PID to Gaggia Classic

I bought an old Classic from Ebay, and added a PID to it, here is how I did it.

I also bought a used Fuji PID from Ebay, model number PXV3-RCY2-4V.
This model is discontinued, was replaced, but it works fine
PDF User's manual

This guy used the same PID, on a Silvia.  He has info on setting up the PID.
Silvia with Fuji PID

I also copied this guy's work
PIDed Classic

PARTS USED
Fuji PXV3-RCY2-4V PID
D2440-10 40A Solid State Relay, made by Crydom (I bought a lot of 4 of these SSRs, used on ebay.  They come in handy for these projects)
Type K thermocouple wire
Some teflon wire for connecting everything else
A couple lug connectors, for connecting to some existing wires.
Small piece of heat shrink
A small plastic project box



INSTALLATION
I had a small plastic project box laying around, so I decided to use that one to mount the PID in.
I had to cut a square hole in one side of it, for the PID.  I needed to use a dremmel to grind down some plastic inside, so the PID would fit through the hole, and the PID mounting piece would  fit inside.  I glued the mounting piece inside, next to the hole, to hold the PID in place.  The mounting piece had plastic clips on top and bottom, to hold the PID, but I could only get at one of the clips after installing the clip in the box, so I cut off the other clip, otherwise I would not be able to take the PID out after pushing it in.

I mounted the SSR in the back of the Classic, so you can't see the screw holes that hold the SSR in place.  I used #6 screws to mount the SSR, because those were the largest size I could use, and get a nutdriver on the nuts, when they were in the SSR.


Here is the connection diagram for the Fuji PID.

Input is connected to a Type K thermocouple. I bought some 4mm metric screws, and drill a hole in the screw, to feed the thermocouple through.  This was the hardest part of this project, getting a hole in the screw, and then feeding the thermocouple wire through the hole, and screwing it in, so that the screw would wedge the thermocouple against the body of the boiler.

I could not do it with a thermocouple that had the wires fused together in a little ball, it would come out when I tried to tighten the screw.  I had to twist the wires together, which let me use a smaller hole in the screw, and then pull the end to the side a little bit, and I was finally able to get the thermocouple installed like I wanted.

An easier option would be to get a washer style thermocouple, which could be wedged against the outside of the boiler, but I wanted it closer to the water, and in from the surface of the boiler.  I think I am getting more accurate readings like this.

Portafilter Pressure Gauge

This is how I made my portafilter pressure gauge.

I used a portafilter with a threaded exit hole from an old Krupps Gaggia, which is an older model of the Gaggia Baby.

I bought this liquid filled pressure gauge, from Amazon
200 PSI Liquid filled Pressure Gauge

I bought a few parts from Home Depot
The most important one is a 3/8” Female Pipe Tee, Watts Part number A-758.

Here is a pic of the Tee, attached to the portafilter, with the valve also attached to it.

I also bought a couple of 3/8” male (MIP) to ¼ female (FIP) reducers.

The gauge screws into a reducer, which screws into the Tee.

The guage has an 1/4" male NPT thread on the bottom, reducer is on the right.

This pic shows the bottom of the gauge, with a of 3/8” male to ¼ female reducer on it.

I also bought a valve, I think I found one rated to about 180 PSI, at a local OSH (hardware store). It had ¼ threads, so I used a reducer there also.

One thing I found is that hardware stores have different names for NPT threads.
From Wikipedia
Sometimes NPT threads are referred to as MPT ('Male Pipe Thread'), MNPT, or NPT(M) for male (external) threads; and FPT ('Female Pipe Thread'), FNPT, or NPT(F) for female (internal) threads. An equivalent designation is MIP (Male iron pipe) and FIP (Female iron pipe).

I think Home Depot calls them MIP/FIP, and OSH calls them MPT/FPT, but they were all interchangable.

Here is a pic of the whole thing put together.

And, it seems to work fine.  There are a couple little leaks, which I could probably fix, but it doesn't effect its operation.  I open the valve just a little, so the water trickles out when the pump is on, and I was able to set my machine to 9 bar easily with this gauge.

Randy

Randytsuch coffee stuff

Here are my coffee pages.



I am into home roasting, have a PIDed, modified Gaggia Classic, a Vario grinder.

This blog shows how I made a pressure gauge using an old Gaggia portafilter
Building a Portafilter Pressure Gauge

Here is how I built a PID for controlling heat to my air popcorn popper coffee roaster
Building a Coffee Roaster PID

Making a preheater for a Gaggia
Construction details of the 1st revision of the preheater
Building the Revision 1 preheater

How the Rev 1 works
Preheater Rev 1 in use

Construction details of the 2nd revision of the preheater
Building the Revision 2 preheater

How the Rev 2 works
Preheater Rev 2 in use