Workable budget setup for roasting really good coffee whirley pop w/tweaks

[SpecialReserve]

we love the whirley pop concept for coffee roasting and its a great tool. The thing that I never cared for even when popping corn in the thing is the impossibly thin bottom. It makes it impossible to regulate the temp evenly. So one day I had the brainstorm of putting a heavy cast iron skillet between the pan and the fire. It evenly disperses the heat along the entire bottom and provides for a nice even roast then I added a 12 volt digital temp indicator with high temp probe. You can put the probe right down in the beans which gives an accurate bean temp I drilled a 1/4 inch hole in the lid that snaps shut and feed the probe through that hole. The heavy cast iron lets you throttle the heat up and down evenly. We use an old antique chambers stove and the burners are pretty high output. Not sure how well this would work with low output burners. So for sample roasts its perfect and for someone who doesnt want to spend the $$ on a roaster its a great alternative. I typically roast a pound (453 g) at a time and the average roast times are between 16-18 minutes. If you get the digital temp indicator be sure its a high temp. I got mine off amazon. Wife uses a wooden spoon towards the end to sample the beans right through the flap on top. I have a small trolling motor battery powering it because it was sitting there nearby. You could use any 12 volt power supply. note the olive oil container ... use a drop on the gears of the whirley pop between roasts to lube the gears and keep it turning smoothly. Just a drop so it doesnt get inside your pot. With a bit of practice you can do some pretty consistent roasts and the coffee? Isn't it always better when you roast it yourself? Happy roasting!!


There are better setups for temp monitoring but sticking to the budget mindset these work and are cheap chinese import.
I used this one: https://www.amazon.com/gp/product/B071LQBK6X/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Or this one: they both work good. https://www.amazon.com/gp/product/B01IGUGO1E/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

[Ascholten]

The trolling motor battery works, but always needs to be recharged and eventually will go bad, at about 50 bucks or so a pop.
A cheap battery charger works too, or if you are nerdish enough to hack it, an old computer power supply.  the battery charger does not have to be fancy just something that can put out a few amps.  Nice setup there, good job, I love seeing where people make personal roasters with a bit of creativity and ingenuity.

Aaron

[Ascholten]

Also, as another thing to think of.
The pot may not fit completely all the way down etc into the cast iron skillet so heat transfer is weird.   You can fill the skillet up to whatever point you need with clean sand, then push the pot down snugly in that, the sand takes ALL the heat from the skillet evenly and passes it to the roaster evenly.  The added heat mass will also help stabilize temps too, it won't swing as wildly on BTU changes, the sand buffers it.

Aaron

[SpecialReserve]

true on the trolling motor its a temp solution for sure. I actually thought about using a 12 volt wall wort power supply. It was one of those things I did out of necessity one day and it worked pretty good and I stuck with it for quick little sample roasts. If I was going to use it as my main coffee roasters Id go with the 12 volt power supply and probably step up to a connector like on our bigger roaster like this one https://www.amazon.com/50x5mm-Thermocouple-Temperature-Sensor-Meters/dp/B00C97J5EE/ref=pd_sim_328_2?_encoding=UTF8&psc=1&refRID=HAH8NYV93QEK4SD2M1JT&dpID=41xANkyt14L&preST=_SX342_QL70_&dpSrc=detail .

I do like the ability to take the probe and put it down in the beans as they are roasting it really allows you to nail the temp. a person can get creative there on how they keep it in place. I used some small stainless wire to stiffen it and hold it down in the beans as they turn.

[SpecialReserve]

The sand is an awesome idea. That is how they prepare turkish coffee. When I was overseas I used to get it prepared that way. Luckily I have a big skillet it sits down inside of good but that sand will buffer the heat even better. Gonna try it

[Ascholten]

Does the bottom of the pot touch the inside bottom of the cast iron pan fully or does it somewhere almost all the way down, outer edge of pot connects with pan so there is an airspace?  Even if it does fit all the way down it's not a full surface area metal to metal because of ridges on the pot, stuff like that so is a bit inefficient.  Not that we are going for perfection but.   The sand will fill in the gaps and help transfer the heat to more surface area of the pot and more evenly too.  When I work circuit boards that's how I depop them to get the heat evenly across them with all sorts of wild ridges / sides etc etc.

Id do a dry run first, GENTLE just to see how long it takes the sand to heat up, pass heat on etc, that way it gives you the ability to adjust your roasting style so you don't either go too slow or race off with a batch and ruin the coffee while learning the new heating curve.

Let us know how it works for you, this will be interesting to see how much better you do!

Aaron

[Badam]

Very cool setup. Always nice to see that you don't need $100's to bust into this hobby. Just for the Geisha beans. 

I agree Aaron's sand idea would be another step up. Any issues with the plastic gears? I'm sure you already know this, but they make the same setup with metal gears, it might be able to turn the beans faster and possibly even more beans. I think you can buy the lid separately on their site if the tried and true lid bites the dust.

[SpecialReserve]

speaking of geisha and the corn popper  ... got some from slim and wanted to try a few different roasts to try to nail it so I went with the corn popper 300g drops . First sample sucked we dumped just at the end of 1C. @ 219 celsius. Tasted grassy and nassy. Next one I  Took it just up to the edge of second crack and when I brewed that first cup I instantly got greedy and ran and stashed all I had HAHAH! Nice even roast and great in the cup! Dont have quite the control ya have with air and more BTUs in a bigger roaster but you can play with it and get a good roast. When we drop the beans we turn the fire off .... let the beans temp turn then turn the fire back on. I turn the fire down slightly when in the drying stage to lengthen it a bit and it seems to bring out more sweetness in the cup. My first thought "Im dropping Geisha in a popcorn popper?" But turned out awesome.

[peter]

Nice work, SR.

Have you modded the stirring arms?  What do they look like in your popper?

[SpecialReserve]

Thanks Peter... they are just the stock arms. I did bend and tweak them by turning the beans and watching them and then bending a bit and so on. I bent the ends out straighter slightly and it seemed to move the bed of beans more evenly. I have tried varying amounts/weights per roast and really around the 14 oz mark seems to roast the best and isn't to much for the mechanism and as we know its not very "sophisticated" LOL .

[Ascholten]

One thing I noticed when I was playing with popcorn thingies and roasting coffee, the arms like to just slide the beans along often, not really rotating or mixing them up.  If you start having problem with uneven roasts, this is one thing to look into.

Aaron

[stevea]

Yeah the sand idea is clever.  Somewhere (David's book?) I read that in Arabic culture they would roast beans in sand beneath a fire ... then sift out & crush the beans.   Of course you wouldn't want to run any sand through a burr grinder, but it's a useful way to distribute the heat.

Silica sand is actually a crummy thermal conductor, but metal filings near flames (or lungs) have it's own set of (major) problems, cooking oil won't take the temps, DowTHERM 'A' & 'G' aren't very kitchen friendly.   Difficult problem.