Drawing scales recommended by JIS and practical drawing scales

Here.mechanical drawing　inDrawing Scales Recommended by JIS and Practical Drawing Scales."　Note on the following.

What is a scale?Ratio of the length dimension of the object shown in the original drawing to the actual length dimension of the object　However, in our mechanical draftingJISZ8314 Drawing - Scales　defines the scales that may be used for drawings.

Today, I would like to make a note of the scales specified by JIS and the points to be considered when actually using them in practice.

Scale, scale, and double scale of drawings

Types of scales and rules for description

What is a scale?Criteria for measuring length　However, in drafting, there are three scales.

• Present scale = 1:1
• Double scale = scale greater than 1:1 (2:1)
• Scale = scale smaller than 1:1 (1:2)

It is.

This scale is often used for several scales on a single drawing,Only the main scales are shown in the title column; the other "all scales" are shown near the figure with details.　The rule is.

Also, for the scale, the scale that is considered recommended (first choice) and,If the recommended scale cannot be applied due to unavoidable circumstances, an intermediate scale (second choice) may be selected. There is also a rule thatThe following is a list of the following items that are included in the list. *The double scale shows only the first choice. Red bold type is the second choice.

• Present scale = 1:1
• Double scale = 50:1, 20:1, 10:1, 5:1, 2:1
• Scale =.1:1.5, 1:2,1:2.5、1:3, 1:4, 1:5,1:6, 1:10,1:15, 1:20,1:25、1:30、1:40, 1:50,1:601:100, 1:200 ・・・・・

The first two are the following.

Otherwise, as a special condition,If a scale larger or smaller than the scale shown above is required, it may be extended up or down beyond the above scale, but the scale to be used should be the scale in this table multiplied by an integer power of 10.　There is also a rule that

There is no 1:8 in the above scale, but I have a drawing scale of1:8 is added to the operation　I have been doing this for a while.　It may be a JIS no-no, but the choice between 1:6 and 1:8 makes a big difference in the way the drawing looks, and although we don't see it much anymoretrianglescale　I still apply what I was taught when I was just starting out in the design field, which is that if you double the size of a page, you can read it because it has a 1/400 display.

Next, let's look at the JIS description of the figure frame and scale.

The scale should be chosen to match the complexity of the object to be depicted and the purpose it is intended to express. In all cases, a scale should be chosen that is large enough to allow the information depicted to be understood easily and without error. That is, the size of the drawing is determined by the scale and the size of the object.

I will note an addendum on this.

How to Select Scale for Drawing Size

Relationship between Figure Box Size and Scale

Here, though, I will write regarding one-part-one-leaf drawings (one part per drawing),It is not an exaggeration to say that the choice of drawing frame and scale determines the readability of the drawing.　will be.

In my opinion.Because text interferes with shape recognition, the approximate figure frame can be determined by the balance between the size of the text and the model.　I was thinking,It is difficult for some things to be expressed in the present scale (1:1) for assembly drawings,The first candidate for the scale to be used for the parts drawing is the size of the drawing frame that can be drawn at 1:1.　and year,Any A1 to A4　butIt is best to select a size that fills about 70-80% of the parts in the figure frame.　I think it is.

It should not be too small or too large for the figure frame.Parts Drawing Design　Therefore, it is necessary to keep in mind that the drawings should be clean in appearance.Since there is basically no purpose of measurement in oblique views, but to help convey the shape, I believe that the second choice of 1:1.5 or 1:2.5 can be used for oblique views.

In the figure frame, the 

• Basically try to put in 3 sides of the exterior (6 sides if necessary)
• Showing a surface that is easier to understand if shown in cross section.
• Place the area to be detailed (partially enlarged)
• Bring out the diagonal view in an extra place if necessary.

 These are then dimensioned and the contents of theSelect a figure box that provides 70-80% representation for the figure box.　We will continue to do so.

Select a scale by ease of recognition

I have already mentioned that the parts drawing should be based on the current scale of 1:1.　However, as a special case, we can also use a square with only a hole, such as a safety fence cover (guard cover) for a machine.Parts whose shape can be easily recognized are scaled down to a smaller size (e.g., 1:2).　and so on.　On the contrary.Smaller parts should be actively scaled to show larger parts (e.g., 2:1).　It is better to do so.

Supplement: Necessity of putting more than 3 sides in the figure frame

For example, some people may have been taught not to write the side of a hole in a drawing such as "3-φ10 through" because the hole would be fixed. This has a history of being called that because front, side, and plane views are often inconsistent in 2DCAD drawings, resulting in production errors.

I personally think it is necessary to draw sides and planes properly, because in 3D CAD such things basically do not happen.　I rather like 6 sides.

Some of the companies that handle the drawings areBasically, put in six sides because it's so easy to get out."I have a company that says, "We are going to put out 6 sides of the drawing.　There are many advantages to this six-sided drawing process, and I would like to write about them again, but I recommend that at least three sides be included, and for parts that are a little confusing, six sides be included.

Finally.

It may not have been something I bothered to write about in the article,Drawings are design. Even if you have good design sense, it's a waste if your drawings are dirty.　It is.　I will continue to make an effort to draw beautiful drawings.

That's it.