Luthiers bending iron with PID controller
I’m making a two part bending iron with a PID controller. The reason for it being in two parts is so I can unplug the bending iron and plug in a bending blanket. I decided to make my own as the only one I found available in Australia looks to be rudimentary by design electrically. I am not going to go into detail of the wiring of this device here. Just thought I would show what I have come up with. The basis of the iron itself is a solid 80mm diameter block of aluminium 200mm long, I have drilled a hole through the length of this to install a heating element which is 500 Watts, thermal paste has been added also. I have also drilled holes to reduce the thermal mass of the aluminium. Drilled and taped 3 m8 threads to mount the block to the box, the aluminium sits on a piece of cement sheet and the bolts have fibre washers and a sheet of mica to protect the malamine from heat. There is also a taped thread for the thermocouple. I found some connectors from RS Components that were a little more unique than just using 240v plugs and plates, this was to stop anyone plugging whatever to the controller or to the iron. The thermocouple has its own unique connection also. I have used high temp wire and ceramic connectors in the bending irons box, it is also vented. I have created a tunnel in the sides of the box (fully enclosed to keep the wiring away) to clamp it to a bench. I will add an on/off switch to the controller box also.
Here are some pics
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Luthiers bending iron with PID controller
Well I finally got a chance to start making a guitar and using the bending iron. I started at 140 degrees C and that worked well for the shallow radius but upped the temp to 160 which worked better. I ended up with one small split on the inside towards the front of the guitar and have glued with titebond, it will be fine.
Now for the other side which has a much tighter radius in one section, will try wrapping with foil to see if I can get it to sweat a little more on both sides to help with the tight bend.
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I will make up some cauls for the jig to better keep the form of the sides, I didn’t get a chance today to do it.