This is a placeholder topic for “Vibrating Mini Motor Disc” comments.
BZZZZZZZZZZ Feel that? That’s your little buzzing motor, and for any haptic feedback project you’ll want to pick up a few of them. These vibe motors are tiny discs, … read more
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Hi, I’m a bit of a coffee nut and trying to get a better puck by vibrating the portafilter. Any ideas on a suitable linear vibrator and controller/driver? I think a 2mm excursion at 0-150hz to move 250gm total is about right. Thanks for reading this… Cheers Dave
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Hi Dave, Welcome to the forum!
The easiest solution that comes to mind is this little guy:
The manufacturer rates it at 100g, so not sure how it’d behave at 250, but it can provide 7m/s^2 of acceleration at that mass, so I’d say it’d just be less for a higher mass.
Keen to see where you go with this one,
-James
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Hi James, many thanks! Just getting used to your site and missed your reply earlier. Given that I’m a complete novice it would be great to find a guide/coach on this stuff… do you know anybody who might take on that role for a modest sum?
Very excited that I may finally get this project moving.
Happy New Year to you and yours, Cheers Dave
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That’s a FANTASTIC idea Dave!
We upgraded our grinder last year from an old Rancilio Rocky to a Eureka Specialita and now have to stop each grind a couple of times to settle the grounds so the portafilter doesn’t overflow. Some kind of vibe motor would address that brilliantly.
I’m in Newy, walking distance from Core HQ. Where are you?
- Greig.
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Core don’t seem to have a lot in the way of proper vibrating motors - they’re mostly little haptic feedback motors. You could stick an eccentric mass on the end of an ordinary motor, but if you’re using it regularly the bearings in the motor will wear out pretty quickly.
I’d recommend taking a look for a motor out of something like a desktop sized vibratory tumble deburrer. A jewellers rouge polisher comes to mind, like this, but smaller:
Or a battery powered orbital sander could be a good option too. There’s a few projects on youtube where people use them to make themselves a DIY vibratory polisher.
Edit: I found this on Aliexpress. I mostly like the look of it, the dual eccentric weights should practically eliminate rocking torque on the shaft. Ball bearings are not the greatest choice for something like this as they’re susceptible to brinelling (a good sturdy bushing in a nice stiff and sturdy housing would be better), but for what you’re doing I’m sure they’ll last more than long enough.
https://www.aliexpress.com/item/1005001902320542.html
If you shop around I’m sure you could find something similar in Aus. You can also get some pretty good waterproof vibration motors out of/designed for ‘personal massagers’. A trip to your local adult store might be your best bet 
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Hi Greig,
Thanks for your encouragement… Sorry for the late reply, a ping by email from Core reminded me to check in! I live in Melbourne… a long way away! I made a thingy with a zillion pins (a bit like an evil hairbrush) to pierce and break up any clumps in the puck which works really well. I reckon that the profile of the vibration may turn out to be important. A hundred years ago in a different world I did a little peripheral work on some vibratory sorters and I know how important the profile is. For this reason I’m keen to be able to tailor signals and learn what works best… I will keep posting as things unfold and start simply perhaps… all ideas are super welcome!! cheers Dave
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Hi Oliver,
Love the ideas! Yes, I have a vision that may be a little too upmarket at the moment (but I’m not giving up on it) so starting simple may be the best plan. I’ll dig out the old sander for the morning brew… and yes, your “waterproof” ideas boggle the imagination!
Cheers Dave
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OK, progress, and thank you for prompting me to just get on with it a bit!! I got out the old sander from the garage, covered it in clingfilm and gave the portafilter a good buzz… and it worked pretty well… to at least the 80% level which, for zero cost is brilliant! Kudos to you guys for sharing your ideas. Cheers Dave
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Hey Dave,
I’ve not progressed this one, but am watching intently. Something about moving into a new house and needing to repair/replace all the broken things and FILL it with home automation, etc is consuming time - but it’s DEFINITELY still on the ToDo list.
Earlier you mentioned vibratory profiles, so I might be about to spring a trap on myself, but I’ve been wondering if a speaker could be put to some use here instead of a motor-based solution? What’s the optimum frequency, waveform and/or duty cycle for vibrating ground coffee into a portafilter?
I’ve added one of these 3W speakers to my cart for my next order to experiment with, and if that proves unsatisfactory I might ramp it up with something like one of these 25W babies from WES.
- G.
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Hi Greig,
Ooh, you’ve sparked a neuron in my brain with that one! In the home-theater space, some people employ bass shakers, which are essentially weights strapped to beefy speakers. They are usually made for LFE (low-frequency extension) content from movies in mind, but if the optimum frequency is down there, it might be ideal. If it’s higher, you could dissect a smaller driver and strap a weight to that too provided it isn’t too special.
Seeing what others are doing with sand, I’d guess fine coffee grounds would like a fairly high frequency:
-James
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WOW, that is super cool, just love it. Thank you Greig and James for your ideas here. And I may turn out to be just wrong about the profile of the vibration, maybe it will be as good as it gets with a relatively simple solution. My goal has really been to find out what profiles work best (including, possibly, it really does not matter)… The sander I tried produced a very aggressive vibration but worked pretty well. The speaker idea makes lots of sense as it is a sort of vibration machine and responds to different inputs… maybe it will like heavy metal music!! Cheers Dave
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Hi Greig,
Good to hear from you. Wow, not an easy time to be moving house…. All you need to add to that recipe is kids and you have the full suite of challenges!
