Sigma Power Ceramic 400 Advice

[Steve Friedman]

Just received this stone (along with the 1200 - 6000 - 13000 - Atoma 400 set) from Stu at Tools From Japan the other day. This is my first water stone venture, and so far I am thrilled with the results. Gives sharp a new definition. I do have two questions about the 400 stone.

1. Is there a consensus as to the best way to flatten it? I have been using the Atoma 400, but wonder if I should consider something else instead.

2. Has anyone been successful (and happy) using loose grit to make the stone cut more aggressively?

3. I know it's only been a few days, but I am already thinking about adding the 120. Is there any other stone you might suggest instead for something more aggressive than the 400?

By the way, all the reports of how amazing Stu is to deal with were spot on. He is knowledgeable, patient, and honest. These stones are everything he said they would be, and more. I procrastinated on this purchase for a long time (paralysis of analysis) and should have taken the plunge long ago. If I had, my chisels and plane blades would already be sharp by now. Better late than never.

Thanks in advance.

Steve

[David Weaver]

How is the 400 still doing? (the atoma).

Stu has told me a couple of his stones are diamond plate killers. Of the things out there that aren't sintered diamond (which itself is an expensive proposition), we know that everything to and including the shapton DLRP or whatever shapton calls it can be worn out over time. I have been using one atoma for several years, though, and haven't had any issues with it. i don't use it much on my 400 stone ( a chosera) just because I don't think it leaves the surface aggressive enough.

DMT claims to have the hardest coating on the dia flat (but it is expensive, the cheapest I could find it was $170). I have to mail one off to stu tomorrow to see if it is the answer to the wear problems that some stones cause with diamond hones in general (presumably he'll find out pretty quickly if any of his stones eat it).

I would use loose grit, though, if that's stu's recommendation. the nice thing about loose grit is that you generally won't get much to embed in a coarse hard stone, and you can rinse it right off. The not so nice thing about it is it's not as convenient as a diamond hone.

(if I were in your shoes, I might be more inclined to buy another stone to rub against the 400. A two stone setup in skilled hands usually keeps stones flat, and even in unskilled hands, it will keep stones flat longer than doing nothing. If rubbing two stones together keeps them from being as aggressive as you want, there are many ways to solve that, some very cheap (like 2 pounds of silicon carbide grit for $10)

[David Wong]

​I do not have the Sigma 400, but have a Beston 500 and an Arato-kun "pink" 220, for coarse stones. I generally flatten both with loose grit on a compact Shapton lapping plate. In a pinch, I may use my Atoma 140 plate to flatten the stones, but they seem to perform better with loose grit.

I have used loose grit on the 220 stone attempting to make it more aggressive. This works, but results in rapid uneven wear on the stone. Plus I find loose grit destroys the blade edge and makes for more work to clean it up later. The loose silicon carbide grit does not last for long, and needs frequent refreshing.

The Beston 500 is a very nice stone, but I would not recommend the Arato-kun 220. It is a fair performer, but my sample of the stone does not cut evenly across entire surface, and is fairly soft so it dishes easily. Both are thirsty stones and require soaking.

[Steve Friedman]

Thanks David.

The Atoma is still fine, but I have only had it since Monday. I would love to avoid using loose grit, but what do you mean by another stone? Wouldn't it need to be more abrasive than the 400? Not many of those out there.

I thought about getting the Sigma 120, but I would still need to use SiC to flatten the 120.

I tried to use 320 SiC wet/dry sandpaper on granite to flatten the 400 stone, but it didn't want to cut metal after that. A few swipes with the Atoma and it was happy again. Not sure if this would help, but what about using sandpaper to flatten the 400 stone and then using the Atoma to "dress" the surface. That way, the hard work will be done by the sandpaper, hopefully saving the Atoma.

When you add SiC to a stone, what grit do you use? The same grit as the stone?

Thanks,

Steve

[Steve Friedman]

​In a pinch, I may use my Atoma 140 plate to flatten the stones, but they seem to perform better with loose grit.

