Before using it for the first time, it is a good idea to clean your weed grinder. Start out by unscrewing each of the 4 pcs and inspecting them. Sometimes there could be small flakes of material left from the manufacturing process or from the screen edges. Wipe the grinder down with a little isopropyl alcohol and use a q-tip if needed to get into the grooves. It is now ready to use.
Frequent cleaning isn’t necessary, but if the kief clogs the screen or makes the weed grinder difficult to turn you may want to clean it. Before cleaning, you will want to collect as much kief as possible. A trick for this is to place a piece of paper on a table and tap each piece of the grinder on the paper thus shaking off the kief. If there is a lot of buildup, you can place the grinder in the freezer for 15-20min prior to this as it will help loosen it up.
Once the bulk of the kief has been collected, use a toothpick or fine tipped object to remove as much as you can from the grooves. You can try flicking the screen with your index finger, but be careful not to dent or damage it. Finally, wipe the grinder down with ISO alcohol and use a q-tip to get in the grooves.