Thread: How long will a DMT duostone last?

Indeed, HSS is some pretty amazing stuff. In an unfortunate turn of events while drilling some stainless I unintentionally melted/abraded/deformed the cutting tips off the HSS drill I was using (it was a cheap drill so OK). Resharpened the drill on the grinder back to fresh drill area (maybe 5/64 of metal removed) and had at it again to finish the hole without trouble.

Although punishing any blades like that would be blasphemy, it goes to show how much of a flogging even cheap HSS will take before being ruined. If you ever have to push a woodworking tool within a mile of that point, I would be highly surprised.

While more suitable for the carbon steels in older tools, a trick I use is to keep the steel cool by using a dish of water next to me, but I know that it is time to cool down again when the water on the back of the blade evaporates back around 1/4". This is a fair indication that the steel in getting up around that 120 degree mark which is what I find to be a safe, and reasonable temp to cool at. It is not so high as to alter the steels temper but still gives you a fair go at removing some metal before cooling again.

Acc to the eggsperts Durdge39, water cooling leads to microfractures in the tool tip. I've assumed that this applied to HSS as well as HC steel so correct me if I'm wrong.

I use a heat sink which is just a thick HSS scraper, and lay the tool on it to draw some of the heat away. Prob a lump of alum. alloy would work better.

Cheers for the tip Ern (pun only slightly intended). I can't say I've looked at it under the microscope but the chisels I have used after grinding this way haven't shown any noticeable lack of performance. Perhaps the material removed in forming and honing the micro bevel is the cracked steel of interest and I have been lucky thus far.

Knowing what critical temperature the steel has to be when dipped into room temperature water to start the formation of these micro-fractures would be something very handy to know.

I'm starting to think for my projected usage pattern, I might not really want M2 blades. I wonder what the resale market on TS's blades are?

However I still have the A2 blade to contend with, so I'll have to price out a suitable set of stones for that at least.

I think Stu should maybe work out a package deal on a set of stones suitable for M2 blades, bulk volume, ready to distribute after Feb.

Did I hear somebody mention an M2 sharpening set bulk buy thread? (Not to mention GST )

Fuzzie, if you feel up to it, drop around to my workshop next week and you can have a play on the Shaptons. I have a range of the Kuromaku (Pro) series from 220 through to 12000. It will give you an idea of how the ceramic stones cut - the feel is different from the normal waterstones; e.g. King.

Des

Stu, I would like to use one waterstone to
flatten my other waterstones.

A stone that would only need flattening once in a while, but
that can be used to flatten other stones would be something
nice.

Do you have any ideas for this?

Sazman

uh oh - sounds like another Sigma #120, eh Stu??.........

Trouble with a #120 is that it will hack away too much of your fine stones. And perish the thought leave a few rogue grains behind.

Norton make a flattening stone which is said to be no more than a coarse Norton waterstone with some channels in it, and not flat, and prone to other failures (do a search).

So I'll leave Stu to answer from his knowledge base which is far greater than mine, but just add that I use a coarse diamond stone for everything other than my Shapton #120 and for that I've adopted Stu's advice for the #120 Sigma and use very coarse SiC grains on plate glass.

Elsewhere Stu's posted about using sandblasting grit on plate glass.

Stu sells a variety of coarse diamond plates for stone flattening - I'm sure one of them will do the job.

Forget the Norton flattening stone - I bought one years ago, and its a waste of time. Suffers from exactly the same problem as the coarse Norton waterstones, i.e. it is REALLY soft. You end up having to flatten the flattening stone (!) after every use.

The Sigma #120 is about the only stone I'd trust, and even then I won't condone it. There's a better, cheaper and more reliable way.

Loose grit on something hard and flat.

Really, it's a PITA compared to a diamond plate, but it's the only 'other' proper way to get it done.

