1, r refers to the radius of the circle. For example, i 1, i2 stands for slope, R stands for radius, T stands for tangent length, and E stands for outer distance in architectural drawings. Inverted right angle c or fillet r. R also usually indicates radius in mechanical drawing.

2. In mechanical drawing, appearance in coordination refers to R-level accuracy.

3, r can also be used as reference symbols.

Extended data:

Examples of various dimensioning in mechanical drawing

(1) Numbers with linear dimensions are written in a certain direction, that is, based on the direction of the title bar, the prefix in the horizontal direction is upward, the prefix in the vertical direction is left, and the prefix tends to be upward when tilted.

(2) When the angle is marked by the angle and dimension marking method, all dimensions and numbers are written horizontally, that is, the prefix is always upward, and it is generally marked at the dimension line break.

(3) Pay attention to the dimensions of circle, arc and ball.

[1] When a circle or an arc larger than a semicircle is marked, the symbol "φ" should be added before the size number; When marking arc radius, the symbol "R" should be added before the dimension number. Dimension line should pass through the center of the circle and end with an arrow.

[2] When the arc radius is too large, it is impossible to mark the position of the center of the circle within the drawing range, and only a part of dimension line can be drawn.

[3] When marking the diameter or radius of a sphere, an "s" should be added before the symbol "φ" or "r".

(4) Note method of small size For small size, when there is not enough space to draw arrows or write numbers, you can draw the arrows outside, or use a dot instead of two arrows, or you can use marginal notes or quotation marks to mark the size numbers.

(5) Marking chord length and arc length The dimension boundary between chord length and arc length should be perpendicular to the middle vertical line of the chord. When dimensioning arc length, dimension line should use an arc, and the symbol "⌒" should be added above the dimension number.

(6) Marking methods of other structural dimensions

[1] dimension line should be parallel to the line connecting the two intersections.

[2] The thickness of plate-shaped parts with square structure and injection-molded plate-shaped parts can be marked with the symbol "T" before the size number. When the cross section of a machine part is marked with square structural dimensions, the symbol □ or "side length × side length" can be added before the number of side length dimensions.

[3] Injection method of evenly distributed group structure The evenly distributed group structure is marked with one of them, and the size mark is composed of "number × size (evenly distributed)". When the positioning and distribution of the group structure are clear, the words angle and "uniform distribution" can be omitted or "uniform distribution" can be expressed by EQS.

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