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Sigma Power Select II / 1K

Posted by CliffStamp 
Sigma Power Select II / 1K
August 31, 2013 08:12AM
These stones are designed to cut HSS, I picked up the :

-240
-1000
-3000

from Lee Valley.

Here is the 1000 :



and here is a 1000 King :



This is at 50X magnification. Note the huge difference due to the Sigma having no binder and being solid abrasive, it is a much more open (and likely) aggressive structure.

A light comparison :



On the Sigma :

-Solingen, 300 pps
-MS Chef, 50 pps

On the King :

-Wellington, 375 pps
-Levco, 275 pps

Before anything is made about the difference in the pps amounts, these kitchen knives are highly random in the amount of damage they take when I sharpen them which can literally be from 1 week to 5 months depending on how or what they get used to do. But even based on that simple comparison it seems likely that the Sigma is cutting faster.

In use :

-the king forms a thick mud immediately and it is just that a mud, not an abrasive suspended in water, it is more like a paste
-the Sigma feels like you are working an abrasive, the king feels much smoother, and stickier (mud)
-the king forms an immediate hollow and any isolated work gouges it immediately



You can do what you want with the King in regards to honing all parts of it, doesn't matter the abrasive is released extremely rapidly, where ever you hone it will develop a depression almost immediately. If you do not flatten the stone after each sharpening then after just a few it will be so uneven you can see it obviously.

The downside to me is that this will add a 1-3 dps additional to the apex bevel very quickly. This is an issue for me as I am trying to create particular optimal bevels and thus I have to flatten that King constantly or else I will end up with adding 4-6 di to edges very quickly and that can increase the edge angles by 25-50% .

-the Sigma has no visible wear



Both stones can :

-use the mud/slurry to alter the finish (make it finer)
-need constant water applied (every 50 pps it is wetted)
-take a long time to get wet if fully dried (~15 minutes to stop all bubbling)

A few interesting questions :

-what is the finish produced by each and how easily does it clean up on a 3k stone
-does the Sigma self-cut and renew abrasives, the King always cuts the same way
-how clogged would the Sigma get if you flattened it against the King

The reason I didn't look at the finish on these knives as they are all :

-very soft (easily filed)
-coarse/combination microstructure

The second point is the only critical concern I have with the Sigma, do you have to recut it with a more coarse abrasive occasionally to prevent it from smoothing out. I don't think so because it does form a slurry.

Album : [s7.photobucket.com]
Re: Sigma Power Select II / 1K
August 31, 2013 08:54AM
Cliff, will these stones cut Silky saw teeth that are impulsed hardened? I have read varying reports of the hardness of this steel ( SK4 High Carbon Steel) from 68 to 72 HRC.

The reason I ask is that I'm looking to get a Silky Saw and some models they suggest are sharpenable and some aren't. Of course they are sharpenable, but perhaps the high hardness varieties would not be practicle.


Chumgeyser on Youtube
"No American should find himself in a foreign land without a pistol." - Tom Frost
cKc
Re: Sigma Power Select II / 1K
August 31, 2013 08:58AM
just use diamonds on them grinning smiley

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KnivesAndStuff (YoutTube)
Re: Sigma Power Select II / 1K
August 31, 2013 09:03AM
Quote
cKc
just use diamonds on them grinning smiley

Good idea. I'll go dig some up in the backyard.


Chumgeyser on Youtube
"No American should find himself in a foreign land without a pistol." - Tom Frost
cKc
Re: Sigma Power Select II / 1K
August 31, 2013 09:07AM
if you have them in the yard.. attach some to a postcard winking smiley

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[data.gearbastion.com]
KnivesAndStuff (YoutTube)
Re: Sigma Power Select II / 1K
August 31, 2013 09:11AM
When you say you can use the slurry to alter the finish, wouldn't it make it coarser? Just like with the cheap stone, the mud/slurry would help to release the abrasive allowing it to be more agressive no?

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
August 31, 2013 11:44AM
Quote
Chum
Cliff, will these stones cut Silky saw teeth that are impulsed hardened?