Any idea why that is? I thought about adding the Atoma 140 for flattening the 400, but imagine the 400 would be even rougher on the Atoma 140 than it is on the 400.

Steve

[Christian Castillo]

Use some 90-120 grit SiC, don't use sandpaper or your atoma, I used to own a sigma power 400, after using an Atoma 400 on it, the sigma power 400 cut like my sigma power 1200, it felt really really slow for a 400 grit stone. The SiC abrasive really opens the stone up and makes it cut like it should.

[Sam Takeuchi]

Do you use #400 enough to dish it out? I don't recommend getting a #120. It's one of those things you'd rarely use and for that, it's probably more economical and practical to buy a SiC paper. Stick it on the back of Atoma plate, use it and take it off. Unless you chip the blade or constantly changing bevel angle, it'll be a long time before you need something like that. Do you have any particular use you have in mind that's making you want one? I haven't touched a stone rougher than #1000 in....several years now.

For flattening #400 stone, go with SiC paper too. But something like #400 doesn't have to be that precisely flat though. You can use bare bench top as flat surface and it'll still be okay. Worry about flat and all that when you get to #1000 range and above.

If your #1200 isn't cutting fast, there is something amiss. That should cut plenty aggressive for routine sharpening. If blade seems like skating on top of the stone, give it a quick rub with a diamond plate, get the surface gritty.

[Steve Friedman]

Use some 90-120 grit SiC, don't use sandpaper or your atoma, I used to own a sigma power 400, after using an Atoma 400 on it, the sigma power 400 cut like my sigma power 1200, it felt really really slow for a 400 grit stone. The SiC abrasive really opens the stone up and makes it cut like it should.
Thanks, I wasn't sure how gritty to go. Why is loose grit any different that using SiC sandpaper? I do have tons of SiC in a variety of grits that I got with my LV lapping plate (which I never use anymore). I wasn't unhappy with the speed of the 400, but have no frame of reference for it. Seems to be significantly faster than the 1200.

Guess I have my project set for tonight.

Steve

[David Weaver]

With SIC, something at or more coarse than the stone. i don't generally do that, but for 1000 stones, from time to time I will use the thing that chosera sends as a nagura, which is effectively dumping loose grit that I believe is about 600 grit on the surface (bizarre that they seem to send the same one with all stones). it does help cutting action a lot.

The trouble you may have had with SiC paper and the stone is that the abrasives were fighting each other (dulling each other) and you weren't likely cleaning cutting the abrasive and binder in the 400 SP with the sandpaper.

In a fight of anything else vs. diamonds, diamond will win, thus you have a refreshed feeling stone. I guess where things don't go so well is when the stone manages to reach back and abrade the binder holding the diamonds in place.

If I were going to rub two stones together, I would have them similar to each other. But abrading with something separate is probably still a nicer answer.

[Steve Friedman]

Do you use #400 enough to dish it out? If your #1200 isn't cutting fast, there is something amiss. That should cut plenty aggressive for routine sharpening. If blade seems like skating on top of the stone, give it a quick rub with a diamond plate, get the surface gritty.

Thanks Sam,

Maybe some explanation is in order. I have been struggling with back flattening for months. I have tried SiC grit on a lapping plate, PSA abrasive on granite, DMT diamond stones, diamond paste on Kanaban, and a 1" x 42" grinder. The problem is that the various sharpening tools never seemed to agree on what was flat. I would get the back of a chisel to the point where my DMT stone said it was flat, but then take it to 15 micron paper on granite and discover that it wasn't even close. I finally decided to go to water stones in an attempt to eliminate as many variables as possible and standardize the definition of flat by using the same tool to flatten all the stones.

So, I am now starting to flatten the backs of chisels and planes that are the victims of my failed attempts with all of those other abrasive methods. I have no water stone experience, but doubt that I could have dished the 400 in about 3 hours of total use to date. But, I have flattened it a number of times just be sure that I really am flat. Although I have nothing to compare it to, the 1200 is definitely gritty and might have been enough to flatten all of these backs, but not without a ton of patience. Again, I have nothing to compare it to.

