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Zero cost adapter for portafilter pressure gauge

Postby DaveGrayson on Thu Aug 02, 2012 12:38 am

After a little head scratching it occurred to me that I could make an adapter out of an old presta style bike inner tube valve stem that would be able to pass though the portafilter hole and let me measure pressure with a bike pressure gauge (to fit presta valves). Cut the valve stem out of an old tube (free), cleaned it, screwed it in place with the valve nut, and tried it with my bike pressure gauge. Success!!!

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Postby DaveGrayson on Thu Aug 02, 2012 12:41 am

more pics...
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Postby TomC on Thu Aug 02, 2012 1:04 am

Clever!
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Postby HeyHey on Thu Aug 02, 2012 12:24 pm

You sir, are a thinker!

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Postby nhokt on Sat Aug 04, 2012 10:13 am

Awesome!

After spending many years working in a bike shop we found countless uses for old tubes, never thought of this though.
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Postby bostonbuzz on Sat Aug 04, 2012 10:59 am

Brilliant. The only problem for me is that I don't have a metal gauge like that. My floor pumps will probably not be happy with boiling water filling their non-rated rubber tubes!
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Postby civ on Sat Aug 04, 2012 11:35 am

Hello:
DaveGrayson wrote:... an adapter out of an old presta style bike inner tube valve stem ...

Incredibly ingenious. =-)

I have not ridden a bike in about 35 years, much less repair or take one apart (something I did quite often at when in school). Could you elaborate on dimensions of this 'presta' style stem (outer diametre) and most important, on that pressure gauge (brand, price, etc.) you are using?

I have certain doubts as to the possibility of my being able to use this type of arrangement as the Cimbali PFs that came with my Junior D/1 are not like yours and only have a 7.0 mm hole with no threads.

Thanks for posting your brilliant idea.

Cheers,

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Postby Bluecold on Sat Aug 04, 2012 11:46 am

Presta is racing bike standard. Here in the netherlands we call it a french valve.
Either way, this is why I never throw away bike tubes. High quality butyl rubber with almost limitless uses.
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Postby DaveGrayson on Fri Aug 17, 2012 12:03 am

CIV;

Like yours, my portafilter has a hole between 7 and 8 mm in diameter. The inside of the hole is unthreaded. The Presta valve stem has an outside diameter under 6 mm and it passes through the hole in the portafilter and is held in place with the nut that normally would fit on the valve stem if it were used on a bike (it comes with the tube). The inside is held in place by the flange of rubber left over after cutting out the valve stem. The gauge is a cheap bike gauge (15 bucks i think) that I got from www.mec.ca but should be available at anydedicated bike store. There are also cheap (2 bucks) adapters that screw onto presta stems that let you use normal tire gauges. Should be do-able for you too.
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Postby huw on Wed Sep 12, 2012 9:45 am

That's brilliant!

I remembered your post when I was making my own portafilter gauge and cut a couple of rubber washers from an inner tube. No PTFE tape required...

Sealed watertight to 12 bar and easy to lightly unscrew from the portafilter to let some water leak out to simulate a shot.

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