How often should I sharpen a log splitter wedge?

The frequency of your sharpening will be directly proportional to the use the log splitter gets and the type of wood it is splitting. If, for example, you are splitting soft wood such as pine, you may be able to get two weeks or more (likely more) between wedge sharpening. If, on the other hand, you are splitting oak, you may find that you will have your sharpening rasp out every week or so because oak quickly dulls even the sharpest wedge. Read the manual carefully and you may find that the most modern log splitters are actually self-sharpening. Even if they are self-sharpening, a good rasping will clean off any tars or gums that might slow them down.