First, the good news -- I've been using Sharpton stones and the new Veritas jig and get edges that cause the hair to fall off my arm when testing an edge and 1.5 mil shavings from my #4 plane and 3 mil shavings from my #5 1/2 plane. The Veritas jig makes sharpening repeatable so that less re-shaping has to occur from sharpening to sharpening. One thing I found is that one should not short the course stone inventory. I recently added a #120 and #220 stone to my collection in order to reduce the amount of effort and wear and tear on the #320. That turned out to be an excellent decision; the two course stones quickly clean up edges and take out nicks.
However, my frustration is the amount of time required to sharpen. The first 3 grits go pretty quickly. However, starting at 1000 grit, the process slows down to a crawl. I spent over 2 hours sharpening my #4 plane blade this afternoon. It took a good 45 minutes to get all the scratch marks from the 320 stone off at 1000. Same song, second verse going from
1000 to 3000. I spent some time making sure the stones were flat, so I don't think that is causing the issue. Is this amount of time normal? What does it take others to get to a shiny, shaving edge?
That's the opposite of my experience - most of my sharpening stones are Shapton stones. I spend much more time on the course stones than on the fine stones. I don't remember what grits I have but I start at 120 and end at 8000. My 3000 stone isn't a Shapton, it's similar but it cuts really well. I'm not near my stones now, so I can't check
A few possibilities come to mind. Maybe the scratches were from the 120 stone and didn't show up until you got to the 1000 stone?
Did you pick up some stray grit from either your stone flattening method or from a coarser stone? The Shapton site says that you can carry grit under your fingernails.
There were a couple of nicks on the blade I was sharpening. I don't think I spent more than 5 minutes on the 120 stone before getting them completely removed and an uniform scratch pattern established on the blade. That is one of the really cool things about the Veritas jig, setup is uniformly repeatable between sharpenings, so you don't spend a lot of time re-establishing a bevel due to any kind of misalignment.
What I am seeing is a pattern being established starting near the center of the blade and radiating toward the edges as I complete the process on the 1000 stone. I am seeing the courser scratch patterns disappear, but slowly.
I am very particular about cleaning off the blade, the jig, and my hands between grits; I use paper towels to wipe everything down before moving up in fineness. I also use latex gloves because I really don't like going for days afterwards with blackened fingers and fingernails.
I keep spraying the finer stones down and occasionally wiping them with a paper towel to remove any blackened slurry.
As mentioned above, for the most part, I get rid of all the scratches from previous steps, the problem is that the process takes a very long time and instead of being uniform across the blade, usually starts in the middle and grows outward as the sharpening process continues. Maybe this is indicative of not having the stones as flat as I should have them?
I get very good results with King waterstones, 800 and 6000 grit. It's less than a minute from dull to mirror razor's edge, if the stones are already flat, wet, and waiting. They usually are, but the maintenance -- flattening and soaking them through before use -- are the major drawbacks. This is the kit I'm using:
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$60 shipped with the 2 stones, holder, and Nagura.
Flattening is easiest when they're dry, but I just use 220 wet/dry stuck to a granite surface plate with a film of water. Draw pencil lines on it before you start so you can tell when you're done. When they're dry, the freshly flattened area is a different color from the remaining hollows. They also sell a flattening plate, but $40 buys a *lot* of wet/dry.
Scary sharp with wet/dry paper and the surface plate also works, and is almost as fast. I bought the surface plate from that junk tool emporium about 10 years ago for $30. Alas, I didn't find any on the HF site just now. It might be worth hunting down, but thick float glass should work well enough for the rest of the world. It might work for you too.
Could it be a matter of technique? Are the stone pores clogged? Is the bevel properly hollow ground? Any way, flatten the backs on everything just once, the first time. A few minutes on the 800 grit waterstone was plenty to flatten everything except one very severely hollowed spokeshave blade (which I never did bother to completely flatten). From there on, it usually takes only a few strokes on the bevel to raise a full length burr. Switch immediately to the 6000, and chase the burr a few cycles until you get bored and believe that it will never end. I generally finish it with very short strokes, less than a half inch, one on the bevel and once on the back, to keep from raising the burr again. It really takes less than a minute, and most of it is futzing with it trying to *not* raise the burr again. Grind them to refresh the hollow once the shiny parts meet from repeated sharpening. I don't use a jig. It's very easy to feel the hollow ground bevel when it's flat on the stone.
