Commercially available bending irons are acceptable but leave plenty of room for improvement. After having the heating element fail in my unit, I decided to give the whole unit an upgrade to produce more consistent bending with less chances of burning ribs.
I kept the aluminum ‘iron’ and discarded the rest. I rebuilt the base from maple in a similar fashion to the original. The cartridge heater was replaced with a 250 Watt unit. A PID controller and thermocouple replaced the old-fashioned stove element controller. This allows for accurate temperature setting, with a clear digital display. The PID controller keeps the temperature on target.
The aluminum ‘iron’ was hollow, meaning that the outer surface of the ‘iron’ would cool if it was bending wood, particularly when using a wet cloth for steam. By filling the head with lead free solder, the amount of heat held by the head increased significantly. The temperature stability improves but the initial time to heat-up to bending temperature is increased.
I’ve very happy with the performance of the rebuilt bending iron. I’ve found bending temperatures of 160ºC (320ºF) to 170ºC (340ºF) sufficient.