BassLake Dan

[BassLake Dan]

.. I am very curious about how your formulas work within the spreadsheet. If you care to share some insight I’d be grateful.

The formulas are nothing complicated, it very basic statistical math, computing average , means, and determining meaningful variance from the normal. You can use Excel or Open Office and mouse over the cells to see the formulas that the spread sheet is programmed to use for the output to the graphs. If you have a specific question about one of the formulas I will try to answer it if you can not see how it is done from looking at the spreadsheet.

I just snapped this photo under the microscope at 800x of the blade I’ve been playing with:
..I’ve been using roughly the same spot on the blade for each test so it’s probably exaggerated.

Clay,

I really appreciate the photos ! During the original quest for a reliable way to test blade sharpness we had a email round table of discussion about it (you may remember being on that list yourself!)

There was extensive discussion about using optics as a method of testing apexes. Optics is, in fact, used in the quality control rooms of commercial razor and surgical blade manufactures. I always held out high hope for it to test on a hobby level, but the equipment and skill levels were just too high to make it practical. You have the facilites and the equipment and the skills there at WE to use photos to get very meaningful data on apex conditions and sharpness.

You can give us a good reality check on the jig systems results, and I appreciate that photo you posted very much. It will be very interesting, just fascinating actually, into the future to document with photos the condition of blades that the jig report numbers on.. The way of science and engineering is, of course, careful observation and testing, so we are on the right path here.

[BassLake Dan]

However, the chart doesn’t seem to support the quote by Leo. If you compare the two BG42 curves, at places the 20 degree curve goed down even steeper than the 13-16 degree curve and at no point in time the 20 degree edge comes close in sharpness to the 13-16 degree edge.

Mark,

I posted the CATRA chart only to show an example of the log fall off of sharpness thru initial use. It does demostrate that very well. However:

The subject of proper angles, strops, etc, for a given steel or specific use must be approached very carefully and the CATRA test system is suspect and very controversial. The various machines that CATRA designed and markets to the professional industry is the subject of endless debate, and I don’t want to throw gasoline on the fire here in this forum.

Anyway, long story short: I suggest that everyone do their own testing on their own blades and draw their own conclusions in the framework of very specific local tests that you have control over yourself. This was one of the main motivations I had when going forward with the design and construction of the $50 jig. CATRA uses a very contrived abrasive imbedded propriatry test media that is targeted towards the commercial meat cutting and packing house industry. Hardly the kind of thing you and I are doing with our high end Sushi knives !! The test media is inextricably intertwined with the results. There is a discussion of that important consideration on the jig site.

[BassLake Dan]

It is interesting to note that extremely low sharpening angles do not retain their sharpness for long.

From the jig documentation of degradation tests is this chart from CATRA.. You can see how rapid these curves are typically:

[BassLake Dan]

I’m already starting to build some data and seeing some trends. … I also noticed an impressive deterioration in the sharpness with progressive testings, due I imagine to the repeated force applied to the edge in each successive testing. It should be fairly simple to conduct some durability/edge retention tests…

Yes, this is a common observation when one begins testing blades with the jig. Since the jig is very much more sensitive than non numeric testing methods (paper slicing, hair whittling, etc..) it surprises and hits everyone over the head when you see that (and realize) that sharply apexed steel is actually a very very delicate item and deforms and degrades very rapidly with initial use. The slope of the curve of degradation is extremely rapid. Of course, this is counter intuitve, as we build bridges and freeway overpasses out of steel, so in any form it is strong and permanate?, or so we think. All our understanding of steel works for us in everyday life, until we use it at its extreme application: cutting edges where apex edges are measured in microns.

using the scotch tape media to do this type of testing is described in detail on the jig tester site. Excel spreadsheet templates are provided to record and graph this type of testing: http://www.howsharpisit.com/Edge_Retention_Tests/Template_Degradation_Testing.xls

[BassLake Dan]

Clay,

Excellent job on the jig construction ! I particularly like your improvements to the weight slide bar.

As your time permits, please keep us informed as to the results you get with the jig, and if you have any data sheets of test results. Because of your extensive experience with the practical world of sharpness, I would be most interested to hear if feel that the jig provides:

1.) data that seems to make sense to your feeling about a series of blades and sharpening techiniques. In other words give us a “reality check” on the numeric feedback that the jig provides vrs “expected results”

2.) is the jig providing you an ability to look at a “finer granularity” when appraising the sharpness of a blade over your previous methods (whatever they might have been i.e. paper slicing or whatever) and is the numeric results of practical benifit that offsets the time of using the jig.

3.) your thoughts about possible new test media for the jig

Again, great that you finally, on your busy schedule, were able too put one together !

Best Regards – Dan

[BassLake Dan]

.. super polished bevels..

..

Clay,

I have been meaning to ask, 1.) what steel is this that you were using for these tests, and 2.) what RC? Just curious … thanks

[BassLake Dan]

.. a rather large time commitment..

well, not sure if you mean the time to build a jig (if you have standard hand tools then should be just an afternoon or two..) or the time to test a blade. I timed myself doing a ‘full map testing session’ and it took me about 20 minutes. There is a description in the directions on how to do a ‘fast test’ and you can easily cut that time in half. The results won’t be quite as accurate, but it will certainly ‘ball park’ you.

[BassLake Dan]

Hi,..Call me curious.

