DIY PID Steam and Brew

[majnu]

Wanting to learn more about the intricacies of coffee I installed a PID yesterday. It still needs setting up (Steam Alarm and Brew temperature control values) but hopefully this will bring more consistent tasty shots; temperature stability with the addition of having steam control, if it does then the PID was a success(!)

Compared to the Auber (which from research has a detailed fitting guide, pre-set algorithms, fittings and a nice case) the DIY route imo isn't a difficult task and you can get near enough equal results for a fraction of the price.

Price can vary between £20-40 depending on whether you want to include a RTD PT100 sensor and a project box. Or if you don't have the crimps, wire cutters, spanners, thermal paste terminals and wires, dremmel etc already at home.

Wiring Guide
I wrote below is for a REX-C100 which is readily available on ebay. Hopefully this will help if others want to do the same.

https://docs.google.com/document/d/1...it?usp=sharing

I went for a MyPin TA4 just because of the colourful buttons, but functionality wise they are the same.

Pics






Project Box
One thing I didn't account for when selecting the enclosure was the retaining clasp size, which unfortunately if I mounted the PID in the horizontal position there was no room for it to fit and hold the PID in place. So bear that in mind, you'll probably need a bigger one as I preferred the layout horizontally. Maplins do sell bigger sizes which do match the Classic's housing.


Clip fits in Vertical Position



Drill & Cut enclosure



PID horizontally mounted


PID vertically mounted


Parts
PID Controller + 40A SSR +K Thermocouple Probe - £10.90
SSR-40AA £2.85

These project boxes will only fit the MyPIN TA4, NOT REX-C100
Aluminium Box 11 - £5.00
Aluminium Box 28 seems to be a better PID box but these are limited quantity and available for click and collect only - £1.00

Optional Upgrade
RTD PT100 - £23.32
Forum member MrShades can supply this at a cheaper rate and UK stock - £15

Additional Parts Required but I already had (But all available from Ebay/Maplins) :
24 and 14 AWG Wires (Turnigy or WYH)
Connectors (Piggyback, Fork and Spade)
Sleeving
Thermal Paste
100ma Fuse & Holder

[Dylan]

Very nice Majnu. Is the PID box custom made?

[Mike mc]

Looks good

[majnu]

Very nice Majnu. Is the PID box custom made?

No mate, it's an aluminium box I bought from maplins and cut. Will update the first post later to include what parts I bought, where from and cost.

[marcuswar]

Thanks for posting Majnu, I hope it inspires others to do the mod as it really helps nail down one of the more variable parameters when using the Gaggia.

This is pretty much what I did to mine when I used to use the Classic as my main machine, although I never bothered with the steam side of things just the brew temperature. I seem to remember the PID, probe and SSR cost me £20 all in. I just stuck the probe to the boiler with a big lump of BluTack, although longer term I always intened to use SUGRU instead. I also have to open up the PID to remove the two small relays and solder a jumper across the connections so that it could drive the SSR without the need of an additional DC transformer. Easy enough to do but be careful not to break any of the wires in the ribbon cable connecting the two boards like I did... re-soldering that took much longer !

One thing you haven't mentioned in the document is the "training" of the PID. I seem to remember I had to put it into training mode, set a desired temperature and then let it run through a series of heatup/cooldown cycles while it determined the thermal profile of the boiler. When it does this, it will intentionally overshoot the set temperature and so I would suggest you set the temperature a little lower than the one you will eventually end up using for coffee to avoid any chance of it blowing the internal fuse. I seem to remember I set mine at 70 degree for training but it was a long time ago so I can't be sure... just keep an eye on it and be ready to pull the plug if the temperature starts to climb much over 120 C

[Dylan]

Great, it matches the classic really well.

[marcuswar]

That's a nice little metal box you've used to house the PID. Looks a very neat job.

I used a length of square section (60mm) extruded aluminium tube for my PID Box.
http://www.ebay.co.uk/itm/1603265176...%3AMEBIDX%3AIT
The seller will cut the tube in half if you ask him to so you end up with 2 sections each 125mm long which is just about right.

I then used a couple of black plastic blanking caps at each end
http://www.ebay.co.uk/itm/2710010617...%3AMEBIDX%3AIT
A little time spent with a sharp knife and/or Dremel and the PID slips in nicely.

20141026_163208_.jpg

[marcuswar]

Out of interest Majnu, how did you attach the PID box to the side of the Gaggia ?

I had intended to use some small stick on magnets but in the end they weren't strong enough to hold it in place so it ended up just sitting on top of the machine

[majnu]

Out of interest Majnu, how did you attach the PID box to the side of the Gaggia ?

I had intended to use some small stick on magnets but in the end they weren't strong enough to hold it in place so it ended up just sitting on top of the machine

Just some strong double sided tape.

[marcuswar]

LoL, sometimes the most obvious is the most obscure
Thanks Majnu