The Case for a Case

[Ham]

I've been thinking of making an adjustable seconds timer for coffee grinder for some time. I started off with the idea of rolling my own from scratch using an Arduino or the like, but something like this makes more sense. Only thing I'll have to do with that is fit it in a case.

And there's the problem. I need a window for the display and some means of actuating the buttons. My initial thought is to use a black abs box, cut a window and perspex over the display, drill a block of wood and use thin dowels through holes in the box for the switches. Anyone got a brighter idea?

[grams]

This is why Arduino types end up buying 3D printers*.

Or you could just buy something more pre-packaged. e.g.
https://www.amazon.co.uk/Multifunction-Digital-Module-Timing-Control/dp/B076KDZZPK/

(* that they use once)

[Diver300]

I would buy panel-mount pushbuttons and run wires from them to the board so that either the new pushbuttons or the old ones can be used. The pushbuttons would be electrically in parallel.

And then buy a clear case like this:-
https://uk.farnell.com/multicomp-pro/mp004926/enclosure-general-purpose-abs/dp/3497978

[Kim]

My usual approach to this sort of thing is to panel mount everything as much as possible.  Preferably using switches etc that can be mounted in round holes, because drilling square holes is tedious and always looks a bit shonky, though is usually necessary for displays^[1].  The ubiquitous 16x2 LCDs are a good bet for panel mounting if it doesn't need to be waterproof.  If you get the ones with an I²C interface on the back, it's a neat 4-wire connection to your Arduino or whatever.

Otherwise, a case with a clear lid saves a lot of effort if you don't mind the electronics being on show (although masking out a window and spray-painting the inside can work okay^[2]).  I've done the cut-a-hole-and-perspex thing a couple of times, and it always looks like a bit of a bodge.

Top tip: If it's more than just a couple of power connections, use connectors between the panel mounted components and the board to aid serviceability.  It's tempting to solder wires to the board directly, but you'll inevitably break one while fitting it all together, and now you're trying to work out where that loose wire goes without breaking another one.

If you're not interested in an electronics project, then the timer pointed to by grams would be a good bet.  If it's not clear, that just slots into a rectangular hole and the tabs hold it in place, as is common for cheap panel meters.  Works best if the panel is less than 3mm thick.


_{[1] Having tried various approaches, my preferred method for cutting square holes in ABS or aluminium is to drill accurately-placed 3mm holes to mark the corners, and join them up using either a Dremel with a grinding disc (flexible shaft helps keep things perpendicular) or by melting through the plastic with a nasty old soldering iron I keep for the purpose.  Some filing will then be required to make things straight, but filing ABS isn't too tedious.
[2] One thing that works really well with LED displays is to use translucent red ABS, mask a window and spray the rest of the inside black.  As no light can get through, it appears almost black, apart from the digits shining through.  As a bonus, it greatly improves the readability compared to the bare LED display module.}

[Ham]

This is why Arduino types end up buying 3D printers*.

Or you could just buy something more pre-packaged. e.g.
https://www.amazon.co.uk/Multifunction-Digital-Module-Timing-Control/dp/B076KDZZPK/

(* that they use once)

That has an appeal, but as it would have to go into a case and it starts off substantially larger, I'm inclined to go for the more complex project. The idea of paralleling the switches is exactly the sort of obvious-when-you-know thing I was hoping for, thanks Kim.

[Hot Flatus]

Which grinder is it?

I fitted a really sleek unit onto my Mazzer Major. I can't remember where I bought it but it was very cheap

Something like this...

https://www.alibaba.com/product-detail/dhc10j-digital-counter-timer-mini-timer_1997127859.html

[Ham]

That's neat. I've been looking for something like that for some time, but not succeeded - nothing I could find on any of the standard places or %your_favourite% search engine (and the one you linked to has a minimum 5 order, there may well be others out there)

Grinder is a Eureka Mignon Manuale, so no way to dosey-do. How did you implement it? I'm planning on installing in this, with the power supply in the same box. Use by operating the "grind" switch with the portafilter, then press the button for the grind time. I'm building in a fuse and a switch to take it back to normal, so magic smoke can't interrupt coffee consumption. I've ordered all the bits now, total cost will be about £16

[Hot Flatus]

. How did you implement it?

