Hi all,

I apologize for asking a question about something that has been already discussed in many places on HB at length, but I am having trouble finding information specific to my situation.

I have an older ECM Giotto with a shim-style OPV that I want to upgrade to a more adjustable OPV and I'd like to be able to see the brew pressure as I adjust the OPV.

Can I simply install one of the gauges in the link below after the OPV and before the HX with a T coupling?
http://www.seattlecoffeegear.com/rocket ... sure-gauge

Is there a cheaper gauge that I could use instead? What is the role of the coils in tubing to the gauge?

And one more unrelated question that I am having trouble finding an answer to: If I chop the bottom of a portafilter to make it bottomless, it should then be able to accommodate any size basket right? I.E. my single portafilter should be able to fit a double or triple basket.

Thanks!

itscoffeetime wrote:Is there a cheaper gauge that I could use instead?

There is this: Zero cost adapter for portafilter pressure gauge . I gave that a try and it sorta worked but I ended up springing for this - http://espressocare.com/Qstore/Qstore.c ... sure+Gauge
which worked pretty well for getting my OPV where I wanted it on my ECM Giotto. I used this gauge and locked in the PF without a basket to test my choked max pressure (all flow going through the OPV.)

Note, this gauge will not show you the pressure when you are actually brewing, but that's OK. I set mine to max at about 10 bar, then tested how the machine flowed on finely ground ristretto shots and am happy with the result.

Stefano also found me an easily adjustable OPV that fit perfectly in my Giotto. I see now he has it in his online catalog - http://espressocare.com/Qstore/Qstore.c ... +OPV+Valve

itscoffeetime wrote:What is the role of the coils in tubing to the gauge?

I believe the coils help dampen the pressure pulses produced by the pump.

itscoffeetime wrote: If I chop the bottom of a portafilter to make it bottomless, it should then be able to accommodate any size basket right? I.E. my single portafilter should be able to fi

Yes. My chopped PF holds VST and triple baskets fine.

Thanks. Yeah, I was considering buying or making a portafilter pressure gauge, but I really want one plumbed in so that if I decide to get fancy with a method for changing brew pressure mid shot (with a rheostat or two OPVs and a solenoid like in this post: Brew pressure profiling with front panel controlled dual OPV) at a later date I can see pressure changes as I'm pulling a shot.

So you think that the linked gauge will work for my purposes?

itscoffeetime wrote:So you think that the linked gauge will work for my purposes?

I believe so, although it's the gauge used on a rotary pump machine and you have a vibe pump. I doubt that makes a difference -- Anyone know for sure?

I'm interested in adding a pump pressure gauge to my ECM Giotto and I would like some help identifying the threading on the components of my machine.

My plan is to add another tee connector immediately after the one that my OPV is connected to in this picture:




I'm having trouble finding what threading I will need on this tee connector. I think it is 1/8" BSP male-male-female but I don't know if that is BSP parallel or tapered. I'm assuming parallel.

Is this what I'm looking for?
http://www.discounthydraulichose.com/BS ... p/9090.htm

If so, can I find one for less than $28 dollars anywhere?

Maybe I could just buy this
http://www.discounthydraulichose.com/90 ... p/9086.htm
and two of these
http://www.discounthydraulichose.com/90 ... p/9000.htm

I would also need to replace that copper tubing going from the tee to the HX/boiler with a braided hose or something else flexible so that it will still be able to connect, right?

Thanks!


...moderator merged thread with previous thread on same subject...

Most of those fittings are taper thread, the threads seal against themselves, parallel thread would need a fitting on the end (bullet connector) to seal. Never used braided hose on the inside of a machine. Problem there may be heat. You could get a braided line that will take the pressure but it is going to get hot inside that machine which reduces the pressure rating. You also have a rubber liner in that braided line which may make you espresso taste like a tire. You are best off using coper line and bending it to fit. I did this on my Isomac long, long ago and it was a job to do. Cutting through the stainless to mount the new gauge is also difficult.

If I remember correctly, I cut the HX supply line, removed a little tubing, soldered new ends on and installed a T so I would not have to re pipe that supply line.

That is a lot of work for very little gain . . . but, all of the fittings you would need are available here:
http://www.orphanespresso.com/Espresso- ... c_360.html

There are much easier ways to measure brew pressure that are transportable from this machine to the next.

Thanks for the link, OE has exactly what I'm looking for.

It's not work - it's fun. I'm mainly doing it for the sake of tinkering and to help me develop a better understanding of how pressure changes over the course of a shot. I don't harbor any misconceptions about immediately pulling better shots because I'm able to see the pump pressure.

. . . and to help me develop a better understanding of how pressure changes over the course of a shot.

It doesn't. Given a properly prepared coffee puck, the pressure applied to the top of the coffee will slowly rise to the value set by your OPV and remain at that value during the course of the shot.

I agree that "tinkering" can be fun but make sure you avoid making changes that cannot be easily undone.

Sure it does. Like you said, it starts at zero and rises to whatever the OPV is set at - and the rate at which that happens seems to be at least somewhat important.

I can also probably change the pressure over the course or a shot by operating the pump with a PWM controller or simply adjusting the pump voltage with a potentiometer. If I have any success with that I'd eventually like to add a transducer to the hydraulic circuit. Then I can send that signal to the board controlling the pump so that I have closed loop pressure control and can use a PID algorithm to maintain certain pressures at certain points in the shot.

To do all that I would only need to modify the part of the hydraulic circuit between the pump and the HX (as well as put a relay or pot in front of the pump), which would be very easy to reset to factory condition if I wanted to.

I understand that this will not necessarily improve my espresso and if that were my goal there are probably more efficient ways for me to do that anyway, but it's more fun for me to tinker than to always drink the best possible espresso.

Thanks for your help with the threading. I think I may order one of your E-61 thermometer/thermocouple adapters in the near future so that I can get a handle on temperature, too.