Not too shiny sharpening.

[dddd]

Wonder if anyone can help me, I've recently purchased a hock blade for my No7, plus a couple of LN planes (All A2 blades). I've been reading the DC books as well so I thought I'd get myself some waterstones to sharpen them up on.
So a quick call to Axminster and I am now the proud owner of 250, 400, 800, 1200, 6000 and 10,000 grit stones.
I've followed DC's instructions to the letter and all the blades now have nice flat backs (actually the LN blades were pretty much prefect to start with, although the Hock had more bend in it than my Grans new perm).
All was going well until I got to the 1200 Grit stone where I was expecting the back to start becoming shiny and mirror like, but no, nothing, they're all just as dull as ever, I've tried moving onto the 6000 and 10,000 stones but still no good. The stones are definitely removing metal as I can see it on the stone.
Normally I just use a sheet of glass with sand paper up to 2000 Grit and this usually gives a very nice shiny back, but is a bit slow. I haven't resorted to the ruler trick yet as I'm just the sort of person that likes to have the first inch or so nice and shiny. The blade does suck onto the stone (as DC says it will), so I'm wondering if this is causing the problem.
I've also just ordered DC's sharpening DVD so I'm hoping this might shed a little light on the issue, but was wondering if anyone else has suffered from this.

 

[Philly]

dddd
Dont panic yet!
First thing-check that your stones are flat. They dont always come that way, so do that first, and flatten them on your piece of glass with wet and dry.
Try that and see if that helps.
Cheers
Philly

 

[Shady]

The other possibility is to take care to ensure that you're not carrying over swarf/muck from coarser stones onto the finer grades. Not normally a major problem, but if you're trying to eliminate possible faults, rinse/wipe off all muck before moving to the next higher grade...

Without depressing you, the jump from 1200 to 6000 is also quite 'big'. You might want a 4000 in there...HTH

 

[Noel]

Not all types of metal become shiny? Especially with A2 blades?
Just a thought.

Noel

 

[Anonymous]

dddd

Check flatness. My A2 blades come up to a decent shine on the 1000 grit waterstone (or equivalent diamond stone which i now use instead) and then a mirror on the 6000. However, waterstones become concave across length and sometimes covex across the stone very quickly indeed and you often need to flatten them every 5 minutes or so during use

 

[Alf]

I am now the proud owner of 250, 400, 800, 1200, 6000 and 10,000 grit stones.

Crikey. :shock:

There are a few thoughts here, which may help.

Cheers, Alf

 

[dddd]

The stones are kept perfectly flat, I've got a nice large extra course DMT diamond stone to do that. I flatten them every couple of minutes, especially the low grits which do wear very quickly.

 

[Keith Smith]

Shine isn't everything in fact it means nothing IMHO.

I'm just writing an article about sharpening and I've got a digital microscope to look at the edges. Some of the stones create the most fantastic mirror finish then when I look at them with the microscope it looks like the local farmer has been ploughing them up.

On the other hand the waterstones generally give a matt sheen finish but under the microscope the surface is fine and even.

Keith

 

[Shady]

Now that's an interesting and provocative statement Keith...

I'm willing to be convinced, but in my experience, shine does equate pretty reasonably to sharpness. Sources ranging from David Charlesworth to Kingshott, and from time served mastercraftsmen to physics lecturers, regard shine on a surface (whether a cutting edge or an optical mirror), as a function of the smoothness/lack of scratches on it. This view mirrors (no pun intended!) my personal experience with cutting tools. If you're getting a 'matt sheen', then the waterstones are very unusual - at the finer grits... I get a mirror surface that will 'pop' hairs from my arm at any waterstone grit above 6000.

I would accept, as a separate and 'non-shine related' issue, that there is a different debate to be had about speed of dulling in use with regards to ultimate edges - how sharp is real world sharp enough, in other words, but I am a little surprised by your statement. :?

 

[Derek Cohen (Perth Oz)]

I'm willing to be convinced, but in my experience, shine does equate pretty reasonably to sharpness.

I don't quite agree, Shady. I'm with Keith here. The short answer is that if one polishes before the preceding scratches are completely removed, then these scratches remain and only the "surface" is polished. You may end up with a "sharp" edge (in a blade) or flat surface (at in blade back), but neither is uniform. The blade edge is serrated and this shows up as scratches on the timber surface, and the metal of a blade may just appear matte (depending on the number of scratches).

But the likely reason that dddd is not getting a shiny surface may have something to do with the stones he is using. Some, such as Shaptons (I am lead to believe - I have not used them), and perhaps other (ceramic ?) stones do not leave the shine that one might get with, for example, my King stones or 2000 grit sandpaper (which is equivalent to an 8000 waterstone).

