In order for the seam to be of high quality, proper preparation of the sides for welding is required. If the metal is thicker than 5 mm, one-sided cutting of edges with an angle of 45º is performed. With a plate thickness of 10 mm, cutting is required on both sides. Without such preparation, the metal will not be able to melt deeply and the connection will be superficial. Based on this, the types of chamfers are:

V-shaped;
Y-shaped;
X-shaped;
U-shaped.
Rusty metal leads to unstable arc burning, "spitting" of slag. The sides in the welding zone (at least 20 mm from the connection line) must be cleaned from rust, traces of paint, oil. If you have to weld thin metal 1-1.5 mm butt, a copper substrate is used to prevent burns.

To prevent the workpiece from moving during welding, tacks are preliminarily performed, and they must be on both sides. This applies to all types of connections.