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Corretto Roaster Initial Build - Feedback please
nixda
Hi,

I initially wanted to build a roaster from scratch but found a bread machine in a thrift store and decided I would give that a try first.

Here is my first build. I thought I'd solicit some feedback, before I go on and start improving it.

Bread machine
Breadman TR560K; removed the lid, took the heating elements out and disconnected the temperature sensors. They are currently just dangling outside the case.

Roasting Chamber
Removed teflon from inside; wrapped with 1/2" fiber cement insulation and wire to hold it in place; insulation covered by some thin aluminum foil. I added a thermocouple with exposed junction in one of the corners. I then tried to put a gasket using high-temperature silicone around the rim. I failed quite badly. Apparently, I am not able to lay down a decent bead. Will have to try something else.

Roasting Chamber Lid
I wanted to achieve a good seal and some insulation. To that end, I cut up a cheap aluminum sheet pan and made two matching pieces that fit into the bread machine. I drilled appropriate holes for the heat gun, vent, connecting screws and thermocouples. I then put some left-over insulation in between the two parts. I wrapped the insulation in aluminum foil to prevent any particles from entering the roasting chamber. Not quite happy with that (see below).

Heat source
The heat source is a generic heat gun that is sold under a variety of names. Two speeds, variable settings. It fits snuggly into the opening in the lid.

Vent
The vent is currently just open. I need to make a decent chimney. I used a make-shift funnel for filling the beans into the roasting chamber.

Monitoring
I used a total of three thermocouples. Two are simple exhaust gas temperature probes and are vertically oriented through the lid. One sticks into the beans, the other is centrally located with the tip 2? below the lid to monitor ET. The BT probe is redundant at this point as I have the other thermocouple in the chamber, but I wanted to compare the two. Not surprisingly, the one with the open junction responds much quicker. There is also a slight difference in the reading of the two. I will only use the one on the chamber in the future.
In my first roast (see below), I used two simple monitors, but I have since obtained an Amprobe TMD-56, which I will use in conjunction with Artisan next time, after I am done with my current pound of beans?

First roast
I had done some 1/2-lb batches in this roaster before, but it was entirely unmodified back then. For my first ?real? roast, I also used a 1-lb charge and didn?t really know what to expect. I pre-heated the chamber to 250?C (setting ?6? on a scale from ?0? to ?9? on my heat gun) and charged it. See the profile below.

I was very happy with how it all went. I was expecting to have to reduce the heat somewhat after getting to 150?C, but the profile slowed down on its own, which I intended to do anyway. The same thing happened at 1C: the RoR decreased, to a point where, at 212?C, BT didn?t change for 30 seconds. Fearing I would stall the roast, I panicked a bit and increased the heat gun to ?7?, but only for about 30 seconds, after which the roast continued with an RoR of about 10?C/min to 230?C when I stopped it. It seems the setup is very responsive; 6.5 would have done it probably, if it was necessary at all.

Bean Cooler
I then dumped the beans into my cooler, which took about 6 seconds. The cooler is nothing else than 10? aluminum cake pan, with lots of holes drilled into it, set into a 5-gallon bucket and connected to a shop vac. At an ambient temperature of 13?C, the beans were warm to the touch after about 30 seconds, and completely cool after another 15 seconds! Wow!

How it tasted
After the beans had cooled, they immediately emanated a typical roasted-coffee aroma, easily detectible in my driveway. I have not had that before. I have seen other people report the same when they for the first time used a roaster that gave solid, uniform results. The beans aren?t my favorite, but when tested the next day, I could not detect any gross defects, so I think everything went really well. I have to say that I practically exclusively drink Cafe au lait, with about 16oz of whole milk and coffee made in an Aeropress. So, I am certainly not out there to make highly detailed flavor assessments, but I do realize when there is bad coffee in my mug...

So, that?s it for now. I am very happy with how it all went but wanted to see if there are any suggestions for improvements at this point, so please critique away!


Further planned modifications

- remove electronics and put in switch for the agitator. Not really necessary as the machine has a setting for a 2-lb loaf of French bread that kneads for 23.5 minutes! I am aiming at getting my roasts done within at most 16 minutes. It would look a lot neater, though.

