DMT Progression

[Acmemfg]

For straight razors…Anyone ever use a series of DMT hones from start to near-finish (600, 1200, 4000, 8000) and finalize on an established finisher (like a black Ark, Zulu Grey or something like that)?
I’m looking at a DMT Medium extra fine claiming to be 4k; I can’t help but wonder how that would compliment my honing quiver . Any ideas?

 

[JPO]

Yes.
It was a dead end for me. I even tried resin bounded diamond stones/plates.

 

[Herrenberg]

A microscope would quickly put you off of diamond hones for razors. They make nasty deep scratches. You'll see a bunch of sort of reasonable scratches, then a few really deep ones. That leads right to chips in the edge.

The two I found that are closest to tolerable are the Nanohone 1 micron resin-bonded, and the Poltava 15k metallic-bonded CBN. In both, the diamonds are more constrained. However, they still produce uncomfortable edges.

A diamond plate like a DMT is the worst possible case, because the diamonds are so exposed.

 

[Mr Kooby Shemayrew]

Please PLEASE read the ScienceOfSharp on the diamond plates.
The best of the bunch for razor honing is the Coarse and which is also the slowest. Every step finer is faster with a worse edge. The Extra Extra Fine being the fastest and worst edge of the bunch.

I’m a bit of a fan of DMT and I have / had the EEF. It is a beast for hogging off steel, like as fast as the fastest 120 grit stone, and edge quality about the same. It also loses its diamonds fast and becomes just a plain bare plate in relatively short order.

There are cheaper and better options for razors. If you are wanting a 4K, read this: Naniwa Gouken Hayabusa & Fuji Test | TomoNagura.Com - http://www.tomonagura.com/honing-straight-razors/naniwa-gouken-test.html

 

[captaincaed]

I also settled on this pair as a setup for final finishers and am quite happy after struggling with a few others.

In short, on the “pro” side I’ve found they polish and flatten the bevel much better than many other stones. This makes refining on the “finisher” that much easier. On the “con” side they can feel a bit plastic-y, a bit flat soda. They perk up with a quick refresh from a 600-1200 diamond plate and start cutting again. But they need a refresh every, say 5-10 min in my book. YMMV. But I’m sticking with them for now because they set up for finishers so well.

 

[Mr Kooby Shemayrew]

I also settled on this pair as a setup for final finishers and am quite happy after struggling with a few others.

In short, on the “pro” side I’ve found they polish and flatten the bevel much better than many other stones. This makes refining on the “finisher” that much easier. On the “con” side they can feel a bit plastic-y, a bit flat soda. They perk up with a quick refresh from a 600-1200 diamond plate and start cutting again. But they need a refresh every, say 5-10 min in my book. YMMV. But I’m sticking with them for now because they set up for finishers so well.

Same here. I could have saved some time and money had I known about them earlier. I had a couple disappointments searching for good mid-grit razor stones.

Also on the pro-side, Naniwa made them just the right hardness to make them easy to clean. My Spyderco UF and Suehiro 20K are PITA to clean. The Fuji 8K as a set up stone just does everything well. It is priced nicely too.

 

[captaincaed]

Yeah they’re not nearly as bad as I thought. The naniwa pro 5k helps bridge the gap. I know I know it’s not necessary but it speeds things up and plays the same polishing game. Quite some coin though. Got it from the local sharpening shop on their recommendation.

And yeah those spydercos are just hard

 

[buca3152]

I have the dmts up to 8k for knives.The most useful one for razors imo is the medium extra fine which is 6 micron or 4k equivalent. Works great for stupid hard steels. It cuts faster than a chosera 1k and doesn't leave deep scratches.

 

[H Brad Boonshaft]

I look at honing as a 2-step process, flattening the bevel in the proper bevel angle and creating the edge. With some stones you can do both at the same time but often, when doing edge repair, it is best to do each separately.

Diamonds are great for removing a lot of material quickly. But Diamonds cut deep and those deep cuts end in a rough uneven edge. If you use diamonds for flattening a bevel, you can fairly easily refine the bevel, (polish off the deep stria) and straighten the edge on aggressive synthetic stones and some low grit natural stones.

