Cotter Pin Joints
Cotter Pin Joints for Teddy Bears and Other Critters
Each cotter pin joint consists of five pieces two hard board discs, two metal washers, and a cotter pin.Sizing the Cotter Pin.
Smaller bears, under ten inches tall, typically require only a 1/16" diameter cotter pin. Edinburgh stocks 1/16" thick discs from 1/4" to 1 1/4" diameter with a hole to fit the 1/16th inch cotter pin. To create a tight joint, you will need to put a full circle curl (or more) in each leg of the cotter pin. Test your cotter pin to make sure that it is long enough to make the curl with your fabric.
Bears taller then ten inches typically require 3/32" diameter cotter pin. Edinburgh stocks 1/8" thick discs from 1/2" to 4" diameter with an 1/8" hole to fit the 3/32" cotter pin.
To create a tight joint, you will need to put a full circle curl (or more) in each leg of the cotter pin. Test your cotter pin to make sure that it is long enough to make the curl with your fabric.
The disc size is typically confirmed by measuring the flat width of the assembled Teddy Bear arm where the arm mounts to the body. This dimension is the maximum disc diameter that will fit in the arm; however the disc should be somewhat smaller than the maximum in order to allow for the fabric to curve around the stuffing.
The size of the disc center hole is determined by the size of the cotter pin as described above.
Sizing the Washer
Including a washer in the joint makes a more durable joint by creating a metal surface for the curled cotter pin to rest on. This is particularly important if the bear will be handled a lot and is good practice for your bears because you can't predict how often the joints will be moved.
Edinburgh carries the W7 and W8 brass washers for the 1/16" cotter pins and the disc diameter of 3/4" or less. For larger discs the W5 works best.
Edinburgh carries several different washers for the 3/32" cotter pins. W5s make the tightest fit on 3/32" pins but we also carry W3 for 1/8" cotter pins and W1s with an even larger hole.