We use a stencil exclusively. I tried it by hand once - I couldn't do squat.
We are working on a stencil ordering system as well. Cheap. Less than $50 a stencil. But with what we've seen from the PCB service, we don't know how to handle the problem orders. I'll post another topic about this specifically.
Phil and Jmoyer - great feedback! I dunno if a control loop will work. I don't think these resistive coils can react fast enough. The coils in our 'real' oven are IR coils that burn out over time - basically really expensive high wattage bulbs.
Yes - the AC could kill you. The original board just had 12VDC control though a screw terminal that allowed the end customer to attach to whatever relay or control unit they wanted to use. This can also be done with the latest revision PCB - I'm thinking the user could just not mount the relay we provide, and solder into the connection holes.
If you read through some of the toaster tutorials, most gloss over the relay connection. It's the hardest and most screwy part of the project. This is not for the faint of heart. The control board is more for the data aq. and the decision making. How you physically turn on/off the oven is still sorta in the air.
The im-precision of the voltage regulator carries through to the thermocouple amplifier and finally to the ADC on the PIC. As long as all line are steady (lots of decoupling caps) we are ok. If the VDD line is 4.95V or 5.12V, doesn't matter as long as it doesn't vary +/-0.5V (I've seen +/-2V on some wire wrap boards...).
Time for a silly question - How is a triac better than a relay? Solid state relays would be fine, but for one that size, it could easily be $30 a pop.