# Corretto Roaster Bits and Bobs



## PottyMouthedBuddhist

Hi,

After a very helpful suggestion in the newbies forum, I'm thinking of having a go at making a Corretto roaster as an intermediate step between my current skillet / whisk setup, and a retail home roaster. Since I already have a bread maker sitting in a cupboard collecting dust, it seems silly not to try that before splashing out on something more expensive.

So I'm wondering if anybody can save me some time and point me toward some components - I realise that not all of them are necessary, but I'm sure people here have got some fairly creative setups, so I'm hoping to benefit from their experience.

I'm looking at buying the Screwfix Energer heat gun, which is 2000w and has 450f and 600f heat settings, and 300lt/m and 500lt/m air flow settings. I've also got a cheap ebay drill press, which I think I can mod to give me adjustable height on the heat gun.

The videos I've been watching show a setup with a temperature probe attached at bean height in the bread maker, a variable input controller for the heat gun, and an "ambient" (ie internal "above the bean" air temp) thermometer. I'm thinking these are nice to have, but probably inexpensive and quite necessary if I'm going to get any real control over the whole thing, so I might as well start looking out for them now.

So I wonder if anyone has any comments on my selection of heat gun, or could point me in the direction of some suitable thermometers, probes, and input voltage controllers?

Thanks in advance for any help


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## jimbojohn55

no idea re components etc - but will watch your progress with interest


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## Stevebee

I now have a Quest M3 and a Gene Cafe CBR-1200 but also have used a Bread Machine / Heat Gun for almost 5 years.

I didn't need to mod the BM at all - select the dough cycle and go. After a few minutes intermittent stirring it then goes continuous which is when I add the beans.

For the heat gun I had an old Earlex one but the important thing is it is variable from 1 to 10 which equates to 100 - 550c. I would spend more on the heat gun, you can pick up a Dewalt or Bosch variable on Amazon quite reasonably. You can use one with just 2 settings but you won't get the fine control over your profiles etc..

I use the heat level to control the roast and don't move the gun up and down.

I have used a fire blanket to insulate around the bread tin, kept on by some wire. I use a lid made from a baking tray with a hole for the nozzle of the heat gun cut out together with a small rectangular viewing window. An empty can is screwed to this which supports the handle of the gun so I don't need to hold it.

I have two small holes drilled into the back of the machine which go through into the bread tin, one about 1-2cm from the bottom, one half way up. Two thermo probes are inserted so one measures BT and is in the bean mass all the time the other ET. The BT one is pushed in far enough but misses the paddle. These are standard k-type solid probes. I connect these to an Amprobe TMD-56 which cost just over £100. Omega also do loads but are a bit more expensive. It's important that they are compatible with Artisan free software logging.

The final part is to connect the Amprobe to a laptop / pc that can run Artisan. This way you get a live graph showing BT, ET and Rate of Rise. You can have in the background a previous roast to follow. Due to working like a fluid bed roaster it can give fine control, especially post first crack, if you wanted to stretch the development time but not let temp increase too much - but NEVER let the temp fall.

When you get to cooling, I bought a £3 bucket with a lid, a stainless pasta strainer (with holes only at the bottom) and a valve use it a toilet. I cut a snug hole in the lid to fit the strainer, the valve goes at the bottom of the bucket in the side and I attach a vacuum to this. 250g of beans are cooled to ambient in less than 2 mins.

Hope this helps and go for it


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## PottyMouthedBuddhist

Stevebee said:


