Yes, you can bring a weed grinder on a plane in Canada. However, there are some restrictions and things to keep in mind when doing so.
First of all, you can only bring a small amount of cannabis with you on the plane. This means that your weed grinder must be able to fit within the maximum allowed quantity, which is 30 grams (1 ounce). If your grinder is larger than this, you will not be able to bring it with you on the plane.
Secondly, you must make sure that your weed grinder is completely empty before going through airport security. This means taking out any leftover cannabis from previous use and emptying the kief catcher if your grinder has one. Security may ask to see inside your grinder, so it's best to be prepared.
Lastly, while cannabis is legal in Canada, it remains illegal under federal law in the United States. Therefore, if you're flying into the US from Canada, do not bring your weed grinder with you as it could lead to problems at customs.
So long as you keep these things in mind, feel free to pack your weed grinder in your carry-on luggage and enjoy using it once you reach your destination!