DIY diamond stones: Initiial report

[Matthew Springer]

TL;DR:
Basically with almost no skill or ability I was able to out grind my regular DMT diasharp Xcoarse and duoshap course diamond plate by a large margin. And it's much, much bigger.


Backstory:
The shop has been packed up for the last 8 years in boxes since getting married, living in a bunch of countries, having kids, switching states, etc. So I have a _lot_ of tool restoration to do. I also had never really gotten anything truly flat (irons or chisels) before I packed up the shop because I used to suck at sharpening. I still do, but I used to too. I'm not a good woodworker so it turns out I did not understand the importance of, say, taking off the rust inhibitor with mineral spirits _before_ trying to flatten backs.

Suffice it to say I'm in the process of reflattening basically the entirety of my hand tools cutting edges. (but not all at once)
After some folks here got me thinking about diamond pastes + steel, I decided to give it a whirl. I'd tried sandpaper on surface plate, and that seemed to work better than the 12 year old DMT duosharp I have.


Setup:
So I bought a 4"x12"x3/8" "precision ground low carbon steel bar" from McMaster and a sample pack of oil/diamond lapidary pastes from Amazon (the Kent's Supplies ones). It's $36 for the plate and ~$13 for the paste so we'll call it $50 in materials. Since this is me, I bought 3 (plates and pastes in 40u 28u and 5u).

There was some question about if these plates were actually flat or just even thickness. They are _not_ quite dead flat, I had one that was in very slight twist by about .002 but you can probably hand lap/grind that down on the granite surface plate pretty quickly (After all you have a supply of diamond pastes ). The other two were dead flat within what I could detect. I had an old Stanley #3 from the 60s that needed serious help.


In practice, I made 3 plates at the 3 coarsenesses, and went to town. I was able to get slightly less polish then the equivalent 5u sandpaper but in about half the time. The 40u cuts very aggressively. It does seem to have the same problem I have with my DMTs which is just that the particle size can be inconsistent leading to some deeper scratches that take time to get out. You can see in the progress of the blade back with only about 3 mins of work. It's a very aggressive cut.

I'll try to update more once I get some modern tool steel on there.

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[John Kananis]

Hi Matthew: Interesting efforts (I know little about machining steel, etc, etc so this looks impressive to me as a layman). That said, IMHO, it will take you an eternity to sharpen all the edge tools in your shop if you intend to flatten that much of the blade. About a half inch is all you need.

GL with your plates.

[Brian Holcombe]

It's good that you are taking the time to flatten them, it pays off in terms of easy maintenance. All said and done each time you sharpen make certain that you are completely removing the wear bevel.

I like to keep all of my stones very flat, but pay additional attention as they go up in grit. Removing flatness is easy, but maintaining it requires more careful consideration.

The plus side is that you will have an entirely new meaning to the word sharp after this is complete.

[Normand Leblanc]

Matthew,

You would save a lot of time if you were to use D. Charlesworth "ruler trick".
http://www.finewoodworking.com/how-t...lane-iron.aspx

Have a good day,
Normand

[Lasse Hilbrandt]

Hey Matthew

so nice to hear, that im not the only one, not the perfect skilled woodworker here, with a dream.
Just curious to hear about all those countries you have been living in, which are they and why ?

Best regards Lasse

[Matthew Springer]

You would save a lot of time if you were to use D. Charlesworth "ruler trick".

I know about the ruler trick, the main issue is you have to keep using it once you start. FWIW I do use it sometimes if I'm in a hurry but only on the very last grit. In my case, I'd never actually gotten anything even approaching flat, so that was the first priority.

so nice to hear, that im not the only one, not the perfect skilled woodworker here, with a dream.
Just curious to hear about all those countries you have been living in, which are they and why ?

I'm just not that great a woodworker (or guitar player for that matter). A lot of my problem is not actually being consistent about layout and cutting to the lines. I have built some decent stuff, it just takes a while. I think it took me ~2 years to build a machinsts chest and it still doesn't have hinges.


Locations:
Germany (Munich), Sydney Australia, USA. But over that same period the wife lived in +2 more. (Belgium, England, different parts of USA and Australia). Stateside-wise, we were spread across CA, CO, KS. I'm in software, she's in bio-pharma engineering consulting and pretty much went where the work was.

We're now mostly localized in CO. We figured after 4 years of marriage and with a kid on the way, we should move in together. But you don't want to rush these things.

[Patrick Chase]

Matthew,

You would save a lot of time if you were to use D. Charlesworth "ruler trick".
http://www.finewoodworking.com/how-t...lane-iron.aspx

Have a good day,
Normand

As David himself has pointed out the ruler trick is for honing an already-flat blade, and he's published a number of articles about how to flatten in the first place that are worth checking out. The ruler trick doesn't help things like cap iron to blade interface except in very specific circumstances, so you do in fact need to flatten at least to some degree.

