03-21-2018, 11:44 AM
Hello KG. The built in 10° angle of the bearing roller simply assures that the 150 gram force is applied with a lateral component. We want to assure ourselves that the edge is not being crushed but rather rolled. To date that design element seems to be doing its job. Having said that, we have only tested edges sharpened at 19°. The sharpening angle, in theory, shouldn't have a bearing on test procedure (as opposed to test results) though because the edge apex should always be orientated vertically no matter the sharpening angle. Here is an illustration that demonstrates the principle and a photo of the roller sitting on the edge:
See the black marks on the bearing surface? Those were made initially so that we could assure ourselves that the bearing was actually rolling and not just dragging across the edge. It rolls smoothly and doesn't drag so now we don't need marks.
We feel confident that this arrangement works well because when dealing with edges that have been rolled 200 points or so we are able to restore those edges to their original sharpness reading simply by stropping and straightening the edge on a solid surface. Of course this ability indicates to us that the edge apex was not damaged by the rolling process. Here's a better idea of how the test is conducted:
The roller is lowered at "A" then moved (rolled) over to "B" and then back to "A". Just like rolling out dough. That's one cycle. Five cycles equals a set. Five cycles (1 set) seems to even out inconsistencies and provides for a single, accurate, measurement of roll. Both pre and all post roll measurements are taken right in the middle of the rolled section. The force applied during roller movement (A-B-A) is kept constant because the roller assembly is attached to a piston shaft that can freely move up and down. This up and down freedom of movement automatically compensates for any small deviations in the height of the edge along it's 1.5 inch travel. Of course this is all powered by our favorite transmission source, gravity.
Now to your next question concerning "will we will be able to decrease/increase the load". Yes, you will and simple provision has been made for that. If you refer to the picture of the device in our preceding post you will note the circular platen at the top of the force piston. Weight added to the platen will be directly transferred to the roller. Added weight would be what we would refer to as "advanced testing". Standard testing will consist of a 150 gram load with a roller angle of 10° and one set (five cycles) of movements. These parameters will keep all tests on a "apples for apples" basis. If someone wants to experiment using other parameters then feel free but one needs to keep in mind that these changes need to be referenced if reporting results publicly.
Just a little bit more on your first question KG concerning the 10° angle. This angle is actually adjustable from 0 to 30° or so. This change would fall under "advanced testing" as well.
While we're feeling expansive here one last thought. After our failed experiment with attempting to take physical measurements of the roll with a micrometer set up then "thank our lucky stars for edge testers" or this facet of edge retention testing simply wouldn't be feasible in any practical way. We always knew that edge testing would be more valuable information than physical measurements because once you tell someone that one edge rolled 5 microns versus another edge that rolled 9 microns they're going to look at you and ask "so what?". In other words, how does this information translate into how well my edge cuts? An edge tester will tell them precisely how that information translates. That being said, it would still be nice to have a physical measurement of the roll as just one more piece of information to work with. It's just not going to be in the cards. At least not for now.
See the black marks on the bearing surface? Those were made initially so that we could assure ourselves that the bearing was actually rolling and not just dragging across the edge. It rolls smoothly and doesn't drag so now we don't need marks.
We feel confident that this arrangement works well because when dealing with edges that have been rolled 200 points or so we are able to restore those edges to their original sharpness reading simply by stropping and straightening the edge on a solid surface. Of course this ability indicates to us that the edge apex was not damaged by the rolling process. Here's a better idea of how the test is conducted:
The roller is lowered at "A" then moved (rolled) over to "B" and then back to "A". Just like rolling out dough. That's one cycle. Five cycles equals a set. Five cycles (1 set) seems to even out inconsistencies and provides for a single, accurate, measurement of roll. Both pre and all post roll measurements are taken right in the middle of the rolled section. The force applied during roller movement (A-B-A) is kept constant because the roller assembly is attached to a piston shaft that can freely move up and down. This up and down freedom of movement automatically compensates for any small deviations in the height of the edge along it's 1.5 inch travel. Of course this is all powered by our favorite transmission source, gravity.
Now to your next question concerning "will we will be able to decrease/increase the load". Yes, you will and simple provision has been made for that. If you refer to the picture of the device in our preceding post you will note the circular platen at the top of the force piston. Weight added to the platen will be directly transferred to the roller. Added weight would be what we would refer to as "advanced testing". Standard testing will consist of a 150 gram load with a roller angle of 10° and one set (five cycles) of movements. These parameters will keep all tests on a "apples for apples" basis. If someone wants to experiment using other parameters then feel free but one needs to keep in mind that these changes need to be referenced if reporting results publicly.
Just a little bit more on your first question KG concerning the 10° angle. This angle is actually adjustable from 0 to 30° or so. This change would fall under "advanced testing" as well.
While we're feeling expansive here one last thought. After our failed experiment with attempting to take physical measurements of the roll with a micrometer set up then "thank our lucky stars for edge testers" or this facet of edge retention testing simply wouldn't be feasible in any practical way. We always knew that edge testing would be more valuable information than physical measurements because once you tell someone that one edge rolled 5 microns versus another edge that rolled 9 microns they're going to look at you and ask "so what?". In other words, how does this information translate into how well my edge cuts? An edge tester will tell them precisely how that information translates. That being said, it would still be nice to have a physical measurement of the roll as just one more piece of information to work with. It's just not going to be in the cards. At least not for now.