A few things you did not mention. What kind of blades are you using? I use to sharpen my solid steel blades, but most of what I have now are carbide tipped.
The frequency depends. You may want to first clean your blades to remove any pitch and resin buildup. Many products sold for this process, search Rockler or Amazon for pitch removers. You could even use an oven cleaner.
If I have a clean blade, and I’m pushing with more force than I’m used to or my cut line has burn marks, it’s time for sharpening.
For sharpening, I have been using http://ridgecarbidetool.com/sharpening/ and have not been disappointed. Forrest also sharpens blades, see http://www.forrestblades.com/aboutsharpening.htm and they have had good reviews from this site.
I’m mainly using Frued blades, and have a few of each type, rip, combo and cut-off. I’ve sent two off for sharpening this year. Clean blades last a long time.
-- Nicky
