Some measured geometries

[sputnick]

I was tired of not knowing enough about the specific geometry of my blades when i evaluate them so i picked up a digital caliper and took a few quick measurements. I get a lot more chips in the kai then i ever get in the benchmades. Some of you guys sharpen at 40degrees for folders?

Please add/comment on any of your working geometries and steels and how they are working for you. (yes i know geometry has been discussed before) I'll get up some better measurements a bit later on. It would be interesting to calculate the volume of steel behind edges of various sizes to see how strength should increase with blade cross section.

 

[the possum]

I have to thank you for the effort of measuring your blades, but would you mind providing some clarifications on the table? What does the blade flat mean? Is that the width of the primary grind? Am I correct in assuming all these measurements are in milimeters? And the edge flat also refers to width? The thickness is measured at the top of the edge bevel? Are the angles listed included angles, or per side? Were the angles measured directly, or did you calculate them based on the thickness and width?

 

[sputnick]

Yeah i posted that right before i had to make dinner so its a bit lacking in readability as well as precision (dropped a few decimal places here and there). I'd get my butt whipped if i made a chart like that for school (my chemist father wouldnt be impressed either)

You've got everything right. The angles are included angles calculated from the width of the 2 flats (edge or blade faces) and the thickness at the top of the edge and the top of the primary grind. I havent figured out a way to accurately measure the edge angle directly. BTW, this franklin armory digi caliper is nice for something you can pick up at the local gunstore but i am spoiled by the starrett calipers and micrometers we got to use in the university labs. Still, 0.01mm precision is good enough for the tool box.


I'll get up some better numbers and a protocol in a bit (lady is at the park with the dog). I'd appreciate any observations you may have.

 

[sputnick]

Here are some more reliable numbers. The 710 got resharpened yesterday with a slightly different technique. Normally i loosen the flat plate of the bladesharpener to get the knife in but this time i loosened the curved plate to see if i couldnt get a more even edge on it. You'll notice that the primary grind widths are different. The chart in my original post i just duplicated the numbers assuming they would be the same, as it turns out the grinds are just a hair off. I also added a distance from the point that the measurements were taken so the tests can be replicated. Thats also why the numbers on the 710 primary dont match the first set.

Picked up a scrapper 6 and HRLM from the PRO gun show today so those measurements are as received from the factory. The scrapper 6 has full flat grinds so the primary width was the same on both sides, however the HRLM crinkle coat makes it very difficult to get an exact position to measure from for the top of the grind. Also on the HRLM there was a slight rise on the left edge grind centered on the point of measurement, the rest of the left edge facet is closer in width to the right side.