Make Your Own (Wobble Disk) Coffee Roaster

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thef0x
Posts: 30
Joined: Mon Jan 29, 2024 2:46 am
Location: PNW

Make Your Own (Wobble Disk) Coffee Roaster

Post by thef0x »

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Problem: while free, cast iron roasting was producing inadequate results with yields dropping by 20% from the jump because of under and over roasted beans.

I also was not excited by the flavor here and would not continue to roast my own beans with this level of quality.

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Looks good

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Horrible performance.

Solutions:

1) Popcorn maker + microcontroller + smart logic / or buy this from a company

Yes, cool, yes pretty cheap, but can only handle up to 100g of beans per roast. For the smoke/smell and time, I'd prefer to roast larger batches.

2) Larger batch roasters

Works great, variable heat and bean rotation, but expensive and also I didn't make it or learn anything.

3) DIY Wobble Disk Roaster

Found from the Sweet Maria's youtube channel and then found 3 others including great instructions on specific materials here: https://www.youtube.com/watch?v=_s0Wc1roCYE

Ding ding ding, we have a winner.

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Disk compression .. joint? I have zero background in construction despite having constructed some things.

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Disk from small aluminum pizza pan

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How brilliant is this: a 6 cup stainless steel flour sieve with predrilled holes. I cut the existing rod and replaced it with a 1/4" threaded rod. It required a bit of extra drilling on the existing holes.

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I'm using 1/4" nuts with 1/4" locking washers

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Make sure to center the disk. When cutting the disk I made sure there were no contact points during the spinning. I sanded both the disk and joint smooth.

Video: https://i.imgur.com/jrkyKzG.mp4

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Here's our heat source! I have since replaced the footer block with non-moldy wood.

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Holes for heat to vent ensuring the wood doesn't burn.

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Test fitting

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Took apart a single speed battery operated screwdriver from black and decker.

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Using a 5amp 3v power adapter, I soldered the positive and negative on the terminals after testing.

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Zip ties on the cord for durability, more to hold down the power button, and to attach to the 2x4 scraps underneath.

The baseboards (cedar fencing scraps) are not connected together so I can slide the drill into place / the fit is very snug. I also have guide screws (see vid) to secure the flour sieve.

Video: https://i.imgur.com/6N5RXPX.mp4

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Way way way better results.

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Two 200g batches.

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20% yield loss vs 0% yield loss.

Net cost of ~$70 USD.

Sweet Maria's 20lbs Coffee with shipping: $113

Yield cost delta / 1lbs: $1.13

Total lbs required to pay for roaster: 62lbs

Net savings / 10 years: $339

Quality increase: 5 --> 8 (so far)





This came together in a short afternoon.

v2 (upgrades): update to PWM servo + d1 mini for smart rotation control. Set up "dumb mode" with a simple physical 'throttle'. Add temp sensor + microcontroller for (input) data. Connect it all up to my home assistant.

Software v1: Learn enough to write custom logic for starting temp to roasting time. Have an alert go off on my phone when the roast (based on the ambient temp) should be done. Have settings for light, medium, and dark roasts.

Software v2: Learn enough code to write logic to modulate servo rotation speed based on temp inputs.

loutfard
Posts: 290
Joined: Fri Jan 13, 2023 6:14 pm

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by loutfard »

May I suggest you look into esphome as your esp32 platform? As a configuration based platform, it can do much more than you'd imagine at first sight.

How much roasting time is actually involved? Quite relevant for European users. Many of us pay 0.3-0.4€/kWh. At a typical 2 kW, that's 0.6-0.8€/h. Unless done with excess own solar while the sun is shining...

sodatrain
Posts: 103
Joined: Tue Sep 20, 2022 5:43 pm

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by sodatrain »

Hey this looks fantastic! Thank you for all the pictures. I'll save this for a future project for sure!!

thef0x
Posts: 30
Joined: Mon Jan 29, 2024 2:46 am
Location: PNW

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by thef0x »

loutfard wrote:
Fri Feb 09, 2024 3:38 am
May I suggest you look into esphome as your esp32 platform? As a configuration based platform, it can do much more than you'd imagine at first sight.

How much roasting time is actually involved? Quite relevant for European users. Many of us pay 0.3-0.4€/kWh. At a typical 2 kW, that's 0.6-0.8€/h. Unless done with excess own solar while the sun is shining...
Exactly what I use today! ESPhome has super easy to use language for coding and configuring microcontrollers and has saved me a ton of time.

Have used the servo, ir receive and send, weight sensors, ppm sensors, and temp sensors so far in diy projects.

Time: ~12 minutes. 1800watt heat gun. Cost of electricity here is ~0.11/kwh. My power is roughly 50*% sourced from hydro power.
sodatrain wrote:
Fri Feb 09, 2024 9:08 am
Hey this looks fantastic! Thank you for all the pictures. I'll save this for a future project for sure!!
Besides a little prep, this project really did come together quickly and paid off at all stages of building (steady "it's working" dopamine drip of DIY/MYOG glory). Majorly satisfying! Would love to see your results if you decide to make one.
Last edited by thef0x on Mon Feb 12, 2024 2:46 pm, edited 2 times in total.

candide
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Location: red state America
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Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by candide »

Would it be insulting to you to nominate this for the annuals of junk punk? Or is this, in your mind hacking?

Either way, I love it.

This sort of thing is my bag.

thef0x
Posts: 30
Joined: Mon Jan 29, 2024 2:46 am
Location: PNW

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by thef0x »

candide wrote:
Fri Feb 09, 2024 11:11 am
Would it be insulting to you to nominate this for the annuals of junk punk? Or is this, in your mind hacking?

Either way, I love it.

This sort of thing is my bag.
I'd be honored and really zero creative credit goes to anyone but the creator, Larry Cotton, who has since iterated a few times on the design (seemingly to make it look cute, not sure anything mechanically was changed).

But hey, I'll take it!

Mostly just glad I could provide some value here.

PS. Today's Americano was sublime. I got to enjoy it slowly on the couch while playing with my son and snuggling with my wife, sounds of the rain's pitter-patter outside. On a "work day" no less! Hard to beat.

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loutfard
Posts: 290
Joined: Fri Jan 13, 2023 6:14 pm

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by loutfard »

thef0x wrote:
Fri Feb 09, 2024 10:54 am
Exactly what I use today! ESPhome has super easy to use language for coding and configuring microcontrollers and has saved me a ton of time.
As an aside, I see a glimmer of hope in esphome for rescuing certain electric household appliances with broken pcb's.

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Sclass
Posts: 2778
Joined: Tue Jul 10, 2012 5:15 pm
Location: Orange County, CA

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by Sclass »

That came out nice. I use a popcorn popper and it is a lot of smoke and I risk burnt fingers. It was so much hassle I gave up and went back to roasted beans in a bag.

Great machine. It looks like the form factor can evolve now that you have the proof of concept going. I bet you can shrink it to half the footprint by replacing the motor with a chain or pulley system and a smaller motor.

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maskedslug
Posts: 6
Joined: Fri Feb 09, 2024 4:40 pm

Re: Make Your Own (Wobble Disk) Coffee Roaster

Post by maskedslug »

Ahh, this is so cool. I also occasionally roast in an air popper, and find the work/reward ratio difficult to justify with the tiny ~80g batch size. A wobble roaster project may be in my future!

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