When sharpening the blades for your mower, is it best to sharpen them on equipment that has high RPM's of low RPM's? Have been sharpening with a bench grinder. Just purcahsed a sharpener form lowes however, it only runs at 120 RPM, seems awful slow. also, should the wheel be soft or hard? The cost of some of the sharpening machines ($900 or more) is just way out of my price range. I am going to buy another blade balancer though. Have the little $5.00 cone job.
I use a 9" angel grinder for standard blades and a 4 1/2" on mulchers, chunk them in a vise and be done in a couple minutes.
You can use a high or low speed grinder. A high speed grinder will be much faster but easier to overheat the blade. If it has blue spots it got too hot. This weakens the temper of the metal and makes the blade nick easier.
I use a bench grinder on mine, never had any problems running 3000 rpms on the grinder itself. Soft wheels will sharpen faster but wear quicker, they dont heat the metal as quickly, hard wheels will last longer, sharpen slower, and heat the metal more.
Get a grinder and use the sandpaper pads with a grinding wheel backup and nothing overheats and the total cost is less than $100.
I used one of those and the pads kept coming off after each sharpening. Nothing compares like a dedicated mower blade sharpener. A dedicated sharpener does it a lot faster and gives a precise even angle and sharp edge across the whole blade. You can get one from Landscape Supply from Travis (one of the sponsors) for under $300. I got the Oregon 88-023 model. Do not get the cheaper 88-021. I can tell a big difference in the cut of the grass after getting a dedicated blade sharpener.