I have several brands of diamond plates from eBay Chinese no names to Atoma’s in all the grits. They all work for removing steel and lapping stones.

I also have the Naniwa 6 & 8k Resin Diamond stones, I don’t think the 8k is available any longer. Both will produce a mirror bevel finish, but with a harsh shaving edge. They are excellent pre finish stones for a natural finish jump.

The benefit of Diamonds is quick cutting for hard steels, not many razors are that hard and regular synthetic stones will easily cut razor steel at half the price. I use the Resin Diamonds for hard knife steel, some tools and razor edge repair, always finished with natural stones.

For me any time saving honing razors on Diamonds is way off set in removing the deep stria and making a new edge that will shave well.

An all diamond progression, not for razors.

I clean Spyderco UF and Suehiro with a Tsushima, or Kita tomo and scotch brite, cake!

 

[captaincaed]

For me any time saving honing razors on Diamonds is way off set in removing the deep stria and making a new edge that will shave well.

Having just restored 3 that needed to go down to 220 to geometry, this was true for me. The resinoid or vitrified diamond stones are much better about this. The diamonds are embedded in a matrix. Allowing the to wear through a couple knives seems to chill them out further. But I had to go backwards on one after getting up to 4k and realizing I still had 800 grit diamond grooves. More time on the synthetic 1k would have been a better use of time. I got away with it for a second razor.

 

[psfred]

There are two issues with diamond hones and razors. Diamonds are extremely hard, and while they do fracture under high pressure, they only fracture into more extremely hard and pointy shapes, not finer grit. They will "wear" on plated hones from fracturing, but they also get dislodged from the plating holding them down and float around (and get embedded in softer stones, etc).

Since the particles are very hard, quite "sharp" in shape, and rigidly plated down on plates (or firmly bound in vitrifed or resin "stones") they make deep scratches with a very acute "valley" and do not yeild at all to pressure short of breaking or rolling off the substrate. The acute angle at the bottom of the scratch is a stress concentration, and along with any significant pressure will result in crack formation, however small.

This means you not only have deep scratches to remove, but especially near the apex there are likely micro-cracks or over-stressed steel at the base of the scratch. Polishing will not remove the cracks or over-stressed steel, and pressure on finer stones or from shaving results in micro chips as the steel breaks. Forming an apex on coarse stone make of silica or aluminum oxide will do the same thing, but less reliably. I still don't recommend actually forming an apex on coarse stone, it will always be necessary to remove more steel with a finer stone in the normal honing progression to remove the microcracks.

Colicules also have very very hard abrasive material (garnet), but those are nearly spherical in shape and produce wide, shallow scratches rather than steep walled acute valley shaped scratches, so they don't stress the steel or produce micro-cracks nealry as much.

No reason not to used a diamond plate if you have to hog off a lot steel to fix a bad chip or correct geometry, but remember you will have to remove all those deep scratches AND more steel to get a stable apex.

 

[JPO]

In my opinion, unless you are doing major geometry corrections, or large chip repairs, you are not saving any time using diamond stones/plates.

It's not enough to just remove the visible scratches. The compromised steel (strain hardened and brittle) will extend deeper.
So, you need to remove more steel then you would if you used a traditional water stone. So, you are really not saving time if you use diamonds for regular honing and bevel setting.

 

[JPO]

Part of the problem with using diamond plates is that you are riding on the top of the abrasives. That means you are cutting deeper at the base of the bevel, and you might not have enough support behind the apex to actually remove any steel at the most flexible part of the bevel. Instead you are pushing the edge over. This causes a plastic deformation, and thus strain hardening and a convex apex.

In the first image you can see that the striations are not going all the way to the edge. This is not because it's not a flat bevel, because when i flipped the blade over the opposite side of the bevel had striations all the way to the edge. See sketch 2. This is because it got pushed over.
In Photo two included in sketch 1, you can see how this gets worse and worse as you hone.

