Motivation
I bought a used Baby Gaggia, and also got a Baratza Virtuoso Grinder. I was brewing on a budget. I thought people went to crazy lengths to get the perfect shot. Now, I find I am one of them. I put a PID on the machine and will probably make the Virtuoso a stepless when the warranty expires. In the mean time I thought it made sense to be able to put a pressure regulator on the machine. Shouldn't the ability to adjust the pressure for each blend be as important as adjusting the temperature, grind, and dose. When I read this article, ( http://www.home-barista.com/tips/...ofiling-t3478.html ) about changing the pressure during the pour I was convinced this was a good idea.

The plan
I found the food grade regulator that could deliver the pressure needed for espresso. It is the Watts 26A range D (http://www.watts.com/pro/_product....asp?pid=768&ref=1 ). The regulator comes in 4 pressure ranges A-D. Range D will give up to 175 psi(12bar). The 263A is the same regulator with a 3rd port, presumably a gage port, but if it is a relief port, you could eliminate the over pressure valve OPV. I got a local dealer for watts from there web site and was able to get it for ~$80 with shipping. I spent about $40 on fittings, but I bet you could do better. The regulator would go between the OPV and the boiler. I would adjust the OPV ( http://coffeesnobs.com.au/YaBB.pl?num=1175171794/0 ) to increase the pressure behind the regulator to about 160 psi (11 bar) so I can get up to 145 psi (10 bar) from the regulator.

Parts list
1 Watts 26A regulator range D 1/4 NPT ports
1 200 PSI water pressure gauge w/ 1/4 NPT male fitting
2 1/4" NPT nipples
1 1/4" NPT T female
1 1/4" NPT coupler
2 1/4" NPT male to 1/4" compression elbow
2 1/4" compression to 1/4" compression coupler
2 1/4" compression insert sleeves for plastic tubing
1 1 3/8" U-bolt 1/4-20 threads
1 custom mounting block
2 8-32 3/4" long screws of wood screws
1/4" copper tubing
Teflon plumbing tape


Assembly

The mounting block was machined out of aluminum but could Just as well be cut out of a block of would. It is an L-shaped block wit the critical dimension being the 3/8" step. The square part of the regulator rests on the lower step and the round part rest on the upper step. The block is 1 1/4" wide and 1 1/4" high and 3/4" thick. The lower step is 1/2" deep.

I assemble the regulator and fittings as pictured. I should have used a longer nipple between the T and the regulator so the gauge could face forward and still clear the regulator handle, but I am comfortable with the Gauge facing up. Of course the gauge then the tank is connected to the OUT port and the pump will be connected at the IN port of the regulator.

At this point tubing is used for the rest of the plumbing. If you're going to use copper tubing I recommend getting a 1/4" tube bender. I slightly kinked one of the tubes and I think I could have bent them sharper. I probably should have gone with 1/4" OD plastic tubing instead of copper. I used 1/4" to 1/4" compression couplers to couple the 6mm tubing that fits on the tank and the OPV to the copper tubing I used. Don't for get the insert sleeves for the 6mm plastic tubing. They're a tight fit but will work. I fit everything together before mounting the regulator

I drilled 4 holes in what Gaggia calls the assembly plate. 2 for the U-bolt and 2 for screws to hold the mounting block. Make sure the rear hole for the U-bolt is far enough from the main body under the assembly plate so you can turn the nut for the U-bolt. I had to make one of the hole a slot because it was just to the side of the mount hole for the cover. I screwed the block onto the machine with 8-32 screws or wood screws and attached the regulator with the U-bolt.



The cover needed to be cut to make room for the regulator and the gauge. I did not do a very clean job.


Results
I tried to increase pressure from the OPV with a 5mm hex wrench from the bottom. But I could not turn it, and I did not want to force it. I was able to get up to 145 psi (10 bar) anyway, but I had to increase it almost all the way. My first try was with some decaf beans that went stale while I was making the mod. I had difficulty getting a shot in more than 10sec. When I ran out of those I pulled my favorite blend out of the freezer, Steve's blend from The Coffee Tea Exchange ( http://www.coffeeandtea.com/ ). I switched to singles so I wouldn't waste so much coffee. The first shot I pulled at 130 psi (9 bar) was great. When I tried a double it was extracted a little fast about 15 sec. It was drinkable. I think this blend is very forgiving. The next one I turned the pressure down a little and it took a little longer but still on the short side. It was good. I need to do a lot more experimenting. As for changing the pressure during the extraction, it is too hard to adjust the regulator when it is under pressure. I will keep you posted.
My Baby is growing up. Though I would gladly throw it out with the driptray water in favor of a plumbed in double boiler. My next mod for the machine may be a preheater described here ( http://www.home-barista.com/espre...=preheat%20classic ). I think improving the equipment one of the more interesting facets of the hobby.

UPDATE:

I have used my newly pressure regulated Baby Gaggia for almost 2 months. I think it has helped because my virtuoso grinder has steps that are too big. I was able to use the change in pressure as well as tamp and dose to adjust the extraction. and I think it improved my shots.

I made the Virtuoso grinder stepless about a week ago. I only took out the wedge that sticks in the steps. Now I have been using the grind more to adjust the extraction. I will write up an overhaul with locking mechanism etc. later.

Matt