Other Topics      Sharpening

 

Q. What is this Scary Sharp(tm) System and why is it trade marked?

A. The originator of the Scary Sharp(tm) System is generally accepted to be Steve LaMantia who described it in a post to the "rec.woodworking" newsgroup in November of 1995. I'm guessing that he added the (tm) to be humorous, but it stuck, and is usually included in the descriptive name. Scary Sharp(tm) is a sharpening system which employs the use of progressively finer grits of "wet or dry" emery paper which have been affixed to a flat surface, usually a float glass plate.

 

Q. Will anything else work for the flat surface?

A. Anything which is truly flat will work. A granite surface plate would work extremely well, but these are not cheap, and they are a little hard to move around and store, and a serious machinist probably wouldn't glue anything to his black granite plate. I don't recommend using the top of a table saw or jointer table for reasons which will become obvious. Regular plate glass, while not as flat as float glass, will probably be OK. Just make sure it is at least 1/4" thick and well supported when in use. Get the sharp edges sanded when you buy it. Some have recommended using square granite or marble floor tiles for this surface, but I checked several and didn't find any that were truly flat, and they are too small for a setup which includes several grits.

 

Q. Does the paper have to be glued down?

A. I think so. You will see descriptions where the author advocates just wetting the paper and letting it adhere to a flat surface with surface tension. I keep a plate with all grits ready to use at any time, so it is essential that the paper be stuck to the glass firmly. Any tendency of the paper to lift off the flat surface will cause problems.

 

Q. How do you glue the paper down?

A. I use 3M Super 77 Adhesive Spray. A fine mist from a spray can held about 2 feet from the back of the paper works perfectly. Spray as little as possible and roll the paper onto the flat surface with some pressure device immediately. I use a rubber J-roller designed to roll out plastic laminate. It is important that the paper be held tight to the flat surface. If not, you will slice through it when you get to the finer grits. For the same reason, it is also important that the flat surface be clean. I wipe my float glass plate with Goof-Off, a commercial solvent which works very well, but acetone would also work. Remember to invert the can of spray adhesive and clean the nozzle with the propellant in the can before you put it away. This stuff costs 6 or 7 dollars a can, but will last a long time if you clean the nozzle.

 

Q. Isn't this complicated?

A. Not really. If you use a fine mist of adhesive the paper will peel easily from the glass when it is time to replace it, and the adhesive will come off the flat surface with just a little solvent. I've probably made it sound more complicated than it really is. It takes about 20 minutes to clean a glass plate and glue on 10 pieces of emery paper. I spray the adhesive onto the paper out side my shop. It helps to place each piece of paper very close to the bottom edge of the plate glass because it is easier to wipe the burr off the back of the tool if the paper is close to an edge.

 

Q. What grits of emery paper do you use?

A. I have two float glass plates with 10 pieces of paper on each. The larger of the two is 20" by 30" and takes half sheets. This is the one I use when sharpening chisels or plane irons for the first time, and I often sharpen several in one session. The reverse side of the large plate has zirconia sanding strips for lapping plane bottoms. Because I already had the glass, I made up a smaller plate, 16" by 25" which takes quarter sheets and is used to touch up a tool which has already been sharpened once. These touch up papers last a long time. I put the following grits on each plate -- 180, 220, 240, 280, 320, 400, 600, 1000, 1500, and 2000. I seldom use 180 and 220 grit unless the chisel or plane iron is badly in need of reshaping. Generally I begin with 240 and shape the primary bevel with 240 through 320 grits. The primary bevel is usually set at 25 degrees. I then set the honing guide for 30 degrees and hone the secondary bevel (micro bevel) with grits 400 through 2000. It takes only a few strokes with each of the finer grits. After a few strokes with each grit, I flip the tool over and using the same grit wipe off the burr which has formed on the flat surface on the back of the tool. When you finish with the finest grit you should feel no burr and both the flat surface and the bevel should be mirror-like in appearance. This of course assumes that the flat portion on the back of the tool has been lapped flat and honed prior to starting the sharpening process. Yes, this takes a long time to accomplish, and yes, it is quite a bit of work for some tools, but this only needs to be done once for any given plane iron or chisel.

 

Q. Where do you find the finer grits?

A. An automotive paint supply dealer will carry the finer grit papers; the others can be found at any good hardware store.

 

Q. Should I use a honing guide?

A. That's your call. I've been sharpening and honing tools for more than 40 years and I always use a honing guide when sharpening a plane iron. I even went so far as to make a couple of honing guides designed to take advantage of the wide surface afforded by the plate glass. The registration strip on the side of each guide makes sure that the edge which is formed is exactly square to the axis of the plane iron or chisel. When I start to form the secondary bevel, I hone until I can feel a rough burr across the entire back edge of the bevel. I turn the tool over and wipe this burr off, and then progress through each of the remaining grits knowing that the final edge will be square. These guides are described in more detail on the Sharpening page.

 

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