While weed grinders basically make your life easy - the hardest part of having a weed grinder is when it comes to cleaning it. This is hard because weed (especially when fresh) is often very sticky and can stick on to the teeth as well as to the sides of the grinder. If you don’t clean it when it is still fresh, it will become hard to scrape later on. Use a hard toothbrush along with salt or isopropyl alcohol which will help the weed that might be stuck on to the teeth slide off with relative ease. However, don’t sweat too much over it if you’re not able to clean it and order a new grinder if you’re having trouble cleaning it as grinders tend to be quite inexpensive in any case.