Yes, I just checked one on a impulse saw and it does fine, however I think you would be better acid sharpening it than trying to abrade it unless you are extremely familiar with saw sharpening or want to experiment. That is about the hardest thing you can attempt to sharpen.

Quote
Cashmore
When you say you can use the slurry to alter the finish, wouldn't it make it coarser? Just like with the cheap stone, the mud/slurry would help to release the abrasive allowing it to be more agressive no?

With the cheap stone the slurry is necessary as without it the stone just glazes over and it starts burnishing. However here I would be surprised if that happens, it doesn't appear to. The slurry just works down and will form a paste if you don't flush it and this contains finer abrasives than the surface of the stone. You have to achieve the balance of finish/sharpening though because as the paste gets very thick it rounds the edge off as it is abrading the sides and thus at some point it won't sharpen further and you flush the surface and hone ultra-light.
RFL
Re: Sigma Power Select II / 1K
August 31, 2013 11:55AM
The slurry is composed of fractured abrasive (since the abrasive is friable), therefore the coarseness should be reduced. However, if the binder is soft, fresh (coarse) abrasive will be released continuously. It seems to depend on the force used on the stone. High force will result in a coarser scratch pattern, low force will refine that scratch pattern due to the slurry.
Re: Sigma Power Select II / 1K
August 31, 2013 11:56AM
Quote
CliffStamp
Yes, I just checked one on a impulse saw and it does fine, however I think you would be better acid sharpening it than trying to abrade it unless you are extremely familiar with saw sharpening or want to experiment. That is about the hardest thing you can attempt to sharpen.

Acid sharpening? That's a new one to me. I'll look into that.


Chumgeyser on Youtube
"No American should find himself in a foreign land without a pistol." - Tom Frost
Re: Sigma Power Select II / 1K
September 01, 2013 12:16PM
Thank you very much Cliff and RFL. Also, I was wondering what friable meant with respect to abrasives. Cliff used it on me the other day, but I had already asked him enough questions that day smiling smiley.

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
September 01, 2013 01:20PM
It means breaks down rapidly.
Re: Sigma Power Select II / 1K
September 01, 2013 01:33PM
Quote
CliffStamp
It means breaks down rapidly.

Sorry, that's what I thought after you used it, and RFL's use really cleared it up. I didn't make it clear in my last post. Thank you though for answering it again. It is very appreciated it.

Doesn't Lee Valley say these stones will wear faster than the King and Norton?

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
September 01, 2013 03:53PM
They make a general comment about breakdown, but that is just marketing. The numbers they cite such as " the 1000x stone cut O1, A2, and M2 steel 10-15% faster than 1000x Bester/Imanishi stones" to me reads like nonsense. That kind of precision is simply impossible, 5% of a range/precision - good luck. If the stone was only 10% faster then you would never notice a difference at all in use. I would really like to see the data that produced that claim.

Doing some work with Kyley's O1 (62 HRC, cryo/triple tempered) :

-King, 400, 350, 450 pps to apex (three times)
-SPS II, 150 pps

Note I only was stopping every 50 pps on the King and 25 pps on the SPS II hence the numbers are to the nearest 25 and 50 pps respectively.

I was working on evening out the edge and the primary grind and doing a little experimenting with apex refining. The SPS II could be influenced by all the previous work with the King, but again another point in its favor. It still doesn't show any surface depression and there is no issue with the finish. This is the edge without any slurry modification/manipulation or ultra-light honing :

Re: Sigma Power Select II / 1K
September 01, 2013 08:42PM
My experience with the King 200x SiC waterstone mirrors in yours in how alarmingly fast the stone wears and builds up mud/cake/sludge. The Lee Valley guide wasn't clear enough to distinguish among the choices, at least in terms of the coarser grits. Now I wish I had bought the Sigma Power Select one, which was only a couple of dollars more expensive.
Re: Sigma Power Select II / 1K
September 01, 2013 11:19PM
There is a little discussion on this thread about the Sigma stones. Most of the info comes from post #7 Stuart. He says the coarser stones do wear and compares the wear to a Norton stone, but admits to being a shill for them.
[www.sawmillcreek.org]