The Frank Klausz video on hand tools was useful to me.
320 to 1000 is big jump. I use 3M wet/dry sandpaper (400, 600, 800 &
1200, 1500, 2000) in between to cut down on the time. I buy half sheets in 5 packs from an automotive painting supply store.
The symptom that you're having means that the surface of the blade and the surface of the stone aren't mating. In particular, the center of the blade is rubbing more than the edges. The possible reasons that I can think of are: - the surface of the stone is convex - the surface of the previous stone is concave - the surface of the blade is convex - the Veritas jig isn't as stable as you think
In woodworking, the closest we come to precision lapping is sharpening. In doing precision lapping (i.e. sliding two surfaces against each other with abrasive embedded in one), there are really only two types of surfaces that will mate in all orientations: spherical and some sort of saddle. I've never studied topology, so I can't comment on the saddle shape but I know that if you are making a surface plate, you need to be a little careful to avoid getting a saddle instead of a flat.
What about flat surfaces? Don't they mate? Well, they would but when you lap a surface, it really wants to be a section of a sphere. That's just the way the world works. When making something flat, say like an optical flat, it still wants to be a section of a sphere. You just need to make the radius of the sphere large enough so that it's close enough to flat that the curvature doesn't matter.
So, what's that got to do with your problem? When you flatten your sharpening stones, it would be easy to get a slight convexity or concavity to the stone. If the previous stone were concave, you could be grinding a slightly convex surface on the blade. With a sharpening jig that maintains the angle precisely, then it's possible that the when you move to a finer stone that is flat (or convex), you'd have to remove metal from the center of the blade before the edge of the blade can touch the stone.
How to check for flatness? Well, I'd start by getting the stones wet and rubbing them together. Pull them apart and look at the abrasive slurry. Do both stones look like they are making uniform contact? Ideally, cross compare using 3 stones. If all 3 meet evenly, the odds are very good (but not 100%) that all three stones are flat.
Another way to check for flatness is with a good straight edge and a very gentle touch. First I'd put the straight edge on the stone and gently see if the straight edge would rock at all. I'd do that at several points along the length of the stone and along the diagonals. No rocking would mean that the stone is fairly flat or concave.
The next step is to put the set things up so that there is a bright light behind the straight edge and look for light coming between the stone and the straight edge. If your straight edge is thick, you might need you might need to put a small paper shim at each end of the straight edge to make a gap. The narrower the gap is, the better as long as you can see light coming through from the back. You're looking for a uniform gap. With practice and a decent setup you could detect differences much smaller than we're worried about (0.00005 of an inch is possible, though you almost certainly don't have a straightedge that is that good). If I didn't have a straight edge, I'd use a sheet of opaque paper.
The same sort of check-for-a-uniform-gap on the blade might be enlightening :-) For the blade, I'd use a single edged razor blade as my straightedge. The blade is pretty small, so it's hard to get a good setup. If the blade looks flat, I wouldn't put much stock in it.
If your stones are flat, then there has to a technique issue.
I hold my blades by hand, so I can't comment much on the Veritas jig. However, I could imagine that pressing too hard on the push stroke could flex the jig a little and grind the heel of the blade more than the cutting edge. I can imagine ways of pushing too hard on the jig that would grind the cutting edge more than the heel, resulting in a convex surface on the blade.
What happens to the scratch pattern when you move the blade side to side on the coarser stone instead of back and forth? Does the scratch pattern change uniformly? What happens to the scratch pattern if you go from the finer stone back to the coarser stone?
The symptom of polishing from the center out is not what I'd expect if you somehow got some coarser grit from a previous step. I'd check the stones for flatness as described above.
That's the conclusion I am coming up with, then at the finer grits, it takes a very long time to remove the amount of material required to get uniform scratch patterns across the tool.
a and b are probably the most likely. c is unlikely since the blade is being well-shaped at the lower grits (assuming flatness on their part of course). I don't think d is likely, the jig in use is:
The setup gauge ensures repeatbility, the wide roller prevents tipping, and the frame is sturdy enough that it holds the blade securely. Given that the lower grits even up pretty quickly also makes me think this isn't the issue.
