Don't sweat the details...
Unless, that is, you want to make espresso
I fired up little baby Gaggia this morning and timed the temperature of the group as I was planning on doing some boiler recovery testing and a few pulls with the thermistor bead resting on the prepped puck to see how the intra-shot temperatures were performing. I made it about 15 minutes into the warm up when I swore the PF handle crept a bit to the left. I grabbed it and gave it a slight tug to the right and "crunch". Ugh. I crushed the thermistor bead on my Taylor thermometer. Not a huge set back as I can get a replacement for a few bucks on Digikey once I ascertain the Beta value. It's a 50k NTC thermistor, in case anyone ever needs to replace theirs...
Anyway, I cleaned everything up and tried a timed approach to temp surfing and figured out I have an 18 second window between element on and element off after purging the group one time to initiate a much shorter heat cycle and then purging again to kick the element on a second time.
Ok. Purge, wait, purge, lock PF in group, set shot glasses on scale, tare scale, and start shot at 9 seconds as a baseline. Got it. So I go dose my usual 16.5g into the Gaggia PF, do a little WDT, give it a quick groom and gentle NSEW tamp and go through the whole process outlined above. I find myself really missing Miss Silvia's hot water button... I press the brew button and wait.
Then it dawns on me that I preinfuse for ~20 seconds on my commercial machine, and that 20 seconds of preinfusion requires a very fine grind. I then remember that I haven't yet set the brew pressure on the Baby. Crap. About 2 minutes later, I have 30g accumulated in my shot glasses and I relish in the sweet smell of failure. Oops.
What to do? Remember in the first post when I cracked the OPV loose with it on the bench? There's a reason for that. I popped the spout off the PF, gave the threads a quick wrap of Teflon tape and threaded on my ridiculously oversized brew pressure gauge. I popped the basket out and placed a broccoli rubber band around the basket and dropped it back into to PF to great a seal between the pressure gauge and the basket so it doesn't leak all over everything and locked the whole shooting works in the group. Well over 12 Bar. That helps explain the 2 minute shot. Ugh... Better fix that!Slide out the tank:
This reveals the fill port at the back and the OPV port to the right and forward of that.Find the spot:
Way up in there is the OPV spring adjustment/discharge port. 5mm hex is your friend.Righty tighty, Lefty loosey
We want loosey. 2.5 full turns loosey, to be exact. Success!
We don't do "small" 'round these parts...
But of course this was after
ruining a perfect dose of beans, and I'm off to Atlanta for a few days, so it'll be a while till I can try it out yet. Not sure just how much I'll have to coarsen the grind to get a properly timed shot.
Until next time,