Homemade Power Sharpener

This is the sharpener I use for knives. It is based on the type which Ferd Nordstrom of the Mid- America Woodcarver's Club in Omaha, NE made in the mid 1970's. I used such a machine for both knives and gouges for 20+ years before I tried a belt sander with an adjustable arm. Now I prefer a 1" belt sander type sharpener for gouges such as shown at the bottom of this page. But I still prefer the wheels for knives.

I use a 5/8-inch shaft, I just like the "feel" of 5/8 and self-aligning pillow block bearing in that size are cheap. I get the shaft from a local hardware store or machine shop, for two wheels 18-inch shaft is about the right length.

The bearings have used are Washdown Pillow Block Bronze Bearing, Pressed Steel Housing, Self-Aligning Type, 5/8 inch Bore Size DAYTON 2X529/36/18 In the past I got them from Grainger for about $4.75 each but haven't found them there recently, closest they now show on web site is $11 so check your local stores and other web sites. Let me know where you find them cheaper. The advantage of Grainger is they have retail stores in most medium size cities so you can avoid shipping charges. Click here for the $11 pillow blocks. You can search for other pillow blocks or look up Granger store locations or order on line from Granger here

Cut the wheels about 6.5" in diameter. I like 2-inch wide wheels, which takes 2 pieces of 1-inch particle board glued together. The only place to get 1-inch particle board that I know of is from kitchen counter tops or use 4 pieces of 1/2 inch MDF board from Home Depot (used for shelving). I get rolls of 2-inch wide "gold" from Klingspor in Hickory, NC so it is just easier to have 2-inch wheels. Also many knives are longer than 1.5 and less than 2 inch and I like to get the whole knife blade on the wheel. The rolls I use 2"X 10 METER 180 GRIT GOLD CLOTH ROLL. For Klingspor web site click here. On the other wheel I use a thin (1/6 inch thick) synthetic leather. I glue both down with UHU stick glue from Michael's or Walmart. If you use a thicker piece of leather you will have to find a stronger glue.

Cut the wheels as best you can on band saw. Don't be too concerned about how truly round they are as we will true them up later. Drill a hole in center with a 5/8 spade bit which you file the sides a little first (a few thousand of an inch) to make it a tight fit. Drill on a drill press to ensure hole is perpendicular to the wheel. chamfer the ends of the shaft a little and drive the shaft into the tight hole with a hammer (and piece of pipe to hold wheel once shaft comes through other side) using WD-40 to make it go easier. The fit should be tight enough that you don't have to fasten the wheel to the shaft with any kind of fastener. There is not much torque on the wheels when in use so a tight fit works.

On one wheel you screw (after mounting both pieces on the shaft) a 3/4 in piece of particle board that is about 6 inch in diameter. This is to make the pulley out of. Note the screw through the pulley to one wheel. When the pulley and wheel are butted together there is always a little space where it doesn't come together as tightly, this is where you place the screw which causes a little more pressure on the shaft providing a tighter fit and allowing more torque on that drive pulley.

Keep wheels about 10 inches apart on the shaft or more so you can get the knife handles between them. Getting both wheels positioned properly is a challenge as the first one moves when you start pounding on the second. A little patience and experimentation will work it out. Just watch what is happening with each hit of the hammer and learn what is happening. I put the pulley part of the one wheel such that the pulley is facing in between the wheels, not outside both wheels. This allows positioning the motor closer to the center for better weight balance when carrying it and a shorter overall size.

I like enough shaft sticking out each side of the wheels so I can mount a threaded adapter on each end of the shaft to put cloth wheel for polishing tool shafts or another wheel with coarse grit for shaping blades. you can buy the threaded adapters for about $4 each.