The bottom is a review for the Sigma 400 and is compared to a Shapton 320.
[www.sawmillcreek.org]
Re: Sigma Power Select II / 1K
September 04, 2013 05:11PM
SRM 710 :



-hollow grind
-edge is 0.018"/14.5 (5) dps

First side on the 1k King :



-500 passes

The edge is now 0.005" thick, at this point all the main performance has been gained. The cutting performance gains diminish and the work to progress further increases rapidly (more steel to remove as the bevels widen and the pressure is reduced) but if you want optimal then :



-2500 passes (total)

This is true zero, 4 dps.

This shows the benefits of a hollow primary and a decently easy to grind steel because even 2500 passes, while long sure is still doable and doing both sides would not even get you through "Inara, Jungle Girl".

Looking at that knife I think I know what the operator-ninjas feel when they see a Medford as that knife to me just screams lazor like cutting ability and trivial ease of sharpening.

Onto the 1k SPS-II :



-1000 passes

The difference in cutting speed is fairly dramatic. The stone is still very close to flat. Another way to compare them :



Look at the difference in the amount of material removed from the King vs the Sigma.

Now both sides are not guaranteed to be equal sure (primary hollow), but there is no way that they are uneven it could explain a 2.5x difference. This stone cuts so fast that even 100 passes made a large difference to the edge thickness. Again this is an easy to grind steel, but still with just 100 passes per side this knife would be cut to match the same edge thickness on a typical Wilson.

This also isn't the coarse stone, they get much more aggressive.
Re: Sigma Power Select II / 1K
September 04, 2013 05:29PM
That is an impressive difference in cutting. What is the steel of that knife? Also you got a more coarse stone too didn't you?
Re: Sigma Power Select II / 1K
September 04, 2013 06:33PM
It is 8cr13MoV, fairly easy to grind.

Yes, I have a 240. I am just playing with the 1K the 240 would be much more suitable regrinding. However once the edge is set at that angle sharpening it on the 240 would likely gouge the edge so ideally you take it down until you almost can't see the edge and then switch to the 1k.

I am going to check these again on the Fallkniven PXL.

I have been doing some reading, all kinds of different reports on these including a few which are the complete opposite of my experiences which leads me to wonder about variances in the stone.
Re: Sigma Power Select II / 1K
September 05, 2013 03:58PM
PXL :



Is now a knife, very respectful 6.5 dps. The SPS II powered through it, much more demanding, did one side on the 1k king, had to flatten it twice. The SPS II still has no visible wear.
Re: Sigma Power Select II / 1K
September 05, 2013 05:00PM
Seeming like a great stone so far.

I assume when you use the 240 you'll compare it to something as well?

Also, what do you think about the jump in grits Lee Valley sells, particularly the 3000 to 10000? Do you know if this is standard in the line or is there an intermediate LV just does not sell I wonder?

Thank you

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
September 05, 2013 05:15PM
There are many more than what LV sells, I assume they just picked the popular ones. Stu (TFJ) has the full line : [www.toolsfromjapan.com] .

Yes, I am talking to Stu about this, I am getting fairly interested in stones because of the conflicts I am reading. I am finding out it isn't as simple as I thought it was because of the lack of information because no one tells you how they make them, at most you get the abrasive type.

Imagine if you had to choose knives but you knew nothing about the steels they were made from and how they were hardened and you tried to learn about steels and HT in using them. That is what it is like trying to understand stones, a curious problem.
Re: Sigma Power Select II / 1K
September 05, 2013 05:56PM
I find it interesting for the same reason...and because of the massive amount of contradictory reports that you also noticed. I saw where the one fellow (a professional sharpener in AZ) commented that he did not like the Sigma's on youtube. Basically had the opposite experience of yours. I know who the fellow is from bladeforums, and he loves the Nubatama's.

At any rate, if you remember, please keep us posted on what you learn about the grit jumps. I would like to add a hard 3K to my stones as I have a soft one right now, and something 6K plus as well, but I don't want to make too big of a grit jump.

