PSN-L Email List Message
Subject: Re: Teflon tubing for paper recording system...
From: "Charles R. Patton" charles.r.patton@........
Date: Thu, 04 Aug 2011 09:24:02 -0700
As I have never used an ink pen system, this may be totally off base,
BUT....
My understanding of most pen chart systems is that the ink flows under
capillary tension down the tubing (** this note excludes pressure feed
ink systems **). If this is true, then it would seem to me that Teflon
would be one of the worse tubings to use as it basically doesn't wet.
This would then block the flow of ink in the tubing. The chart systems
I have seen have always used a steel tube for the final "pen". No
problem there as steel will wet just fine. The tubing I thought I saw
was either rubber (short life) or PVC. PVC is extremely easy to find.
Pretty much any hook-up wire is using PVC insulation except for
aerospace and military wire insulated with exotic materials such as
Teflon, Kynar, Polyolefin, etc. Strip the insulation off of #14 house
wire for tubing with an ID of .0663". For something on the small end,
use solid CAT5 or similar (PC LAN cables or the inside-of-the-house
phone wiring.) A piece I just measured is 0.0193" which puts it at
about #24 gauge. So depending on your selection of wire, you very
likely have a source close to hand. Cheaper than ordering out!
For needles two sources I can think of are:
1) Your friendly doctor. I think that it may be illegal to own a
needle in the United States, so you may not be able to go this route.
2) A lot of epoxy applications use a syringe to apply. Usually the
tip is a plastic part that screws on (half-turn). But metal needles are
also available. They just aren't sharpened like an injection needle.
Instead they are cut off square. This would be nice because it also
gives you method of removing the needle and refilling your "syringe ink
cartridge" with the simple pull of the plunger. So check with your
local plastics/epoxy supply company.
Regards,
Charles R. Patton
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