Toaster oven reflow project goes way overboard

This project may take the cake on high-end reflow retrofits. It’s a HUGE project which uses a toaster oven to reflow surface mount circuit boards. And the fact that it bursts with features makes us giddy.

So what parts have we come to expect on these devices? Obviously a heat source which usually comes from a reused toaster oven. Then you need a way to switch the heating elements on and off based on feedback. Since solder profiles have precise timings and temperatures a clock is usually involved. All of this can be done with a temperature probe on a multimeter and a smartphone as the timer. But what we have here is full-automation and then about a thousand more features.

The driver above has a full user interface. It’s got its own PID routines which help to ensure proper holding temperatures and accurate ramping when going from one temperature to the next. The cable exiting the controller below the red buttons is providing feedback via a thermocoupler.  So program in your solder profile and let it go. But wait, don’t you want to record and graph what actually happened during this reflow run? Well that’s what the serial connection is for. In fact, you can even load new profiles and control all aspects of the device from a PC interface.

Switching for the toaster oven is done in a different way as well. Instead of just switching mains power, the circulation fan and the heating elements have been electrically separated. This way the fan can run whether the elements are on or not.

Comments

  1. dext3r says:

    Super sick project. Great job!

  2. Aaron says:

    That’s not a hack — that’s better! Awesome./

  3. MS3FGX says:

    I…I have no words.

  4. nice one says:

    That reminds me of one of my own oven control projects (wasn’t for soldering/reflow though).

    I just didn’t feel like wasting time on buttons and an LCD screen. The computer is the main user interface, along with importing & editing profiles, saving logs, graphing, etc. The MCU was used largely as a USB to mains switch bridge (PID loop and everything else happens on the PC).

  5. George Graves says:

    IMHO – Best HAD post of 2012!

  6. modernwarfare2forums says:

    You have to be kidding me. Props. Awesome project.

  7. Reg says:

    I think “very professional” is the correct description.

    I’d love to be able to buy a kit w/ the board, thermocouples, etc.

    I can’t think of a HaD post as good ever.

  8. hobbybotics says:

    Thanks to all for the kind words. I am working on some updates to this project that’ll allow for simultaneous PID loops (I have more goodies in store also). I’m also working on making the design more polished. I’ll offer some kits once I finish the redesign (I’m porting the board files over to a more open schematic/PCB package). I’m always looking for suggestions and of course all of the project files are open.

  9. Rob says:

    this is off the hook…

  10. Bogdan says:

    Very well done! Excellent design.
    I too am interested in a kit. Keep up the good work!

  11. einballimwasser says:

    Holy sh .. !

    Too bad it’s a Microchip controller. I have no clue about them.

    I currently have 2 ovens here and eager to get the heaters out, when my hands are fine again.

    How can one isolate such an oven? temps are up to 400°C. fiberglass wool?

    • macona says:

      You mean insulate? I don’t think you want to. It needs to be able to cool when the heat is turned off.

      Usually Rock Wool is used for high temp insulation, though.

    • hobbybotics says:

      I’m working on a design with an AVR also. I’ll post up the board files and such when I have it completed.

      • einballimwasser says:

        Thank you very much!

        Iam looking forward to use your control in my oven!

        The thing with Microchip is that I have no clue about them and if the thing will fail one day I can’t repair it without a lot of effort.

        Your control is great! :)

        • hobbybotics says:

          Everyone’s mileage may vary but, I consider Microchip controllers to be a bit simpler in some aspects over AVR. The PIC I chose in this design was two-fold; the first being I had a ton of them left over and the second being it’s easier to pop the chip off the board and replace if it happens to let the magic smoke out. There are really mature tools to program Microchip PICS however, I’m not sure any of them can touch the ease, convenience and price of the Arduino or free AVR tools. Keep a look out for the updates and be sure to get in touch with me if you have any questions with your reflow project.

      • einballimwasser says:

        True thing. I’d really appreciate an AVR version, but it’s clearly not a *must do*. I’d build the Microchip version too :)

        If you consider those chips as a little bit more uncomplicated, I’ll have a look at them.

        I just added your website to another browsertab :)

  12. Pun says:

    Well designed, well explained, and very professional. And the way you have it in that benchtop enclosure is nothing short of beautiful. :)

  13. markS says:

    don’t forget osPID for the rest of us ;-)

    http://www.ospid.com/blog/

    • hobbybotics says:

      Yep, I even have a link back to that project on my blog. In fact, the creator of the firmware for that controller answered a few questions for me when I was developing my controller. Great stuff!

  14. Truth says:

    It is a thing of beauty.

  15. Cabe says:

    If something is worth doing, its worth doing right. If something is worth doing right, its worth overdoing.

    Fantastic work.

  16. John says:

    Great project but one thing that would make it greater is to port the entire system to a Raspberry Pi and dump the Windoze program and give it a WEB interface. Now you can run in from any platform not just Windoze.

  17. hobbybotics says:

    Yep, already in the works as a side project. I didn’t have a Pi at the time.

    • devinkb says:

      Awesome! I would love to see this using a raspberry pi. As a software developer it would make this project much simpler from a component standpoint. 1 raspberry pi and a simple circuit for relay control and temperature monitoring.

  18. John says:

    Even though a Pi center Reflow Oven would likely be WEB enabled I’ve already designed a board with a 20×4 line display along with buttons just for a reflow oven be it this one or the one that another group is doing.

    The display is totally compatible with the 16×2 line display that adafruit has for the Pi plus a speaker for clicks and tones using the extra output the adafruit one didn’t use. It is a bit larger but so it the display.

    In addition the Pi mounts to the back of the display and then you mount the whole thing to the panel.

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