I honestly can't remember. Vaguely recall drilling four holes to form a square but I can't remember how I cut through the very thick aluminium body.  I'm pretty sure I got the idea from one of the very neuro diverse coffee forums I frequented at that time. And with that in mind I'd recommend you try same route. Somebody will have succeeded in a neat cheap way to fit a timer and will be able to provide a source for parts.

Actually, thinking back, once Id done all the prep work somebody from the coffee forum came to my house and helped me do the wiring because I didn't understand the wiring diagram.

I gave up on coffee forums years ago (too wanky even for me) so I don't know what is out there, but I you Google for one, join then ask somebody will help you

[Ham]

I'm sure I'm a member of a couple....

I was more interested in how you implemented it in operation, it sounds like you wired it to override the "grind" button (which on the Eureka is operated by pushing the portafilter in) - that's part of plan B for me if it ever gets that far. If that is the case, where was the override stop? On the timer itself?

To use my Plan A, I will have to push the portafilter in (nothing will happen) then press a button on the box to dose. To get to Nirvana Plan B, I would rewire to use the Eureka switch as the start button and mount another button as an override stop - the real switch is a little pricey. There may be room inside the grinder, I may find a smarter box, or I may just push the box behind the Rancillio (where a 4-way power strip lurks unseen, already)

[Hot Flatus]

Could always just buy a better grinder...

Niche are quite small, excellent, and if they are no longer the flavour of the month will be being sold off by the nerds for whatever is the latest and greatest.

Unfortunately I have no recollection of what I did to the grinder. It's probable I never really knew but just followed step-by-step instructions from a blueprint. I was baffled by the wiring diagram after all.

[Ham]

Could always just buy a better grinder...

Niche are quite small, excellent, and if they are no longer the flavour of the month will be being sold off by the nerds for whatever is the latest and greatest.

I had been thinking long and hard about the Niche zero, especially as I like a variety of coffee. Ultimately as I have just stepped into retirement it was the outlay - considering what your friend and mine, Liz Truss, did for my pension fund - that put me off.

Unfortunately I have no recollection of what I did to the grinder. It's probable I never really knew but just followed step-by-step instructions from a blueprint. I was baffled by the wiring diagram after all.

I was actually thinking about how you used it in practice, not how you got it working?

[Hot Flatus]

Oh, sorry, I've got covid brain.

Yes, I have 3 buttons. One is not timed, so will grind for as long as you press. The other two are connected to the timer and programmable.

Obviously you also have the grind setting, so if you grind finer for the same time, you get less coffee.

I'm not very scientific with it. I've been doing this bollocks for so long it doesn't take me long to dial in. The only time I'm thrown is when I change from my staple Italian bar filth to some single origin medium roast ponce and have to extend the time significantly to ensure a full basket otherwise I'll end up with something that tastes of cardboard.

[Hot Flatus]

I left the coffee forum world just as the Niche obsession was starting, but, as ever, a quick look back and I can see it was overhyped and it looks like it isn't flavour of the month. I've just read some reviews highlighting its flaws.

You could, of course, pick up a used Mazzer for bugger all. My Major is an excellent grinder and will outlive me.  The Royal is a monster, but has the advantage that you can easily remove the motor and powder coat it.(you'd have to bake the Major to release the motor)

I see there is one in Brighton on ebay for £100. A decade ago that would have been £300 and gone in seconds.

Not that I'm up on these things but certainly when I was last interested it was the case that all grinders had faults of some sort, whether it be inconsistent grind quality, clumping, grind retention, static etc. I've had a few grinders and the difference in flavour surprised me. The Mazzers were consistently good.

