There are many questions about messuring a blade. Are the blqde sides really parallell on a parallel blade, are a triangular blade really triangular for example. My answer is that parallel blades are surpicering often not parallel and that triangular blades surpricing often are not centered...
When there is a problem here, the problem also concern the edge becouse the problem from the sides slides over to the edge. I have never, so far, meassure a edge that have the same angle on both side of the edge.
Older blades was often stamped out with a big, heavy stamp, from sheatmetal. If the stamp did not hit the metal 100% correct, the stamped blade come out not parallell from the stamp. I found this out on old Mora blades for some decades ago. I could se how the stamp hit the blade and where the biggest power in that hit was.
Then a rotating big grinding machine grind out the edge, one machine on one side, a sexond machine on the other side. If those machines grind in different angles (and they allways did) the edge was not perfect
centered allreasy in this stadge.
of cause, i talk here about very small meassures, some hundered parts of 1 mm. For a normal knifeowner, this small things so not matter, they so not even se it or feel it. But - for understanding how edges work, this is importent understandings about how the problems are when we like to meassure our edges as exact as possible...
In my mind, we must build something that meassure one side at the time to get as exact figures as possible. The two sides meassuring is not as accurate we need to have.
One side meassuring are, in my mind, more easy to conatruct with the laser but more difficult about hiw we fix the blade to the "meassuring table". The "laser tower" that gives the height, or, yhe meassuring table, must be able to slide forward and back (the measuring table also in height up and down in a secure way so that it is possible to meassure blade sides in exactly the same height (all blades have not the same thicknes). Perhaps can we adjust the laser height instead of the meassuring table?
All tye meaasuring devices I have seen meassuring a free hold kniveblade and the edge cut the laser beam and show the result on both sides of the edge with red dots on a double "protractor". To get the dots correct on both sides they adjust the red dots by turn the blade a little - so the red dots shows the result after a man made adjusting of the angles.
That is why we need a tool where the blade are fixed in position on a "meassuring table" where the blade cannot move during the meassuring.
In my mind this tool must allways use the same distance between the cutting edge and the laser head. Thats why the rool need a sliding part. Then it is possible to meaasure a small blade and a cleever in the same tool.
Depending how we like to read the result we can construct this tool in many different ways, shall we read behind the edge as on the tools there is today, or on (or thru) the "roof" in a box?
This is just lose thoughs from my side, if someone like my way of thinking, use what I wrote and build a tool
Thomas