Sharpening

Re: Sharpening

Jim in Burlington Ontario

>The simple answer is yes it will affect it because you've created a valley at the cutting edge. A decent loop or magnifying glass would have helped you see it long before you polished the edge.

Re: Sharpening

Jonathan Peck - N.Y.

>The only part of a blade that is "sharp" is the tip where the to planes bisect (the front and the back). Everything else is just...uh..well...polished metal...right?

I would suggest a secondary bevel so you can get the scratches out where it counts, at the tip (where sharp happens), without having to spend alot of elbow grease and wasted metal trying to grind out the whole bevel. Making a secondary bevel is much easier with either a home made or store bought jig.

That is assuming the scratches extend to the tip, and in that case...yup...it's a problem. Just my two cents and probably worth what you paid for it.

BTW - How did you contaminate your stones?

Re: Sharpening

Al DaValle

>Thanks Jim. I do have a decent loop and the scratches I am refering to did not stand out visually until the polishing steps. I just seems to me these are small enough not to effect things to any real degree.....but I just wondered what other's experiences have been.

Re: Sharpening

Al DaValle

>Thanks, but the scratches are on the face side of the blade. They appeared in the flattening process. Therefore, a micro bevel wouldn't really solve the problem.

I assume the contanimation occured due to poor cleaning of the blade and/or blade jig when switching from one stone to the next.

This link might... *LINK*

Jonathan Peck - N.Y.

>...be helpful

"The examination of blunted cutters has shown that these premature fractures often originate at small nicks in the edge formed by face scratches during honing. This suggests that the extra load consequently exerted at these points in the cutting process tends to break away the metal."

Full article linked below


Sharpening technique notes

Re: This link might...

Al DaValle

>Jonathon,

Thanks for the the link. It is an interesting site. And your reference provided a logical explaination as to the impact of these very fine scratches.

Al

Re: Sharpening

joel

>The scratches are cosmetic only and do nothing to compromise performance. THe reason is that a scratch either goes to the edge of the blade or it doesn't. if it doesnt there certainly is no issue. If it does, all it means is that on very fine cuts the cut may not be continueous. Much like a toothing blade only in miniature you might even get less tearout on the work than if you had a continuous shaving.

As for the scratch being the start of a fracture - this is sort of true. However the scratch will probably be a lot bigger at the edge than a very small nick you would get anyway after a few passes with the tool (we are talking tens not even thousands heree) - and of course being less compulsive in sharpening saves lots of time.

Incidently if you use oilstones you never get a polish anyway and you get equally sharp and equal performance - the point being here is that a mirror polish is cosmetic only.

Re: Sharpening

Al DaValle

>Hey Joel,

Thanks for the the insight. It really is what I waas hoping to hear. I am getting tired of all this polishing.

By the way....these chisels and plane blades I am working on are from yours truly. I am enjoying them!!!

Al

Re: Sharpening

Jim in Burlington Ontario

>Al I really try to perfectly polish the back as for the bevel the Rob Cosman method is the one that I use only polishing the last little bit. Polishing the whole bevel is a waste of time. As for the magnifing glass I use 2 a 10x and 30x with good raking light as there's nothing worse thans seeing the scratch to late in the process. If as you say they are very small as you use the iron and sharpen it over time you'll get all the flaw's out.

Same experience with Shapton stones

Steve Elliott

>I've done some near-compulsive sharpening with a Shapton 8000x stone and had the same experience as yours, with deeper scratches appearing on the polished surface. The more I polished, the more deeper scratches would appear. My guess is that when I flattened the stone using wet/dry sandpaper, some of the larger grit embedded in the stone.

I doubt the scratches affect the performance of the blade to any significant degree. I've been using a small microscope to examine used blade edges at 200 power, and have found that small nicks (chips or whatever) appear in even the most carefullly honed edge almost as soon as the blade takes a shaving. I've increased my bevel angle to 32 degrees, which has helped a great deal, and plan to test even larger bevel angles to see how it affects both the performance of the plane and the durability of the edge.

When I do actual woodworking using a plane, I use the blade until it gets too hard to push or won't produce a good enough surface. I've examined blades after this kind of use and they have wear that WAY exceeds the level of the rogue scratches left by the Shapton.

Re: Same experience with Shapton stones

Al DaValle

>Steve,

Thanks for the info. I wonder what the people at Shapton would say. I flatten my stone using their system (with the powders). I wonder if that is where I am getting the contamination? It seems very possible that their grit powders could get lodged into the stone. In any event....it is nice to know that the impact of these small scratches are most likely minimal. But it sure is nice to have that mirrored polish on the blades. If nothing else, it inspires good work.

Re: Sharpening

Al DaValle

>Thanks Jim.

Oil stone...you never get a polish?

WoodburnBob

>Joel, I've seen you or someone say this before and it puzzles me what you mean. If I spend a little time on a small translucent Arkansas stone, I get a pretty sharp reflected image with the naked eye. If I then spend some more time with a smoother "surgical" black stone I have, the reflection is crisper/sharper and under a lens the finest scratches become finer and I don't loose the edge. Granted, the reflection is less sharp and "polished" than if I'd done the same thing and followed up with a Norton 8000 water stone. But I've micro-dubbed and lost more good edges in the waterstone "polish" than I've refined.