> I now have a Quest M3 and a Gene Cafe CBR-1200 but also have used a Bread Machine / Heat Gun for almost 5 years.
> 
> I didn't need to mod the BM at all - select the dough cycle and go. After a few minutes intermittent stirring it then goes continuous which is when I add the beans.
> 
> For the heat gun I had an old Earlex one but the important thing is it is variable from 1 to 10 which equates to 100 - 550c. I would spend more on the heat gun, you can pick up a Dewalt or Bosch variable on Amazon quite reasonably. You can use one with just 2 settings but you won't get the fine control over your profiles etc..
> 
> I use the heat level to control the roast and don't move the gun up and down.
> 
> I have used a fire blanket to insulate around the bread tin, kept on by some wire. I use a lid made from a baking tray with a hole for the nozzle of the heat gun cut out together with a small rectangular viewing window. An empty can is screwed to this which supports the handle of the gun so I don't need to hold it.
> 
> I have two small holes drilled into the back of the machine which go through into the bread tin, one about 1-2cm from the bottom, one half way up. Two thermo probes are inserted so one measures BT and is in the bean mass all the time the other ET. The BT one is pushed in far enough but misses the paddle. These are standard k-type solid probes. I connect these to an Amprobe TMD-56 which cost just over £100. Omega also do loads but are a bit more expensive. It's important that they are compatible with Artisan free software logging.
> 
> The final part is to connect the Amprobe to a laptop / pc that can run Artisan. This way you get a live graph showing BT, ET and Rate of Rise. You can have in the background a previous roast to follow. Due to working like a fluid bed roaster it can give fine control, especially post first crack, if you wanted to stretch the development time but not let temp increase too much - but NEVER let the temp fall.
> 
> When you get to cooling, I bought a £3 bucket with a lid, a stainless pasta strainer (with holes only at the bottom) and a valve use it a toilet. I cut a snug hole in the lid to fit the strainer, the valve goes at the bottom of the bucket in the side and I attach a vacuum to this. 250g of beans are cooled to ambient in less than 2 mins.
> 
> Hope this helps and go for it


That's fantastic info, thanks! I definitely see the logic in a variable heat gun, so I'll look around for one of those instead of the cheapo one from Screwfix. The Amprobe is a little more than I was looking to spend at this stage, but it's something that I'd go for later. For now I'll probably buy a couple of food grade analog thermometers and set one at bean height and the other at air height - that should be enough to get a feel for it, and I can develop something a little more professional from there.

I had also seen the Artisan software - that is so far up my street that it probably won't be long before I end up going for it


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## PottyMouthedBuddhist

JimboJohn55 - I'll certainly update the thread with my progress. This is man toy Utopia


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## Rob1

You can make your own probes using a couple of k type thermocouples and adafruit devices. Will probably be about half the price of buying one.


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## Stevebee

Rob

I've seen what you've done with the Gene 101 re getting a probe to work - great piece of work!

I've done the power mod on my Gene cbr1200 which gives me control at the end of roast but still need to look at the analogue dial to get an approximate of bean mass temp. I'd love to attempt something similar but my level re adafruit is non existant. Another reason I bought an off the shelf datalogger (in addition to my incompetence) is the need to be compatible with Artisan.


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## PottyMouthedBuddhist

Rob1 said:


> You can make your own probes using a couple of k type thermocouples and adafruit devices. Will probably be about half the price of buying one.


Excellent, thanks. I had a look at the Amprobe but it's about £165 on ebay, so not something I want to splash out on just yet. I will have a look at the thermocouples and adafruit devices though.

I've ordered a Steinel heat gun with digital heat control from 0-650 degrees, so that should be a good start anyway. I'll have a couple of goes with that and some analog thermometers to begin with and see how I get on - should be a huge improvement over current performance at least.


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## PottyMouthedBuddhist

Stevebee - quick question of you don't mind - what did you use for cutting the baking tray? I've removed the lid from my BM and I think a 20cm tin will fit perfectly. So the intention is to cut a hole for the gun, and also a viewing tube / exhaust as well, which I can cover or uncover depending on my needs. I figured this would be good for chaff removal as well.

But I'm not much of a one for metal work, so just wondering what you did there?


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## Stevebee

A Dremel with a cuttinng disc. Cut through really quick. Anything that cuts through metal will work though as it's not too thick. Even a jigsaw after initially drilling a hoe should work


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## PottyMouthedBuddhist

Brilliant, thanks









I had a look at the arduino stuff and it looks like there are plenty of guides online, and the parts look like £30-40 worth at most. So I think I'll sit and order those this weekend ready for the build and my first attempt next weekend.

I'll get some pics up once I'm done - I know there are loads out there already but I'm finding the more I look at the better idea I have on what I want to do, so hopefully I can add to the info that's already available.


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## Stevebee

Don't worry about chaff. The heat gun blows it out the pan and it all ends up in the bottom of the bread machine but outside where the beans are.


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## PottyMouthedBuddhist

Stevebee said:


> Don't worry about chaff. The heat gun blows it out the pan and it all ends up in the bottom of the bread machine but outside where the beans are.


