Looking at plastics like UHMW and delrin... wondering how important
is "UV stabilization" for outdoor use? How long does it take for
ultraviolet light to damage the plastic? Months?
If it really matters, is black Delrin most likely to be the UV
stabilized type? Many of them say the color is black but they don't
specify UV stabilization or the specific Delrin part number/type.
Polyethylene tubing will positively crumble after a year or two in
sunlight. I had an injection line on my pool that would leak under
pressure after 3 or 4 months.
Consider wrapping with aluminum duct tape.
Yes, months but varies with your climate and sun exposure. If it is not
specified with UV inhibitors, don't count on it being there.
If a grade is not specified chances are it can vary or be mixed. Black
molded parts are the best for getting rig of rejected parts by grinding them
and blending in the virgin material.
For the vast majority of projects, I would guess No.
My problem isn't just a matter of cost, I'm going to start with only
about 1 foot of Delrin rod. The problem is trying to figure out what
is UV stabilized and what isn't. I asked McMaster-Carr and they said
they don't have any more information than what is on their website,
the specifications listed with the product. Other online outlets give
about the same information.
My project is experimental and maybe the exposure to sunlight will be
limited enough. It's a first design, and that usually sucks anyway, so
I should probably back off on the UV concern for the moment. If it
works, I'll take the advice and spend more on the subsequent design,
ordering from a more specialized store like the ones that require
minimum line item and total order amounts. But, to begin with, I'd
like to experiment with a short rod of several different Delrin/Acetal
types. The project can actually use more than one type at a time.
For what it's worth. I'm making stopgaps for between in-line skate
wheels. The Acetal rod will be underneath and supported by a U-shaped
DuPont's UV-stabilized Delrin (there are several grades) is a popular
material for sailboat sheaves, and has been for decades. I had some of them
on my keelboat that was in the water 6 months out of the year, with the
sheaves constantly exposed to the sun, and I had no problem with them over a
period of 5 years or so.
It's a common material. You shouldn't have any trouble finding it.
I think you'll find balck Delrin will last several years under
moderate sunlight exposure. I used to build hardware for high-end
custom sailboats. We made custom fitted anchor rollers with a choice
of bronze bushed stainless or Delrin sheave. A Delrin sheave was
considerably less expensive, and I don't recall ever receiving a
complaint or a request for a replacement.
Here's the sort of thing I'm talking about, from the present
incarnation of my business. The anchor is resting on the sheave.
I bought some of that black Delrin from McMaster-Carr and made some
masthead sheaves for my little sailboat out of it. I also made two
spares just in case. It only took 1 hr to make them. Haven't tried
them yet, the ice just melted. I'll let you know if they fail this
I bought 9 feet total of small diameter Delrin and acetal copolymer,
much more than enough. If it's not slippery or durable enough, I
might try Delrin AF later. All of the stuff in my most recent order
was either rod, flat bar, or tube. I was pleasantly surprised they
were able to ship the stuff UPS ground, including two 8 foot long
aluminum tubes, for only eight dollars. Shopping online is great
when you need to know technical information, even though they
couldn't tell me whether it's UV stabilized. The local Borg wouldn't
even know what type of aluminum or steel their rod/bar/tube is made
of. All the online merchant has to do is include the technical
information with the product description.
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