Hello Gui -
Hopefully I can answer your question regarding the differences in extrusion systems. My engineering company used many other brands in the past, but because we require performance and value, we settled on the "item" brand (not to be confused with the IPS brand - which is not and has never been the same as "item") extrusions in our shop. As Tim mentioned, there are wide differences in dimensional tolerances and alloy which in turn reflect on the strength of the extrusion. Equally important is the method of attachment - other systems have copied the item fasteners but they do not work unless you have a high strength extrusion to use them in. item has been in business for over 26 years and is the world sales leader in structural aluminum systems. So why is this important to you? It means you get a highly engineered and respected building system with very high level of engineering support. item is committed to staying at the top which is why they have decided to support FIRST teams with an outstanding value in the form of "kits" that contain the neccessary extrusions and fasteners to put together a modular and strong robot. Team 930 has used these kits exclusively for the past two years - and as anyone that has seen our robots will attest too - they are strong, rigid, and light and we have never had a fastener break or come loose. If you or anyone else reading this post has any questions about applying the system to your project, please contact me at
loren@aes-wi.com.
Good luck this year - it is a great game!
Loren
engineering lead
Team 930
www.team930.com