Drafting Standards Question

[neondeon298]

Ok... so I have seen on some drawings that the draftsman will add "First Angle Projection", "Third Angle Projection", that time of thing to assist the viewer in understanding what they are looking at.

 

I am adding a circle with 0, 90, 180, and 270 degree locations with centermark to make sure whoever is viewing knows those directions for all holes on the drawing.

 

What is that type of thing called? A Compass, a datum.... I have no idea and can't find it in any of my books or can't google because I don't know what its called.

 

Any ideas?

[lrm]

I think the term you are looking for is "compass rose".

For example, https://www.shutterstock.com/image-vector/brown-compass-rose-isolated-on-white-40971652

 

There are standard symbols to indicate whether a drawing is 3rd angle (USA and Australia) or 1st angle (ROW aka Rest of World). Google "3rd angle projection symbol".

[ReMark]

Can we see what the drawing looks like?

[neondeon298]

I can't post company drawings. Maybe I'll draw one up and put it up here later that isn't a job drawing.

[ReMark]

Irm's answer wasn't what you were looking for?

 

What kind of drawings are we talking about?

[neondeon298]

I did use Irm's. I just have this funny feeling there is a more technical drafting term as a "compass rose" is used for maps and globes.

[ReMark]

What kind of drawings are we talking about?

 

Are you showing all the typical views one might expect to see such as top, front, side and isometric?

[neondeon298]

Its basically a 5x5x0.5" block of metal with 5 holes drilled from front face to bottom face. And due to the amount of different details on the drawing I didn't want to add 0, 90, 180, 270 to each (or one) of those holes. So bottom left corner of paper gets a compass rose. But drawing had Front Face, Side view, and other specific detail. Sorry I have to be vague.

[neondeon298]

Instead of Front Face, I should have said top face. So they are drilled straight through from Top to Bottom (the thickness of the plate).

[ReMark]

I guess I'm just not understanding the need for the 0, 90, 180, 270 markings. Wouldn't the center of each hole be indicated by distances from the centerlines of the plate?

 

I do tank fabrication drawings and we locate nozzles on the top, bottom (where applicable) and sides of a tank using a degree circle because when the tank is placed in the field the nozzle positions are critical for matching up with existing and new piping.

[neondeon298]

This job itself is putting the 5 holes into the plate, with centermark locations off of one corner. But inside those holes are EDM notches with super tight tolerances. The orientation of that notch on the hole side-wall is what the need for degree location was. Notch A may be at 90, another at 270, that kind of deal. And I didn't want to call them out individually for lack of space with leaders.

[ReMark]

And now the picture becomes a little clearer. OK. Well I've seen a number of different types of drawings from different disciplines in my career but I can't recall there being a special symbol for what you are attempting to show. Are the notches only located at the quadrants of a hole? Could a notch be located at 127 degrees for example?

 

Are the holes numbered?

 

Is the location of the notch somehow indicated on the edge of the hole with a symbol of any kind?

 

I'd consider numbering each hole then including a table that indicates the hole number and the location in degrees of where the notch should be located.

[neondeon298]

In this case only on quadrants. I have had others that require non-quadrant locations. That's why I felt it simpler to just keep a General notation of which way is 0°.

[ReMark]

I like my table idea.

[neondeon298]

[rkent]

In this case only on quadrants. I have had others that require non-quadrant locations. That's why I felt it simpler to just keep a General notation of which way is 0°.

 

Better include the other quadrant degrees so they know for sure that what you consider as 90 degrees is not 270 to them, etc.

[neondeon298]

I did. I put 0, 90, 180, 270