RE: drying coil forms/acrylic fab techniques

To: tesla-at-pupman-dot-com
Subject: RE: drying coil forms/acrylic fab techniques
From: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 09 Dec 1999 22:49:46 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Robert,
                Thanks for the info on plexi tubing.  ROC stands for 
radius of curvature.

Regards,
Malcolm


> Original Poster: "ROBERT CRESSLER" <59CREROB-at-menasha-dot-com> 
> 
> 
> Malcolm,
> snip
> Tubing seems to be particularly 
> susceptible to this. I've often welded sheet acrylic like this with no
> problems. Perhaps tubing is stressed for some reason associated with
> its manufacture or perhaps it has something to do with the different
> ROCs inside and out. Anyone know? snip
>         Acrylic tube is can be purchased in either cast or extruded.
>         Cast
> acrylic tube is made 
> by pour the raw monomer into a mold,curing. then grinding,polishing to
> size. optical,mechanical.and chemical properties are superior to
> extruded.the latter method is cheaper but has extrusion lines,residual
> plasticiziers,and residual stress from the process. lower chemical
> resistance + residual stress=crazing. Also,when solvent cementing
> tube(ie cementing a bottom on) the easy way is to apply the solvent
> from the inside. unfortunately this also makes it likely that solvent
> fumes will build up inside and cause the tube wall to craze and not
> appear till minutes or hours. sorry for the long winded reply,bottom
> line cast tube with good fabrication methods should do  the trick.

<snip>
 if
> you are interested can forward a copy of a series of booklets I will
> forward a copy from the Rohm&Haas company on
> sawing,cementing,forming,machining,painting,ect. of Plexiglas.They are
> all old (circa 1970)  but good from the heyday of Plexigals
> GM......... (ie cell cast acrylic )
> 
> hope this helps 
> Robert  Cressler
> (a.k.a. ex Plexiglas salesman from the seventies)
> 
> PS this will no doubt make me look dumb but what does "ROC" stand
> for??
> 
>