09-08-2017, 07:20 PM
“I'll remain skeptical… “. Truly, a man with an iron will, eh? 
“I just had a horrible thought…”. I wouldn’t let it keep me awake at night. Check this out. Here is an image I took of a burr standing straight out from the edge. The test media simply smashed it down to the nice clean edge when I took a reading.
Indeed, in some circumstances a sharp wire edge can cause an erroneously sharp reading, but more than likely a burr will cause a higher, not lower reading. To avoid being misled by that, or to at least better understand what is going on, I generally take more than one reading on the edge.
Keep in mind that the test media is very small in diameter, and will definitely indicate if variations exist along the edge. That can at once be informative, misleading and even frustrating. Nonetheless, it is telling a truthful story about the edge. I’m quite sure that after a while you will accept, trust and even delight in the readings along the edge.
Obviously, variation along the edge is more pronounced with a toothy grind than with a smooth grind. For instance DE razor blades show very little if any variation.
If a polished edge chisel is showing much variation, I would suspect first burr, and second, uneven sharpening such as not actually reaching the edge when grinding. From what you have posted you seem very good at sharpening, so in your case I would suspect burr. A good light and magnification will more than likely resolve that question.
“I just had a horrible thought…”. I wouldn’t let it keep me awake at night. Check this out. Here is an image I took of a burr standing straight out from the edge. The test media simply smashed it down to the nice clean edge when I took a reading.
Indeed, in some circumstances a sharp wire edge can cause an erroneously sharp reading, but more than likely a burr will cause a higher, not lower reading. To avoid being misled by that, or to at least better understand what is going on, I generally take more than one reading on the edge.
Keep in mind that the test media is very small in diameter, and will definitely indicate if variations exist along the edge. That can at once be informative, misleading and even frustrating. Nonetheless, it is telling a truthful story about the edge. I’m quite sure that after a while you will accept, trust and even delight in the readings along the edge.
Obviously, variation along the edge is more pronounced with a toothy grind than with a smooth grind. For instance DE razor blades show very little if any variation.
If a polished edge chisel is showing much variation, I would suspect first burr, and second, uneven sharpening such as not actually reaching the edge when grinding. From what you have posted you seem very good at sharpening, so in your case I would suspect burr. A good light and magnification will more than likely resolve that question.