Sharpening Questions

[Dave Easley]

Greetings Everyone,


I’m teaching myself to use handplanes. A critical part of this is learning how to sharpen the plane irons. I have a set of DMT Dia-Sharp bench stones and a 3000/10,000 waterstone.


I started with the extra-coarse diamond stone and worked until the scratches went uniformly across the top inch of the back (I decided to forego the ruler trick). I then switched to the course grit and worked in the perpendicular direction (up and down?) until the extra-course scratches vanished. Then on to the fine grit and the sideways direction.


After a short time the fine grit gave me a mirror finish. Being somewhat compulsive, I then went on to the extra-fine grit to polish the blade even more. Much to my surprise, the mirror finish vanished and the back of the blade had more of a satin finish. I tried the extra-extra-fine grit and the back became even less reflective.


At this point my curiosity got the best of me so I went back to the fine stone and restored the mirror finish. Then I tried my waterstones. Same thing - the mirror finish was gone and the back of the blade appeared dull (finish wise - not dull sharpwise).


Does anyone have an idea of what’s happening here?

If I were to go on longer with the finer grits would the mirror finish return?

Should I keep progressing through the finer grits once I have a mirror finish, or is that unnecessary for the back of the blade?


Thanks for your help!


Best wishes,
Dave

[Patrick Chase]

Greetings Everyone,


I’m teaching myself to use handplanes. A critical part of this is learning how to sharpen the plane irons. I have a set of DMT Dia-Sharp bench stones and a 3000/10,000 waterstone.


I started with the extra-coarse diamond stone and worked until the scratches went uniformly across the top inch of the back (I decided to forego the ruler trick). I then switched to the course grit and worked in the perpendicular direction (up and down?) until the extra-course scratches vanished. Then on to the fine grit and the sideways direction.


After a short time the fine grit gave me a mirror finish. Being somewhat compulsive, I then went on to the extra-fine grit to polish the blade even more. Much to my surprise, the mirror finish vanished and the back of the blade had more of a satin finish. I tried the extra-extra-fine grit and the back became even less reflective.


At this point my curiosity got the best of me so I went back to the fine stone and restored the mirror finish. Then I tried my waterstones. Same thing - the mirror finish was gone and the back of the blade appeared dull (finish wise - not dull sharpwise).


Does anyone have an idea of what’s happening here?

If I were to go on longer with the finer grits would the mirror finish return?

Should I keep progressing through the finer grits once I have a mirror finish, or is that unnecessary for the back of the blade?


Thanks for your help!


Best wishes,
Dave

What's happening is that you're falling into the trap of thinking that a mirror finish is a useful indicator. It isn't.

A very coarse finish can be mirror-like if the scratches are all oriented identically, but that's not what you want for sharpening. A matte finish is fine. If you keep working on the 10k stone for long enough you'll probably get back to a mirror sheen, but it would be pointless. All that matters is that you've taken out the scratches from the lower grits.

[Stewie Simpson]

A few points to raise; I am pleased to hear you have bypassed the ruler trick, if the dmt stones are new they will likely need a top dressing to even out the diamond height, and lastly, achieving a mirrored finish can be an excellent indicator to the overall sharpness, and longevity of the cutting edge. imo

Stewie;

http://i1009.photobucket.com/albums/af219/swagman001/new%20stropping%20block/natural%20honing%20stones%20purchased%20from%20the %20uk/_DSC0224_zps5a081w93.jpg (http://s1009.photobucket.com/user/swagman001/media/new%20stropping%20block/natural%20honing%20stones%20purchased%20from%20the %20uk/_DSC0224_zps5a081w93.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/new%20stropping%20block/natural%20honing%20stones%20purchased%20from%20the %20uk/_DSC0225_zpsb7ngupgu.jpg (http://s1009.photobucket.com/user/swagman001/media/new%20stropping%20block/natural%20honing%20stones%20purchased%20from%20the %20uk/_DSC0225_zpsb7ngupgu.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/new%20stropping%20block/_DSC0212_zps1wng0fyv.jpg (http://s1009.photobucket.com/user/swagman001/media/new%20stropping%20block/_DSC0212_zps1wng0fyv.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/new%20stropping%20block/_DSC0216_zpsipubvijs.jpg (http://s1009.photobucket.com/user/swagman001/media/new%20stropping%20block/_DSC0216_zpsipubvijs.jpg.html)

[Jebediah Eckert]

Stewie, you don't like the "ruler trick" I take it?

[Stewie Simpson]

Jeb; I use W1 and 01 tool steel on all of my chisels and plane irons, I don't need to use the ruler trick. If you go back in time to the inception of the ruler trick by David Charlesworth, it was biased on the hardness of A2 cryo tool steel. Not only was he honing a back bevel, but he was also honing a 3 tier primary, secondary, and micro bevel to achieve an overall 35* cutting edge. I can feel a likely storm brewing. http://www.popularwoodworking.com/techniques/the_ruler_trick

http://www.popularwoodworking.com/wp-content/uploads/2010/10/P85-1-1575.jpg (http://www.popularwoodworking.com/wp-content/uploads/2010/10/P85-1-1575.jpg)

[Patrick Chase]

Jeb; I use W1 and 01 tool steel on all of my chisels and plane irons, I don't need to use the ruler trick. If you go back in time to the inception of the ruler trick by David Charlesworth, it was biased on the hardness of A2 cryo tool steel.

