I put together one of these last Spring. Picked the induction heater and timer up through Amazon.
I works great. It is very consistent. I use it with 30-06 brass (so far).
I changed the wiring a bit, for two reasons.
One, I was concerned about switching that much current through a relatively light set of contacts might reduce the life of the relay.
Two, when you switch off the power the fan turns off also - cutting airflow and allowing heat to build up.
What I did was to drill a small hole where the handle transitions to the larger diameter (near the button switch). A small four conductor cable was routed through the hole with a zip tie inside serving as a strain relief. Inside, the wires from the switch were connected to 1 pair, and the other pair to the wires that went from the switch to the control board. This allowed me to switch the low-current side of things. I believe it solves both issues, as I'm switching a low-voltage / low-current signal that stops the induction heating but since I'm not removing 110VAC from the device the fan continues to run. No cooling issues.
I could have pulled just two wires and inserted the relay into one of the two wires between button and control board, but I wanted the options for other features of the timer and the 4-conductor cable was small enough.
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To help with consistency I put two pieces of wood together at a right angle, and drilled a hole just the right size to hold the case (horizontally) while I slide the coil over it. I'm careful to locate the coil consistently to get the heat to affect the brass just where I want it, centering the case in the coil for uniformity also.
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The timer runs about 10 seconds. Use anything handy to remove the brass once hot, and place it elsewhere to cool.
No complaints here.