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Application of Scale

Application of Scale

Application of Scale

(OP)
Hello everyone

There seems to be some confusion in our design/drafting department regarding the application of scale in drawings.

We know that its generally not a good practice to take a detail view from a section view, however, due to the nature of our product, its often the cleanest and most convenient to accurately define our design intents. The confusion we have is, when performing such an action, how should we relate the scales of the children views?

For example, lets say there is a parent view at 1:1 scale. From that parent view, a section view is taken at 2X scale. From the section, we take a detail view at 2X scale relative to the section view. So, on the drawing, do we define the detail view at 4X scale, relating it to the highest level parent view from which the children views originate, or do we leave it at 2X scale, relating it only to the previous section view with the direct callout?

Possibly complicating this issue - we actually don't specify a real scale on our parent views, so all subsequent view scales are relative, not absolute.

I looked through the Genium drafting manual, and ASME Y14.3, but couldnt find anything really definitive at a quick glance. Looking at Y14.41, it states that section views must be at the same scale as the model (appendix 1 3.4b in the 2012 edition), which would of course mean in the above example 1:1, making a detail view scale 2X anyway you look at it - but often its just not practical to leave our section views at the same scale.

Thoughts?

RE: Application of Scale

Quote:

We know that its generally not a good practice to take a detail view from a section view

How do you "know" this?

RE: Application of Scale

ASME Y14.3-2003 is the relevant standard and the same one that effectively precludes taking a 'section of a section'.

Quote (ASME Y14.3-2003 Section 3.2.5)

The cutting plane should be shown through an exterior view and not through a sectional view.

However, I don't think it precludes taking a detail view of a section

"So, on the drawing, do we define the detail view at 4X scale, relating it to the highest level parent view from which the children views originate" - Yes that's my common practice but now I can't find the section on scale in 14.3 - maybe I'm imagining it that I saw it earlier.

<Edit>

I phrased that badly, what I really mean is since 1:1 is true scale, then the detail view scale label should be relative to true scale regardless of what scale view it is projected from. So if you are showing a detail of a Ø.5" hole, and in the detail the hole is 'drawn' Ø2.0" then the scale is 4:1. Doesn't matter if the view you indicated that the detail is projected from is say 2:1 itself i.e. showing the hols as Ø1.0".

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RE: Application of Scale

I have always put the scale relative to the paper size so in your example it would be 4:1

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Application of Scale

AMontembeault,

What do the end users of your drawing need to know?

If there is a sheet scale somewhere, every view that does not conform to it should have its own separate scale specification. I have of those triangular drafting scales sitting here at my desk. I have a full sized plotter here, and I hang E-sized plots on my wall. The scale on the drawing tells me which scale to pick up from my desk. The scale should be relative to the sheet of paper.

--
JHG

RE: Application of Scale

As for Y14.41 stating that section views must be at the same scale as the model, you have to take into consideration that it is a MBD standard more than a traditional drawing standard.

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

RE: Application of Scale

According to ASME Y14.100-2004 Paragraph 4.23 Scale:

"Scale expresses the ratio of the object size as drawn to its full size."

So, to the full size, not to some other view.

Where exactly people get ideas that it should be done the other way around? Any reference?

"For every expert there is an equal and opposite expert"
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