I should really say that I am on two tracks here. One is pretty much fixed…. Something that works at the 80-90% level…… that is a very noisy old low frequency power sander with the sandpaper replaced by clingfilm. The result is a pretty even distribution in the puck despite being ridiculously over the top power-wise (350w motor). The second one is still in the making and is an experiment to find out what the ideal vibratory mix would look like…… time, waveform, frequency, amplitude, direction of oscillations, oscillation profile over time etc. It will probably turn out pretty simply, but I won’t know that till I test it out and discover that most things make little difference. In a perfect world I would have a signal generator, a driver and an electro-mechanical oscillator (like a powerful speaker driver as you propose). It seemed like a chance for me to learn new stuff if I could find a coach/mentor/teacher….
I have no interest in doing so but I reckon that what I learn could be turned into a simple appliance for baristas to make better and more consistent coffee (possibly using fewer beans as the easy fix for a poor puck is to grind a little coarser and use more beans)…… twenty years ago I might have done that as a side-hustle but not today! Very keen indeed to hear how your speakers go and how you drive them and with what signals…. Would that be a doof doof puck or maybe even punk or rock!? 
How will you transmit the vibrations to the portafilter?
Good luck with your move……
Cheers Dave
Reply to: Core Electronics Forum core_electronics+078a3836c508fc143f6462f4ad4ff0d8@discoursemail.com
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My goal here is to settle the rounded pyramid of coffee grounds into the portafilter, ahead of a tamp, so I’m hoping a basic ‘agitation’ is going to be all that’s required to do that job. (This task is currently performed by a combination of gentle taps on the counter + waving a finger over the top in between bursts on the grinder).
I’ll see if I can knock up a very basic housing this week just to get the ball rolling on this.
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Hi Dave,
Not much progress here, but here’s a brief update.
The hubby was kind enough to print me a portafilter stand that I acoustically coupled to a small 3" speaker, but as you’ve probably guessed I can’t make its cone move sufficiently to excite the coffee beans to settle, and even if I could, it would probably be deafening.
I’ve been waiting on Wagners to get their new Sound Exciter ‘bass thumper’ element in stock, and its mid-Feb ETA has now slipped to mid-March, so we might see some more progress here by Easter. Stay tuned.
- Greig.
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Hi Greig,
Those are some very nice prints! I’m embarrassed to see I haven’t recommended surface transducers yet, could they be a way of getting more motion into that printed piece, and at a broader range of frequencies:
Keen to see what you work out to be the best! Out of interest, how does a solution like this improve on what comes out of a grinder? I would have thought what comes out was already fairly loose and aerated. Always keen to learn more about the dark art of coffee!
-James
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Hi James,
Coffee is I think as much art as science, decorated with plenty of "emotion".
@David188527 might dissent [and that’s a handy tag to rope him in], but as I see our current goal, the challenge is to get the ground coffee from its ‘fluffy’ aerated state into a nicely uniformly compacted puck ready for the application of some hot water.
A grinder like the Eureka Specialita we have here at home, grinds on demand directly into the portafilter - the bit pictured above. It grinds for a specific time, and the idea is that you have the roast, grind and time combined just right so as to deliver a perfect - or at least consistent - 14-20g of coffee every time.
That’s different to many others that grind into a hopper, and you then have a dosing lever that dispenses a supposedly consistent amount into the portafilter. Depending upon how much coffee’s been ground into that hopper and how long it’s been sitting there, it might still be light and aerated, or it might already be compacted. So when you flick the dosing lever there’s a potential for a lot of variation in your dose - and even HOW you flick the lever contributes too.
Thus the grind-on-demand setup is seen by many as delivering a superior grind. Only catch is that BECAUSE it’s so wonderfully aerated, it spills over or out of the portafilter. I usually have to stop my Specialita two or three times through its 10.6s (count them) grind time to ‘settle’ the beans down, otherwise they’re going to end up all over the bench. I’m usually just using a finger and a bit of a light-duty tap on the bench for this, but a nice little acoustic or mechanical assistance is the direction we’re going with here.
- Greig.
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Hi,
I am looking to get something that will provide some vibration to a plastic hopper to keep a powder moving. It needs to be small like this vibrating mini motor disc, but do you think this will provide enough vibration to keep the powder flowing? Is there a better one or another option?
Thanks
Dee
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Hi Dee,
Welcome to the forum!!
Due to the motor only being able to output 0.5W I dont think there will be quite enough movement.
A quick TLDR of the topic linked below: if you want some heavy/customisable vibrations a DIY vibrating motor might be your best bet (or taking apart a gaming controller), grabbing a hobby motor and attaching an offset mass (a metal nut is cheap and easy to get a hold of).
I’d check out this topic: Vibration motor with strongest vibrations - #6 by Elmar155474
On how to get the biggest vibrations from a motor, there is also the surface transducer @James linked above: Medium Surface Transducer with Wires - 4 Ohm 3 Watt | Adafruit ADA1785 | Core Electronics Australia
Let us know how you go!
Liam
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