Once I have the wheels on the shaft I mount them in the self-aligning pillow blocks and the wheel/shaft assembly on base that I will eventual have the motor mounted on. Then I rig up my radial arm saw with a 10 inch sanding disk vice a blade and use the sanding disk to "true" the wheels round and to cut the "v" which actually ends up a "u" in the 6in diameter pulley part. It is hard to describe the process of truing up the wheels with the sander but I will try. The radial arm saw works well because it allows you to have the sanding disk high enough to engage one wheel at a time while mounted on the shaft.

I align the wheel/shaft assemble on the radial saw table such that the shaft is aligned in the direction of radial saw travel although I won't be pulling it out during this operation. In fact it is best to pull it out about have way and tighten it securely their. I get the "face" of the wheel as close to the sanding disk as possible, clamp the base to the saw table at the table front. Before starting the sander, verify you still have both the shaft and the saw travel direction parallel or the "face" of the wheel won't be perpendicular to the sides when you are done. Now turn on the radial saw, while holding the other wheel with your right hand so it won't turn, I use a hammer in my left hand to tap the sharpener base such that the wheel engages the sanding disk. Then I slowly turn the wheel in my hand which also turns the wheel against the sanding disk. after each revolution of the wheel, I tap it again until I take off enough wood that there are no more bandsaw blade marks on the wheel. Now it should be true, check "face" of the wheel with a small square to ensure it is perpendicular to the sides before shifting your setup to the next wheel.

To cut the "V" grove in the pulley, I rotate the entire wheel/shaft assembly so it is perpendicular to the saw travel, move it in until the sanding disk edge engages the pulley and repeat the process above for truing the wheel faces

The first machine I built I had 5 wheels ( 1 leather and the others various grits of cloth backed aluminum oxide) thinking I needed to transition from one to another (but that is overkill). Then I went to 3 wheels which may be better than 2 wheels as I had a 180 grit and 400 grit which allows for both aggressive and fine grinding before stropping on the leather. But I went to 2 wheels for the ease of carrying it around to classes when I started teaching. 2 wheels are much lighter and it balances when carried in one hand by the shaft.

Motor is from an electric clothes dryer. Comes with the motor stand and the pulley, just need to buy a belt. As you want it running slow, a 1760 RPM motor is essential and the dyer uses that. also a 1 inch pulley is essential and it comes with that size.

A smaller version of a wheel sharpen is shown here. This is one that Ferd Nordstom made from a discarded double shafted fan motor. It is about 12 inchches long by 8 inches high and 5 inches deep. Very portasble, fits nicely in my suitcase when I fly to seminars. Not much torque, and the motor gets hot quickly, but it is good for occasssional touch up.

I prefer a 1" x 42 inch beltsander for sharpening gouges such as the one shown below, although with the addition of the same type of adjustable arm for positioning the gouge, the above wheel sharpener will work also. I used the wheel sharpener for 20+ years, without an arm or brace of any kind, before getting a belt sharpener for gouges.

. The big advantage of this belt sharpener is slower belt speed (slower than others) and especially the moveable arm for getting the right angle ( easiest with the digital angle gauge shown here) For an angle gauge click here.

Another less expensive option is to make a similar machining from a standard cheap belt sander. The problem with these cheap belt sanders is they run in a direction which is down into the table when you want the belt running up away from the table for sharpening. The problem with most Asian made belt sanders is the motor direction is not changeable as there are no motor connection leads to provide reversing the starter winding. So you get around this by hanging the belt sander upside down which then allows for adding an appropriate arm for finding and maintaining the correct edge angle. The hieght above the arm you hang the belt sander will determine how long a gouge you can sharpen so think about this when designing your box. Make it high enough for longest tool you expect to own. Then have attachements for the arm that shorten the distance for your shorter tools. The pictured machine is Eric's in Rochester, NY

To see30" Harbor Freight belt sander click here.

For that belt sander I use the 1" X 30" 60 grit Klingspor PLANER BELTS for wood handle and blade shaping, and the 1"X30" GOLD 180 grit and occasionally a 320 grit SHARPENING BELT.

email me with questions and pictures of your homemade sharpening machines - Jim O'Dea [email protected]