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How To Make Your Own Naked Portafilter

Postby cannonfodder on Wed Apr 12, 2006 8:15 pm

I enjoy do-it-yourself projects, so I decided to cut a bottomless portafilter for my Faema. When I got the machine there was an old, nasty, beat up portafilter in the parts pile. Once I finished rebuilding the machine, I ordered a proper portafilter and basket. Problem here is that I have become accustom to using the bottomless portafilter as a learning tool. That tool is especially helpful when dialing in a new machine. So I decided to chop the bottom off of this old reached PF.

I wrenched off the old busted handle and soak the PF head in some Joe-Glo to clean it up and then off to the garage for a lobotomy. The first step is to mount the head on a secure working platform. You do not want this to wiggle around while you are cutting on it.
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There are several ways you can go about chopping the bottom off a PF, but what I find easiest is to drill around the bottom of the PF. This easily removes excess material and makes sure you do not cut to close to the inner edge. As you can see from the photo, I ended up using a rubber-padded clamp to securely hold the PF to my work surface.
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Next, I put a tungsten carbide cutter in my rotary tool and commence to connect the dots. The closer you drilled your holes, the quicker you will be able to cut between them. Keep that in mind as you drill the base.
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A word of caution. Using this type of cutter produces an incredibly fine shaving. Experience has taught me to wear gloves and long sleeves while doing this. Some eye protection would be a good idea as well. This fine metal 'hair' will float on the breeze created by your working tool. It gets on everything and without gloves; you will end up with dozens of these fine shavings stuck in your hands and arm.
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Once the base is off, clean up the shavings and move to a ruff grinding stone. Round out the jagged edges but do not get to close to the inside wall of the PF.
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Now switch to a medium or fine stone to remove the remaining excess material. This is where you want to make the final shaping of the hole and make it nice and symmetrical.
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You could stop here but I like to go one further. I use a polishing stone to remove the mill marks left by the fine grinding stone. This polishes the inside edge and gives it a professional appearance. This is also when you want to remove any burrs around the outer edge. You do not want a sharp base, it will cut your table to pieces when you tamp on it.
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Now you have turned that spare old portafilter into working piece of equipment that should provide you with years of service. Just remember to take your time. You can always grind a little more, but you can never put back. Total start to finish, about one and a half hours.
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Postby HB on Wed Apr 12, 2006 9:46 pm

Excellent work Dave! Thanks for taking the time to photograph and write your how-to. I've linked this thread to the end of Perfecting the Naked Extraction as an aid to those who want to try bottomless portafilters on a shoestring budget.

UPDATE: See How To Make Your Own Bottomless Portafilter for an easier method using a hole saw and how the pros do it using a lathe.
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Postby s_m_k on Wed Apr 12, 2006 9:56 pm

Nice smooth finish.

I used the same technique with an aluminum (yeah, I know) portafilter. If only I could use a grinding wheel on aluminum. I settled for hand filing and drum sanding with a battery-powered Dremel tool. I still haven't finished it to my satisfaction, but I had to start pulling bottomless shots to satisfy my curiosity.
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Postby cannonfodder on Wed Apr 12, 2006 10:55 pm

Now this is why I like a bottomless PF. Without it you could not revel in my humiliation. Unlike Jon's perfect naked triple, here is Daves' perfect, what not to do, naked double.

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Houston, We have a Problem...

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The puck looks good, no obvious channeling.
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Now in my defense, these are using my new LM double basket, which appears to be part of my problem.
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I need to call EPNW tomorrow morning. My 58mm tamper sticks in my 58mm basket. I have to hold the PF down and wiggle out the tamper, which I am sure, is adding to the above blown shots.
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Postby barry on Thu Apr 13, 2006 1:20 am

a hole saw is so much faster and neater.


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Postby lino on Thu Apr 13, 2006 7:44 am

Huh?

I thought those HB tampers solved all extraction problems...
Has Dan been over selling them? <smirk>




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Postby cannonfodder on Thu Apr 13, 2006 9:20 am

I had thought about a hole saw, but I don't have one. This is what I had in the garage. If i ever cut another I will pick one up to try.

I brought my LM basket to work with me so I could try my generic 58mm tamp. It fits that one. I wonder if the basket is slightly under sized or my HB base is a hair too large. It fits my Isomac baskets just fine.

Normally, I can pull a pretty darn good shot. Having to wiggle the tamper out of the basket has to be disrupting the packing, or at least that is the excuse I am going to use for now.

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Postby shadowfax on Thu Apr 13, 2006 4:31 pm

last year I just took my Gaggia's PF to a local machine shop and they lathed it out (very well) into a naked PF for about $15, and 2 days' wait... How much is your time worth? ;)

Looks cool, though, I don't think I could get one looking that nice with a dremel!
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Postby cannonfodder on Thu Apr 13, 2006 9:17 pm

There are lots of other options. EPNW will also cut one of your existing PF's. I am a do it yourself guy and enjoy tinkering so I enjoyed cutting it. My time is free and I already have the tools. It just takes a little time and patience, and it beats sitting on the couch watching reruns.
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Postby OlywaDave on Fri Apr 14, 2006 12:13 pm

And you did a really nice job of it. I got a dremel and all the attachments... Hmmm I have to say it looks like so much fun that I'd think about doing this at home too.

The new factory bottomless PFs are pretty nice too. Lots of options with more to come I suppose.
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