Thanks again,

Steve

[David Weaver]

You can get it out of flat in 10 minutes if you use it really hard. Not really really out of flat, but out of flat enough that if you move to a 1000 stone that's freshly flattened, you'll notice that the edges have been relieved a little bit.

I am a big proponent of 80-120 grit diamond on a mild steel kanaban, but even at that there is some skill involved because anything that is flat at some point will always be working away from it, be it stones or metal plates, etc, as long as abrasives are involved.

I've seen other people mention how hard the 400 is, and it probably dishes slower than a lot of other 400 stone, but any stone that doesn't dish at all in 3 hours is likely to be one that will cut slowly if you don't refresh it constantly - unless it's a hard surface with diamonds attached (and those hard surfaces are often not flat).

[Sam Takeuchi]

Diamond paste on kanaban would be my first choice out of all options. That will not dish and with the right grit, it can be fast.

If you could post pictures if your problematic chisels and plane blades, people might be able to point you to the right direction (or tool) for the task in question.

Don't get too obsessed about flatness. And what matters is basically blade is flat along the edge. So if you manage to flatten first 1/2" from the edge, you are set for quite a long time. As you sharpen blades, you'll be rubbing the flat side onto the stone in the course of normal sharpening, this flat area moves back somewhat, if you reach a point where bump or hollow still persists, you worry about that when it becomes a problem. I know people insist on flattening the entire back of chisel saying it helps to register better and so on, but in practical use, it doesn't matter.

[Tony Shea]

I have been using the Chosera 400 stone a bit lately and have had to flatten it with my DuoSharp xtra coarse stone. It does flatten it nicely and still gives a decent surface. But Im also afraid that I'll wear this Duo sharp out prematurely. The Duo has been going fairly strong for all my stone flattening needs Shapton 1000, 5000, and Sigma 10000 for over 2 years now and still has some decent life to it. But if I keep up flattening the very hard Chosera 400 I'm afraid it wont.

So if I was to get the loose grit setup, what should I get? Keep in mind this is only for my Chosera as I'm plenty happy with the Duo for anything else. Should I just do loose grit on plate glass like LV shows?

The only loose grit I have experience with is 120 diamonds on a kanaban, and damn that works good.

[Jack Curtis]

Very interesting. I've thought of getting a SP400, too; but not for regular sharpening work. Instead I plan on making some CPM 3V chisels in the near future and need something for basic shaping. The SP line claims to handle the PM's with no problem; and shaping can be done fine on non-flat stones.

For regular sharpening I agree with Sam, and start at about 1000 if I have to do more than touch up.

[David Weaver]

Tony- loose dry silicon carbide grit on a piece of glass would be fine. 60 or 80 grit should flatten it out and wake it up.

[Christian Castillo]

I agree with David, use 60-80, I used 220 grit SiC with a sheet of mylar on top of a granite plate, 220 is way too slow. The sigma power 1200 is indeed a very fast cutting stone for its grit, but the 400 should be in another level of metal removal.

[Steve Friedman]

I agree with David, use 60-80, I used 220 grit SiC with a sheet of mylar on top of a granite plate, 220 is way too slow. The sigma power 1200 is indeed a very fast cutting stone for its grit, but the 400 should be in another level of metal removal.
WOW. What a difference. I just flattened the SP #400 with 90 grit SiC (the most abrasive I had) and the stone went to a completely different level. I used some spray glue to stick a piece of Lexan to a granite slab and had both sides of the stone ready to go within around 60 seconds. I was tempted to add a bit of grit to the stone, but there was already enough wet SiC all over the place. Mess notwithstanding, it was extremely effective. Makes me wonder what the Atoma 140 would do to it.

Many thanks!

Steve

[Stuart Tierney]

Hi Steve,

Not sure if I addressed this elsewhere or not.

