Subject:
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RE: Pneumatic tubing...
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 2 Feb 2001 18:28:07 GMT
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Original-From:
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John Barnes <barnes@+NoMoreSpam+sensors.com>
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Viewed:
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650 times
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Jeff wrote:
> I measured some today, and I'd bet a micro scout that it's 4mm OD x 2mm ID.
> I suspect the material is actually polyurethane, although silicone would
> work just as well.
>
> It's easy to find the 4mm OD, but the 2mm ID is tough. I couldn't find
> anything in the usual pneumatics catalogs, some of which are European.
> There does seem to be a standard 4mm x 2.4/2.5mm, but that may be a bit
> loose. Most pneumatic fittings grab the OD, even the very small ones.
> Barbs are used only on the smallest of fittings, because with significant
> air pressure the tubing swells and blows off the fitting.
>
> Interestingly, the barbs on Lego fittings and valves measure almost exactly
> 0.125" OD, decidedly not metric.
I have done a lot of chasing around, and have some limited experience with
tubing.
Firstly, I haven't found anything quite like the Lego tubing commercially
available.
Secondly, be very careful selecting the ID. You need to select tube that is a
tight fit, otherwise you'll suffer from pop-off! (Nasty ... ;)
I have investigated many of the available neoprene tubes and none have the wall
thickness of the Lego tube, therefore they pop off too easily.
There are some rubber type tubes with thicker walls but they are too
resilient -
they don't bend easily enough.
I have been using thin walled plastic tubing myself. It's flexible but not
as stretchy
as neoprene, so it resists popping off. Consequently, it can be harder to
push onto
the Lego fittings.
I have tried the transparent stuff typically used for models, aquariums and
motor
vehicle windshield washer type applications but I have found it to be too
rigid.
What I have ended up using is;
Stock number;
McMaster Carr (www.mcmaster.com) 5255K11
Description;
Tygon Chemical Pvc Tubing, 1/16" Id, 1/8" Od, 1/32" Wall
This stuff is hard to push onto the fittings, and even harder to get on to
the recessed
fitting on the blue air tank. But it is a nice shiny black and looks pretty
good when
installed.
Perhaps Jennifer C. would comment, I had sent her a trial piece a few weeks
ago, if
she's listening.
McMaster are good about shipping small quantities and are quite quick about it.
JB
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Message has 1 Reply:
 | | Re: Pneumatic tubing...
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| (...) I'd pretty much echo what John has said - it is good stuff, with a couple of limitations, the main one being that the inner diameter is too small to allow it to be pushed onto flex system tubes. I've used it on the bucket section of my skid (...) (24 years ago, 6-Feb-01, to lugnet.robotics)
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Message is in Reply To:
| | RE: Pneumatic tubing...
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| I measured some today, and I'd bet a micro scout that it's 4mm OD x 2mm ID. I suspect the material is actually polyurethane, although silicone would work just as well. It's easy to find the 4mm OD, but the 2mm ID is tough. I couldn't find anything (...) (24 years ago, 2-Feb-01, to lugnet.robotics)
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