- use different material for insulation. I am thinking of using automotive firewall insulation padding. I do not know though whether, once cut up, there is material exposed that could contaminate the beans during roasting.

- work on sealing the roasting chamber rim. Perhaps an oven seal would work. Alternatively, put the silicone gasket on the underside of the lid, rather than around the rim of the roasting chamber.

- make an improved version of the lid, with proper exhaust vent, potentially attached to the bread machine using hinges, so that it could be tilted backwards for faster dumping of the beans.

- anything else?

Thanks for reading.

Cheers!
nixda attached the following image:
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nixda
Don't know quite yet, how to post images properly. Short on time, so this must do for now.
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nixda
Picture 3
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nixda
Picture 4
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nixda
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Picture 6
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Picture 2
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Profile
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Airhan
Wow, that is a nice looking bm/hg roaster, how long did you spend putting it together?
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
nixda

Quote

Airhan wrote:

Wow, that is a nice looking bm/hg roaster, how long did you spend putting it together?



~1 hour to strip the teflon from the pan (it's advisable to wear a respirator...)

~1 hour to admire the innards of the bread machine, take the heating element out, and detach the temperature probes

~2 hours to cut the lid components to size (advice: start with a flat sheet of metal, not a curved one like the baking sheet I used)

~30 min to insulate the pan (advice: 18 gauge wire to attach the insulation is larger than necessary)

~1 hour to figure out the placement of the various holes in the lid

~2 hours to drill the appropriate holes in the lid (includes getting a 1/2" hole saw mandrel when my drill chuck is only 3/8" and going back for a different mandrel...)

~1 hour for cutting rather small pieces of sheet metal (quite dangerous) in order to cover one of the large holes again and make another one somewhere else Shock

~30 minutes to insulate the lid (includes locking away my toddler who wanted to eat the small insulation cut-offs)

~30 min to thoroughly botch up the gasket

~5 min to place the BT probe

~2 hours to drill all the holes in the cake pan. Includes 30 minutes to remove all burrs (advice: drill holes with backer in place to avoid forming burrs in the first place; use a high-quality brad-point drill bit)

~2 weeks to admire my handiwork

The total elapsed time was about 2 months from the moment I locked in the design, most of that time was waiting for various things I ordered.

Great fun, and I am happy that I'm not done yet.
 
Airhan

Quote

nixda wrote:

The total elapsed time was about 2 months from the moment I locked in the design, most of that time was waiting for various things I ordered.

Great fun, and I am happy that I'm not done yet.


That is a pretty impressive time frame, it seems like you're going to have a lot of fun continuing to work on it, just like everyone else who builds their own roaster!
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
David
Hi nixda,
I just saw this thread and wanted to respond.
No advice, just words of admiration.
Strong work, brother!

David
 
yolacacero
Hi, first time to post but long time lurker. I was just wondering if your pan has a smooth surface after you removed the teflon coating? Coz in my case, i had the pan sandblasted and instead of having a smooth surface it happens to be rough and I was thinking if this is safe to roast with. Thanks!

PS: Nice looking roaster btw..
 
MerlinWerks
I had the teflon bead blasted off of my pan leaving the finish you describe and I have probably a dozen or two roasts on it now with no ill effects. If you want I'm sure you could take some sandpaper and get most of it to a smooth finish, not sure why you would want to though. What is your concern with the sandblasted finish?
 
jkoll42

Quote

MerlinWerks wrote:

I had the teflon bead blasted off of my pan leaving the finish you describe and I have probably a dozen or two roasts on it now with no ill effects. If you want I'm sure you could take some sandpaper and get most of it to a smooth finish, not sure why you would want to though. What is your concern with the sandblasted finish?


Your finish is fine. Teflon is gone.. it doesn't matter if it is totally smooth or not.
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
yolacacero
No concern at all. I was just curious about the finish of the blasted pan. I only roasted on it once so I'm about to season it a little more. Thanks for the prompt reply guys.
 
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