With all the focus on blade performance why no standardized cutting tests?

[Ankerson]

No test is perfect is the bottom line with so many variables to take into count.

That is why real world testing is a good edition to machine testing so we can get some sort of idea where to draw the lines so to speak.

The best that we can do is supply a general guide, and that's not going to be 100%, nothing really is.

My recommendation is to use the knives and enjoy them. :thumbup:

 

[REK Knives]

No test is perfect is the bottom line with so many variables to take into count.

That is why real world testing is a good edition to machine testing so we can get some sort of idea where to draw the lines so to speak.

The best that we can do is supply a general guide, and that's not going to be 100%, nothing really is.

My recommendation is to use the knives and enjoy them. :thumbup:

Exactly. but a good way to test sharpness for edge retention tests would be something that can measure the force used on both a push cut and a slicing cut... something like this

 

[jpm2]

I can do the job with the cheapest blade steel, but my clients ain't gonna like it when they're losing $100+ per minute and I have to stop work and repair my edge to finish the job..

Gotta ask. What job do you have that you charge over 100 bucks a MINUTE to use a knife?

Not sure how you got from my post that I charge $100 a minute.
When certain machinery is down, they are losing $100+ per minute in lost product.

 

[chiral.grolim]

Exactly. but a good way to test sharpness for edge retention tests would be something that can measure the force used on both a push cut and a slicing cut... something like this

Hmm...

http://www.edgevue.us/Test_Results/KNIFE_EVAL/Results/Angel_Slice/Test_1_Sum.pdf

The tests they promote report the "maximum force" used by the tester, NOT the maximum required to complete the cut. For example, all of the knives in the angle-test are sharp. You can see from the wavering in the charts how the amount of applied force changes as the user is making the cut according to how he takes more or less time to complete cutting lengths. In the results they present, the user completed the cut most quickly with the 21-blade ... and naturally it required more force (indeed the highest spike) to do that as he was wedging the blade more quickly through the card. With the 19-blade, the user started out using a lot of force (second highest spike) but then backed off on the force (second lowest trough) and took more time (the most). With the 15 & 17-blades, you see a similar pattern of spikes/troughs related to the amount of force the user was applying against the card over the time-period of cutting. The primary slope of each graph is the primary bevel wedging its way through the card, and the only reason they are not all in line is the varying time it took for the tester to push the knife (same knife every time) along its track. The high variations in front of that slope indicate that the edge-angles tested have no measurable impact on cutting performance in this test, all that matters is that the knife is sharp and then how quickly the tester moves the knife through the card.

In edge-retention testing, and indeed in sharpness testing in general, all we care about is the first few mm of edge-height - i.e. the edge-bevel - all that is in the data collected before the big slope, the data pretty much ignored in their print-out for the various tests