Assembly is easy. The Bearing will come already installed in the bottom piece and the top piece placed on it. All you need to do is determine which spool pin is ideal for your solder and insert the M3 screw into the plastic washer and install it into the bottom of the spool holder and up into the spool pin making sure to not over tighten. This holds everything into place. The top portion of the spool should spin freely. Finally install the four plastic no slip feet onto the bottom of the spool holder and assembly is complete.