Used a hole saw to convert portafilter to bottomless [pictures]

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#1: Post by coryforsenate »

I think using a hole saw bit is probably a lot easier than drilling 20 holes in a circle and then using a cutting bit to connect them. The hole saw bit also has the added advantage of the guide that centers it using the hole in the portafilter. It leaves a perfectly round, centered hole that just needed a little brushing with some metal finishing pads to take care of the sharp edges.

I used a Lenox 2 inch tungsten carbide GRIT hole saw (be sure NOT to get the one meant for wood). This is the cheapest 2 inch one that I could find (~$10). Lowes has a much better selection than Hope Depot for hole saw bits, at least here.

I secured the portafilter in a vice with wadded cloth on each side so as not to scratch up the outside. Using hearing, eye, and breathing protection, I inserted the guide into the portafilter hole and went to work. I occasionally dipped the portafilter and bit in cool water. After I finished, I took a metal finishing pad to smooth out the spikes and sharp edges. Viola!

All in all, it took about ten minutes.

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#2: Post by iginfect »

Did the same with a 2 3/8" hole saw bit ... ral/273511.


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Randy G.
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#3: Post by Randy G. »

I used a bi-metal hole saw that looks like your carbide unit and it has done four PFs so far.

TIP: If you are going to attempt this, when you get close to cutting through, lessen the force used to avoid peeling the chrome off when the brass is cut through on the far side. - 2000-2023 - a good run, its time is done

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Team HB
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#4: Post by cannonfodder »

I use a bi metal made for cutting metal. Mount the portafilter in the milling vice, use the pilot point to center the cutter, turn the drill press speed down and go. Then a couple of stones in my rotary tool to sand out and polish the cut edge and a fine metal file to flatten off the sharp edge. Which is nice if you have the tools but getting an $800 drill press, an $80 vice and a $15 bit to make a $40 bottomless portafilter might be a little excessive for a one and done process.
Dave Stephens

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#5: Post by Juanjo »