Oh great, then that will simplify things a bit. I just picked up a couple of 20cm square baking trays from Tesco for £2.50 each - looks like they were made to fit the bread maker, so I'll dig my old Dremmel out later and see what I can do.


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## PottyMouthedBuddhist

Sorry for disappearing - I've had nothing to report to date because I am still waiting for some of the Arduino components to arrive in the post. However, I decided yesterday to give it a whirl with the BM, heat gun and my infra red thermometer, in order to get some practice, and because I needed coffee. Bit of a disaster because I was too slow in getting the temperature up, only to find that the BM cut out just before first crack because as part of it's cycle it stops for a bit at 17 mins. I'm not too worried about this - I'm aiming to do batches of 200-250g, so 17 mins should be plenty, but I will probably look out for a friend who can wire it up directly to the motor to give me more flexibility.

So today I had another go with a PNG Grade A, and it went pretty well! I was still a little slow getting up to temp but we had a nice steady rise and then got to first crack at 12:45. I must admit I panicked a bit at that point and started faffing about turning down the heat on the gun to try to prolong the time to second crack. As a result, it seemed like 1c didn't really complete, although the bean temperature could only have dropped for a few seconds at most, I would have thought.

Anyway, I pulled it at 15:00 because the light wasn't great and I didn't want to overdo it. And the beans are beautiful! Fantastically even, medium looking roast, with a gorgeous aroma. In fact they look so lovely that I decided to throw caution to the wind and brew up a pot. And it was good, so hopefully it's only going to improve overnight.

I am delighted - not least as it's really given me confidence that I should be able to knock out some super roasts when I have the Artisan software all hooked up.

Thanks to you all for your help so far - I'll update further when the setup is complete, but at this stage it's all looking great!


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## PottyMouthedBuddhist

I now have a functioning Corretto roaster with Artisan integration









I'm sure people have seen plenty of these but thought I'd post up some pics and prices for anyone else who is interested.

Cost wise, I already had a bread maker, so no cost to that. I spent £40 on a used Steinel adjustable heat gun, the most expensive part. The heat gun fits into a £2.50 baking tray; I imagine this won't last too long, so I might look for a more permanent solution at some point, but it's fine for now. The Arduino was £6.99, and I bought two thermocouples with MAX6675 breakout boards attached off ebay for £5.50 each. Add in a bread board and some jumpers, the total Arduino / Artisan integration cost was about £25.00. Actually it's more than that because I bought some bits that I really don't need, so I'll have to flog them, or just hang on and maybe use them in the future. So total cost to anyone doing the same is about £70, perhaps £90 if you have to buy a bread maker. And it works a treat!

Here's the gun, baking tray and BM. I cut the hole in the tray with a dremmel, and frankly made a right hash of it. Fortunately the hole was too small, and since I had a spare baking tray, I tried using tin snips to make perpendicular cuts about 2cm long all round the circumference, then pushing the tapered end of the gun into them. That worked better than I imagined, so the tray now supports the gun and I have a nice tight fit. It even looks neat and tidy.









The original intention was to drill the thermocouples through the side of the BM, and I might still do this. But I also have the option to bolt the sensors through the holes that I drilled in the side of the internal bread mixing thingie, so for now I'm just leaving it all loose until I decide how best to permanently fix it. The key for me is to be able to get the beans out of the BM and cooling asap, and I think I need to play with it a few times to decide how to do this.









As you can see I have spared no expense on a case for the Arduino, and have gone for the Hillbilly Deluxe casing. I need to find somewhere better to put the laptop so it doesn't get covered in chaff, so I may buy a longer parallel cable at some point. That one is just a metre long, and it got a bit messy when I used it for the first time last night.









And here's the Arduino. Not a great picture, but for anybody thinking of doing the same and concerned at the complexity, you can see it's not overly complicated. I'll do a separate post on that below for anyone interested.

So there it is. I did my first roast with it last night, and got a lovely smooth curve on Artisan. I made some screw ups so won't post the log here, but the integration works absolutely fine - the errors were all at the operator level. And I learned some interesting stuff about my mistakes, which I intend to rectify next time.

Any downsides? Only one - I drilled the BT sensor hole a little too high for a 200g batch to properly cover it, and therefore the BT reading on Artisan was too close to the ET. I will take a look and see if a 300g batch will cover it properly, and if not, re-drill a little lower. Apart from that, I'm a very happy man.


