Using a portafilter mounted brew pressure gauge (tester)
my pressure measuring portafilter leaks all around the rim when I try to measure brew pressure?
This problem comes up from time to time and is normally answered by at least 6 people on any forum, within 5 minutes of having posted. The poster of the problem usually ends up feeling a bit silly having asked, but it's suprising how often I see it come up.
The reason this happens is because the person asking usually has the double or single basket inserted in the pressure measuring portafilter. Remove these baskets and allow the "rim" of the portafilter to seal directly on the gasket and it won't leak any more…….promise!
Just a tip….the rim of the portafilter isn't as "rounded" as the filter basket and sometimes has a raised edge, so don't lock it in too tight, or you might damage your group gasket. It actually doesn't need to be locked in too tight.
Note: there are some Portafilters where this won't work, some of the stock Bezzera portafilters have "notches in the raised rim of the portafilter basket. In this case you may have to buy a portafilter and grind the rim down flat as usually other manufacturers portafilters have the ears in different places, or find one that fits without "notches".
addition, some inventive chap on Coffeegeek had this problem with his Silvia portafilter, which has a notch and used a "rubber band" on the inside of the basket….this apparently worked, so some hope for the Silvia owners out there