To take any serious dishing out of the Sigma #400 (you need to be a masochist to do that), I use an iWood #150, because it was cheap. I've used loose grit in the past, and it does leave a coarser, more pitted surface on the stone which translates to it working faster initially and greater speed later on as well. I've used the Atoma #400 with it, and while I can't prove it, my old Atoma (newly refurbished) started to lose it's bite rather rapidly. It still works well enough on most stones, and it still flattens the Sigma #400 well enough, but it sure isn't anywhere near the plate it used to be.

Regardless of anything else, loose grit ALWAYS works. Sandpaper is a fools errand with the Sig #400 so please avoid doing it. It's frustrating.

That's all I've got. I'd like to mention other things, specifically regarding the Chosera, Beston, anything else in the grit range, but I'll refrain for the most part.

Perhaps I should say that the Sigma #400 is a completely different animal, and it's the only stone I know of that can be used for flattening blade backs and used with confidence in that capacity. Everything else, either slower, suffers from more dishing or costs an arm and most of a leg. To throw out experience with 'other stones' in the belief that they're somewhat similar to the Sigma #400 isn't doing anyone any favours at all. I don't want to cast a cloud over folks here with that kind of comment, but in all honesty, the Sig #400 was specifically designed to NOT be like anything else. The 'other candidate' to become the Sigma #400 was too much like everything else, which is why the one you can buy now is brownish pink and not dark green.

It was made for a purpose and it was designed with tool sharpeners in mind. Yes, it makes a big, big difference.

(It's also why the #1200 is what it is. Designed for toll sharpeners, and it shows. ;) )

Stu.

[David Weaver]

You'll be able to make some first hand comments on the beston soon enough!

Just like somehow, I have sudden unexpected familiarity with the 1200 as of yesterday :eek:

The cho is a nice carbon steel stone. If it turned it that it didn't handle HSS and other such things that well, I'd certainly not be surprised.

[Terry Beadle]

I bought a Sigma #400 from Stu and spent a good hour getting both sides fairly flat. I was not able to get dead flat and the areas that weren't dead flat were near the ends.
So I wimped out and started using it. Great results. I've kept at the flattening using my extra coarse DMT and occasionally using a King 800 and even once a 220 to see what it would do.

I must say the Sigma #400 is a tough customer. I figure in about 2 years both sides will be dead flat.

As long as I'm getting good results on my blades and chisels, I'm going to take the slow road to Kansas ( also known as dead flat USA ...hoot! ).

Be patient and just check the results, 2 cents and worth it !

[Stuart Tierney]

I bought a Sigma #400 from Stu and spent a good hour getting both sides fairly flat. I was not able to get dead flat and the areas that weren't dead flat were near the ends.


I bought this up with Mr. Saito of Sigma Power.

He gave me 'that' look.

Or in other words "we have trouble getting them flat, so you're on your own bucko".


Just used mine with my jointer's blade. Max hardness O1, 2.5" wide.

I wish, wish, WISH I'd had that stone when I first made the blade. Would have prevented me needing to run a back bevel on it just to get an edge on the dang thing.

(FYI, Starrett O1 warps a little too much when you heat treat it. Avoid it if possible. Apparently Timken (I think) is more stable...)

Stu.

P.S. I'd tell you how I heat treated that blade, but apparently it's dangerous and the extra steps I went with it don't do anything for O1.

[Steve Friedman]

I bought a Sigma #400 from Stu and spent a good hour getting both sides fairly flat. I was not able to get dead flat and the areas that weren't dead flat were near the ends.
So I wimped out and started using it. Great results. I've kept at the flattening using my extra coarse DMT and occasionally using a King 800 and even once a 220 to see what it would do.
I didn't find it hard to flatten, but that was with a brand new Atoma. In an effort to save the Atoma, I did once try it with an XC Duo-Sharp and then followed up with the Atoma because I don't trust the flatness of the DMT because I have used it in the past as a sharpening stone.

The loose 90 grit SiC worked as well, but was a mess. Need to solve that.