[blau_schuh]

I can't tell from the pictures what the cross sectional dimensions are for many of the cnc frames. It looks like "40 series" T slot.

Im not sure if the T-slot 15 series 1.5"x1.5" is going to be rigid enough. Whats the bare minimum I should be looking for?

I'm looking at 8020inc's offerings on ebay.

[stevespo]

It depends on the design and size of your router. What type of loads you anticipate, both in terms of your router design and the materials you'll be working with. The 8020 site has a deflection calculator that is very helpful.

http://www.8020.net/Downloads.asp

I am building a 32"x42" gantry style router and went with 3"x3" (3030) on the long axis. Very stiff - probably overkill, but only a modest cost increase over the 1530 or 4040 offerings. I also assumed the extra mass would help dampen vibration. Time will tell - I still haven't put anything together - just accumulating parts...

Steve

[blau_schuh]

thanks for the info, im in the same stage.. just picked up some linear bearings, and 3 servo motors. not sure what im buildin' yet, but just adding to the pile. ultimately i want to route guitar bodies/necks, and signs.