From three views to general oblique (third angle)

You are given the three orthographic views of a part, in THIRD ANGLE. Read them, then draw the part in GENERAL oblique, which reduces the depth to two thirds — six units deep is four diagonals back. This part has a step cut at BOTH ends, and the two are NOT the same size; read each one off the views rather than assuming symmetry. The depth goes back at 45° up and to the right — one step right and one step up per diagonal. This is a pictorial, so leave hidden edges out entirely: draw only what you could see. Place the drawing anywhere with room around it.

The part, in three views

Third angle projection. Each square is one unit: count them to read the sizes off the views.

The method

Worked example: a plain block in cavalier oblique, with the 45° receding axis marked. It illustrates the method only, not this exercise's answer.

Line

Oblique projection: hints

The front face is drawn true shape
That is the whole point of oblique, and what makes it quicker to draw than isometric: the face you put at the front keeps its real widths and heights, so a square stays a square and a circle would stay a circle. Choose the face with the most detail to sit at the front. Every exercise here states which face that is.
The three types differ only in how much depth you draw
Cavalier does not reduce the depth at all, cabinet halves it, and general oblique takes a fraction in between — two thirds here. Nothing else changes: same front face, same 45° axis. Cavalier looks too deep because the eye expects foreshortening; cabinet looks closest to right. Drawing the same part in all three is the fastest way to see why.
Count depth in grid diagonals
The receding axis runs at 45°, so each diagonal is one step right and one step up — the diagonal of one grid square. In cavalier, one unit of depth is one diagonal; in cabinet, two units of depth make one diagonal; in general oblique, three units make two. Count diagonals along the axis, not squares across.
Hidden edges are left out of a pictorial
This is the opposite of the rule for orthographic views, and it is easy to carry the wrong habit across. A pictorial shows the part as it looks, so an edge you could not see is simply not drawn — no dashed lines. Draw only what is visible from the front, above and the right.
Only 45° works on a grid, and that is not a limitation of the method
On squared paper the receding axis has to run corner to corner through the squares, which is 45°. Other angles are used in practice — 30° and 60° are common on plain paper — but they do not land on grid intersections, so every exercise here uses 45°.

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