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Fully featured dough proofing box

A device for maintaining a perfect environment for proofing bread doughs of all kinds.

Jan
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As a long-time hobby bread baker I came to the point where I wanted a certain degree of uniformity with my breads. This is when I searched the web for dough-proofing and found very few devices of which I think they´d be worth their money.

There are hobbyist proofing devices out there (think Brod&Taylor™) which offer very little functionality besides keeping a certain temperature over time. Many people built their own proofing boxes with more or less the same "one feature functionality".

So here are the key features DoughProofBox will offer:

- maintaining a specified temperature over a given period of time
- temperature/time-profiles for different doughs, especially all kinds of sourdough as these demand very special treatment if you really want to "get them right"
- adjustable START/STOP-time (RTC)
- windowed front door so you always know about the ripeness of the dough
- big LCD with background lighting and easy to understand UI

Scope of this project

My aim is to build a dough proofer with a lot more functionalities than any of the hobbyist devices on the market. For most white bread doughs you don't need anything fancy. Just keep it good and warm (preferably around 24-28°C, depends on a lot of things) and you're good. You could simply use a wooden box with a lightbulb in it.

Things get a lot more exciting when working with sourdoughs of various kinds e.g. rye or wheat. To keep things short and simple let me put it this way: You can influence a breads flavor greatly by varying

  • amount of sourdough
  • its temperature
  • ripening times

This is where a good proofer comes in. Bakeries use huge proofing racks or whole rooms for this purpose. Thats not feasible for home use.

Features

1. General, technical features

  • Easy to navigate user interface. Do everything with just one button (even wearing gloves)
  • Real Time Clock with buffer battery. Keeps time, weekday and month for a few years without mains voltage
  • Buzzer / blinking LCD-backlight for signaling end of modes / errors
  • User may define START or END time in every mode.
  • last used parameters are saved (and stored without mains voltage)

2. Modes

  • Constant Temperature – User defines temperature, duration and start/stop-time
    Description: perfect mode for bulk proofing and last rising process
    Range: room temperature to 40°C
  • Reviving Sourdough – pre-set but changeable temperature (28°C) and time (6h)
    Description: used to stimulate yeast-production in sourdough
    Range: 28°C pre-set, changeable to own needs
  • Detmold 1 stage process – similar to constant temperature mode
    Description: long ripening times (15-20h) at moderate temperatures (24 to 27°C)
  • Monheim salt method – high temperature and long ripening time
    Description: addition of salt requires temperatures of 30-35°C and long ripening times of up to 24h

Hardware

1. The Box

Basically, the proofer consists of a insulated container which retains as much of the thermal energy the heating elements give off. A few additional thoughts were easily cleanable surfaces (food grade) and some kind of material machinable at home.

The BastaBox XL is made of foamed polypropylene and its inner (540 x 340 x 240mm) and outer (600 x 400 x 300mm) dimensions are perfectly suited for my needs. The surface is washable and HAACP-certified.

[INSERT PIC of BastaBox]

2. Tiltable door with window

As I wanted the proofer to have a big window, I had to cut out a huge opening on one side. That imposed some structural problems, as there was only a 30mm wide strip of 28mm thick EPP left where the lid "sits". Also, a 1mm thick stainless door with a plexiglas window, insulation and most of the electronics weights way too much to be bolted directly to quite soft EPP.

So I sketched a front-frame and attached door and had it laser-cutted from stainless steel (1.4301, 1mm thick). The frame is glued to the box with clear 30 minute epoxy resin. Unfortunately it moved a bit in its fixture, so now it's a bit sloping to the down right corner. That won't impede functionality anyway...

Frame glued to box

The front door is connected to the frame with two stainless hinges via M3 flat-head socket head cap screws. The plexiglass window is bolted to the door with the same screw type. It's this 5mm thick sheet which provides the structural strenght to the quite wobblystainless steel sheet!

Hinge

The front door also holds all the electronics, there's a cutout for the LCD and rotary encoder.

The black lines are on the protecting foil, so one remembers to peel them off of the display before finally mounting it into place.

The back of the front door will be fully insulated so no bare metal is exposed to the chamber which would yield a huge thermal bridge and literally suck the heat out of the box...

3. Heating plate

As mentioned before the heating plate is a 3mm thick aluminum plate which I could get for little money. I glued two 65W self-adhesive heating foils under it. These operate off 230V mains, so the plate (and every other metal part of the box) is tied...

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  • Menu mock-up

    Jan04/04/2016 at 21:27 0 comments

    Hi folks!

    Progress is a bit slow at the moment, but I sat down and made a little mock-up of the menu. In the upper status bar there's the active mode and time. The bar at the bottom will have a start/pause button and the remaining time.

    I did not yet decide what information I want to put on the main screen, there are things like temperature, start time and duration. Things will change for sure...

    There will be a settings screen of course, I want to move global settings there. The screen above is where you enter all your parameters. It will be similar for all programs. Once started, it will change to some kind of status display, showing temperatures, time and some status icons.

    Cheers!

  • PCB up and running

    Jan03/21/2016 at 20:48 0 comments

    Just a quick update:

    Board is up and running. It's just showing temperature and LCD background brightness level (0-255) atm which can be controlled with an encoder. I hope I'll have some spare time for my project over the following long easter weekend...

