Strong 2020 corner brackets

These are 90 degree brackets for 2020 aluminium extrusion. They provide rather strong and stiff connections. They only need 20% infill to be effective although I printed with 2mm shell on all sides and print in ABS.

There is two versions. The one without the notch is for joining extrusions where they have slots meet and the notch has the corner removed for situations where that is needed.

I use a M5 x 10mm cap screw with matching T-nuts to attach this bracket.
The design works well for the pre assembly t-nuts and for the post assembly t-nuts needs a fraction shaved off the slot edges to allow the nuts to rotate into position. I will likely fix that later with a new stl version.

Updated to fix an error with a mismatch in the bolt countersink on the two sides of the version with the corner notch. The filename is now "cnr_bracket_strong_braced_notch_fixed.stl", Accidentally uploaded the wrong file last time.