Hi all.

Attached is an article I have written (and continue to tweak) , which discusses CNC right from building a small HobbyCNC Machine through using Mach3 and beyond.

Although originally intentioned as a forum thread, it sort of "grew out of control" and became the attached article.  It focuses on R/C airplane building, but covers topics applicable to many applications.

I'm sure anyone new to CNC as a Hobby will find something in this article useful.  It answers, or at least talks about many of the questions I have seen on the Mach support forums and beyond.

E-mail me with feedback if you'd like.

P.S.... I had sent to to Art for approval before posting 

Rich.

Thanks Richard,
Very well written and informative with lots of good links.

Have you tried the plaster-of-Paris for the vacuum forming yet?  Are there any problems with the plastic sticking to the plaster? 

I built a rather big unit handling 24” x 24” plastic sheets and the 3mm thick plastic sticks tight to my aluminum
molds when the plastic shrinks.  I wonder if the plaster would survive. 
It might be ideal for thinner plastic though.  It is also a great idea for making the rubber molds.
Thanks again,
Bertho

Admittedly I have not tried vacuum forming on the plaster just yet.  But, my thinking in doing so would be to use Dow Corning RTV 3110 mold making material over the initial CNC'ed mold.  RTV 3110 separates real easy and makes a perfect mold without bubbles.  Then use this RTV 3110 "negative" to poor plaster of Paris into that for subsequent molds.  The RTV 3110 negative would become the template. I could even set aside the Original CNC'ed mold at that point for safe keeping.   So, if I couldn't find a good parting agent for Plaster of Paris and the plastic, I could simply use the RTV 3110 mold to pour in a material that would be more favorable, liquid plastic perhaps.  Vacuum forming is on my "list of things to get to..." :-)

Rich.

I haven't read all of it yet, but so far, it looks good. Thanks for shareing.

Brett

Thanks Brett... hope it helps.. if any sections are worth elaborating, let me know.

Rich.

Hi,
  great article,two things:
couldnt see how to export stl file in sketchup
& I always use MDF or better still HDF or tanalised MDF
for vacuum moulds before I go to aluminium,to check sizes/prototyping.
when youve cut, seal it with a good few coats of watered down PVA glue.

   Tony

Ah yes....

Go here http://www.ohyeahcad.com/download/ and about a third the way down you will see the .STL plugin for Sketchup...  Once you have the plugin set up, you must remember to "Explode" any 3D drawings you download such that the .STL export works properly.

I suppose I should eventually add that goodie to the article too. :-)

Let us know how it works out for you.

Rich.

Hi...

I have updated the document to reflect a discussion of the previous post regard the .STL plugin and Sketchup.  It includes the web link and some screen shots for clarity. 

Just redownload for the latest release.

Rich.