Patents and legal issues with FDM

How come the reprap project isn't under attack from Stratasys? They've been using this tech for 20 years.

If the answer is because it's an open source project then how come companies like Makerbot or Bits From Bytes don't get sued?

I'm counting my blessings this hasn't happened but is there a chance that the project will come under attack from patent holders?

Edited 1 time(s). Last edit at 01/15/2011 08:01AM by Tramagust.

I believe the original FDM patent has expired.

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[www.hydraraptor.blogspot.com]

The original one [www.google.com] expired (probably - I can't find any resource that definitely says it expired) but there are quite a few issued in '95 and '96 that still haven't expired.

My guess is that the open source RP community hasn't yet become a monetary threat to commercial systems. Until that becomes the case, none of the commercial entities can afford the black eye of suing organizations that have a very positive public image.

That is, if there are in fact specific patents being infringed. I haven't looked into it. Was this examined in any of the academic research?

surely they didn't invent extrusion though.. just first to put it with a CNC? I can imagine infringement would be stealing the exact design, reprap has gone on it's own journey for the extruder mechanism so i imagine it's pretty different? Also you would probably getting away with copying their exact mechanism but changing it all just enough so it's different, like jingles being based on real pop songs but changed enough not to get sued

for example:

The term Fused deposition modeling and its abbreviation to FDM are trademarked by Stratasys Inc. The exactly equivalent term, Fused Filament Fabrication or FFF, was coined by the members of the RepRap project to give a phrase that would be legally unconstrained in its use.

[en.wikipedia.org]