How to measure a ground blade edge thickness prior to sharpening.

[Brad Gover]

Hi all. Just joined this forum. I have a question on how to measure the blade edge thickness after bevel grind. I have tried using an Optical Comparator to measure the edge. I have tried using ground anvils that hold the bevel ground blade where the anvil contacts the flank angles of the blade. A fixed mounted micrometer can them measure the blade edge thickness a small distance from the actual edge. We trig out the thickness at that distance from the edge. I have tried using a go/nogo gap parallel bars too. Is there any specific gaging method that has a high repeatability value and is accurate enough to use that measured value in making process adjustments to the bevel grinder? I appreciate any thoughts.

 

[Stacy E. Apelt - Bladesmith]

You are overthinking this. Just use a hand held metal jaw micrometer and get as close to the edge as you can. It isn't going in a rocket engine ... it is just a measurement for a rough idea. As long as you measure all your blades at the same approximate spot, it will give you useful data.

 

[Ken H>]

What Stacy says. Take a micrometer set gap to what you're looking for - say .005" (or what value you wish). Slide edge along gap, you'll tell when the edge will catch in gap which is the .005" you're looking for. If edge won't slide into gap, grind a tad more and check. You can open micrometer gap to the point where the gap just allows edge to catch in gap and you'll have "pretty much" the edge thickness.

While this method might not measure to tenths of a thou, this gives a workable measurement.

 

[jdm61]

Digital calipers from HD or Lowes. You will figure out pretty quickly how to measure right on the edge or darn close to it.

 

[Stacy E. Apelt - Bladesmith]

Adding to what Ken said:
Most good micrometers/calipers have a lock screw. Just set it to something like .005" and lock it down. Set it on the blade edge amd slide the blade down while looking down on the edge. An optivisor is very useful here. You will easily see where theblade is thicker or thinner than .005 ( or whatever it is set at).