To check refrigerator temperature, place an appliance thermometer in a glass of water in the center of the refrigerator. Read it after 24 hours. To check the freezer temperature, place a thermometer between frozen packages. Read it after 24 hours.
Using thin wood wafers called biscuits can strengthen wood joints by providing more glue bonding area. You can use a biscuit joiner (also called a plate joiner) to cut precision mating slots in boards for the biscuits, which are available in three sizes. Or, to save money you can buy a kit to convert either your router or right-angle grinder. The conversion kits will generally cost about half that of a dedicated biscuit joiner.