AndyT":15v69qpa said:
I can't see any problems with those drawings! All the information needed seems to be there and I can't see any extraneous lines.
The top orthographic drawing in custard's post is laid out using (essentially) first angle projection, although the standard first angle projection symbol is missing that would immediately tell the viewer that's the convention in use.
Therefore the top left hand drawing is the front elevation. Dashed lines indicate hidden detail. Conventionally in first angle projection the drawing to the right of the front elevation is the side elevation, and the drawing below the front elevation is the plan view. To get the side elevation the drafter pivots the front elevation bringing its furthest left side towards the viewer using the furthest right position as a pivot. Similarly, to draw the plan, raise the topmost point of the front elevation towards the viewer using the bottommost point of the front elevation as the pivot.
In this case, the plan is correct, but the side 'elevation' omits details. For instance, where is the L shaped piece as seen in plan with its dovetailed corner? Who knows because it's omitted? If this top right hand drawing is actually a section there should be section indication lines and direction of view letters on the front elevation drawing, but none of these indicators or pointers exist. The side 'elevation' also isn't a section because if it was a section drawing the 1-3/8" square 'leg' would include lines 3/8" apart where the bridle joint passes through, and hidden detail lines to indicate there's a 5/8" thick piece of wood on the far side of the leg. That detail is omitted too, so it's not a section of the piece. Finally, to the right of the 1-3/8" square leg in the sort of side elevation, sort of not a section drawing there are two short heavy lines indicating that they are either something, or perhaps just a couple of random lines for no good reason.
True, there's more than enough information to make the piece from the drawings provided, including the isometric projection, but sloppy drawing practice doesn't make for clear communication, and can lead to errors. I've had to deal from time to time with sloppy drawings for longer than I care to remember, and drafts people who nowadays are a whizz with all the functions of things like 3ds Studio Max, AutoCAD and Rhino, but they have no real idea of how to set out orthographic projections in both the common drawing convention, i.e., first angle projection or third angle projection. I have sometimes received drawings that are copper bottom guaranteed (sic) to be set out in third angle projection, for instance, but in reality the drawings on the page are a mixture of third angle and first angle, with the added complication that the various elevations, sections, detail drawings, etc are set out randomly on the page or pages. It's no wonder that some complex jobs can sometimes end up made seriously out of whack. Slainte.