After a while the steel behind the edge will get hard and brittle.
No matter how good the edge looks it will not refine as it should going forward if you continue using diamond plates.

If the deformation had been elastic it would be less of an issue, because it would spring back to a neutral position every time you flip the blade over.
Sketch 1
The dark shadow in photo no 2 shows how the edge is being folded over.

Sketch 2

Sketch 3
The apex gets convex and the material gets fatigue damage.

 

[SliceOfLife]

I do 1200 to 8000... 600 occasionally, but really not needed. 320 and below are for lapping stones.

Works fine. Most people struggle with the 8000, but 1200 used to be quite popular. Haven't checked lately.

8000 needs to be kept clean and you need to control pressure and respond to behavior of the edge.

Is it folding? stop torqueing the blade or reduce your pressure.

Is edge too fat? Not really a problem, a good finisher can fix it; but increase pressure/hold the razor more securely and make sure your plate is clean.

It typically needs cleaned between every 1-3 razors. Maybe the interrupted are a bit better about that (mine predates the EE being available in Interrupted plates); but the continuous will stop cutting efficiently quite quickly. The interface is fine enough the oils/reside from your hand is enough to mix with swarf and clog on water. Don't use oil. Suds make it easier to clean but I've never worried. It's easy enough to clean as is. Light rub of the surface under water gets you 80% clean... add a scrub of a bar of soap or drop of dishsoap to get it sparkling.


It's fine enough it can be hard on a properly prepped razor to determine the embedded side. Plenty of guys hone on the wrong side and don't realize it. Top of text is surface.

Dry it after use. Takes longer than a cheap plate; but the nickel plate isn't perfect on the sides and they will start to degrade eventually.


If the 4k existed when I bought my setup, I'd have bought one. Having used this setup for over a decade... it's 100% unnecessary for razors. 8k is plenty fast. I'd say it's primarily good if you dont WANT an 8k edge... IE some knives the 8k actually reduces cutting ability after the 1.2k... 4k may hit their sweet spot. No reason to buy it for razors. I think DMT actually initially said when asked for a 4k that its dumb... the 8k is so fast you don't need it... before changing their minds.

 

[JPO]

Is it folding? stop torqueing the blade or reduce your pressure.

This is a 1200 edge. The reason it is folding isn't because of torque . It is because you are not able to reach the required local pressure over the diamonds to cut the steel before the thin edge just behind the apex starts to give/deform.
You will end up with striations that starts off deep, and then tapers out.
This is also a stiff grind, and not allot of pressure is used.

 

[SliceOfLife]

Here's an example of DMT's in use.

eBay special "wedge" (actually a near wedge, but one of those early 20th century american razors they called "wedge" to mean not full hollow).

400x Optical, cheap scope... 400micron FOV if memory serves?

Previous owner used tape, natch. But Not terrible. On arrival.


<2min on DMT 1200 to cut a clean bevel


<1min on DMT 8000 and it's ready to finish

 

[JPO]

Is edge too fat? Not really a problem, a good finisher can fix it; but increase pressure/hold the razor more securely and make sure your plate is clean.

The problem is that this fat apex has damaged and strain hardened steel. You will then end up with an edge with poor steel quality.

 

[JPO]

Here's an example of DMT's in use.

eBay special "wedge" (actually a near wedge, but one of those early 20th century american razors they called "wedge" to mean not full hollow).

400x Optical, cheap scope... 400micron FOV if memory serves?

Previous owner used tape, natch. But Not terrible. On arrival.
View attachment 1834605

<2min on DMT 1200 to cut a clean bevel

View attachment 1834608
<1min on DMT 8000 and it's ready to finish
View attachment 1834609

How did it look like when it was finished?

 

[SliceOfLife]

About 2 minutes honing on a 13k:

Total time from eBay special (in good shape, but taped edge so needing rebevel) to finished... <10min.


400x optical, 1600x on my 27" monitor.

 

[JPO]

About 2 minutes honing on a 13k:

Total time from eBay special (in good shape, but taped edge so needing rebevel) to finished... <10min.

View attachment 1834627

In my eyes I am looking at a burr.