Just received an email from a customer with a question. He just finished sharpening a blade and  then garnered these three measurements at three different points on the edge: 90, 180, 220. He was wondering if his test methodology might be flawed.

First of all - even if one were intentionally trying to screw up the measurements, it's doubtful that one could produce this disparity in readings on a well ground and thoroughly deburred edge.  Now, please don't take this as a challenge Exchange members! As a rule though, the statement is accurate.

90 - 180 - 220 do bear the mark of a wire (or false) edge however. In the first case (90), the edge had just enough structural stability to sever the test media cleanly. In the latter two measurements (180, 220) it didn't and either dented or folded the wire edge over before severing the test media. There could be other edge problems that could manifest in this manner  but I advised the customer to look for a wire edge first.

Wire edges do make me think though. Usually, once a  wire edge is removed, there is no significant reduction in sharpness. In the case of our customer, and once the wire edge is removed, he should end up with an edge that measures around 90. This leads me to believe that the  width of the wire edge is about the same at the top as it is at the base where it will be separated from the newly created and structurally improved edge apex. So the problem with wire edges is that they are just "too tall" for their own good. So how's that for pure conjecture on my part? My mind is a terrible burden. I visualize microscopic things in dinner plate size and then draw conclusions. Those visualizations are sometimes later proven correct and sometimes not. I never reveal my batting average - too embarrassing.

Just realized that the edge scoring 50 BESS has an apex of the same size as the coronavirus COVID-19.
Actually, apex in the best disposable shaving razors is even less.

The following was sent to us by one of our international customers. The picture shows how the test media passes beneath the bearing seat and is pinched between washer and test fixture when the clamping nut is snugged up. Atop the bearing seat is a thrust bearing. This arrangement insures that test media cannot be over-tensioned when tightening the clamping nut. Thanks for the picture Chico!

   

    Tormek redesigned the SVM-45 knife jig in 2002. The jig was shortened. I need a pre 2002 longer jig for a Tormek related project. If anyone has one and would be willing to part with it, I would gladly trade either aa brand new latest version SVM-45 or $40 US, the cost of a new jig. The photo shows the different before and after 2002 lengths.

If you can help me out, please send me a message.

Thanks, Ken Schroeder

Hello. 

I use Viel S-5 belt grinder for sharpening. Recently I have been having problems with static electricity. It gets worse when using a Trizact belt or leather belt. Do you know any solutions?

I'm going to post all (most?) of my knife and sharpening related videos here to make them easier to find.  These are mostly all on my youtube channel, which you can link to from any of them.

Let's start with my latest.  A how to on assembling and installing Grepper's KallyRest:





Brian.

Thank you to the innovative team at Sharpening Supplies for opening up an entirely new area and means of edge sharpness testing.
Follow this link to the new product. https://www.sharpeningsupplies.com/Butte...-W253.aspx

Stay with me here.  At the end I’ll show how we can do this in only 15 seconds.
 
To calculate the taper of the blade all we need to know is the thickness of the blade at the spine and the width from spine to edge.
 
This is the knife from this post: http://bessex.com/forum/showthread.php?t...17#pid5317
 
The green/blue just shows the blade bisected into two triangles.  We know the thickness at the spine and the width from spine to edge.  Divide the thickness in half to get ½ the thickness.
 
   
 
Here is the triangle formed by ½ of the bisected blade.  Why do this?  Because now we have a simple triangle.  We know three things:  The length of two sides (2.012, 22.999) and one angle 90°.  This is cool because we can use SAS (Side Angle Side) calculations to get the length of the hypotenuse and from there the interior angles.
 
   
 
All that’s left to do are some quick and simple mental calculations to determine the taper angle is 5°.
 
   
 
Of course some (most?) blades get thinner at the spine from the handle to the tip.  Oh well, other than using a CNC machine with some complicated programming for sharpening, we’ll just have to live with it.  Maybe the best thing to do is to pick some mid point and call it good.
 
As promised, here’s how to do this in 15 seconds!  Go to either of these two web sites, select SAS calculation, enter ½ the spine thickness for one side and the width of the blade from spine to edge for the other side and 90° for the angle.  Press the GO button.  Done.

https://www.triangle-calculator.com/?wha...bmit=Solve

http://www.1728.org/trig4.htm

A Google search turns out many triangle calculators.

See?  Easy!

I just did some more work on my (now world) famous Tramontina kitchen knife.  The one that scored about 190-ish after very careful deburring, following a 380 grit belt.  Well I decided to polish it a bit so I used a 600 grit belt, then leather, scotchbrite, leather again.  Terrible scores!  200, 350...  So more polish.  I went straight to a smooth leather belt with green compound.  Very little compound left on the belt, but it's there.  Eliminated the remaining LOW.  ...and it scored 125, 125, 175.  The 175 was in the curve.  So back to the loaded leather.  I did 5 or 6 passes and got a little too casual with my motions.  Sliced open the top of my index finger.  Ooops.  Nice *cleeeeeean* cut though.  It didn't even bleed for 20 or 30 seconds.

After cleaning that up, I tested the curve again.   One handed, because I was holding pressure against the finger of one hand.  Balanced the blade on the fulcrum on the tester, and leaned it over to the media.  Lean, lean, lean, lean... and the media broke.  At 80 grams.  No freaking way.  I must have sliced it somehow.

So I went and got a bandaid and got my finger taken care of.  ...and tested again.  In the curve with the fulcrum, but this time with the other hand on the tip of the blade helping to guide it down.  ...and it read 135.  Now that's more believable.

I can only guess that with one hand the blade slips some and creates a slicing motion, which obviously "tricks" the tester because the force is not straight into the media, it's at an angle.  I think if you were really clever you could slide the blade sideways and get nearly zero readings by doing an extreme version of this.  Does that sound about right?

Anyway, seems like I need to be more careful when sharpening knives. 

Brian.

for many years i have used A16's @ 1200 grit and i likem.

opinions on the next two higher grits A6 @2500 and A3 @ 4000.

i need some really super sharp blades for a butcher shop i just acquired for 1 of my exchange programs.  he has been happy with the A16's and leather after a two week exchange, but said could i make them sharper.

would it pay me to invest in the A6's and A3's...........or a better way to sharpen them to hold up better.

they get a lot of use.

i have tested toothy edges, but they do not work for him for two weeks.

let me know......................