What pen is used to draw thick solid lines and thin solid lines in the national standard of mechanical drawing?

1, b or HB pencil, draw a thick solid line (outline);

2. H pencil: write in the picture; ?

3, 2H pencils: draw thin solid lines, center lines, dimension line, two-dot dash lines, section lines, etc. ?

4, 3H pencils: draw a manuscript.

expanding materials:

1. What is the line width regulation of mechanical drawing?

mechanical drawing stipulates that the line width (d) of all line types should be selected from the following series according to the type and size of the pattern:? .13mm； .18mm； .25mm； .35mm； .5mm； .7mm； 1.mm； 1.4mm； 2.mm?

the width d of thick solid line can be selected between .5 and 2mm (usually .5~2mm is used in practice), and the width of thin line is d/2. ?

2. Selection of line width

(1) "The number of fonts, that is, the height h of fonts, can be divided into eight types: 2, 14, 1, 7, 5, 3.5, 2.5 and 1.8 mm." -Mechanical Drawing (4th Edition) P8? ;

(2) "There are two types of letters and numbers: A type and B type, and B type font is recommended. The stroke width (d) of type B font is 1/1 of the word height (h). " -Mechanical Drawing (4th Edition) P8;

(3) "The line width d of all line types shall be selected from the series of .13, .18, .25, .35, .5, .7, 1, 1.4 and 2mm according to the type and size of the pattern." -"Mechanical Drawing (4th Edition)" P1? "The height of Chinese characters should not be less than 3.5 mm" —— Mechanical Drawing (5th Edition) P7? ;

(4) "In mechanical drawing, there are usually two kinds of line widths, the ratio of thick line to thin line is 2: 1, and the width of thick line is preferably .5mm and .7 mm.. In order to ensure that the pattern is clear and easy to copy, we should try to avoid the appearance of lines with a line width less than .18 mm. " -"Mechanical Drawing (5th Edition)" P1? . ?

based on the above viewpoints, the following 7 pairs of optional thick/thin line widths are obtained:?

a..13：.25、b..18：.35、c..25：.5、d..35：.7、e..5：1、f..7：1.4、g.1：2? ;

3. collocation, font size, line width, evaluation, reason, thin line and thick line?

（1）? .13? .25? Neither manual drawing nor computer drawing is recommended. First, there is no corresponding font size; Second, the line width of thin lines is too small; ?

（2）1.8? .18? .35? Neither manual drawing nor computer drawing is recommended. First, the font size is less than 3.5; Second, the line width of thin lines just reaches the minimum recommended value of 1.8mm, and Chinese characters will be unclear; ?

（3）2.5? .25? .5? It is recommended to use computer drawing (AutoCAD). If the font size is less than 3.5, the Chinese characters will be unclear, so manual drawing is not recommended. ?

4. In computer drawing, the default configuration of AutoCAD line width is .25, with .25 as the thin line width and .5 as the thick line width, which is just one of the recommended thick line widths. Therefore, it is recommended to choose this configuration in AutoCAD (for unified examination and normal drawing).

It is estimated that this is also the meaning of .5mm recommended for thick lines in P1 of Mechanical Drawing (Fifth Edition). ?

（1）3.5? .35? .7? Suggest manual drawing (pencil drawing)? The font size of this collocation is the recommended minimum Chinese character font size of 3.5, so this collocation actually becomes the "minimum collocation" allowed by manual drawing, and the drawing we are making at present is usually the smallest A4 drawing, < P > of course, the smallest font size is selected, so this collocation is often used in manual drawing at school at present. It is estimated that this is also the meaning of .7mm recommended by P1 in Mechanical Drawing (Fifth Edition). ?

（2）5? .5? 1? Is it recommended to use manual drawing (mechanical pencil drawing)? .5 and 1 are selected for manual drawing, because it is recommended to use movable pencils when drawing manually, and .5 and 1mm refills are easier to find. ?

f? 7? .7? 1.4? Neither manual drawing nor computer drawing is recommended. ? g? 1? 1? 2? Neither manual drawing nor computer drawing is recommended.

5. conclusion:?

(1) The line widths of thick/thin lines that can be selected are: 2:1, 1.4:.7, 1:.5, .7:.35. ?

At present, the A4 drawing that is most frequently contacted is the smallest drawing. If the font size is the smallest recommended value of 3.5#, the corresponding thick/thin line width collocation is .7:.35, which is the most qualified collocation and recommended by many teachers.

However, in manual drawing, it is strongly recommended that you draw with a movable pencil. In order to facilitate the purchase of movable pencil lead, the pen widths of 1 and .5 are selected for manual drawing, which is also allowed, but it is only slightly larger than one size; ?

(2) The default line width setting of AutoCAD is .25mm Many people are used to this setting, and computer graphics are usually drawn by printers. It doesn't matter if the line width is a little thinner.

Therefore, line widths of .5 and .25 are adopted. In the national standard, this line width corresponds to 2.5#, which is smaller than the recommended minimum font size of 3.5#, but it can be seen when printed.

Reference: Baidu Encyclopedia-Mechanical Drawing