Toaster Oven to Reflow Oven

For a while I was thinking about buying a small reflow to make SMD reflows in my home lab. But after a thorough research over the web, I understood that cheap reflow oven like T962 may have a serious problem regarding its temperature distribution over the whole heated area. Obviously there are many guides for how to hack T962 to be more reliable and less dangerous 😊

Instead, I decided to build my own reflow oven from a toaster. I liked the thorough guide from Whizoo very much. They did a great job 💪! I purchased their Controleo3 Reflow Oven Build kit.

The main difference between the Whizoo guide and my build is the 220V instead of 110V in USA.

I thought that it may be a minor difference in means of the build guide.

Spoiler: I have never been so wrong in my life before 😖

The first problem that I struggled with was to find a small toaster oven with controllable heating elements. In my country most of the small toasters have two elements in series. This means that each element is for 110V (problem ☹). I watched a video of making a reflow oven with Controleo3 and 220V oven: https://www.youtube.com/watch?v=8IZIGu6rKEs&ab_channel=nihtila.com 

But I thought that there would be a lot of metal work, which I didn’t want to do.

So, I tried to hack it by buying one small standard toaster oven and one small portable infrared heater. The purpose was to use the heating elements from the infrared heater for the toaster oven.

Long story short: NEVER MAKE THIS MISTAKE! 🥵

This was a bad idea🤬, a total waste of time and a lot of cuts in my hands from the heater opening. The heating elements were too short and had a different diameter, which made it difficult to install them inside the oven.

So, the only available option that remained was to roll up my sleeves and start working.

I bought the second oven to make one reflow oven from two similar toaster ovens.

There is an excellent guide for toaster oven conversion to reflow oven on Whizoo’s website. The purpose of this guide is to expand the guide for ovens that operate at 220V.

Before reading this guide, I highly recommend reading the building guide from Whizoo:

https://whizoo.com/pages/buildguide    

Materials:

1.     Controleo3 kit - check that you have all the things for the building

2. Toaster ovens - Make sure to buy a similar toaster oven, so your heating elements will match the toaster

Tools that may be needed for the building:

1.     Masking Tape

2.     Electric screwdriver

3.     Drills: 1.6, 2.5, 3.5, 4.0, 6.0, 8.0 and 10.0 mm size (or similar)

4.     Philips screwdriver

5.     Cutter

6.     Plier

7.     Wire stripper

8.     Crimping tool

9.     Dremel tool

10.  Scissors

Open both toasters, remove the heating elements. Pay attention to the fact that the elements are fragile, so store it somewhere where it won’t break.

Remove the old controller from the toaster that will be your Reflow oven. And the important thing is to save all the wiring, you will use it later.

The reason that you need to do this is because you want full control over the top and bottom elements. Since each heating element is designed for 110V, you need two heating elements on the top and two heating elements on the bottom in series so you will be able safely to plug in 220V.

WARNING! If you don’t fully understand the right electrical connection, consult with a professional. It is high voltage and may be dangerous!

Remove the front and the back oven panels before the metal work.

I used an electrical screwdriver with 2.5 mm drill to make holes in the perimeter of the rectangular shape for the heating element installation (8 openings in total). After I did it, I understood that it may be easier to make these openings using a Dremel tool.

When you decide to make the openings, pay attention to the fact that many ovens have a door spring that is located on the side of the oven, as shown in the picture above (marked by the blue line). So, place your opening on the side walls in such way that you will be able to install this spring afterwards. 

Don’t forget to install the covering metal shields for the heating element at this stage for both top and bottom element. These shields are required for good reflows as they prevent hot spots during the heating process. In addition, these shields will prevent you from breaking the heating elements during the insulation placement.

Install the heating elements and secure them in their places with some metal pieces that will prevent them from moving. Seal the whole oven, don’t leave any open spaces. You can use a flashlight to locate the holes that were not sealed well. See the original guide for additional information. 

Leave the sealing paste to dry for at least 24 hours.

These steps are like the steps in the original guide (steps 5 to 12).

https://whizoo.com/pages/buildguide#Step-5    

The only thing that can be tricky is adhering the Floor & Tunnel Shield II insulation below the bottom heating elements. Don’t reveal the whole adhesive layer as it will be difficult to locate the insulation in the right place. The trick is to reveal a small strip of adhesive in the far part of the insulation, and only after it is in the right place you will be able to reveal the whole adhesive layer (it’s not an easy task but you have to believe that it is possible 😊).

The wiring is like in the original guide, but now you have two heating elements in series on top and bottom part of the oven. So, wire two heating elements in series on top and two elements in series at the bottom.

I think it’s a good idea to cover the spring with some kind of sleeve that will withstand high temperatures because the spring will be covered in the next steps with ceramic blanket. The sleeve should prevent ceramic blanket wear because of the spring movement.

From this step you may follow the original guide for the low voltage wiring, controleo3 wiring, ceramic blanket insulation, oven closing, door servo installation, configuration and final finishes.

You may need to cut your PCB tray to the right size according to your oven size. I used a Dremel tool with a cutting wheel to cut it to the right size. Don’t forget to remove the sharp edges with grinding paper.

Hopefully everything was wired well, and you can run the learning cycle. I loved it that the controleo3 learns the oven parameters by itself (very smart! 👏👏👏).

I made my temperature profile according to the solder paste that I’m using. It is a low temperature solder paste: CHIP QUIK SMDLTLFP15T4.

Very nice reflow result from the first time 🎉🎉🎉

I have to say that I needed to make some minor fixes on the USB Type C connector with soldering iron. But the pitch size here is very tight, so it is fair, and the fixes were very easy to make.

Inputs for future improvements:

1.     I was a bit disappointed to see that there were only two reflow profiles preinstalled on controleo3. I think that it will be nice to add more profiles. The nice thing is that it is easy to make my own profile.

2.     The controleo3 enclosure is attached to the oven with two screws on an aluminum plate, it doesn’t seem to be very strong. So maybe an improvement can be made here.

Summary:

It was a nice project, and I am happy with the result. The building took much more time than I expected, mostly because of trying to figure out how to adapt the building guide for my oven. The part that may be seen as the most complex is the metal work to make holes for the four heating elements. But eventually it wasn’t so bad and if you have a Dremel tool it may be even easier. Finally, if you are thinking of building it, you totally should not be afraid of any of the work that needs to be done.

It may take a few days to finish it, but you will love it. 

Eventually, you can say: 

I made this!