Oh, man,.. you are prying open the lid on pandoras’ box.. last time I got near this subject the topic ran on for days.. see: “question with a sebenza..”

Although there are many knowledgable “steel junkies” that hang around this forum, i would suggest you also cross post your above “curious” to Cliff at: the towards .1 micron Forum..

[BassLake Dan]

..
You can also get some to the Veho 400 knockoffs..
Phil
.

For what it is worth I would suggest that you get the genuine Dino-Lite /Veho or better. I had a bad experience with trying to save a buck going the route that Phil suggested above, and just wasted time and money trying to out-smart myself.. Optics are funny that way, you *do* have to pay for what you get.

[BassLake Dan]

..the big boys ..

huh?

[BassLake Dan]

BLD – I’m about halfway through reading the new site. It looks terrific. Thank you for sharing with with everyone here. I can’t wait to build one and add it to the testing I’m doing.

Well, Clay there are two ways to skin the cat, as you know. One is to do actual mechanical tests on the blade like CATRA and “the Jig hobby project”.. the other way is to do what you are up to with the 800x scope, that is, just *look* at the apex and see what you can see.. actually your way has a lot to recommend it.

Of course the whole subject (of sharpness testing) can be argued/ explained/ discussed on and on/ for many days and many pages in a forum, and we certainly do not want to get near that right now, but one thing that your optical system can *not* do is return to you numbers, except for the reference scale nano-meters numbers. If you have a mechanical tester that returns numbers then you can get output like this from our latest excel spread number crunchers. Who knows if they mean anything, but they are sure fun to look at: http://www.howsharpisit.com/Elmax_ZT0560_Map.pdf

[BassLake Dan]

..
This is a clear demonstration that the long relied on “fingertip test” is not worth much. .. I’ll keep everyone posted on how it stands up

I think what you might be saying is that testing a knife for sharpness in a reliable way can tell you a lot.. there is valuable information to be gained in assessing your sharpening methods when you start asking How Sharp Is It, and you are able to find the real and reliable answers to that question. If you are interested in blade testing on the hobby level you might want to drop by : http://www.howsharpisit.com/%5B/url%5D

[BassLake Dan]

I am very happy with the Elmax steel of my 0560. ..

My only niggle is that I cannot get it really shaving sharp. …

Well I can’t imagine what the problem is there. Of all my newer ‘particle steel’ knives I like Elmax and the way ZT handled the treatment of the steel the very best of all of them. I guess we all have our problem knives, for me it is the sebbie.

Anyway your comment above made me drag out my pocket carry 0560 and see how sharp it is after a week of on and off duty of doing the usual for me that include everything from trimming a rib-eye on the grill to opening the occasion box. You can see from the chart below that the heel is getting duller thru this use, but portions of the curve of the knife are still at shaving sharp, reading numbers as low as 140g, which is within 20g of a reference double edge razor blade. I know for a fact that I can get my example of the ZT0560 to a flat 170 Apex push Cut sharpness all the way across the blade using a WEP. That is easily sharp enough to shave with. I can not comment on the ‘comfort shave factor’ as I never really tried to actually shave with it, I just am reading the numbers..

above Chart/ data generated by: HowSharpIsIt.com

Here is a picture of the Out of Box factory Edge on the ZT0560: It takes some work, of course, on your WEP to get this to the ‘shave point’

[BassLake Dan]

It might be interesting to set a few benchmarks which should be extremely high (or low as it were) :

-standard utility razor blades as-new
-double sided razor blades
-“shave ready” straight razor

I have tested utility knives like what you find sold as ‘utility knife replacement blades’ at Home Depot and True Value hardware under brand names like “Stanley” and “Irwin” but they are just very dull, usually baseline numbers in the 350-400g. The Gillette type double edge replacement blades in the pharmacy are much more like what you would want as a reference, as they are consistent and very sharp across their entire length. I do not have access to ‘straight razors’ so, sorry to say, can not test them

The following chart is an example of results from a generic double edge razor sold by the Rite-Aid pharmacy chain stores. This data is simply sorted low to high, not put thru a proper data cruncher, but I thought I would present it this way as an easy way for ‘laymen’ to get the gist of it. (throw out the lows and the highs!) 😆

Note: low numbers= sharper, high numbers= duller

[BassLake Dan]

..
(from an earlier post…–>) If the Sebenza has a lower relative ability to hold the low grit finish it is a fairly strong indication of a micro-structure issue as the teeth are approaching the size of the micro-structure (micron scale).

..Now that just means *for this run* it was sharper, it does not mean that it always would be, Dan would need to sharpen a few more times and if the Sebenza was consistently sharper then an inference could be made about the steel.

This is interesting, and I will put this on the ‘to-do’list. I was looking through my stack of testing that I have done with the jig and came across one early on that was done with the ZT and the baseline numbers started as low as 175g so I know that I can get at least that far with it. It would be interesting to see if that could be brought even lower, and if the sebbie could be brought along with it. It would be interesting to see if I could ‘find the bottom’ (so to speak..), but with S35vn I don’t think I have the equipment or the skill here to really find out the answer to that, but it would make an interesting afternoon of sharpening 🙂 I do know that I have found such “bottoms” with certain knife steels: for example I tried pushing a CRKT M16 every finer and found out that the jig told me I could never (no matter what I did!) get it sharper than 180 or thereabouts. CRKT says the alloy is 8Cr15MoV.

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