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Effect of Chopping Board Material on Edge Longevity
#1
Thanks to the Mike B. SET-testing stand we've completed a research on chopping boards.

Video of our research:




Complete experimental data and discussion are in our article "Effect of the Chopping Board Material on Edge Longevity" in the Edge Stability Testing section on our website http://knifegrinders.com.au/16SET.htm
(the last research in the list)
http://knifeGrinders.com.au
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#2
Thank you Mr. KG!  Very interesting and surprising stuff.  I've got to say your sheer diligence and dedication is amazing.  Your contribution is truly appreciated as I know that I for one would not have the patience to do the thousands of cuts necessary to duplicate your tests.  When I saw 2,000 slices per knife in your video I was amazed.  

I have heard many times that end grain cutting boards are more forgiving on an edge, and it sort of makes sense.  Until now I've never seen anyone actually test that assumption.  I'm not really surprised at your findings, but thank you for empirically demonstrating that's one less thing to worry about.

We've seen a lot of myths debunked by actual testing here on the Exchange. Some of those findings were as expected.  Others seem to defy first blush logical thinking exposing our multiplicative propensity to accept old wives tales and disseminate them as fact simply because on the surface they kind of seem logical.

Watching your video I saw the results from edge friendly cutting board displayed and I thought I had misread the data shown so I watched that part again.  Can that really be true?  At this point I have only watched your video, but I will visit your site and review your thoughts on the subject.  I'm sure that you can both appreciate and understand why I find those results unexpected.  I suspect that you too were surprised when you saw the numbers!

Again, thanks for the cool post!
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#3
For many years I have been intrigued with the factors which help make a very educated and skilled person. This has been mostly, but not entirely, part of my desire for self improvement. Recently desiring to help my grandchildren has been an additional driver.

Vadim (Knife Grinders) combines the best of a highly educated mind with a craftsman's desire to improve the craft. He is continually growing and quite commendably, he has unselfishly shared his growth with like minded persons on this exchange and elsewhere. After all the amazing progress on this exchange, I still believe there is much of the iceberg remaining for us to discover and explore. Our group efforts are supercharged.

Keep up the commendable work, Vadim!

Ken
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#4
Mr. Vadim, please, can you explain why you use the term torque to characterize the cutting action of a knife? (Generally it is used to describe rotation effect of force. In US physics the word torque is used, while in UK and the EU torque is referred as moment of force abbreviated as moment.)
 
In my understanding the torque it is fully adequate to describe a cutting action when the knife tip rests on the board and serves as a lever fulcrum.
 
My understanding of the mysterial increase of edge sharpness observed in your experiment is following: deburring the knife edge using low speed hard felt wheel impregnated with 1 micron diamond abrasive results in edge surface with roughness cca 0.1 micron. That can be considered a nice, clean smooth surface, until we realize, that the apex diameter is only some 0.2 or 0.3 micron (for edge with BESS score 100 or 150). Some of the edge surface irregularities may be caused by burr residua which were more firmly attached to the edge and survived the deburring. The experiment shows that repeated movement of the edge in a 32⁰ V groove can remove/smooth some residual edge surface irregularities and lower the BESS score.
 
As mentioned by Mr. Vadim on another occasion, edge burnishing may also play some role in the explanation of this experiment. Smile
 
Jan


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#5
My first guess as to why edge sharpness increased with edge friendly boards was, as others have mentioned, due to deburring.  I thought this especially likely as the testing was with factory edges.  At that time, I also thought that if the knives were sharpened and deburred at KG that the increasing sharpness effect would be either reversed or at least not as pronounced as I'm sure the KG deburring process is quite effective.

So then I visited the site and reviewed the the data.  As I read, I was pleased to see that testing was performed on resharpened edges.  Surprise!  The resharpened edge percent sharpness increase was greater than factory edges.  Most gobsmacking is the percent sharpness increase is not trivial as I would have expected, but actually up to ~50% sharper in some cases.  

I find this difficult to explain as resulting from burnishing of hardened stainless steel by slowly rubbing against soft plastic by hand.  Deburring seems more likely to me, but even so, considering that the edges were most likely well deburred at the start of the test, the percent sharpness increase is a head-scratcher.  Edge straightening seems even more unlikely, but at this point I'd believe almost anything.

It would be interesting to see before/after microscopy of the edges.
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#6
It is counterintuitive, I know. Moreover so amazing.

As shown in the video, the way we tested was 20 sliding cuts under 2 kg load in the same line on the board, move the edge to a fresh board surface, do another 20 slices and so on. By the end of the test the plastic boards had noticeable grooving in the tested areas. The wooden end-grain boards also had some grooving, while the long-grain almost none.
The edge-refining effect must be due to something happening inside the tiny grooves in the boards that were forming during the 20 sliding cuts.
Something made the edge apex narrower and firmer as we sliced the boards in those grooves.
Remnants of the microburr, if any, get removed in the first tens of cuts, while the edge-refining effect fully develops after hundreds of cuts, as seen in the table of sharpness numbers taken every 200 cuts.

We've stumbled across a method to refine the edge, that thanks to our research of the chopping boards had been proved even before we realized we discovered it.
In the coming weeks I am going to experiment with various plastics to pick the best material for that, need to talk to our local plastic plant to obtain offcuts of the plastic.

(Estimation of forces in meat cutting at the meat plant is a New Zealand research, not ours - I can email their report if someone wants the boring details.)
http://knifeGrinders.com.au
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#7
Two thoughts first Vadim; It took a lot of effort and some expense to put this together. Thank you for putting in the work and sharing it with us. Second, what a brilliant adaption of the SET unit! You just expanded the scope of that instrument by a factor of 100. Really great use of your creativity there Vadim! But you weren't done because then you turned around and re-purposed one of our old PT50 instruments into a device that determined the force  required to slice common foods. That was really inventive as well!

Kudos all the way round and thank you for bringing this to the BESS Exchange!
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#8
Mr. KG, did you ever take any microscope images or do further testing to try and ascertain the cause of your results?
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