Anyway, I'd be curious about the definition for polish-no polish you're using with regard to oil stones.

Bob

Re: Oil stone...you never get a polish?

joel

>By polish I mean mirror polish -

with an *k (and to a lesser extent a 4k) waterstone you get a mirror shine. I can shave in the reflection.

with an arkansas stone you get a surface that is satin - it relfects light but certainly isn't a mirror polish -

but as I have said many times before the quality of the edges are the same.

Re: Sharpening

Tim of San Leandro

>Pehaps you are applying a bit too much pressure when flattening the stone(s)....causing the Si

carbide grit to embed into your shapton's?

I didn't notice any problems with grit contamination when using waterstones. That is probably one of the better aspects of waterstones.

Re: Sharpening

Andy Lincoln,in Dearborn,MI

>Al,

I have nothing more to add to the sharpening/scratch dilema. There is already some great answers posted by folks much more knowledgable than I. I just wanted to welcome you to WoodCentral,hope yopu find it as enjoyable and informative as I do.

Andy Lincoln

on "mirrored" surfaces

Bill Tindall, E. TN

>If the scratches are less in size than the wavelength of light(about 0.5 micron) and the light is reflecting from pure metal, the metal surface will appear as a mirror. This condition can be achieved in principal with any abrasive of sufficient small size. So if the surface does not look like a mirror either the reflecting surface is not metal or the scratches are larger. To say another way, if rock A leaves a duller surface than rock B then rock A is yielding larger scratches. It can be debated how small scratches must be before any practical difference in plane performance is detectable. My personal notion is that a "perfect" edge gets dull so quikly (see Elliot below) that 1 micron scratches are no worse than considerably larger scratches that can be readily see. Hence, mirrored surfaces are not a useful goal as proposed by Joel. Furthermore it is not a given that the mirror quality extends to the edge as described by Brent Beech.

Now in the case of diamond abrasion with a cast iron plate the surface always appears greyer than it does with other abrasive formats. I believe this is the result of tiny carbon particles from the cast iron trapped in the scratches.

PS we are getting the diamond particle carry-over problem under control. It seems from this thread that it is a problem with more than just diamonds.

Re: on "mirrored" surfaces

joel

>"Now in the case of diamond abrasion with a cast iron plate the surface always appears greyer than it does with other abrasive formats. I believe this is the result of tiny carbon particles from the cast iron trapped in the scratches."

while I don't know for sure I would suggest that the reason the surface appears greyer ( a phoenomen I have seen also on on all grits of diamond) is that diamonds are a sharper abrasive and stay sharper compared to softer abrasives. I would suggest they are producing narrow deep scratches with reflect light differently than shallow rounded scratches caused by softer abrasives.

(just a theory don't know for sure)

Check latest FWW

Bob Rozaieski in Eastern PA

>If you are that concerned about the fine scratches going to the edge, you might consider trying David Charlesworth's "ruler trick" as noted in the latest FWW. It puts a very low angle microbevel on the back (face) of the iron just at the very edge that would solve those concerns. I'm thinking about trying it myself, but my only concern is that eventually I would need to completely re-flatten the face after the face microbevel got large enough from continued honing.

Re: Sharpening

Al DaValle

>Andy,

Thanks for the welcome. I am a long time reader but first time poster. I really appreaciate the responses and the info.

Al

Re: on "mirrored" surfaces

Joe Rogers, Northern Virginia

>Bill... what is the solution to the grit contamination issue?JR

Bill...I tried to answer your post...

Joe Rogers, Northern Virginia

>Bill, thanks for the e-mail. My return post got nabbed by your spam blocker.

Regards,

Joe

Re: Check latest FWW

Greg B

>Bob,

Using Charlesworth's ruler trick will never necessitate a full reflattening of the blade's back. The ruler trick results in a removal of the wire edge and a minute but highly polished back bevel. One would eventually remove it, I suppose, by regrinding the bevel-side, although he advocates the regrinding should stop before the wheel reaches the bevel's edge. (The honing of the secondary and tertiary bevel take it down to a fresh wire edge.)

I can join the many who vouch for the simplicity and effectiveness of the overall method, including the ruler trick. It is extremely effective, yields superb results and is FAST!

I believe anyone who is on the fence about sharpening methods would do well to order his first video via the Lie-Nielsen website and give the method a try. Articles are good, but the video is superior. For amateurs, I'd characterize it as a public service.

Cheers,

Greg

Re: Check latest FWW

joel

>for years I have flattened the backs of my plane irons simply by using the edge of the stone or and end (I don't mean the side) seems to work fine. it's very fast too. and it's repeatable without adding a back bevel (which won't work on a bevel up plane or a chisel anyway). I just don't understand the reasoning behind adding a ruler. (in my case I would spend more time looking for the ruler than sharpening anyway).

Also by using the ends of the stone for doing the back (the shorter stroke isn't a real disadvantage if the back is in pretty good sharp to start - which is is except when the blade is new) you save a lot of wear and tear on the stones and for waterstones - that means a lot frequent flattening time.