Matthew, IMO what you're doing here is about right - You said you'd flattened to the equivalent of #3000 (5 um paste). From that starting point you can use the ruler trick for final honing to whatever ultimate grit you want. I think that you may have gone a bit further back than you needed to on a plane blade though.

FWIW I go down to 0.5 um when using diamond, or 0.75 um (Sigma #13000) when using waterstones. You can stop earlier with the stones because the abrasive breaks down and yields a finer scratch pattern than the particle geometry suggests.

[Patrick Chase]

I know about the ruler trick, the main issue is you have to keep using it once you start. FWIW I do use it sometimes if I'm in a hurry but only on the very last grit. In my case, I'd never actually gotten anything even approaching flat, so that was the first priority..

The ruler trick is only meant to be used on the very last polishing grit[s], per Charlseworth.

If you use the ruler trick properly (only for final honing of an already-flat blade) then it's extremely easy to undo. David's recommended configuration corresponds to 1/2 deg of back bevel, and maybe 1 mm of beveled edge length after several honings. Grinding through the math that means that the tip is recessed ~9 microns from the back of the blade. That will be removed VERY quickly by any subsequent flattening.

FWIW I use a 1/4 degree configuration (10 mil shim stock instead of a ruler) and if you do that then it's *really* easy to reverse.

[Matthew Springer]

Got some more time on the plates and can post some more observations. I flattened a 1" Marples blue handle chisel in, umm, Record time. The diamonds, they work.

Stuff to watch out for:
-> The 5u diamond paste seems to leave a much coarser finish than 5u sandpaper. I suspect the grit sizes just aren't as consistent.
-> Watch out for rust. There's no nickel coating on the top of the diamond plate like on a DMT, so you will get rust if you hit them with water. I used 3-in-1 oil since I'm too lazy to stock a proper sharpening oil.
-> Watch out for gouging. The tools steel is much harder than the plate, so you can get deep scratches if you catch a corner. They will fill in with paste, so they didn't bother me all that much.
-> Watch out for gumming up your sharpening jig wheel. Because you will initially have a decent thick slurry on top, it tends to stick to the wheel of the jig, so clean often.
-> Label your plates in terms of grit size. They all look the same once you start honing, which is dull gray. Make sure to keep track of which paste you used where.

Rough methodology if you're going to do this at home:

Plate prep:
1 Be sure to knock the sharp corners of the plates off with a file. Clean off the gum with mineral spirits or alcohol.
2 Before you get the paste on there, check your plate is flat, I'm doing the granite surface plate + 40u PSA paper. It shouldn't be out by much. I _didn't_ do this, but I'm goign to flip my plates and do so next time i'm in the shop.
3 Consider making your plate/stone holder now to make it easier to lap the top of the plate flat if you need to. That way you can grab onto the plate holder instead of the stone. These thigns are stupid heavy.
4 Note that lapping a full 4"x12"x3/8" plate is a metric crapton of work. The plates are heavy and hard to move. Consider picking on a smaller plate. And consider not trying to kill yourself getting it machinist flat.

Technique:
It's pretty much like regular sharpening. Only be sure not to press down too hard in the bevel config since you can gouge the plates just liek you can gouge your waterstones. I used a bit of 3in1 oil mixed with the diamond paste. I used way too much, you only need a drop or two. I applied the pastes to the plate using the latest in paper towel technology. Once the paste is spread out, it worked pretty similar to a regular diamond stone with the exception that the slurry is much thicker so I had to keep cleaning off the jig wheel.

I found I liked using the sides of the big plate for flattening and a 3 by 1 arrangement didn't let me really use the plate sides, so I'm going to make individual plate holders that will mount long wise or fat ways on the bench. I thought I was going to make a big bench hook style plate holder, but it turns out a whole square foot of steel is too damn heavy to lug around. So individual holders it is.

[John Kananis]

Matthew: You may want to consider trying the Gramercy paste - its water-based instead of oil so not that messy at all and you don't need a "slurry". If you let it sit on your plates long enough, the water starts to evaporate leaving the diamond particles behind; all you need to do to 'freshen it up' is add a drop or two more paste. I honestly can't see myself going back to stones and am so surprised that many more haven't jumped on this bus.

[Patrick Chase]

Got some more time on the plates and can post some more observations. I flattened a 1" Marples blue handle chisel in, umm, Record time. The diamonds, they work.

Stuff to watch out for:
-> The 5u diamond paste seems to leave a much coarser finish than 5u sandpaper. I suspect the grit sizes just aren't as consistent.

Quality diamond pastes (3M, DMT, PSI, etc) are very tightly graded, more tightly than CAMI or FEPA sandpaper. I suspect one of three things here:

1. Your paste isn't very tightly graded. I've gotten stuff from Kent's before, and it's definitely on the low-price, low-quality end of the scale so that wouldn't surprise me.
2. Paper is compressible and abrasive particles on sandpaper tend to recede into the backing with use, causing the effective particle size to decrease
3. SiC in particular breaks down into smaller "shards" with use, again causing the effective particle size to decrease.