[chrisbainbridge]

Would suggesting a Nespresso be considered heresy?

[Ham]

Don't most of the Mazzers grind into a hopper and dose from there? (As makes perfect sense in a commercial environment)

Whichever, while I wouldn't like to represent myself as anything but a bit of a wanky ponce when it comes to food things, after all for years I used to be into wine and going into places where you needed to tug one off to get through the door, with aging has come a degree of acceptance. That is, there is such a thing as "good enough" and my current coffee making capability - even if it could be improved - is good enough for me. I can make a cup which tastes good to me, and crucially carries on tasting good long after it has been drunk. Consistency isn't wonderful, but again is good enough, getting the same quantity in the portafilter is the most challenging part, hence the dosing timer seems like a worthwhile addition for not a lot of money.

Getting used to the idea  that I have to be careful with cash these days is challenging after a load of years of having a decent salary. I discovered that the "points" that I had collected at work (doled out at £10-£50 a time) over the years had amounted to some £600 of value, I cashed them in for Amazon vouchers and was trying to think of something fun/luxury that I could use them for as a memento. A single dose grinder was what I was thinking about, but ultimately decided not to, although I keep on going back to the idea. Another option, less than perfect admittedly, but likely again "good enough" would be to get a single dose hopper for the Mignon.

[Hot Flatus]

Most artisan cafes use doserless these days. The doser is a relic of Italian bars where they would grind up enough for many shots in one go and they weren't too exact about doses.

My mazz has a doser, because the electronic doser less versions are pricy. As it happens the doser is a marvellous de-clumper. The timer delivers an exact dose. I then work the dose lever to deliver the grinds into the portafilter.

I suggested 2nd hand Maz not in an attempt to get you to spend money, but to avoid spending on a Niche, and and up with a very much better grinder than your Mignon for very little money, and one which is big enough for you to do a timer mod for about £20.

I agree with you about the whole thing though. I was never particularly obsessive about it. I just kept boing until I find a good balance of faff-free to drink quality.

[T42]

I just weigh 18g of beans into the hopper and grind until it's empty.

[Hot Flatus]

I can't be arsed weighing beans 

[Ham]

Would suggesting a Nespresso be considered heresy?

While I'm not against it in principle, it promises to be more off a faff. I've yet to have a ready made nespresso capsule that is anything other than a bit "meh", and as you can only cram about 7g of coffee into one capsule, that means two capsules for each drink, which if you are using home loaded capsules (no idea if there is any downside to that) means an awful lot of faff per cup, and doesn't do away with the grind of preparation

I suggested 2nd hand Maz not in an attempt to get you to spend money, but to avoid spending on a Niche, and and up with a very much better grinder than your Mignon for very little money, and one which is big enough for you to do a timer mod for about £20.

Probably the best idea, especially if I sold the Eureka, but past experience tells me I am shit at selling stuff, I admire those who can.

I just weigh 18g of beans into the hopper and grind until it's empty.

There's always that 

[Ham]

I can't be arsed weighing beans 

Volume works for me, although in the name of SCIENCE I have broken out my drug dealer scales to discover that I need 13s = 15g for the portafilter I'm using with current beans and grind in present ambient temperature and humidity.

[Ham]

Well, this will be fun.



The module appears to function correctly, but the display is around 10mm lower than the top of the relay, but it is readable through the translucent box. More concerning is the separation



The Com, NC contacts are fine, but the NO..... gulp. The NO terminal is the last one on the edge as you might expect, as is the NC. The NC relay contact is the one immediately above, on that island. The NO contact is the one above that (in the middle of the board) - track must be across the top of the board. And that separation around the terminal and the LV ground. What could possibly go wrong?

[Kim]

Use the relay to switch another relay?

[Ham]

I was thinking that - have a mains box and low voltage box.


Paging Mr W Heath Robinson, Mr Robinson to the domestic design communication device.....