Boca Boca roasters thermocouple mod

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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#1: Post by borrik »

Hi, I've just wanted to post here my solution for temperature measurement problem for BocaBoca owners. The problem is that 250/500 models designed as closed drum that has no ability to connect wired thermocouples because there is an axle at both ends. Original gauge is spinning that is annoying as well. There is no ability to connect cable because everything is rotating.
I've seen here few questions without answers
Thoughts on BOCABOCA 250?
BocaBoca - thermocouples
And I want to share how possible to solve this if you not ready to change this roaster to something else.

My solution for this is to make front plate of the drum static. For this I've drilled a hole in the "drive" nut to place screw here and use this nut to tight the drum with some loose for front plate. Basically we need to get this plate rotating between the nut and the axle, and in the same time provide axle rotation with loosen nut using additional screw. After this need just make some stopper for the front plate. I've simply screwed some metal rod to the hole of original gauge. In my case I've got an issue with charging door spring lock that stick inside - beans started to jam between this lock and rotating drum plate ends and make front plate rotating again. So I've just "inverted" this spring as seen on the picture.
With this modification it's possible to fit some small probe and get BT at ~8 o'clock close to the front plate of the drum. I've got convinient on-screen readings, could connect this to roasting software etc. I've got TP readings and there is no overall measurement lag that comes with original gauge because it mostly not touching beans during rotation cycle.
How it works:

I've did several roasts and got huge difference it temperature measurement and there is no rotating gauge hypnosis anymore.
For sure there is no warranty, do it at your own risk :wink:

As next step this setup was updated with Arduino thermocouple with modbus output, here is first result:


#2: Post by sloppypuck »

Thanks for posting this - its the best solution I've found so far and like to try it myself.

Would you mind posting some more pictures of the nut modification as I couldn't work out how it works from the pictures...



#3: Post by sloppypuck »

Actually now I understand what you did! Its a nice solution. Thanks for posting


#4: Post by shingz »

Hey sloppypuck - just wondering if you tried the mod and if you were successful. I'm still trying to get my head around this solution as I very much want to make a similar modification. The gauge that comes with the roaster is impossible to read while rotating. Very poor design.

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borrik (original poster)

#5: Post by borrik (original poster) »

Hi, guys, glad to see here some feedbacks :)
The mod itself is to drill front nut and put a small screw there. Then need to set this nut to make front plate loosen and rotate independently to the drum, then tighten the screw to make the shaft and the nut fixed and provide momentum from the motor. Also it's possible to put some additional washer between the shaft and front plate to lower the tension. To fix the plate I've screwed some flexible rod that comes with some IKEA kitchen equipment - see the pictures.
With static front plate we get ability to put some short thermocouple at front side of the drum. I've used fluke's one from multimeter tester, it's open junction and has too reliable readings, so I've fitted small piece of aluminum to smoothen the measurements.