At 01:03 AM 8/16/2007, you wrote:
>I have tried to use heated pen-knife to rework/mod-work on some plastics
>part.
>
>Though this method can be fast but the finishing is bad.  Additional
>finishing is needed as the cut-surface is rough.  My process is a simple
>flame-heated knife (to shape or cut) or pipe (to reduce diameter).  Any
>tips? or advise? or comments?

I don't know if this is in your budget, but you can pick up a small
bench top lathe for less than $500 USD, and it will do excellent work with
a sharp HSS bit when you get the cutting SFM right. It will cut metal too.

This one has a spindle bore of 20mm, but you can turn short pieces of much
larger diameter.

http://www.grizzly.com/products/G8688/images

Here is some info on proper cutting speeds and feeds and coolants for 
cutting plastics
with HSS (high-speed steel) tools (which should apply to similar 
Dremel cutters too)

http://pergatory.mit.edu/2.007/Resources/

(see General Manufacturing Information)

>To polish up, some cutting and shapings, I am thinking to load up some
>Dremel accessories, but the information on using Dremel to work on plastics
>is very lacking.  Now I wonder is Dremel the wrong choice?  If it is not so,
>what are must-have accessories to help shorten the purchasing process as
>well as to save some dollars and iterations.



>Thanks.
>
>Ling SM
>--
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Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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