Drawings, 1st Angle or 3rd Angle?

[magicniner]

Which do you prefer to work with? And do you use dotted lines for hidden features?
I was taught engineering drawing in the 80s and so learned mostly in 1st angle projection but as part of the course we were required to be able to recognise and work in 3rd angle.
For most things I will now work in BOFP (Back Of a Fag Packet) but anything which requires some clarity of features I revert to 1st angle.

- Nick

[komatias]

Which do you prefer to work with? And do you use dotted lines for hidden features?
I was taught engineering drawing in the 80s and so learned mostly in 1st angle projection but as part of the course we were required to be able to recognise and work in 3rd angle.
For most things I will now work in BOFP (Back Of a Fag Packet) but anything which requires some clarity of features I revert to 1st angle.

- Nick

Whichever your organisation works in. My mind always works in 3rd angle. French and Norwegian companies work in 1st.
Either way, always pays to look at the projection symbol.
Hidden lines are always dashed, not dotted. And you never ever ever dimension them.

[m_c]

As long as all the information is on the drawing in an understandable format, I don't really care what projection is being used.

For anything I've designed on the computer, I'll create a drawing with only what information I know I'll need to machine it, which will most likely only include a single view with dotted lines where needed.
However I use the newer version of BOFP for most stuff, know as the RBOP (Random bit of paper), or if I can find one, a notebook.

[Neale]

Back in the 70s when I spent 6 weeks in the Marconi Drawing Office School, I think we were taught 3rd angle. These days, I use BOFP standards, which for me generally means a rough isometric sketch (and I mean rough) with dimensions. If I want better, I usually go to F360 at that point. BOFP sketches don't file very well - tend to be single-use only, but fine for the one-off smaller job. I probably do do the odd "projection" drawing, but I have to admit that I can't now remember which is 1st and which is 3rd...

[magicniner]

Hidden lines are always dashed, not dotted.

My SNAFU, you are, of course, entirely correct!
Regards,
Nick

[johnsattuk]

Back in the 50's I was taught 3rd angle, 1st angle was referred to as 'American projection, I think that at some stage there was a general change to 1st angle, perhaps to conform with other counytrys.

I still use 3rd angle, seems more logical to me, and use dotted/dashed lines for hidden entities.

I asked my enginneering mananager son what they used and he said 3rd angle, he said that in a previous job 1st angle caused so much hassle with customers and suppliers that they changed to 3rd angle.

[magicniner]

BOFP sketches don't file very well.

At the recommendation of a friend I installed Google Photos on my smart phone, now when I snap something it synchronises to my Google account and is usually instantly available on my other devices :D

- Nick

[johnsattuk]

My SNAFU, you are, of course, entirely correct!
Regards,
Nick

Isn't a dot just a very short dash :whistle:

[Neale]

At the recommendation of a friend I installed Google Photos on my smart phone, now when I snap something it synchronises to my Google account and is usually instantly available on my other devices :D

- Nick

Good idea - I use the phone camera a lot to record things I'm stripping for maintenance or whatever. Hadn't thought of it for recording sketches.

[routercnc]

When I was tought technical drawing way back in uni days it was all 3rd angle projection drawn in pencil on a proper drawing board with fancy rulers that moved along parallel lines. All had to conform to British Standards for layout and content. There is a symbol for 1st and 3rd angle which is a truncated cone on its side and end so you can see how the part is rotated when switching views.

Nowadays the CAD creates the 3 views automatically from a solid model but I still try and keep to the main standards for dimensioning and highlighting parts of the drawing. I also tend to include an isometric view in the corner as this is so easy with CAD and can add to the clarity and avoid annoying mistakes when machining!

But if it is a part that I've drawn on a piece of paper for me to quickly make then it's just whatever works to get the thing made.

[routerdriver]

The last post tells the truth about modern practice.The days of using a board and pencil or even using a computer as a 2D drawing system have faded away.A 3D model will help you avoid spatial clashes and can be viewed from any angle and with layers turned off or objects hidden for clarity you will have no trouble visualising the article.Best of all you can now find 3D CAD systems for little or no cost and why wouldn't you?Should you need a 2D drawing for any purpose a couple of mouse clicks will get you there.

[russell]

I've always preferred third angle as that's what I was taught at university in the 60s.

Does anyone know what happened to second angle?

Russell

[magicniner]

Does anyone know what happened to second angle?

That's when you show the same thing in all three drawings, but flipped 180 so from the back in two views, not very useful!
Not uncommon for Millennials :D

[Ger21]

Best of all you can now find 3D CAD systems for little or no cost and why wouldn't you?

Because 2D drawings and 2.5D CAM can be far faster, if you know what you are doing. 99% of what I do on my router are done with 2D CAD, where I can draw and create toolpaths faster than just creating a 3D model.

[johnsattuk]

Because 2D drawings and 2.5D CAM can be far faster, if you know what you are doing. 99% of what I do on my router are done with 2D CAD, where I can draw and create toolpaths faster than just creating a 3D model.

:thumsup: