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sigma 3k / 10k apexing difficulties of wear resistant steels

Posted by JSCT 
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sigma 3k / 10k apexing difficulties of wear resistant steels
June 23, 2020 10:57AM
Intro:

Bought a sigma 3k and 10k from here
Both stones indeed cut fast relative to their stated grit.. Perhaps they work excellent
for AEB-L and RWL-34 and hardness makes no noticable difference..
I am noticing a behaviour similar to usual AlO waterstones..
I used both sigmas to sharpen 2 knives from K110(D2), 2knives from elmax
and 2knives from V4E one at 61HRC one at 65.5HRC..
Compared to the RWL-34 I noticed a drop in a cutting speed at low pressure
and so It causes me difficulties to achieve a clean thin "sticky" apex on high wear steels)

That was unexpected as its claimed to be designed to sharpen HSS..

How to actually know if stone that I bought is vitrified or resin bonded ?

How to be able to identify type of abrasive stone contains ?


I could start by detecting Si by spectrography to have an idea about SiC presence..
And Al to detect AlO presence..

But I have no experience with resins for such.. I am not able to say if stones
release more abrasive when soaked.. f.e.

Any ideas ?

www.instagram.com/jscuttingtools
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 01:35AM
I have the SPS-II, the only issue I have with it, is that it free releases grit under very low pressure, now here is where this starts to get vague as measuring contact pressure isn't trivial, it isn't the load (force) that you apply that matters, but the pressure (force/area) and when you sharpen a knife the pressure varies significantly. I sharpened CPM-M4 with it and it worked very well, as it freely released grit, in comparison to a Heckels 3K stone which didn't and in a short period of time, well the stone is just burnishing. Now you can just increase the load, increase the pressure and fracture any stone (within reason, you can't on solid sintered stones like the Spyderco ceramics).

[multimedia.3m.com]

As to tell what type of bond? The type of bond normally is chosen for the durability requirements, heat, shocks, acid exposure, etc. . Vitrified bond are very much immune to solvents etc. but don't handle shocks, resin bonds handle shocks well. For your stone, you are more interested in things like :

-percentage of bond/abrasive
-porosity

Now what I will say though, is that often stones can behave a bit odd initially, maybe they are not homogenous. A quick test is to just flip it over and use the other side and see if that makes a difference. In general you only want to use one side, as otherwise you have two sides going out of flat and that gets annoying fast. The other thing I would say is just do a fair amount of grinding with it for awhile, try varying the amount of water you use on it, try a light soaking (light as in you don't leave it, just until it stops bubbling), then try a little more. Try increasing the pressure, and you can do this by just using knives with smaller bevels (more narrow) or shorter blades.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 09:59AM
Cliff, thanks for the answer,

Stone feels it contains more abrasive than anything I came across so far from waterstones..

I tried soaking them twice for over 24h in water with detergent and havent noticed
much change in water color nor softening the stone, maybe but I am not sure..

I tried actually all 4 sides of the stone - havent notice any difference and also flat lapped and conditioned
all of them too.. I use flat lapping machine also for stone lapping so works fast for me
- flattening stones to any finish isnt a problem.. Initially both stones were more porous than after lapping.

It could be that lapping method I did was not good for this type of stones..

I have an impression that the small abrasive particles which are result of fracturing SiC grains
in the process kinda seal the pores in the stone somewhat and stone then release abrasive
slower.. (I dunno what type of abrasive stone contains but I was flatenning on SiC lapping discs)
Yes AlO or diamonds may be better for this, but I used what I had..

I had V4E at 65.5hrc that was not apexed at all had thick reflection from all over the apex.
I guess 20+um thick apex.. and 3k apexed it and cut bevels at decent speed
- faster than any other stone would perhaps edge length is like a scalpel
so its difficult to sharpen.. I would assume thats issue with my technique..

Perhaps I sharpened 260mm long RWL-34 and 230mm long V4E and I tilt blades
typically way more than 45deg so I really use the biggest contact area I can on the stone..
V4E blade is about 0.12mm bte and RWL-34 is 0.18mm both at similar angle (freehand)

On both 3k and 10k I am able to apex rwl34 one signifiantly better to sharper edge
on any media I tried - cigarette paper, soft tissue paper etc..
I can approach HHT2/3 off the sigma 10k with RWL-34
where HHT1 was my best result on same hair for V4E..
I tried many times at many spots to be sure..

I can get a knife sharp just not as much I am used to with rwl or aebl etc..

www.instagram.com/jscuttingtools



Edited 1 time(s). Last edit at 06/24/2020 10:00AM by JSCT.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 10:09AM
I also tried various soak times generally long soaks had no benefit over 5-20minutes ones..
even 2minute soak works ok.. stone loads very little.. cutting action is there just with V4E
it feels it doesnt cut once pressure is very low - low enough to actually form HHT apex
I guess thats what you call ultra light passes when edge barely touches the stone
with just fraction of the weight of the blade..

For apexing I went with stone almost dry so it would release less abrasive if possible
or even worked on sligtly loaded surface to get effect as on a finer stone..

It worked great for RWL knife same didnt work so well with V4E blade..

www.instagram.com/jscuttingtools



Edited 2 time(s). Last edit at 06/24/2020 10:11AM by JSCT.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 01:57PM
JSCT,
Have you tried the stones with a slurry?

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 04:23PM
How are you apexing on the stone?
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 05:30PM
Quote
jasonstone20
JSCT,
Have you tried the stones with a slurry?

Never managed to make slurry on them, they are pretty hard..
But I didnt want to / tried neither..

www.instagram.com/jscuttingtools
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 05:42PM
Quote
CliffStamp
How are you apexing on the stone?

I start with 3 to 6 passes per side before alternating side..
back and forth movement with medium to light pressure about 45deg tilt..

Once I notice bevels met I drop to 2pps with light pressure
and only edge leading and test edge for feeling little sticky on 3 finger test..

If I am not going to sharpen on finer stone / respectively i finish like:

Alternate side each pass. ultralight pressure and increase tilt to about 75deg
maybe increase angle by 1 or 2deg per side..

never must do more than 10pps at this stage for edge to reach max initial sharpness
I am able to get from the stone..

Did the same for both blades..

EDIT:

between the steps I may cut into the stone if I manage to create burr bigger than I like
or I am not sure enough steel was removed from the apex... never happened at later stages..

www.instagram.com/jscuttingtools



Edited 3 time(s). Last edit at 06/24/2020 05:46PM by JSCT.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 06:22PM
With more wear resistant steels, it takes more work to remove metal - that part isn't surprising, but it means you have to be more careful in the work. If I am sharpening a basic steel (low carbide), something like this works :

-set edge on coarse stone
-1K clean up, don't even check the knife for sharpness
-apex on a mxf-DMT

But if I try that on a high carbide steel, I have to :

-set edge on a coarse stone, take care not to over grind
-1K clean up, make sure the knife can slice newsprint cleanly
-apex on a mxf-DMT

If I over grind on the first, it takes much more work to remove the damage on the second step.

If I leave the apex not well finished on the second step, well it takes much more work on the mxf-dmt. That stone cuts so slow that the knife has to be pretty much sharp before I apex it.

Of course if I want a more coarse apex, even on higher carbide steels it doesn't matter because a 600 DMT will apex even something like 10V almost immediately, diamonds doesn't afraid of carbides at all.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 07:46PM
Quote
CliffStamp
Of course if I want a more coarse apex, even on higher carbide steels it doesn't matter because a 600 DMT will apex even something like 10V almost immediately, diamonds doesn't afraid of carbides at all.

That’s why I’ve really come to prefer the DMT plates for an apex finish.

I have about a 50/50 mixture of low-carbide simple steels like 420 stainless or Svord carbon, and more complex high-carbide ones like VG-10 or XHP, and I get virtually identical results across all my knives with the DMT 600. I like the way that apex finish cuts when freshly sharpened, I like that it will continue to draw cut effectively for a very long time, and it works very well on all my knives.

One plate for all knives, only the Spyderco Fine for my kitchen knife and the Naniwa SuperStones in 400 or 1,000 for choppers.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 08:06PM
JSCT,
You are not the only person to have difficulties with the Sigma II Select stones. I am borrowing a set cut for an Edge Pro Apex, as soon as they get here I will be able to play around with them and give some input.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 08:48PM
Cliff,

Yes I expected it will take longer for V4E to sharpen, I could see how much longer it takes
to grind on belts compared to something like AEB-L.. everything higher than P120 cuts it
real slow relative to the belt speeds..

Perhaps I hoped with some extra time I can free hand it to same sharpness as my other knives..

I still think I may have little ruined the stones surface by lapping..
They were much more porous out of the box and I think thats why
their cutting action may not be as before..

I will condition them all and try again..

Jason,

Thanks, feedback would be great.
Yes I remember Ben dislike them a lot..

EDIT:

1st two times I apexed V4E blade before I did that on P1200 SiC lapping disc
on machine and got better apex than on the stones..

www.instagram.com/jscuttingtools



Edited 1 time(s). Last edit at 06/24/2020 08:53PM by JSCT.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 08:52PM
JSCT,
Yes, waterstone are a weird thing. Some people hate some stones, while others love those same stones. Not sure why. I haven't had a sharpening stone I didn't like.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 06/25/2020 12:03AM by jasonstone20.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 08:53PM
Just to be clear, even the SPS-II's will not cut 10V as fast as AEB-L, 10V has a lower grindability. In fact even diamond/cbn will not cut at the same speed simply because at a given load they will leave a more shallow scratch pattern.

Consider for example your knife is harder than wood, that doesn't mean you can just press the knife into wood like it wasn't there. The knife being harder just means it doesn't deform when you press it into the wood, it doesn't require less force if the knife was 70 HRC vs 50 HRC.

Same thing with cutting abrasives, the big advantage I saw with the SPS-II stones is that they cut freely at low applied loads on high carbide steels, whereas something like an India stone would start off cutting well, but as the alumina wore it stopped and I had to condition them.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 09:01PM
Quote
CliffStamp
Just to be clear, even the SPS-II's will not cut 10V as fast as AEB-L, 10V has a lower grindability. In fact even diamond/cbn will not cut at the same speed simply because at a given load they will leave a more shallow scratch pattern.

Consider for example your knife is harder than wood, that doesn't mean you can just press the knife into wood like it wasn't there. The knife being harder just means it doesn't deform when you press it into the wood, it doesn't require less force if the knife was 70 HRC vs 50 HRC.

Same thing with cutting abrasives, the big advantage I saw with the SPS-II stones is that they cut freely at low applied loads on high carbide steels, whereas something like an India stone would start off cutting well, but as the alumina wore it stopped and I had to condition them.

Yes thats a nice example, this behaviour is what I expect..

Briefly I have spent at least 4x times the time with V4E (even narrower bevels)
than with RWL-34.. So it must be either something with my technique
or stones.. I can see stones remove metal as I notice the residue
to appear quickly so they cut ok I guess.. Its just apexing to very high sharpness issue..

Will play more and will see.. Thank You.

www.instagram.com/jscuttingtools
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 09:05PM
Quote
CliffStamp
Consider for example your knife is harder than wood,

I really hope it is grinning smiley

www.instagram.com/jscuttingtools
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 24, 2020 10:35PM
My dumb ass bought 3 of the Sigma Power II stones. I don't remember the grits but I think they were all 1000 grit and less. I didn't have much luck with them so I put them away and haven't used them lately. I'm sure my failure has to do with my sharpening skills or the lack thereof. I will not dis the stones because of that. From what I remember (it has been several years) the stones release grit very easily and therefore dish quickly. Before I retired, I went on a stone buying spree and bought probably 25 or more water stones.
Now, I use diamond stones (DMT and EzeLap) almost exclusively. I am able to sharpen my knives as well as I need with them. I learned here how to minimize burr formation and that was a great help. Thanks.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 26, 2020 08:08AM
As for the Sigma Power II stones only the 1k is SIC the rest are Aliminium Oxide as far as I can gather so that may be part of the problem here.

[mtckitchen.com]

Quote
The 1000 grit Power Select II is a vitrified stone with silicon carbide as the main abrasive. This stone stands out among others in this line as one of the fastest-cutting stones among comparable stones in its grit range. The structure is quite open and porous and benefits from a short soak, although we've found that simply running water over it for 30 seconds or so is generally sufficient. It cuts very effectively with minimal pressure and its bind is on the weaker end of the spectrum so it's recommended to use just enough pressure in order for it to cut the steel effectively to avoid excessive dishing. This stone was very effective on all steels we tested including Sukenari's HAP40 at 68HRc as well as Honyaki single-bevel knives in the 65-66 range.

[mtckitchen.com]

Quote
The 3000 grit Power Select II is a resin-bound alumina stone. The stone may be used as a splash-and-go stone but does benefit from a short soak and may be permanently soaked which will change the feeling during use; the bond will weaken a bit and it will release fresh abrasive more readily. This stone has a high concentration of abrasive and provides aggressive cutting speed relative to its grit rating. Loading is not a large issue but if you notice more than you would like, it's helpful to generate slurry with either a nagura or diamond plate.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 26, 2020 02:00PM
JSCT,
Well, I have on loan a full set of the Sigma II Select stones, including the 3k and 10k, so I will let you know what I find. I plan do to some sharpening today.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 26, 2020 06:28PM
Quote
marcs
As for the Sigma Power II stones only the 1k is SIC the rest are Aliminium Oxide as far as I can gather so that may be part of the problem here.

[mtckitchen.com]
Quote
marcs
[mtckitchen.com]

Yes I ve came across them some time ago.. Its 3rd source of info about stones
and they all say something else.
Additionally:
I contacted german dealer - they have no info and werent willing to contact the manufacturer
and I also emailed to saicom directly as well - never received any reply..

I have access to spectrography so I will try to identify type of abrasive in them..

www.instagram.com/jscuttingtools
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 26, 2020 07:47PM
JSCT,
These stones cut fast and are awesome. They just don't polish that well, probably because of the near %100 abrasive in the stone. I sharpened S30V. I have S90V and M390, along with ELMAX I can try also. To get the best results off the 10k stone, use trailing edge passes. The difference is shaving sharp if you do edge leading and tree-topping if you do trailing passes.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 27, 2020 08:28PM
Well, I used these stones with my clone of the Edge Pro Apex, and I got awesome results. Polished very nice, a mirror without stropping, and with stropping even shinier. Shaves above the skin like a straight razor. Angle was 8°DPS/16° Inclusive on S30V.



"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 06/27/2020 08:34PM by jasonstone20.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
June 27, 2020 08:59PM
[www.youtube.com]




"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 05, 2020 03:26AM
JSCT,
I just sharpened a knife in M390 on the Sigma II Select stones. I see why you are having issues apexing. I had to use the Spyderco UF to get the edge to shave in both directions, I had a very hard time getting the burr to come off. It was a small burr also, hard to detect, but also hard to remove. I strop loaded with 1.0u diamond compound didn't fix it either. It did remove most of the burr, but the edge wasn't great. The edge was fine off the Spyderco UF.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 05, 2020 03:01PM
Can one, or both of you, make a video showing :

-the knife on the stone
-ideally a close in shot, I want to see how the stone is acting to the knife slurry wise
-what the sharpness is after the stone
-ideally cut some very fine paper, newsprint
-the apexing process
-similar sharpness test

If possible, but not necessary :

-shoot the edge on magnification before/after the stones

As a few notes, on video :

-go slower than normal to make it easier to see what it happening
-try to focus on the stone/knife, you are not the subject but the stone/knife

If that sounds harsh, this isn't about an Instagram influencer, I just want to know what the stone is doing, as your stones sound different than mine. I also have some time next week so I might be able to do some comparative sharpening.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 05, 2020 04:21PM
Cliff,
I will try and get a video up today or within the next few days. I haven't really used the stones a lot yet, and I want to try them out some more. They seemed to work nicely if the fixtured system I was using.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 05, 2020 09:52PM
Did some sharpening with the stones on M390. Again, the edge would shave, but it wasn't tree-topping. I needed the Spyderco UF to get it tree-topping sharp.

[www.youtube.com]




[www.youtube.com]




[www.youtube.com]




[www.youtube.com]




Microscope shots:
Close:


Very Close:


"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 07/05/2020 09:53PM by jasonstone20.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 06, 2020 12:28AM
Only watched pt. 1 video, but I'd say your issue is at least in part due to using edge forward strokes on the next stone after the 1200 grit. Waterstones need edge trailing strokes to bring out high sharpness due to grit shedding and impacting the apex.
Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 06, 2020 01:07AM
Nothingman,
You will see trailing strokes in part 2.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: sigma 3k / 10k apexing difficulties of wear resistant steels
July 06, 2020 02:16AM
After the Spyderco UF and stropping on 1.0 micron diamond spray and 0.5 CrOx on leather, the edge was decently sharp and 'crisp'. It would tree-top arm hairs, and catch the ridges on my fingerprints. The edge would slice paper towel, freehanging and folded.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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