Regards from Perth

Derek

 

[Shady]

The short answer is that if one polishes before the preceding scratches are completely removed, then these scratches remain and only the "surface" is polished

Derek, I agree that what you describe would create a matt surface, but I don't believe that this validates the idea that sharpness and shinyness are not linked. Indeed, what you are saying appears to be that incorrect sharpening technique (ie jumping too large a grit size from initial shaping to polishing, or just not staying with a particular grit for long enough before moving on), will only provide a superficial polish that does not remove all scratches from the previous grit - which is exactly what I do see if I am lazy, and as you say, it does indeed leave marks on the wood.

It might explain why a blade doesn't cut well despite looking shiny, if incorrect technique is used, but it brings me back to my original belief: a properly prepared blade will have 2 shiny faces meeting at the tip - otherwise it hasn't been properly prepared. The more I think about this, the more I may be prepared, for once in woodworking discussion, to go out on a limb and make a definitive statement: if it ain't shiny, it ain't properly sharpened and best prepared to cut wood.

This does not ignore the fact that you can cut with duller blades - but I would really suggest that proper prep will produce a mirror finish - I don't see how it can do anything else. We are talking about exposing fresh steel, and scratching it with successively finer and finer abrasives. For each abrasive, we should work the blade until all marks from the previous grade are removed. By the time it's sharp enough to use, the abrasive is in the micron grit size. If we want to get really technical, the wavelength of visible light is in the region of 0.4 to 0.7 microns. So if we can use a finishing abrasive with a 'grit' size of 0.4 microns or smaller, the blade must appear mirrored, even under any (optical) microscope magnification, as we've gone below the wavelength of visible light. Note to techies - diamond abrasive paste can be bought at 0.25 microns... :wink:

(but, just to re-iterate before anyone climbs all over me, I fully accept that 'how sharp is sharp enough?' is a different and just as interesting question - my comments are purely related to the suggestion that shiny and sharp are not related.... I reckon that fundamentally, they are.)

 

[Frank D.]

Most people who have verified edges under a microscope have found that the shiniest edge is not always the sharpest. Kieth has come to the same conclusion as Brent Beach (who has done extensive tests on sharpness and edge retention), that shiny isn't always the sharpest (also see the thread from Wood Central above) My Norton finishing stones do not always leave a shiny surface on A2, not matter how much time I spend on a blade, and I don't rush through the grits either. A friend of mine also compared three stones with Japanese blades under a micrcoscope and the Honyama left the sharpest edge and the least shiny surface. So while many people affirm the shiny is sharp, as common sense would dictate, people who have investigated the question in depth have so far found no necessary link.
Frank

 

[Noel]

Frank, how do you find the Nortons compared to King or similar? Thinking about going for a 4000X and an 8000X. Bigger size much of a benefit? Extra cost worth it?

Rgds

Noel

 

[Shady]

Fascinating Frank. So if shiny isn't the sharpest, what is and how is 'the sharpest' defined? The only way I can see a less shiny surface being sharper is if it is less shiny because it's more or less uniformly serrated, so that you're getting a 'sawing' or 'bread knife' effect. I suppose it's possible that, provided the serration/scratch pattern is smooth enough, it won't leave unsightly marks on the stock being worked. I do not wish to anger/alienate anyone, but I'm gonna need a lot more than anecdotal evidence to accept this idea. It is just too counter intuitive and counter basic physics (and counter all the in-print experts I can lay my hands on at the moment) for me to really believe it at the moment.

This link:

http://www.physics.mun.ca/~sstamp/knives/blade_testing.html

reinforces the point about the need for standardisation of definition, and does, to be fair, also make the point about 'serration-enhanced cutting' that I suggest above:

These tests are both highly dependent on the edge alignment. However more polished edges will score better on the push cutting while the poly cutting can do better with a slightly rougher edge. Blades also show quite different rates of blunting on both tests, for example soft steels with lots of carbides can quickly lose performance on the thread due to roll, but keep much better performance on the poly

This is what I would expect: a serrated edge cuts a thick rope better. However, for 'push cutting' (like a plane's action, with minimal sideways movement), 'more polished edges will score better'...

this url: http://www.uspto.gov/go/classification/ ... efs356.htm

is for the US govt Patent and trademark office - a body who need to be absolutely sure about claims and counter-claims, I'd suggest. From the body of the text:

CUTTING BLADE SHARPNESS
This subclass is indented under the class definition. Subject matter including a light source for shining light on a blade edge together with optical or photoelectric means for determining the reflectivity and thus the sharpness of the blade.

Ie, the US patent office use reflectivity (aka 'degree of polishdness') as their definitive assessment of how sharp a cutting edge is... Good enough for me..

