(no subject)

From: Gregory Pettengill (Cote Art & Engineering)
To: Jon Hunwick (Delcam  International PLC)
Date: Wednesday, July 27, 1994
Forwarded to RP-ML by Greg, 94 08 03
Jon,
You wrote;
>Although the project was a success, it was found to be only marginally
>more cost-effective than traditional NC machining as the part was so
>complex. (We define complex as having doubly curved surfaces - rather
>than complicated which we define as being feature rich). We concluded
>(and proved later to our satisfaction) that a more cost effective
>solution is to build the part in FFFF and then take resin castings
>from that. 

Could you tell me more about how you make a resin casting from a FFFF model.
Do you believe that in most cases it would be more cost effective to have a 
mold made by traditional means (from a positive image) for a resin casting 
than to design the FFFF part as a mold (a negative image) for the resin casting?

You wrote;
>All of this is fine, of course, unless you have a part which would (in
>plastic injection moulding) need side cores (slides, up-and-aways,
>lifters) etc. etc. to actually get the tool to open. 

What is the most flexible material that you can produced as a FFFF model?
I am thinking of something that could be used as a flexible rubber mold.  
Perhaps polyethylene.