Chris "Anagarika";12662013 said:
Martin,
Thank you. I have just watched One and Two. Your voice came through nice and the sound of the abrasive at work is clear as well!
One thing that you might want to further emphasize is that a loaded sandpaper can cause edge burnt (de-tempered), as debated over the cliff stamp thread in spyderco.com forum. It also depends on the speed and pressure I guess, and using erasier to lift off the swarf is great idea.
:thumbup:
@Mag,
The instruction is very good also for beginner and old timer alike, to reminde us all on the basic steps. You might want to add this to the sticky there
Chris, First off thanks for watching! The last series was done so poorly I could barely watch, glad this one is noticeably better.
I find that by the time the sandpaper degrades to a point where it
might cause de-tempering at freehand speeds, its pretty obvious I need to replace it. I am almost obsessive about keeping that sandpaper clean though, and doing so really lets me know when
it is time to replace or move it around some. A lot of this comes back to my theories when working with all stones, especially waterstones or sandpaper - move around the surface at the initial grinding phase and you won't have to worry so much about things like dishing and plugged/glazed sandpaper or stone surface. Then the surface is in good shape at the sweet spot for burr removal and finishing touches.
Somewhat ironic, until I started using it on the Washboard I had all but given up on sandpaper as I could see no advantage over hard stones. Now I only use the stones when I need to do some heavy stock removal. For regular work, the paper is holding up better than I remember.
Personally I am very dubious of a modern heat treated steel loosing its temper at freehand speeds, but then I seldom do any faster than what you see in the video. I know there have been studies showing elevated spot temperatures on a steel block being dragged over dry abrasive, but am unsure how these sensors were positioned to avoid false readings from bits of steel that were no longer connected to the main block, or how the actual pressure or friction coefficient compare to hand sharpening. The couple of times I've used a scale to see how much pressure I normally use, it clocked in at a couple of ounces at the high end. There's a lot of speculation about the heat concentrating at the apex, but that's also where the highest rate of heat exchange occurs.
In my own experience, and I can't assert this with any real authority
- edges that are physically clean last a long time - most issues that crop up unexpectedly were from physical defects (dud metal on the cutting edge as opposed to de-tempered steel) already there and just being revealed by use, not structural ones.
Bottom line - avoid the issue altogether and keep the paper clean and in good shape. This also avoids a lot of frustration, which is just as good a reason
Martin
