I am a professional knife sharpener and hobbyist. Most of the time I use a basic 1x30 belt grinder (like many other professionals). Among grinders, these are inexpensive and high speed, though messy.
I wish show two main paths to go to sharpen nearly any knife or scissors. The first is with belt sharpening. Then I will present a few low or no cost options.
The most important thing in sharpening with any tools is a consistent angle through all grades of roughness. If you have an assembly that insures this, you can skim to the next paragraph, otherwise there are three techniques that will yield adequate results.
- First, a three-foot clamp is long enough to insure accuracy if the
opposite end is held in place, either free-hand or anchored.
many sharpening services use a simple lean-to metal rod, like a
clamped dowel rod, that can guide the flat side of the blade.
you can create or buy a V-shaped guide that fits around the belt and
only lets the blade in a single way. The Work Sharp Ken-Onion
Edition sharpener is a good example of this.
The simplest and most flexible to use is the three-foot clamp, or a one-foot clamp for hand sharpening on a bench or table.
After the angle, the next most important thing is to go through multiple grades of roughness. Going straight to fine (from 300 grit to 3000 grit) with eagerness to see a sharp edge will be very slow and wear out the fine abrasive belt more than necessary. The magic in "grit" measurements is to go up approximately 70% per step: 200grit to 360grit, 400grit to 700grit, etc.
The last most important practice is to use the right belts and medium. If your belt grinder comes out of a typical hardware store, then all except 220 grit ceramic belts may have to be mail ordered. The best belts for any size grinding system will be the Eastwind Diamond Abrasives products, but they must be water cooled (a fast dripper or water stream added to grinder frame). Another great wet/dry belt would be cork-composite-grit which range from around 120 grit to 800 grit to no-grit. If you want the blade sharpened super-fine and you use the cork-based belts, then you will need to have a Surgi-Sharp leather belt, as well.
As a general rule, plain aluminum oxide and silicon carbide belts either wear out too quickly or are too slow. If you need to sharpen ceramic knives and you don't have diamond, however, you will need the silicon carbide.
Water cooling/rinsing is the best, but if that is not possible, then frequent use of a belt lubricant is required to keep the belt from loading too much in the abrasive surface and to keep the heat down. If the blade gets too hot, the carbon will burn away, softening the metal, and the heat may shorten the life of the belt drastically. A big green 2000 grit compound block, or a silicone-based Crystalube syringe should be the bare minimum.
Now, there are only two definitely-need-to-know items left. Never put the sharp edge of a blade to a medium-to-high speed belt opposite to it's running direction, except with the thickest, hardest-abrasive belts, and with a tensioning back-plate under the point of contact. If the belt material is soft or if the belt vibrates in the slightest it will probably catch on the edge of the blade and be cut up and destroyed. The last item to need to know is to always keep the belts trued with a dressing stone (a ceramic stick made with 220 aluminum oxide). Without this, the belts will have inconsistent performance and will break down faster.
If you want to invest little or no money into the matter, There are four options:
(1) Go to a thrift store or junk yard and look for several roughnesses of straight, narrow ceramic or hard glass materials, like car windows with dulled edges, kitchen-ware, or large heating element insulators. Most ceramic and hard glass objects make good sharpening surfaces for a medium sharpening.
(2) Any whet stone or nickel plated diamond sharpener that can be used on a bench or flat surface. These are common and available in almost any camping store, just don't expect razor sharp results.
(3) An old real solid leather belt (layered leather doesn't work well). Just a little polishing compound and you can strope a knife like an old-fashioned razor.
(4) A can or tube of Flitz polish, if you have one in your garage. This with the leather or any flat-micro-textured surface makes a beautiful, shiny, sharp finish.
Even with these cheap methods, remember to use a one to three foot clamp to hold the blade at exactly the same angle (ideally 20 degrees on each side, approaching 40 degrees total edge angle), except of course, the stroping with leather belt. This can be done on a bench, but may work poorly. Also, with all methods, you must carefully, thoroughly scrub your finished blade, since there will be metal particles too small to see in all the microscopic grooves that could end up in your food and your body.