ISO Drawing Questions - Views & Hole Callouts 1

[Jieve]

Hi Guys, 2 Quick Questions:

Working to ISO. I have a rectangular part that I am showing in 5 orthogonal views on a 2D drawing. There are a total of 6 holes in the part. 2 are visible in the front view, 2 in the rear view, and 1 on each side view (L & R). The 2 rear holes are 9mm in diameter, and the rest are 6.6mm in diameter. If I were to specify one hole with a 2x 9mm callout in the rear view, is it clear that this is only relating to that specific view? In general, is it assumed that any multiple-hole callouts specified in a specific view are only relevant to that view? Or is there some other way to designate that the 2 x 9mm holes are ONLY the holes shown in the rear view and not in the other views? Is there a clean way to designate, also, that the rest of the holes in the other views are all 6.6mm diameter without dimensioning them separately in each view?

Second, in some cases I have found myself wanting to show only the top and bottom views, or only the front and back views of a part on a 2D drawing. This is likely a very basic question, but can I skip views on the drawing and make it clear that the views are the top and bottom, and not the top and front, for example? How would I designate this on the drawing correctly working to ISO? Would I just write the view name underneath the view or something? The drawings are all in first angle projection.

Thanks!

 

[SeasonLee]

I am not quite sure the ISO standard on your first question, but here is the reply on your second question:

The ISO standards support three methods of view projection on technical drawings: the first angle, third angle and arrow methods of projection. Most people are quite familiar with the first angle and the third angle method but seldom knows about the arrow method, here is the snap shot from Alex's ISO reference guide page 10, I am sure the arrow method is the way you wanted.

SeasonLee

 

[dgallup]

You could put a note on the drawing to the effect that unless otherwise specified, all holes are 6.6 diameter. Then your 2x 9mm callout on the rear view is sufficient.

I like to keep the number of views to a minimum as long as nothing is left ambiguous. I rarely use 5 views, typically 3 are enough but it is entirely dependent on the geometry. You can always throw in a full or partial cross section in one or two views if that helps.

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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.

 

[Jieve]

Thanks for the replies.

Seasonlee, thanks for that reference, I have seen that method used before but was somewhat unfamiliar with it. I'm not sure that it solves my problem though, because if I only wanted to show top and bottom views of a part, i would still need a third view (front or back) to which the arrows are drawn in order to designate which views are which. I am trying to avoid using a view which doesn't contain enough information to be useful for the manufacture of the part.

Is there another way to do this?
Thanks!

 

[CheckerHater]

Jieve,
I am curious what kind of magic parts are you designing, so they not require front / side projection and yet need both top and bottom views.

Even if you cut your part from flat material, you still have to put your thickness dimension somewhere and your top and bottom will look about the same.

As a suggestion; your views don’t have to be in the same scale. You could place small view(s) with necessary explanation somewhere in the corner, and dedicate the rest of your drawing sheet to top and bottom views.

About marking your holes; the general rule is to call out every feature only once. Some local/company standards allow to clarify, if you have small groups of holes far away from each other, shown on different views or even on different sheets. The total quantity should always stay the same.

More importantly, do you apply GD&T to your holes? If one references datums as |A|B|C| and the other as |B|A|C|, they are not the same pattern and can be treated as 2 separate features.

 

[Jieve]

Thanks for the reply.

One example of the magic parts that I'm producing is the assembly drawing of an oil pan. The parts to be welded together and how the should be welded is located On One drawing. After the welding process, holes need to be drilled. On a second drawing sheet, the views where the hole locations are relevant and their dimensions are shown. In this case, the only views necessary are those to depict the hole locations, the top and bottom views. The other views are clear from the first sheet. I could have done this On One sheet, but the drawing became cluttered.

So it's standard in ISO to only describe each feature once? Or should I put 4x then the dimension, for example? The 4x seems clearer to me, that's what brought me back to my original question. I sometimes get confused between ANSI and ISO conventions.

Thanks.

 

[CheckerHater]

I meant you say “4 holes” unless you have very good reason to say “2 holes” and than “2 holes” again

Sorry for confusing you.