The ruler trick is nothing more than a microbevel on the back. Microbevels long predate A2. Also, I've read several of Charlesworth's articles in both PWW and FWW, and never seen him state that the bevel trick was "biased upon" [sic] or created in response to A2. Can you please provide a citation for that? In the one you cite he merely advocates as an aside that people should switch to A2, not that they have to use the bevel trick if they're already using A2.

Charlesworth isn't "honing" 3 bevels. The primary is hollow-groud on a bench grinder, while the secondary is roughed in with a medium (1000#) stone. Only the tertiary is honed. It's basically a conventional primary/secondary arrangement wherein the top 2/3 or so of the primary has been relieved on a grinder to ease hand-sharpening.

35 deg cutting edges work very well BTW. Not sure what your point there is.

[Stewie Simpson]

Patrick; your quite correct in pointing out the primary bevel is ground. A mistake in my typo..

Stewie;

[Stewie Simpson]

There was an interesting discussion back in Sep.2013 on the ruler trick . A lot of for and against commentary. http://www.theunpluggedwoodshop.com/the-ruler-trick.html

[Jebediah Eckert]

My apology............:D, but thank you for the response Stewie. Also I appreciate the link, great stuff for and against.

[Stewie Simpson]

Thanks Jeb.

regards Stewie;

[Rob Luter]

To the OP...

Are you certain of the grits of your sharpening media? I've never had a situation where going from a coarser to finer grit didn't improve the quality of the mirror finish. I use 3M abrasive film on float glass in the following order:

40 Micron (400 Grit)
15 Micron (1200 Grit)
5 Micron (4,500 Grit)
1 Micron (14,000 Grit)
.3 Micron (60,000 Grit)

On my planes I start with a hollow grind from a low speed wheel, followed by a 25 degree primary bevel. I add a tiny secondary bevel of about 30 degrees with the two finest grits. I flatten the backs to about 1/2" from the edge up to 4500 grit, then use the ruler trick for the very edge with the two finest grits. I wind up with a mirror finish and a cutting edge that is scary sharp. Periodic touchups with the two finest grits keep things fresh.

[Stewie Simpson]

Rob; just for clarity to the OP and others, can you explain the following further;


I flatten the backs to about 1/2 from the edge up to 4500 grit,

I assume you saying 1/2".

regards Stewie;

[Rob Luter]

Rob; just for clarity to the OP and others, can you explain the following further;


I assume you saying 1/2".

regards Stewie;

Yup. I flatten to 1/2" from the cutting edge and usually with grit no finer than 4500. A mirror polish that far away from the cutting edge looks great but serves no function beyond the sensory (it looks cool). This will vary based on the quality of the blade. Old Stanley irons are sometimes anything but flat. In those cases I focus on the 1/8" or 1/4" closest to the cutting edge. I have some Hock and Veritas irons that were so flat and true it was easy to get them looking like mirrors an inch from the cutting edge.

[Frederick Skelly]

Interesting. Mine often get what I'll call "foggy" when I move from the 1000 grit diamond to the 6000 grit Shapton. The fog will sometimes clear up if I use a clean strop.

[Dave Easley]

Hello again everyone,

Wow! Thank you for all the replies.

To Patrick: One of the strange things I noticed was that the DMT fine stone (25 microns) at first produced uniform fine scratches (horizontal at this stage, replacing the vertical scratches from the coarse stone), but after a while they seemed to vanish into the mirror finish. The scratches were barely visible under a 20x magnifier. It was hard to tell if the scratches from the even finer stones were smaller or not. It seems like, by definition, they'd have to be smaller. What you said, though, makes sense: moving to the finer grits will improve the sharpness (or in this case, flattness).

To Stewie: Your comment about top dressing the diamond stones makes perfect sense. While honing with the fine stone, the resistance to moving the blade along the stone was small and uniform. The blade slipped nicely over the length of the stone. With the extra-fine and extra-extra-fine stones the blade tended to jerk in places, as if there were high and low spots on the stones - exactly what you mentioned about needing to level the uneven diamond height. The two finer stones are newer. So:

How do I top dress my DMT diamond stones? I know how to dress waterstones, but I have no idea how to dress diamond stones. It sure feels like the finest ones need it.

To Rob: That's what occurred to me too. I wonder if the stones could have been labeled incorrectly.

Thanks to all of you for your help.
Dave

[Robert Engel]

Dave, not nearly as knowledgable as some here, but I can get my sharpen, shave some hair and be back to work in less than 2 minutes, so take this FWIW.

