Quote Originally Posted by reefy86 View Post
dont know if im being stupid but what i had in mind was to only bolt the top alu profile untill its square then had the bottom.

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Sounds great in theory and will work treat in Cad but can tell you in practise it will be pain in the arse and you'll struggle to get linear rails to align and be parallel.
Fraction of degree error on wide machine shows massively at other end and you'll want easy way to adjust without affecting other areas of machine.

Then you have the fact that really you want to be bolting the bearing plates to the lower profile to stiffen the gantry.

Would be lot easier and stronger if you made the bearing plates longer and bolted to gantry. Also like whats been suggested you also want to move the gantry back to better balance the gantry on the bearings. Plus will bring the cutting area more into the machine foot print.