How to calibrate your OPV - With the tools you have at home...

System

Many talk about and reference the "Scace" or the "Scace II" but these are tools that take measurements and provide you with information. How you interpret the findings and or then make adjustments is what will drive the outcomes.  These tools do not do it for you and assumptions as to a reading and what that might mean is just that: An assumption.

Importantly, unless modified, a scace II will measure the group head pressure at the head and other measurements BUT does not tell you what the OPV is set for!

WARNING: Access to the OPV in many cases, will exposes you and the machine to an electrical risk. While you may not be doing electrical work; you are exposed and have the potential to breach the integrity of the electrical safety, once you access the internals of a machine.

In this case I shall refer to the (Brewtus) Minore II / III and IV, as access to the OPV by the user is provided and no covers need to be removed.  (An often overlooked positive for this machine)

Prerequisites and Tools:

A: Know your OPV, they are not all the same and the adjustment screw can sometimes be not so easy to access. see the OPV 101 thread and the pre reading document.
B: Have a dual floor/walled (DF) fake crema PF basket on hand
C: Have a true blind or insert for your PF  ( This shall allow NO flow)
D: Some coarse grinds or other stale supermarket ground coffee
E: Shots in my case is always referenced as a standard double shot for time and volume, of which I do manually -  Aprox.

Set your base line and get to know you machine:

A:  Insert the blind and run a couple of shots and record you Group Gauge reading.
B:  Insert the DF basket with no coffee grinds and run a couple of shots and record you Group Gauge reading and the volume.
C:  Insert the DF basket with a dose of the coarse / crappy coffee and run a couple of shots and record you Group Gauge reading and the volume.

You should now have a BASIC understanding of how YOUR machine is running... Everyone is different and accuracy of gauges and different DF baskets and so called

hazbean

Excellent article, good to see an informative well written piece like this. Just to add a little information, here is a link to some pics from when I finally worked up the courage to do the adjustment on our Mondiale. The major difficulty here was not so much the adjustment of the OPV as the removal and in particular replacement of the casework, with its rather springy stainless steel panels. One point about the adjustment. Because I wasn't sure how well it would go, in order to return to original settings, I made a couple of alignment reference marks on inner and outer parts. As it turned out, adjustment was easy. I had a borrowed manometer and set it from that, confirmed with a reading of just over 10 on the machines's gauge (about 11 blind). The improvement from the 13 odd that it had been running at was quite significant. https://picasaweb.google.com/haazbean/Mondiale (some pics are a bit noisy, sorry, wasn't paying attention) It's worth noting that the internal layout of many other Isomac machines is similar.

UNM

Good, but not much use to those of us without brew pressure gauges :-[ Anyone want me to post a summary here of making rough adjustments to vibe pump machines using flow rate? Or would that be better elsewhere?

shape_shifter

I've updated my blog with the BES900 OPV adjustment, only photos, no video since the stupid VirtualBox died on me.

shape_shifter

How is this for cool, people are already using the instructions on my website to adjust their OPVs  ;D