In any case, 5u is pretty coarse for a final grit. It's the equivalent of #3000 if properly graded. Diamonds on metal are "unforgiving" in the sense that they neither recede nor break down, so I suggest 1 um as a reasonable minimum. I use 0.5 but am not convinced it buys me much.

-> Watch out for rust. There's no nickel coating on the top of the diamond plate like on a DMT, so you will get rust if you hit them with water. I used 3-in-1 oil since I'm too lazy to stock a proper sharpening oil.

Are you using oil-based or water-based diamond paste? Rust should never be an issue if oil-based and if you store the plates properly (I wrap mine in VCI paper FWIW).

-> Watch out for gouging. The tools steel is much harder than the plate, so you can get deep scratches if you catch a corner. They will fill in with paste, so they didn't bother me all that much.

Wow, if you're gouging 1018 plates that way then you should really avoid waterstones :-)

Rough methodology if you're going to do this at home:

Plate prep:
1 Be sure to knock the sharp corners of the plates off with a file. Clean off the gum with mineral spirits or alcohol.
2 Before you get the paste on there, check your plate is flat, I'm doing the granite surface plate + 40u PSA paper. It shouldn't be out by much. I _didn't_ do this, but I'm goign to flip my plates and do so next time i'm in the shop.
3 Consider making your plate/stone holder now to make it easier to lap the top of the plate flat if you need to. That way you can grab onto the plate holder instead of the stone. These thigns are stupid heavy.
4 Note that lapping a full 4"x12"x3/8" plate is a metric crapton of work. The plates are heavy and hard to move. Consider picking on a smaller plate. And consider not trying to kill yourself getting it machinist flat.

Flatness is less important with coarse grits than with fine ones, for the simple reason that coarse grits remove material faster and can therefore "correct" any flatness mismatch between successive plates. What I personally did was to sort all of my plates by flatness, and allocate grits in that order. The ones that I use at 0.5 um and 1 um are EXTREMELY flat, while the one I use for some 60 um "Amazon mystery paste" that I picked up a while back is out by ~1.5 mils. 60 um is 2.5 mils, so the flatness error is less than the grit size -> definitely not a problem.

[Patrick Chase]

Matthew: You may want to consider trying the Gramercy paste - its water-based instead of oil so not that messy at all and you don't need a "slurry". If you let it sit on your plates long enough, the water starts to evaporate leaving the diamond particles behind; all you need to do to 'freshen it up' is add a drop or two more paste. I honestly can't see myself going back to stones and am so surprised that many more haven't jumped on this bus.

Or get some low-viscosity extender like this: http://www.psidragon.com/products/ML...A%20EXTND.aspx. Light mineral oil is a little cheaper and works well, too (though the PSI universal stuff is handy since it also works with water-based pastes.

The "Gramercy" paste is just the standard 3M water-based line BTW. 3M also makes a very good line of oil-based pastes.

[Matthew Springer]

Patrick,
Thanks for your input. Interesting about the sandpaper. I think it likely just plain doesn't matter since I'm still finishing up the edge on the 5k/8k shaptons.

Wow, if you're gouging 1018 plates that way then you should really avoid waterstones :-)

By "gouge" I meant more "deep scratch". It's from the extreme edges of the plane blade with no previous camber when I pressed too hard on the edge. I basically caught a corner on the stone from being in a hurry.

Flatness is less important with coarse grits than with fine ones, for the simple reason that coarse grits remove material faster and can therefore "correct" any flatness mismatch between successive plates. What I personally did was to sort all of my plates by flatness, and allocate grits in that order. The ones that I use at 0.5 um and 1 um are EXTREMELY flat, while the one I use for some 60 um "Amazon mystery paste" that I picked up a while back is out by ~1.5 mils. 60 um is 2.5 mils, so the flatness error is less than the grit size -> definitely not a problem.

[/QUOTE]

I hadn't thought about sorting the plates by flatness, that's a great idea. I've already got the 1u paste in the amazon cart ready to go. I'll be hanging onto the shaptons for a while more.

Interestingly my green compound hone seemed to also mess up the finish worse. I think I contaminated it with some coarser grit form something.

[Patrick Chase]

The "Gramercy" paste is just the standard 3M water-based line BTW. 3M also makes a very good line of oil-based pastes.

Umm, just replace "3M" with "Norton" in that sentence.

[Patrick Chase]

Interestingly my green compound hone seemed to also mess up the finish worse. I think I contaminated it with some coarser grit form something.

The green compound actually comes pre-contaminated with coarser grit ("coarser" than the advertised 0.5 um CrO2), in the form of calcinated alumina. People get terrific results with that compound on compressible backings (see previous comment about sandpaper and receding abrasive particles) and after a bit of break-in. I sometimes use it on a felt wheel for gouges etc and get good results.

I wouldn't recommend it on a metal plate, though.