 

[Frank D.]

Hi Shady,
You certainly haven't alienated me, I'm no expert and quite Frankly was in the "shinier is better" camp until I started reading some convincing evidence to the contrary which has made me doubt. I think the evidence is more than anecdotal, but there's still not a whole lot of work that has been done on the subject. One thing we have to remember is that the type of steel is definitely a factor. Some steels commonly used for blades were not widely used even five years ago, so not all research that was done before that necessarily applies. As I mentioned, with my A2 blades a cloudy surface is very common; when I first started using A2 blades and didn't get the mirror polish that I had gotten with O1, I did everything I could to get more consistent shine (rinsing and brushing my stones, sharpening under running water, applying more pressure to the blade, applying less pressure, going back down to the previous stone, I even bought a 6000 stone to use between my 4000 and 8000), but to no avail. My experience is anecdotal, but it seems to be very common nonetheless.
And an edge is not necessarily serrated if it has a cloudy finish. One reason that I don't trust the shaving test for blades is because a serrated edge or even a rough burr will take off hair. But the advantage of checking a blade with a microscope is that the scratch pattern, comes out quite clearly, and the size and regularity of all the scratches can be easily seen as would any serrations (even more so). Serrated edges also wear much more quickly than edges with and even pattern (as I think one of your quotes mentioned), so again they are easily noticeable.
I'm not really saying anything new here, this is about all I know. I agree that logically a shinier surface has finer scratches, but my experience with A2 steel as well as some recent findings by people who have taken the time to compare edges more methodically have made me wonder. I'm not in any "camp" though.

 

[Frank D.]

Noel,
I have some Kings as well as a few Debado and Shapton stones, but I really like my Nortons, especially the 8000. I use my #8 plane quite often, and a 112 once in a while, so the width for me is important. The Nortons don't need to be flattened as often as the Kings. I think they are worth some extra money, but I don't know how much they cost in GB. Shaptons are hard as a rock and wear even less than Nortons, but I can't compare the higher grits and frankly whether I have to take five strokes or 10 on a 4000 or an 8000 isn't of much consequence to me. I'd like to try equivalent Shaptons to see if they retain their flatness as long as the course one I have, but I'm so happy with my Nortons that it doesn't really matter. Nortons are also easily flattened. I use a diamond plate which might be worn out prematurely with shaptons.

 

[Shady]

OK Frank - thanks for the 'measured' reply... :wink:

I was going to do some blade tests with my digital microscope earlier this year, but got waylaid by some personal stuff. You've got me interested again, and I just happen to have re-furbed the shop, and have some room and time on my hands...

Gimme a week or so, and we'll see what I can produce for the community to comment on..

 

[Noel]

Frank, thanks for taking the time to give your opinion on Norton stones. Just needed the final shove and will be ordering a 4Kx and an 8Kx this week. Will go King for the lower grits.

Rgds

Noel

 

[Anonymous]

The main thing is how do they cut!

Anywho, the better Japanese natural stones will sharpen really well, and yet they do not create a shiny finish. The prep step on the back where one uses an iron plate and carbide will miror the back like nothing else, but the sharpening process does not make it shine. A good japanese woodworker will come over and look at your tools and you see him fighting not to snear if he sees shinny surfaces. A lot of them won't use artificial stones because they do shine, and they feel they will ruin their tools. I present this just for what it is worth, there are all kinds of ways to sharpen.

BEWARE of flatening japanese stones with a diamond stone. The diamonds are hard, but the vitrious bond that holds the diamonds to the substrate is easily abraded by the mud from the stone. I ruined my first DMT that way. Maybe they have beaten that problem, but I doubt it.

To flaten them, I either go dry on paper, but I prefer to use the stone on stone system. Also, wherever I happen to live I will seak out a piece of flat concrete, and use that, real fast. The Shapton system that works great also, is nonetheless a bit of a kluge. The idea of constantly using carbide to flaten stones, cause they can't be flatened against each other is the reason I haven't bought any of their stuff, though I have used it.

The King 8000 chromes your edges, and can provide really good edges. Just by the way.

 

[Keith Smith]

Thanks to everyone for all their thoughts on this.

I have built a sharpness measuring jig and have been trying all sorts of combinations to get a perfect edge; by measurement rather than anecdotally. So far some of the results are odd to say the very least so what should have been a few days of testing has turned into weeks.

It is very easy to get a super shiny edge, just use honing paste on a leather strop even with the roughest edge you can get a shine. I do accept Shady's point though that when sharpening going up the grits does increase the "shinyness, but my point was that a shine per se is not an indication of sharpness. I only go up to 6000 grit with the waterstones and the finish is definately not shiny.

Keith