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## PottyMouthedBuddhist

I thought a separate post on the Arduino might be a good idea, because I actually spent about £50 on stuff I really didn't need. If anybody wants to buy those bits, then drop me a PM, but note, I really didn't need them. If you still want to buy them, then I also have a bridge I'd like to sell you. It's very nice.

The first mistake was to buy the MAX31855 thermocouple breakout boards, on the basis that they are newer than the MAX6675 and therefore shinier and better. Well they're not - first of all they're a lot more expensive, and secondly they need a 3v power source and the Arduino puts out 5v. So you can use them together, but apparently you'll fry your MAX31855s eventually. Unless, that is, you spend more money on a level shifter to convert the 5v source down to 3v. More expense and complication, unnecessarily. The MAX6675s seem to be perfectly fine and they take a 5v source. And they're cheaper.

The MAX6675s I bought had thermocouples attached already. Possibly a little short, but I can work with that. However, the thermocouple cables were incorrectly marked, and therefore initially showed the temperature as dropping when it was actually rising. No problem, just reverse the connections.

Connecting the breakouts is as simple as connecting the 5v and ground outputs to the breadboard rails, and then connecting the breakout pins to the appropriate rails. The data connections are a bit counter intuitive in my opinion though, and it took me a while to get this right.

The MAX6675 have 3 data pins, basically the clock, input and output. If you're using 2 or more breakouts, then you share the clock and the output pins, but have a dedicated input pin for each breakout. This seems a bit arse about face to me, because Artisan sends a request to the breakouts to send data; so I assumed that it made sense to have that request sent via a shared pin, and the returned data to come from a dedicated pin for each sensor. Not so, Artisan no likey. I also tried having dedicated pins for each breakout pin, which also didn't work. So what worked for me was doing what I was actually told - share the data out pin, and have dedicated data in pins.

Then you simply need to edit the MAX6675 sketch in the Arduino IDE so that the pins are correctly defined - i.e. the IDE knows what each pin is connected to. The whole thing should take no longer than an hour, and if you know what you're doing, more like 15-20 minutes. I took an afternoon....

Just FYI, if you get dodgy readings from the sensors, check your pins are actually aligned correctly. My eyesight is apparently not as good as it used to be, and an early effort was giving me constant readings of 32F with the occasional spike to 1750F. It was just one jumper in a different pin to the one I'd specified.

Connecting this to Artisan caused me a bit of fun and games. Basically Artisan has several predefined sources that you can use, but none of these seemed to work for me. But Artisan also gives you the option of using a program to read the data in. I found a very simple Python script online - Artisan executes the script, the script sends a request the Arduino for data, the Arduino sends it, and Artisan reads it. This is where I first encountered a problem with my incorrect sharing of the pins. I managed to get ET and BT registered by Artisan, but the readings would be stable for an undefined amount of time, before suddenly dropping to zero, and hence giving a very dodgy and spiky curve. Once I made sure that the input (i.e the data request from Artisan) was on a dedicated pin and the output (sent in response) was on a shared pin, it all worked fine and I got very stable, consistent readings. I still don't understand this; I don't get how two thermocouples can send different readings back via a shared pin, and somehow Artisan can tell which is which. Electronics are brilliant!

Here's the Python script that I found on Reddit - copied it verbatim, other than changing the COM5 to COM4 for my needs. If Reddit poster Wakinggiant is reading this, thank you and I salute you. You're the reason I still have hair.



Code:


[font=monospace]import serial
arduino = serial.Serial("COM5", 9600)   
datas = arduino.readline()
output = datas.decode('utf8')
print (output)
arduino.close()[/font]

And that's it. I had some dicking about to do with drivers, had to install Python to be able to run the script, and had to use Windows Device Manager to find what COM port my Arduino was running on, but all these things were solved with a couple of minutes on google, and since those problems will be different for everyone, there's no point detailing them here.

In summary, it's far less complicated that you might think - if I can do it, pretty much anyone who can use a computer can.


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## Rob1

I thought I warned you about the 31855s. :s They can't use a shared line from what I remember.


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## PottyMouthedBuddhist

Nope, can't see it









But no matter, there are hardly any on ebay, so I can probably get a decent price for them.


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