adr1an — Fri, 04/11/2011 - 2:23am
This project is to convert a fairly ordinary (read below - there is some caveats) Toaster Oven into an SMD Reflow Oven. To accomplish this, I've decided to combine an Arduino Mega (I have a few idle Rev A 1280's and need the I/O Ports for…) , a 3.2“ TFT Touch Screen interface, some Thermocouples + Associated Hardware and the Australian Robotics Smart Relay Shield .
I will update this page throughout the Build, but for the moment, heres some information and pictures of the early stages.
I also should really say upfront that you should not try any of this at home unless you are familiar with working with 240V AC and high currents. Do not mess with AC unless you are sure of what you are doing. And never leave this plugged in unattended. Who knows what bugs might be lurking in the code and what might happen. In fact - I'd suggest just walking away now and not even bothering building this project yourself - but do read my build log ..
Whilst you could approach this from 'any old oven will do' - and many do - however I decided I wanted to approach this from the best possible standpoint. When researching many other SMD Oven projects I discovered that there is a lot to be said for Oven Selection. Some of the considerations are:
This bit isn't written yet beyond nasty hacking - I'll put something up on the MHV GIT shortly - however the basic flow is pretty simple:
Well I've succesfully stripped down the oven to commence taking it over (muwhahahaha). I will be ditching virtually all the mechanical controls present! It uses a mechanical switch that then goes to a 3 pole selector (used for bake/grill/toast etc to control element selection via a dial) and a standard bi-metal strip 'tempreature sensor' *cough*. So will be junking all of that. The only bits that will remain will be the actual elements wired in series as they are - and probably the two 240V neon lamps used for the power and thermostats lights - or they might go to and be replaced with some LEDs.
The front slightly convex panel that the dials sit on will also go - to be replaced with a newly fabed panel for the 3.2” TFT - which will probably sit flat for ease of construction/mounting etc. This modification is fine, as the surrond has quite a deep lip on it.
I've ended up going with the Sunbeam BT5300 BakenGrill Oven. Heres their promo shot:
And heres some of the images I took of the initial tear down
The left hand side of the oven simply contains the links for the two element banks. One is insulated because of its proximity to the screws for assembly I assume.
Here you can see the mode selector switch and the wiring running off (or back?) from the top elements. The darker red wire coming from camera-right is the neutral that connects the far side of both banks in series returning to the thermostat.
The convex control panel seen from the rear. All those current knobs will be gone. Top to bottom the Bi-Metal Strip Thermostat, The 3 Mode Selector Switch and finally a combined Manual On/Timer Switch with builtin bell.
Here you can see the interior. The tray sits quite nicely in the centre of the oven. I'm going to shield over the elements to prevent direct heating of the PCB which can lead to scorching.
And all the original wiring seen slightly wider. Nearly all of this will go except for the wiring on the Elements. You can see the Blue wire linking neutral to the top element bank before running back to the thermostat.
Full size images should be visible in a set on flickr
STAY TUNED FOR MORE INFO AS THE BUILD PROGRESSES!