Home Made Coffee Roaster - 2nd Attempt

It's finally happened, after 5 months of roasting coffee beans (and also totally ignoring the phrase 'if it ain't broke – don't fix it') the trusty popcorn popper has died....
Throughout November and December where the outside temperature dropped significantly, serious flaws were emerging with our popcorn popper method of roasting coffee beans.
The popper was unable to reach a high enough temperature to reach the second crack and was cutting out sometimes even before the 1st crack when it's in built safety cut out feature was springing into action.
I tried roasting within a large cardboard box, and also in the doorway to outside to try and shield it from the elements. This helped a bit, but the results were still not satisfactory. I decided at this point that either the popper required modifying or a different method needed to be employed. I started off by looking on the web to try and find information about modifying – this method looked straight forward. Using this method, you can basically bypass the safety cut out feature of the device – I found wiring diagrams – lets get started.
The first hurdle was to get the thing apart....My model was an Argos brand and all the screws were anti tamper types, dammit. After quickly grinding an old screwdriver with a dremel to the correct shape – we were in. Everything inside was pretty much identical to the photos I had found on the web. So far so good....until, in a curious manner (being careful about electric shocks) in a moment of madness I decided to turn on the device whilst it was still in bits to see how it all worked. That was it.......smoke,bad smell and a burnt out popcorn popper......I failed to realise that the heating element needed the fan constantly blowing on it to avoid burning out. Oh well. New coffee roasting device it is then.........
I spent lots of time scouring forums and web pages looking for home made coffee roasting ideas, nothing really grabbed me, so I decided to look around my garage, kitchen cupboards and anywhere I could think of to give me some inspiration...
There it was staring at me on the worktop of our kitchen – an empty tin of Gaggia coffee. It was one of the 250g types. This was the starting point – then my idea came to me.
I took an empty can of beans (washed thoroughly with label removed) and using a pair of tin snips carefully cut strips from the can. Basically I needed four strips, the length of the can by about 25mm wide. I then put the strips into a vice and using a hammer formed the strips into pieces of angle. Then using hand clamps, I secured the four angles to the inside of the gaggia tin at 3, 6, 9 and 12 o'clock positions using pop rivets. The angles are to agitate the beans during roasting (in case you hadn't guessed)
Once the angles were in place I drilled a hole in the centre of the solid end of the Gaggia tin. Then using an M8 x 70mm bolt and a nut I secured the bolt in the hole I has just drilled so that the excess thread was on the outside of the tin. That's it......
This idea is still in its very early stages, but at the moment to use the roaster, I clamp my battery operated drill in a workmate type device slightly angled back, with the chuck of the drill gripping the bolt of the roasting drum (gaggia tin) Using a cable tie wrapped around the drill trigger I can control the speed of the drill and keep it constant. In this instance, the RPM needs to be quite slow. When the speed is set up ok, you can then pour in your green beans, I have found that the batch size using this method can be much larger than with the popcorn popper. By tilting the drill backwards a bit the beans stay in the tin, they are agitated nicely and you have a great view inside so you can see exactly what is going on. In order to get heat onto the beans, I have been using a hot air gun (paint stripper type) By moving the nozzle of the gun further inside or out of the entrance of the tin you can increase/decrease the temperature. This method is by no means scientific, but you do have a certain amount of of control. I have found a typical batch takes about 5-7 minutes and every time the beans are nicely roasted with even colour. Obviously this method of roasting is only suitable outside, as lots of smoke is produced.
Cooling of the beans is carried out using the same method as with the popper – a couple of colanders. Because the weather is so cold at the moment, the beans cool down in no time, whilst you are outside.
I'm really happy with this method of roasting. My next project will be to make something to hold the drill and the heat gun so it is actually a stand alone piece of kit. But I don't have time at the moment – but watch this space. I also have found that the solid end of the Gaggia tin is quite flexible and the whilst attached to the drill it tends to move around quite a bit with the weight of the beans. This can easily be remedied by using a large washer to spread the load.
I wonder if a steel dustbin and a propane heater would work for a really large batch - hmmmmmm
Obviously, like with the popcorn popper method, whilst doing this kind of thing you are using tools and products for things they were not designed to do and so could be potentially dangerous.
This article is intended to share my experience only not encourage you to do it – and I will accept no responsibility for any accidents – If you do want to try, you do so at your own risk.

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