On 8/4/2011 8:07 PM, Christopher Chapman wrote:
>
> Subject: Re: Teflon tubing for paper recording system...
>
>
> Hi Folks,
>      OK, so we want SS capillary tubing to make pens. Would someone who
> still uses ink systems measure the length and the OD of the capillary
> tube actually used please, so that we know what to look for ?
>      Does anyone in the USA have a source of SS capillary tube ?
> Someone must stock it ! I have bought it in 1 m lengths.

McMaster Carr has small SS tubing with an ID of 0.004 inch and larger:
http://www.mcmaster.com/
Type in tubing. From there look under material, metal, and click on 
Stainless Steel. There are many sizes (you can pick inner diameter 
first), and the smaller inner diameters appear to cost $5 to $7 each in 
12-inch lengths. This is cheap enough to buy several and experiment.

But doing online research to find what size works with what ink may be 
helpful. I did a few searches such as this:
http://www.google.com/search?q=ink+pen+capillary+size
but found nothing directly helpful, though Wikipedia's plotter entry is 
interesting:
http://en.wikipedia.org/wiki/Plotter
There seems to be a body of people using old pen plotters, and finding a 
forum of such people may be fruitful. Also, the plotter entry links to 
the Technical Pen entry, which looks very interesting:
http://en.wikipedia.org/wiki/Technical_pen
Such a pen could perhaps be used as-is, or if the in-pen cartridge ink 
supply is insufficient, just use the tip and a plastic tube to feed the 
ink as you were originally planning.

>      Why are you bothered about teflon tube, when PVC wire insulation
> tube is available cheaply ? Don't make the task any harder than it
> needs to be !
>      The smallparts prices seem to be idiotic. If you can get hold of
> a sharpened needle, all you need to do is to snip the tip off with
> wire cutters and it is no longer a medical injection needle !
>      Can someone check Charles' belief that it is illegal in the USA
> to POSSES a medical needle, please ? It sounds highly unlikely to me.
> We have mobile clinics giving clean needles out FREE to junkies
> prevent the spread of disease !
>      Regards,
>      Chris
>
>

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