I'm beginning to think this may be the issue. The one thing I haven't checked thoroughly is the flatness of the lapping plate. If it is not flat, then I'm not going to be getting the stones as flat as they need to be.
I've used a straight edge on the dry stones, it may be that I have allowed too much tolerance in what I should consider "flat".
Lengthwise I'm seeing some concavity (20 mils or so). I need to look across the width to see what kind of flatness is there.
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Your idea of using the stones against one another has merit. That is one way to get a truly flat surface, the only way 3 surfaces will mate is through a plane, so I may need to do something of that sort to get the surfaces I need.
I'll have to check that out also
Given the jigging, I can't really test that out
The scratch patterns get uniform very quickly stepping back down. I attribute that to the fact that much more material is removed much faster when stepping down.
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Thanks for the recommendations, you've given me some food for thought and avenues to investigate here. Much appreciated
Are you changing angles when you change grits? I'd way bump the angle up a degree when going to the 1000-grit, and another degree when going to the highest grit. Doing this means that you need to remove _much_ less metal to remove the scratches left from the previous grit.
Of course some people don't like the multi-bevel, but try it and see what you think.
If you aren't putting on a microbevel when you sharpen, it will naturally take longer to get the entire bevel finely honed than if you do add a microbevel. So that can be a part of what is taking so long. It should still only take minutes however, without the microbevel.
OK, I had a chance to get out to the shop this afternoon and did some checking. It looks like the 320 stone is concave across its width by about
3 to 4 mils. The other stones are flat to within 1.5 mils or less. This explains the problem -- the 320 stone is shaping the front of the bevel such that the successive grits have to lap down about 3 mils of material, no wonder this is taking so long. I checked the lapping plate, it is flat across the width, so it looks like some time on the plate will be needed to get the 320 down to the flatness needed. One of the potential root causes is that the slurry may have built up in the center of the lapping plate, resulting in more stone being removed there than at the edges. Will also need to watch that when lapping the stone next time.
It does indeed do that. But so does learning to sharpen without a jig. There is certainly nothing wrong with using a jig; they are invaluable (for me) for blades with a very short bevel for which I can't get the knack of feeling when the bevel is flat on the stone. But for the bulk of plane irons and chisels, I find it SO much faster to sharpen freehand that I do it more often.
5-10 min including removing from the plane, reinstalling, and resetting depth.
You post raises a question: What are you doing with your plane that requires the level of sharpness you describe, but is usable down to the level of sharpness that needs 120 grit to reestablish the edge? For an application such as a smoother, where such a super-sharp iron is desirable or needed (for me that means sharpening though 8000 on Norton waterstones), the degree of sharpness achievable with a 1000 stone is not acceptable. So I stop using it and sharpen when it is still sharper than the 1000-grit stone could get it, and I just need to touch up on the 4000 and 8000. On the other hand, if I were using a plane for rough work like dimensioning, I would probably only sharpen up to 1000; any more would be a waste. Example: at the Woodworking in America conference this weekend, Michael Dunbar said that he sharpens his drawknives, used for rough shaping, to 330 grit (sandpaper, not stones), but his smoothing plane to 1500 grit.
I think the "usability range" for a plane is probably only one or two grits. I just don't see the need to go through a large range of grits unless repairing a nick or reshaping an edge.
If it works for you, that's great. I've found that hand sharpening tends to put a convex edge on the blade.
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As mentioned in another post, I think the problem has been found -- it rests on the 320 stone being concave laterally across the width of the stone.
Ding! Ding! Ding! We have a winner! [sorry 'bout that]. Yep, the reason for going down to 120 was to take out a couple of unfortunate nicks that were sustained. The rest of the blade was fine, I was getting some ridges due to those nicks.
A hollow ground edge is not entirely without merit or benefit. The thunk you might have heard earlier was my forehead meeting the desk edge on reading your thoughts about convex edges and hand sharpening. Not being able to raise a burr quickly is a clear signal that it's time to regrind that tool. A ding large enough to be felt in the work is about the same. Is it a matter of purity in the way you work?
In this case, yes because I am using that finishing plane to get the final finish on the work so those ridges were quite esthetically unpleasing. I really like to be able to get as much of the finishing completed with the plane rather than a scraper -- I just really like that shiny, glass-smooth look from a plane finish.
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