Two round tubes cannot meet on a square cut. What the saddle curve is, how diameter ratio and angle set the profile, and why fit-up decides whether a joint can be welded.
Every exhaust changes bore somewhere. How the included angle decides whether flow stays attached, when eccentric beats concentric, and where a weld in the path hurts most.
A burr is a notch waiting for a reason to crack. How each cutting process makes its own burr, why a sharp edge breaks the passive film, and what an edge break really means.
Welding moves an assembly, and machining afterwards exists to recover what it lost. Why datums shift, what facing and boring can and cannot fix, and how to sequence both.
A formed bend flattens the tube section before it turns the axis. What that ovality costs in flow, why it ruins clamped joints, and how to place a joint so it still seals.
Three cut processes separate metal in three different ways, and each leaves the edge in a different condition. How heat, kerf and squareness decide which cut actually suits a part.
What a printed model proves about envelope, clearance, assembly order and access, what it cannot prove about heat and distortion, and how to use it honestly.
Casting and fabrication spend money at different times. Tooling, draft, wall thickness, porosity and change tolerance, and where a hybrid route makes sense.