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
September 05, 2013 06:18PM
The shill/bias is still there, people sell and it colors what they say. All I can say is that if someone calls this stone too friable then either the stone I have is different or there are some truly excellent stones out there as this hasn't dished significantly after even the latest SGPS regrind.

I am not the best person to ask about really high finishes as I rarely use extremely high polishes, I don't really see the utility in it for working knives. I may experiment with it for the sake of experimenting.
Re: Sigma Power Select II / 1K
September 06, 2013 02:34AM
Totally agreed on the shill bias. And often you can get an idea for by just how frequently,strongly, and insistently people vocalize their preference.

With the stones it is a bit harder though in the sense that often the stones are not widely in use, and technique and experience can vary so strongly, and there is little to no info as you noted on the make up to help predict expectations. In the case of the Sigma Select, they are definitely not as widely used as DMTs or Kings of course, so it's hard to sort out what is true information, so while improbably, it seems possible your stone is different, or perhaps a new formulation.

I would ask you about the wear for the given number of passes...i.e. where the King would be at at the same number of passes done on it, or eventually how dished (or not) the SS is after the same number of passes that the King has received since the trials began, but well, that will have to wait until after the challenge this week smiling smiley

As for high finishes, I hadn't considered that. It's easy to assume you know what you're doing in all aspects knives. The desire is just a general one on my part to try something higher than 3K, especially since you said it's beneficial on a chopper (well, so long as you don't hit dirty wood, which we all know how that goes...).

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
September 06, 2013 04:47AM
Quote
Cashmore


With the stones it is a bit harder though in the sense that often the stones are not widely in use, and technique and experience can vary so strongly, and there is little to no info as you noted on the make up to help predict expectations.

I spoke to Stu (TFJ) about this stone and he noted that it hasn't changed. He has heard the same issues about wear of this stone and he has noted they are coming from people comparing them to solid ceramic stones (like the Spyderco's). From that perspective yes, this stone would likely wear / hollow rapidly as the sintered solid ceramics (not waterstones) wear extremely slowly. How often do people flatten their Spyderco rods for example. I can only recall Chris (me2) being vocal about wearing a set.

Quote

I would ask you about the wear for the given number of passes...i.e. where the King would be at at the same number of passes done on it, or eventually how dished (or not) the SS is after the same number of passes that the King has received since the trials began...

There is more wear on the Sigma than will produce a large hollow in the King, I did more grinding last night. To be fair, the King series are one of the most known and heavy friable stones, comparing against it for wear is like comparing someone against Medford for non-operator marketing. It doesn't take much to come off as positive.


To clarify I am not saying I don't know anything about high finishes, just that there are people who work exclusively on that alone and they can be extremely particular about details I don't care about at all such as the finish it leaves on the blade. I use high finishes and generally will go 3-5 k on larger chopping knives and kitchen knives, however I just don't see the utility in progressing up to 30-100k and beyond on using knives. I have never seen any evidence that the time invested produces a practical return.

For me, I aways polish on a micro-bevel so there isn't much demanded of the stone aside from being able to cut. This is why I picked up the SPS-II in 3k to see if it will actually sharpen the 710-M4 as the Henckels 3k waterstone will not.
Re: Sigma Power Select II / 1K
September 06, 2013 08:25AM
Quote
CliffStamp
I spoke to Stu (TFJ) about this stone and he noted that it hasn't changed. He has heard the same issues about wear of this stone and he has noted they are coming from people comparing them to solid ceramic stones (like the Spyderco's). From that perspective yes, this stone would likely wear / hollow rapidly as the sintered solid ceramics (not waterstones) wear extremely slowly. How often do people flatten their Spyderco rods for example. I can only recall Chris (me2) being vocal about wearing a set.



Ok, that helps to put things into perspective. I really appreciate you sharing that. Compared to the sintered ceramics I feel like you'll even notice the Diamond plates wearing out faster. I wish more people would use comparisons when speaking as it really helps with perspective. I knwo I don't do it enough though either, so I suppose it's asking a lot.

