Sharporexia Nervosa--aka cumpulsive sharpening

Ah, but now budget calipers have to also be positioned to a precise depth...very precise.

How are you going to calibrate these calipers for depth?

[Wondering out loud mode]
Maybe you can jury-rig a setup using some levels, clamps and a cheap laser pointer and calculate the edge angle from the reflected beam?

[This message has been edited by Longden (edited 05 November 1999).]
 
I'm still thinking. One thing that comes to mind is a magnifying glass and a straight bladed pair of scissors. You tighten the pivot screw on the scissors so they hold their angle. You try and fit the scissor angle to the part of the bevel (primary or secondary that you're measuring). Hopefully you can see what you're doing with the magnifying glass. For the final edge bevel it may help to use a candle and put some soot (lampblack) on the edge for visibility. If you can't see the bevel directly you might slide the scissors along the edge so that you scrape off soot in your contact area. With a little tweeking you may be able to see how flat the edge bevel is (or isn't) and how well you match it with the angle of your scissors. A little trig and a pocket calculator can figure your included edge angle.

The laser pointer sounds pretty good, but may only work when you use a blade clamp when you're honing.



[This message has been edited by Jeff Clark (edited 05 November 1999).]
 
The caliper could be modified by attaching a stop on one of the jaws, a stop which would extend across the opening and allowing the other jaw to move freely. The stop would just be a short bar attched with a couple of screws, something that would be easy to do with the plastic calipers.
 
Jeff, I like scissors idea, tho lasers are always "cooler" (I hate that word).

I wonder what'd be a good way to test the calibration on the scissor measurement? Slightest movement will throw off the measurement, so the margin of error will probably be a concern.

Same with the caliper idea, only there's the added problem of mounting a rigid stop at a precise distance. Plastic calipers may add another margin for error due to slight deformations.

Gotta find a pair of scissors later at home with a pivot adjustment. This seems like something that can be done with a protractor type precision measuring scale ... I'll have to check my hardware store also.

[This message has been edited by Longden (edited 05 November 1999).]
 
Machinists have a protractor with a swinging metal arm that matches my scissors idea. It has a scale you can read. You can probably get one at Sears or a good hardware store. It just didn't fit the bill of something I had at home. (You know you're a nerd when you have more than one pocket laser at home.)


[This message has been edited by Jeff Clark (edited 05 November 1999).]
 
I have always been a nut over sharp blades since I was in grade school! I always had to have the sharpest knife around.
Over the years I have had probably every sharpening device made...my ultimate choice is the Edge Pro "Professional" which will get any blade as sharp as you want and put the perfect angle on the blade!
 
Jeff, I mentioned originally that the stuff should be readily available at a local hardware store.

The idea is that the method would be repeatable by anyone without having to get access to special equipment.

My hardware store was out of those metal protractors, so maybe I'll try somewhere else tomorrow. I kinda wonder how accurate it'll be measuring the final bevel on a two bevel edge. Seems like it'd be easy to push the ruler to the point where you're measuring the primary bevel rather than the final one (ie, Spyderco's 30 deg vs the 40 deg).

I don't have a laser pointer... no real need to (even tho I am a nerd), but I was thinking that a laser aimed head-on the edge would reflect in two directions, and that angle should be easy to measure. Given the parallel nature of the light, it should be easy to calibrate the setup.
 
You might hope to get all your bevels at the same time with a laser. You might need to buff the blade to a high polish to see your result.

 
Oh well, I always wanted me a laser pointer... could be this is a good reason.

Be interesting to see if the light is intense enough to show a clear reflection of a bevel, even unpolished. Should see at least 4 points of light for a double-beveled edge, and the arc between the two closest spots to the light source should indicate the angle at the edge.

Of course, in the real world, aberrations in the edge will probably muddle the whole thing.

Let you know if I get a chance to play with this. One more way to alleviate (or heighten) sharporexia.
 
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