I recently bought the Makita 9820-2 Blade Sharpener from Amazon and I thought that I would give a report on how it works. I brief, I had to fiddle with it when I first got it but now that it is set up it sharpens quickly, consistently and sharper then I got from a professional service.
So far I've used it to sharpen 2 sets of 13" planer knives, 3 knives in each set. I have also used it to sharpen one set of 6" jointer knives, again a 3 knife set. It took about 90 minutes of fiddling with it to understand exactly how to get the knives where I wanted them, get everything adjusted and come up with a repeatable procedure. Now that I have the procedure down, it takes about 4 minutes to sharpen a single 13" knife.
To test the Makita, I took a 6" wide 1" thick piece of African mahogany and sent it through the planer on low speed (10 fpm) with knives that I just got back from a sharpening service. The result was fine and exactly what I had come to expect. I removed the knives and sharpened them on the Makita. I put the knives back onto the planer using the same method and acheiving the same accuracy of knife above cutter head as before. I turned the test board over and passed it through the planer. The result from the Makita sharpened knives was the best quality that I had ever gotten from my planer. With each test, I sent it through until I got a full cut, then turned the crank 1/8 of a turn and took 2 more passes at 1/8 turns each time. It is not a completely fool proof test, but I am confident that the Makita sharpens at least as well as a professional service and probably better.
I had several concerns with the sharpener:
* The method to setup the tool rest and mount the knives in the holder to get the correct angle is not clear, and is rather subjective. It consists mainly of eye-ball it, try it and make corrections, repeat until you think it is good enough.
* The manual consists mainly of how to assemble the machine, however, the machine is so simple you don't need a manual to assemble it. The manual is available in pdf format from the amazon site.
I have one more issue, but it is not with the Makita specifically, but with sharpening in general. I wish there was an objective measurement for sharpness. If the knife has ground the entire bevel, shaves my fingernail easily and has developed a slight burr I call it sharp.
Here is the procedure I have settled on, I would be glad to get suggestions from others who have used this tool.
Initial setup:
I set the knife in the holder roughly 0.5" above the holder. I placed the knife and holder in the sharpener and adjusted the tool rest heights as shown in the manual. I then took a permanent marker and every 1" drew a line from the back of the bevel right off the sharp edge of the knife. I began to sharpen the knife according to the manual. After 1 minute of sharpening, I looked at the pattern of ink marks and adjusted the tool rest and knife height in the holder until the entire bevel was being ground evenly. From this procedure I locked in the settings on the sharpener by tightening the lock knobs, then I measured the height of the knife from the edge of the knife holder and it was 0.43". Your values will be different because your tool rest will have slightly different settings. This process took about 90 minutes.
Standard Sharpening Procedure:
1. I set the knife in the holder with all the depth stops retracted except for the outermost stops. Using the depth gauge on my dial calipers I set the top of the knife to 0.43" from the black steel edge of the knife holder. I mark lines across the bevel as described in the initial setup because it is easy to do and provides positive feedback.
2. I place the knife assembly on the tool rest and begin the water flow if it is not already started. I adjust the flow until there is water all over the back of the knife in the area of the stone.
3. Rotate the knife up and off the stone, start the motor and lower the knife. Keep fingers spread over the entire knife to ensure constant pressure. Start sliding the knife from side to side, completing one slide in 6 seconds.
4. Sharpen for about 2 minutes and check the pen marks and feel for a burr. Repeat for 2 more minutes if necessary. When the sharpener is setup correctly and the knives do not have chips in them, I have never needed to sharpen more than 4 minutes. Typically, to mount a knife in the holder, measure, mark, sharpen, remove the knife, dry it and set it aside takes a total of 4-5 minutes for a 13" knife.
Here is the link for where I bought it
http://www.amazon.com/gp/product/B00...lance&n=228013