What Is a Portafilter?
The naked portafilter is a fairly new innovation in the old process of making espresso. Typically, a portafilter, which holds the coffee grounds and gets clamped to the espresso machine, has one or two spouts that direct the coffee into the espresso cup. By removing these spouts and making it "naked," the coffee maker can clearly see how effective their coffee extraction process is, enabling direct feedback and greater quality control.
Machining a Naked Portafilter
Below are the steps I used to make my own naked portafilter. I made use of a metal lathe and some basic lathe cutting tools. The pictures below are of two La Pavona portafilters: one chrome, one brass. Please understand that there are a million ways to approach this simple machining project. This is the way I have approached it with the tools I have.
Step 1: Unscrew the Double Spout
The spout threaded on the portafilter with a thread-locker. Using a vise makes unscrewing the spout much easier.
Step 2: Remove the Portafilter Handle
Before clamping the portafilter on the lathe, it is important to remove the handle.
Step 3: Clamp Portafilter in Lathe Chuck
Here is the portafilter clamped into the lathe on a 3-jaw chuck.
Step 4: Cut off Spout Threads
Using a lathe cutting tool, I slowly cut off the spout threads, millimeter by millimeter.
Step 5: Remove the Spout Threads
The final cut to remove the spout threads.
Step 6: Open up the Hole
Once the spout thread is removed, the resulting hole needs to be widened.
Step 7: Bore Open the Hole
A boring cutting tool allows the hole to be opened up from the inside out.
Step 8: Bore the Final Hole With the Matching Diameter
I made the final hole about the same diameter as my coffee basket.
Step 9: Add a Chamfer to the Hole Edge
Step 9: Add a Chamfer to the Hole Edge
Chamfering the hole edge removes any sharp metal burrs.
Step 10: Enjoy!
The last step is easy, it's time to enjoy your naked portafilter!
Why the Naked Portafilter Is So Great
The naked, bottomless, or crotchless portafilter is a great innovation that provides the home enthusiast or barista with a fantastic training tool. There are many variables to control when making a shot of espresso. Improper grinding, measuring, or tamping of the coffee can result in a wide variety of bad espresso brewing. The naked portafilter offers a clear window into the coffee extraction process allowing common errors to be seen quickly and easily.
Perfecting the Naked Extraction by Dan Kehn
- Great article on using a naked portafilter
Normal problems that occur during espresso making are: blonding, channeling, over-extraction, under-extraction, and pre-infusion. Get the definitions of these terms and a lot more here. Click on the link to read.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Gary on January 14, 2014:
Would you do this to my portafilter if I paid you?
Rancilio Silvia on February 11, 2011:
What a cool article. I tried doing this a couple of years ago with a Dremel tool and ruined my portafilter, but this looks like a much better way of doing it.
Stephen Bolter on April 16, 2010:
Nice article, I was wondering how to do this, thanks
Gaz on September 30, 2009:
Ahh, if only I had a metal lathe!
Dave McClure from Worcester, UK on August 25, 2007:
There we go. On the strength of this one and your A-bike which I commented on tonight, I've joined your fan-club. Quality stuff. Thanks.
comedyaddict on January 28, 2007:
What an awesome idea. I used to own a cafe in New Zealand, and used to "train" some of our regular patrons about what happens on an espresso machine. This would have been a great demonstration!
Kathy on December 11, 2006:
That is AWESOME - it looks like you're pulling pure crema, not even espresso!
George on November 18, 2006:
This is an impressive Hub! Great photos and explanation.
vic on November 18, 2006:
That espresso oozing into the cup sure looks rich and delicious!