Super Simple Sharpening Jig

[999]

After deciding I was rubbish at keep a sensible angle for sharpening freehand, I decided to make a Sharpmaker-Style jig.

A few measurements and a quick refresher of trigonometry later, and here it is:
http://fistload.co.uk/hosted/sharpjig1.jpg

This is an old test-tube rack. I am assuming the joints are 90°. I marked on the sides for a 15° and a 20° angle for a sharpening stone exactly 10cm long (which is the size of mine). Each end is held in place with Blutack to align with the markings made. The blade is then swiped down parallel to the upright. Because I have only one stone it needed to be turned for each opposing pass but still worked effectively.

Maths (for those interested in making their own)

h=length of sharpening stone
o=long side
a=short side

15° angle:

o=h SIN 75
a=h COS 75

20° angle:

o=h SIN 70
a=h COS 70

SIN and COS can be used from Windows Calculator by pressing after the 70 or 75.


40° only seemed to blunt my Native, but 30° has left a VERY effective slicing edge.

[EDIT] I assume this is the correct place to post this?

[Anarcus]

I like that idear :)

The maths is still a bit clever.
Perhaps an easier way would be to just use a cheap protractor.
Got to be worth a bit of Rn'D on a wet Sunday afternoon.
Tim

[999]

Thanks!
Unfortunately one of my limitations was lack of protractor :D
I will at some point in the very distant future rig up something more permanent (probably with ceramic rods) as it feels a bit weird stroking down a 3cm wide combo-stone.

Hope it helps those like myself who aren't confident at keeping an angle.

[EDIT for typo]

[dtalbot]

Nice lateral thinking, I think I stick to the sharpmaker though!