I dont understand. On the github for spider v2 it says "Build Volume:

I dont understand. On the github for spider v2 it says “Build Volume: 285x285x295mm” but the bed it uses is much larger?

the bed is just larger than the printable area. I guess this design allowed to fix the bed in an easier way to the Z threaded rods.
You can also us a squre build plate, see here https://plus.google.com/communities/108524206628971601859
build plate is 310x310x6mm cast & milled aluminium, mirror tile on top is 300x300mm, printable area is 290x290mm

the eustathios says its 300mmx300mmx270mm build volume. does that meean its larger than the spider in regard to l and w?

I think it depends on the XY carriage, it’s possible that the spider design needs a little bit more room than the orignal design, I think the lenght of the extrusions are the same. @Eclsnowman knows all the details about the v2 spider.

@Dovid_Teitelbaum the original Eustathios couldn’t reach 300x300 in my testing. I could get 290x290 perhaps. But yes depending on which carriage is used print volume goes up or down.

@Eclsnowman Thanks for the info. Can I ask you a question. I have this pegusus kit already and I really want to convert it to a ultimaker gantry. Pretty much all the extrsions I have are 2040 500mm length. Is there any design that will work where I would be able to use my current frames. If not maybe I can cut them down. Would like to be able to have my original 12" build volume if possible. http://www.makerfarm.com/index.php/12-pegasus-kit.html

Perhaps combining the HercuLien and Eustathios design could get you what you want. But would require you do some part redesign. At the end of the day the extrusion is actually one of the cheapest parts. For example you can get the entire extrusion kit from @Makeralot ​ for only 39$

http://www.makeralot.com/20mm-x-20mm-extruded-aluminum-for-eustathios-3d-printer-p207/

@Eclsnowman wow that is cheaper than i thought. but shipping is another $50

I am going to be purchasing my extrusion fromm them (Makeralot), even with the shipping I can’t get it any lower with local alternatives.