Quote

There is more wear on the Sigma than will produce a large hollow in the King, I did more grinding last night. To be fair, the King series are one of the most known and heavy friable stones, comparing against it for wear is like comparing someone against Medford for non-operator marketing. It doesn't take much to come off as positive.


To clarify I am not saying I don't know anything about high finishes, just that there are people who work exclusively on that alone and they can be extremely particular about details I don't care about at all such as the finish it leaves on the blade. I use high finishes and generally will go 3-5 k on larger chopping knives and kitchen knives, however I just don't see the utility in progressing up to 30-100k and beyond on using knives. I have never seen any evidence that the time invested produces a practical return.

For me, I aways polish on a micro-bevel so there isn't much demanded of the stone aside from being able to cut. This is why I picked up the SPS-II in 3k to see if it will actually sharpen the 710-M4 as the Henckels 3k waterstone will not.

Thank you to for the info on the Sigma vs the King. It really seems to be pretty wear resistant then. Have you noticed any loss of aggression at all though? Do you think it's releasing fresh abrasive at all and do you think it will be hard to dress once it stops cutting well/hollows?

And I didn't mean you knew nothing. I apologize if it came off that way...I just meant, well what you said. That I forget all aspects of knives aren't or haven't been in your sights to a detailed degree.

I'm not realy looking for anything above 6K, for the reasons you've mentioned., but seeing as the Sigma is offered in 10K from Lee Valley I was curious about the jump.

When you mention you always polish on the microbevel, you talking the actual secondary or the nonvisible micro that you then back bevel?

Thank you

_______________________________________________________________________________________________

Always in search of a good choppa'



Edited 1 time(s). Last edit at 09/06/2013 09:28AM by CliffStamp.
Re: Sigma Power Select II / 1K
September 06, 2013 09:32AM
Quote
Cashmore

Do you think it's releasing fresh abrasive at all and do you think it will be hard to dress once it stops cutting well/hollows?

Yes, it is releasing fresh abrasive, but at a nice pace. It might be possible to reduce it with a better sintering but you have to be careful because if you go too far then everything will just round out and you have to recut it to get it to work again. I don't imagine it will be as easy to flatten as the king which I can literally take a 1/32" hollow out in less than 15 seconds on a concrete step. However given the nature of the stone I might actually use loose grit on glass on the sigma and use that swarf/grind off as lapping compound.

Quote

When you mention you always polish on the microbevel, you talking the actual secondary or the nonvisible micro that you then back bevel?

I play around with polishing the bevel you can see, but for function I just do the micro, there is little performance from anything else - but the looks of the knives are really critical to some, especially the japanese knives and the laminate/clad lines. Hence those guys are extremely critical of stones because if you lose that line you really devalue the knife in their eyes.
Re: Sigma Power Select II / 1K
September 06, 2013 03:31PM
Thank you for the answers Cliff. Please do let us know how you end up flattening it.

I take it the polish on the micro helps to eliminate any "jaggedness/coarseness" in the apex and prevent excessive fracturing of the edge?

_______________________________________________________________________________________________

Always in search of a good choppa'
Re: Sigma Power Select II / 1K
September 06, 2013 03:56PM
Yes, I normally use it on push/chopping edge and they do not fair well if you leave them coarse. Now of course if it is a machete and you are going to be working close to the ground there is an argument for efficiency and it is not likely I would spend much time on it as all because the difference in edge retention between a 200, 1000 and 5000 grit edge when it is slamming into dirt isn't significantly different.
Re: Sigma Power Select II / 1K
September 09, 2013 02:42PM
As noted :





Another regrind :

-King : 11, 500
-SPS-II : 4, 500

The SPS-II was not significantly out of flat (put a metal ruler on it and no visible gap under it). I then flattened it on a piece of granite with some 60 grit SiC and then some 200 grit SiC. It only took :

-150 passes on the 60 grit to remove most of the pencil marks
-100 passes on the 200 grit SiC to finish

As the piece of granite I have is very small I could only move the SPS-II stone about 4" back and forth and thus with a larger plate it would flatten much faster, 50-100 passes. I am not even convinced that this was just removing some of the initial less than ideal flats. I will keep an eye on it in any case.
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