpening but I gave up on the very fine 4000+ stones in exchange for paper for the reasons you describe. When the paper stops doing it's job I just throw it away.

It's rare for me to have a need to start with 220, if the tool gets that bad it goes on the grinder or belt sander and becomes a truck tool. The most course I start out with is 400 if I have a small nick, then 600, then a 1000 stone and then polish with 2000 then 3000 paper. Since I sharpen often, worst case I start with the 1000 stone. I may one day decide to spend the $$ for an extra fine (8000 grit) diamond since they don't have the issues of the water stones. Also if I buy a new chisel or plane iron, the first thing I started doing is sharpen it. I just recently learned that factory sharp really isn't all that sharp, the tools I buy anyway. I also use a very basic honing guide

I'm not sure this has been made very clear in previous posts. I don't sharpen the entire bevel, only about 1/16" of the leading edge.
 
#22 ·
Yup, you really do. Jumping from 220 to 1000 is way, way too big of a jump, its like trying to read the 4th floor of a building by jumping from the sidewalk. Honestly, going from 1000 to 4000 is a bit much too, personally id like to have a 2500 in the middle there as well.

You mentioned some issues with clogging, what are you using as a lubricant on the stones, and what kind of stones are they? I know you say wet stones, but unfortunately wet isnt really a type of stone, just a catch-all term. Are these waterstones, india, arkansas, etc..?
 
#23 ·
The stones I have are Norton aluminum oxide water stones. They describe them as "For fast sharpening and fine finishes on planes and straight chisels, chose the Norton Combination Grit Waterstone. These dual-grit sided synthetic stones are softer than oilstones and are used with water and minimal pressure to quickly sharpen and polish for a quality final product. Available in a variety of grits for a number of jobs, including the repair of damaged tools, cutting, finishing, and polishing. Color-coded by grit to make selection quick and easy. "

The lower grits I have are individual stones; the higher grit is 4000 on one side and 8000 on the other. I use water as lubricant. I've tried everything from spritzing to a continuous flow across the stone while sharpening. I think I've even tried adding a little dishwashing liquid to the water. They just clog - almost instantly. I suppose it could be the quality of the stone, although these stones weren't exactly cheap, that's why I'm doing some investigation before making a (another) big investment.
 
#24 ·
A Nagura stone will help clogging by creating a slurry it prevents clogging. But I got by for years without using one, just hit it with the flattening a couple seconds to clean up the black schmush. Be sure you wipe or rinse the chisels clean before going to higher stone transferring schmush from the previous grit.

You need a few more stones something on the order of 400, 800 & 1000. I use diamond plates for the lower grits.

Sharp tools are the foundation of ww'ing, so think of it as an investment. There are cheaper water stones on Amazon, but you'll get what you pay for. BTDT.
 
#27 ·
LL point out that really thin steels at an edge are very flimsy.
It's poor thinking to imagine that you can do any better and the pictures are proof of that fact.
I was gung-ho to do 4,000 and beyond until I saw those SEM pictures. Such DOGMA.
I put all the stones away, shifted to simple silicon carbide papers up to 1,500 grit (3 microns)
and never looked back.
 
#28 ·
LL point out that really thin steels at an edge are very flimsy.
It's poor thinking to imagine that you can do any better and the pictures are proof of that fact.
I was gung-ho to do 4,000 and beyond until I saw those SEM pictures. Such DOGMA.
I put all the stones away, shifted to simple silicon carbide papers up to 1,500 grit (3 microns)
and never looked back.
??? So you abandoned honing to a higher grit b/c you’ve concluded it weakens the edge, therefore you’ve settled to work with duller tools? Either you’ve misinterpreted something or the entire ww’ing world is about to be upended.

Seriously, honing is really polishing. It removes very little metal. It’s really nothing more than removing scratches and grooves left by coarser grits. The strength of an edge is a separate issue from sharpness — related to the angle, steel quality and mass of steel backing up the edge. In addition, a secondary or tertiary bevel is higher than the primary.

On a micron level, a dull edge is jagged and less consistent. The more it’s polished, the less jagged IOW more sharp. In use a less honed edge fractures and the edge rolls over much faster. Maybe what you’re confusing is a low angle edge has less steel backing it up, even though it’s sharper, it rolls over more easily.

Sharpening is a very individual thing -- it boils down to what you think is sharp enough. Much depends on the specific tool and also the wood. 1500 paper is roughly equivalent to a 1500 water stone. I’m positive any SEM pic will show an edge honed to 1500 is much more jagged than one polished to16000 — IOW duller.

You’re system would never work for me, as well as thousands of other ww’ers. The paucity of hair on my left arm will prove this 😉😉. I think I’ll stick with the dogma.
 
#29 ·
I've often been curious about the need to sharpen to higher grits. It seems to me that honing a tool to a polish also make it slipperier, making it slide through the wood more easily. I'm kinda thinking it might be different for a chisel that you use by hand versus one you beat with a hammer.

Anyway, my interest in sharpening is that I hope to build a guitar. This involves using a chisel so shape braces that are glued to the top. The margin for error is small (or more accurately, the cost of screwing up is large). The pros do this with ease using sharp tools. While touring a guitar factory, I watched workers shape braces quickly and accurately. I asked if they had a department dedicated to sharpening and they told me that each person was responsible for sharpening their own tools.
 
#31 ·
I can't argue with the factual evidence presented in several pages of scanning electron microscope images of steel edges. I have no unsupported generalizations or assumptions to make.
The finest of edges is needed to cut the softest materials. That, in fact, is why bison meat is so easily cut with flint.

I report a technique for sharpening wood carving tools which is entirely satisfactory for working in soft conifer woods.
However, if you do not select the wood correctly, no amount of faffing around will ever make a useful edge.
 
#32 ·
I agree Example: When I know I will need chisels I bring my own in. An individual at the Senior Center Wookshop picked up one to try it, he got a nasty cut as he was used to what I consider dull chisels there and pushed way to hard. His comment to me as he was bleeding all over the floor, "your chisels are to damn sharp". When I want to shape, shave, or pare I only want to use hand pressure, if doing a mortise I have chisels that I leave at 1200 and use a mallet, but when I want to fine tune it I use the 8000 ones
To each their own I guess.
 
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