Converting the Portafilter to Bottomless

On my pre-Millennium La Pavoni Europiccola, which has two power switches and no PSTAT, I control the temperature by toggling the switches on and off. My main reason for keeping the portafilter stock was as a heat sink, so that reason disappeared. Over time I found the double spout on the bottom of my portafilter a hassle, and it was just impossible to remove. After following directions elsewhere on this site it wouldn't budge. I took it to Christopher Cara and he couldn't remove it either without fearing he would break it. The double spout was extra wide, it required using a larger cup and limited clearance underneath the group. After a brew session I typically insert a small sponge in the portafilter and run a blank shot through the group for a mild backflush, as suggested by Richard Penney. The dual spouts would spray water sideways so I couldn't do this without wrestling a small steam pitcher underneath. And the spout made it impossible to rest the portafilter on a tamping pad while filling an inserted basket. My only remaining hesitation was the idea that the portafilter bottom may percolate the coffee a little longer by forming a semi-enclosed brew chamber. That wasn't enough reason. So this afternoon I freed the portafilter from its nasty spout.

Cutting it was a little tricky. Thanks to Ray Johns who told me that if I use a hole saw, expect to chip away the metal rather than smoothly grind through. He recommended using grease but I didn't have any and it worked fine. The hole saw cost me about $18 at Grainger. It needs to be fastened to a drill bit, and even then it would work its way loose. But I worked carefully, wore protective thick leather gloves and a face mask.



I fastened the spout in a vise and started chipping away and would have to adjust the set screw in the hole saw to re-grip the drill bit. It broke through the bottom of the portafilter at one place at first, so I would redirect it until the bottom and spout were removed.



This left some nasty burrs and an uneven edge on the bottom.



But I used a rotary tool with a heavy duty cutting wheel to remove the burrs, then used a few different grinding wheels to smooth and even up the edges and got it done! It created a few scratches on the outside of the portafilter because I need to be more careful positioning the bit when grinding.



I tried a shot of decaf and was able to much more clearly see when it started to go blonde, so I pulled the shot. This will make a worthwhile improvement in shot quality.

I'll still leave the portafilter on my Millennium machine stock because I actually use it as a heat sink to control temperature.

Hi Ray,

Glad you caught this post. It went pretty much as you described and the hole saw was a good fit in my 49mm portafilter. Afterwards I took your lead from what you did for Tom and finished it off with a sanding wheel on my rotary tool. Next time I'll tape the surfaces I don't want dinged. But after pulling a few shots this morning with the feedback I can get with a bottomless portafilter, it's seeming less likely I'll crave a Cremina.* The shot quality on this vintage Pavoni paired with a Pharos is getting better and better.

* Of course my posts on this thread support the adage, "Never say never."