The bottom frame is connected with screws to the bottom cross beam and the bottom side cross beam, purlin 8*4 square pipes x9 are connected with screws

Each column is fixed with six sets of hexagon socket bolts, and the column screws do not need to be tightened

Measuring verticality of column with line drop and level

The top frame is connected to the top beam and the top side beam with screws, and the drain hole faces outward.

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