Take the remaining long 20×20 extrusion, put on your table and put two M5 extrusion nuts into the top slot:
Put the extrusion between the front posts. Take the HBLFSNK5 bracket subassemblies you built in the previous step, two M5-10 bolts and two M5 washers, and attach the extrusion to the posts:
- M5-10 bolt
- M5 washer
- HBLFSNK5 bracket subassembly
- M5 extrusion nut
Tighten it so that the extrusion is flush to the table and tight to the post:
Repeat on the other side.