  • PCBs arrived – prototype assembled

    Jan03/16/2016 at 11:14 4 comments

    Yeeeeeeha! I got my PCBs 3 weeks after ordering (China to Germany)!

    Soldering was a bit of a hassle and I managed to solder the Atmega the wrong way... DOH! So, fast forward to desoldering most of the parts (as I could get the damn thing off the board)...

    Getting the SMD caps off was a bit of a task with just pointed soldering tips available, but I thought: why not make a special tip for that:

    Yeah, thats a cable lug with a piece cutted out so it fits my capacitors width shoved onto the biggest ttip I had. Worked like a charm. I soldered a new one immediately:

    Looks a lot better now. Uploading the bootloader via ISCP. I'm waiting for socket strips now for final assembly.

    There are two errors on the PCB which I made while designing the circuit:

    Error 2:

    Both errors are dumb mistakes, but at least they won't affect the functionality of my PCB.

  • Display impressions

    Jan02/28/2016 at 13:44 0 comments

    On a lazy saturday evening I had nothing better in mind than hacking together a breakout board for my EA DOGL display. This type does need 9 caps and works with 3V3 only. So I had to add 5 level-shifters (10 resistors).

    Top view:


    Back view:

    Looks a bit botched together, but who cares: Works like a charm. It features a 3V3 VLD voltage regulator and a mosfet which switches all backlight LEDs, which consume 180mA max.

    It does work:

  • PCBs: ordered

    Jan02/23/2016 at 20:43 0 comments

    Yay! I finished my PCB and ordered them at DirtyPCBs. I hope they'll work like expected and there´ll be no errors in my circuit diagram (checked it a few times).

    I had to use standard connectors because the WAGO ones were not in stock. I added an ISCP header and broke out RX/TX as well.

    My final layout looks like this (ordered them in white):


  • PCB Rev3

    Jan02/12/2016 at 18:18 0 comments

    Hi all! Due to space restrictions I switched most of the parts to SMD. The board size went down to 70x70mm (2,78"x2,78"). My goal is to have the PCB ready by sunday.

    The front door istn´t as sturdy as expected and gives way especially where the foam gaskets are. I´ll have to think about a sollution for that.

    Stay tuned :)

    Edit: I finished the PCB. It has got a proper copper fill on both sides now. Here´s the (99%) finished PCB:

    Big changes:

    • ditched the Arduino Nano for an standalone Atmega 328
    • 3V3 operating voltage -> no level shifter needed anymore
    • J2 - J4 and J7 - J9 are WAGO 250 series connectors. Super nice stuff :)

    It the silkscreen has to be refined a bit aaaaand I have to add another voltage regulator for 5V output.

  • PCB in progress...

    Jan02/07/2016 at 18:12 0 comments

    I worked a little on my PCB. I Added a additional solder-pad field if I´d ever need to add something to the board.

  • First try KiCAD PCB

    Jan02/06/2016 at 00:00 0 comments

    Today I finally got around to try the whole KiCAD workflow. Creating a circuit diagram, one or two new footprints and finally routing a PCB.

    This is just the first version. Kind of messy and not completely sane design. Display and Arduino Nano v3 go to the bottom side, rest of the parts to the opposite side.

    There is lots of space left and component placement is far from perfect. Lots of work to do!

    Edit: The board is 100x70mm. That´s all I can cram into the space behind my front door...

  • Help needed realising falling temperatures

    Jan02/04/2016 at 11:20 3 comments

    While heating is no problem at all, cooling down the system is very tricky. Most sourdough techniques do not need temperatures lower than about 22°C.

    In winter thats no problem at all: Warm air could be sucked out of the box with a fan/vent, thus minimum temperature being room temperature or a bit higher.

    But in summer, room temperature often rises above 25-28°C. Thats too much for some sourdoughs (e.g. you want to realise a temp. drop from 35°C to 22°C). So active cooling might be required. I thought about peltier elements (cheap, easy to implement), but these need a lot of power (12V, 60-70W). That´d be a tad too much and I´d need a bigger 12V supply...

    Does anyone have a good idea on that topic?

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AKA wrote 04/04/2017 at 03:40 point

Nice work! I, too, have been looking for CO sensors to alert me at the optimum proofing time - recently a new family of sensors came out that appears ideal, they're factory-calibrated and about half the normal (~$100) price of the older generation: https://www.gassensing.co.uk/products/ambient-air-co2-sensors/cozir-ambient-air-co2-sensor/
A person I admire on github also has an optical detection system to monitor dough expansion, might be worth checking out?  https://github.com/bwhitman/bread-detector

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Jan wrote 04/04/2017 at 10:25 point

Nice find! It seems that everything regarding bread has been done before :) 

I am baking a lot lately, I hope to finish this project some time this year... 

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Christopher Czesak wrote 02/22/2016 at 11:43 point

Excellent, this is good stuff.  I have been pondering using CO2 sensor to work out a mechanism for yeast development (for bread, beer and anything needing fermentation).  This project would control so many variables so then the yeast variability would be the one thing left to crack.  

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Michele Perla wrote 01/29/2016 at 22:00 point

Brilliant!

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Jan wrote 01/30/2016 at 12:42 point

Thanks for stopping by :) I'm not done yet, most of the hard work is (as always for me) the software part. Stay tuned...

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