The problem with using a coarse stone is that again you risk contamination which is not so serious with a very coarse stone, but if something like a #5K has a nice chunk of #120 SiC in it's surface, it's going to make a mess of things. Just like Ern said there, it's a risk, and mainly because chunks are likely to embed from a stone more than loose grit does. I've not yet had a piece of loose grit embed itself, and I've flattened everything with the stuff.

If you did use a very coarse stone, when it eventually goes out of flat, what do you use to flatten it?

I've been toying with the idea of some kind of kit where it'll be not very expensive, and be good enough to flatten any stone successfully. Not as good as a Shapton compact lapping plate (3kg of cast iron and loose grit) nor an Atoma diamond plate, but usable and reliable.

I'll need one of the abrasive/file makers to do it though. Not something I can get done myself.

Until then, loose grit is cheap enough and a little goes a long way. It's also not going to make any stone manufacturer's representative become visibly ill if they witness it.

(Hmm, the surform type tools they sell here might be worth a look, with a replaceable plain steel sheet... )

Schtoo, have you looked at the Veritas lapping plate?

Groggy, I'm well aware of it and there's a few issues with it for waterstones.

#1, massive overkill.

#2, it's too accurate and too nice to actually use for the rough, wet and nasty job of flattening out waterstones.

#3, it's too heavy.

#4, it's too expensive, based on the idea of doing this 'inexpensively'.

Besides, a decent diamond plate goes for about the same, and is better suited to flattening waterstones since the flat bit is not touched, only the diamonds embedded in it.

I like the Vertias plate, but it's not for waterstones.

However, something about 1/100th the weight, 1/100th the price and 1/100th as flat, heck yes!

FWIW, the Shapton plate looks similar, and is about the same price. The difference is that if the Shapton gets out of flat, send it back and they'll get it flat again. You'll have to pay for that though...


Until then, a chunk of glass and some cheapo grit is the best way to get it done when required.

I have been using the three stone technique for
a few days and it works quite well.

I use a 800(1), 3000(2) and 8000(3) naniwa SS. With three
stones one can flatten them all perfectly flat. No
need for sanding paper or diamond flattening plates.

Rub 1 with 2, 1 with 3 and 2 with 3. Usually enough
to get them flat within 30 seconds.

I am going to replace the 800 naniwa SS. It really is a
poor stone IMO. So muddy. The 3000 is nice, but not
needed IMHO. One can skip it and go directly to the
8000.

The 8000 is a nice stone, but a bit soft, my A2 and HSS
steel can dig in the stone.

Stu or anybody else. I want a hard 1000 grit stone that
stays flat for a long time and needs no soaking, with a good
feeling while sharpening.

-Chosera 1000 grit seems great, but needs soaking. Anybody
try without soaking, only a splash of water?

-Shapton GS looks ok, but is thin and no real good feeling
while sharpening I have been told

-Naniwa SS, too soft

-King(the ones I know), too soft, too muddy, needs soaking

-Sigma power, needs soaking. Is it ok to use without soaking;
just holding it under running water for 10 seconds or so and
keeping it wet all the time?

-Bester needs soaking

-Shapton pro, not sure about this one. Thinner than other stones,but
a hard no soaking needing stone.

What do you think Stu?

Sazman - I can't answer for the rest of the stones you mention, but I bought the Sigma 1000 from Stu for sharpening A2 etc.

A really aggressive, hard wearing stone, but as you say it does need some soaking prior to use. It needs more than a splash under the tap, but in terms of soaking it just needs a couple of minutes totally immersed (should NOT be stored in water).

I haven't found this a hassle - just have to remember to plop the Sigma 1000 into a container of water while I get the rest of my sharpening gear set up for use - by then its ready to go. After this brief soak it only needs a small amount of water to keep it going as you use it.

As you say, 3000 isn't really needed in a progression from coarse to fine. I used to go from 1000 straight to 8000 (Norton), but after talking to Stu I now go 1000 Sigma, 5000 Shapton M5, 12000 Shapton M5. Only three steps, but gives one hell of an edge !