1. I've never heard of dressing diamond stones and I've never gotten the impression they needed it. Maybe I will learn something.

2. I use glass cleaner or some other spray general cleaner (I like Top Job) for honing on the duo sharp MESH stones. I find it suspends particles well and cleans up easily. I think WD40 works better on the diamond plates (Dia Sharp).

3. I am not a particular advocate of the ruler trick on plane irons, but lately I've been doing it just to "make sure" I'm totally sharp.

4. Don't worry about mirror finish a tool can be razor sharp without it. Polishing on a strop will do the trick.

5. I think sharpening is quite a simple process but for some reason it is one of the most over anal - yzed aspects of ww'ing.

[Patrick Chase]

1. I've never heard of dressing diamond stones and I've never gotten the impression they needed it. Maybe I will learn something.

Plates with electroplated diamonds and DMTs in particular can have "rogue particle" problems. See for example: https://scienceofsharp.wordpress.com/2015/09/10/diamond-plate-break-in/, https://scienceofsharp.wordpress.com/2015/09/28/diamond-plate-break-in-part-2/

Other diamond media such as lapping films and pastes don't share this issue - it seems to be specific to the nickel-electroplating process used for most plates.

[david charlesworth]

I started using the ruler trick soon after getting my first 6,000 grit Japanese waterstone.

I have just been filming a ruler trick demo for YouTube. It will be on my channel in a few weeks.

https://www.youtube.com/channel/UCQg_yua727tzXh1t6BFLjEQ/feed

From memory this was in about 1980 and partially due to the stiction experienced when polishing the whole of a plane back.

Another question was "why are we polishing all this metal, which does no cutting?"

I hope you will enjoy my YouTube clips, if you have a look.

Best wishes,
David Charlesworth

[Dave Easley]

Hi David,

After spending an inordinate amount of time flattening the back of a 1" chisel, I am convinced the ruler trick will save a lot of time on plane irons. I read that one shouldn't use the ruler trick on chisels, but I'm glad it's fine for plane irons. I realize that sharpening is a bit Zen like, but I don't know if I could tolerate that much Zen just to flatten the entire back of a plane iron.

I found your YouTube videos very helpful. The technique for planing long boards was particularly good for me since I was doing just that when I watched it.

Do you have any tips for planing large table tops? I keep hoping there's a trick to getting to the middle of a 36" wide table top.

Thanks for your help.

Best wishes,
Dave

[Patrick Chase]

After spending an inordinate amount of time flattening the back of a 1" chisel, I am convinced the ruler trick will save a lot of time on plane irons. I read that one shouldn't use the ruler trick on chisels, but I'm glad it's fine for plane irons. I realize that sharpening is a bit Zen like, but I don't know if I could tolerate that much Zen just to flatten the entire back of a plane iron.

IMO diamond paste on flat steel plates is the least painful way to flatten. For a warped chisel or plane iron I start with 60 micron paste (the equivalent of #200 or so) and work down from there. I end at anywhere from 0.25 um (#40000) to 1 um (#10000) depending on the tool. It's several times faster than stones or sandpaper, and significantly faster than diamond plates. Being able to continuously refresh the grit is a big plus.

Note that all of the grits above are roughly as per JIS-1998 (Sigma, Imanishi, etc). Multiply by 1.5x to get "Shapton grit".

[david charlesworth]

Dave,

One strategy is to have a centre joint, with opposite planing directions on either side, so you only have to lean over half the width of the table.

On a particularly wide 10 foot table, I ended up kneeling on the top!

By the way, it is clear to me that different steels on different stones have variable brightness (polish).

Diamond can look very bright, even when the grit size is relatively large.

Best wishes,
David

[Patrick Chase]

By the way, it is clear to me that different steels on different stones have variable brightness (polish).

Diamond can look very bright, even when the grit size is relatively large.

Very true. As I said way back in #2, a "mirror finish" isn't a reliable or useful indicator of anything. Two examples illustrate this:

1. As David says you can get a mirror-like surface from fairly rough (couple thousand grit) diamond plates/films/pastes.

2. Veritas blades come lapped to a surface roughness spec of 5 microinches (0.127 microns) but are matte grey, not shiny at all. 0.127 microns is about what you would get from a #80000 abrasive, so that surface is likely better than any mirror finish you could achieve on your own.

[Stewie Simpson]

Patrick; you need to add some specifics within your statement, are you talking about 01; A2; PM-V11, or all 3 tool steels.

Stewie;

[Stewie Simpson]

By the way, it is clear to me that different steels on different stones have variable brightness (polish).

David; with respect the same applies to your statement.

regards Stewie;

[Patrick Chase]

Patrick; you need to add some specifics within your statement, are you talking about 01; A2; PM-V11, or all 3 tool steels.

Stewie;

I've used all 3, and all of them can achieve very shiny surfaces while being fairly rough, and matte surfaces with highly uniform finishes. Scratch directionality (or lack thereof) matters at least as much as the specific alloy IMO.