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Drawing projection, first or third?

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Steve Garnett05/09/2011 21:51:41
837 forum posts
27 photos
Posted by RILEY COMBS on 02/09/2011 17:26:12:
 
We are having problems with getting each part of the world to understand both systems. We would like to choose one system (I prefer 3rd angle). Do you know of companies that have this problem and how are they dealing with it?
 

 
Unfortunately I suspect that there's only one realistic solution to this, if you want manufactured product without too many mistakes, and on a realistic time scale. That's to find out what the people actually manufacturing the goods can work most effectively with. I say unfortunate, because it's not necessarily going to be the standard you're happiest with... but however you do this, somebody's going to suffer from a bit of in-house training, aren't they?
 
If you want to know definitively though, then doing a bit of critical path analysis to come up with the answer may be the way to go. You have to work out where the longest delay is going to be in a project. Is the drafting delay going to be greater than the manufacturing delay when using each standard exclusively, or vice versa?
 
Even though I said ages ago that I don't really have a preference as to which standard to use, I have to say that if you are going to produce drawings 'after the event' of smallish pieces, it's way easier to do this in first angle than third, if you have the article with you. Turn it 90 degrees to the right on its right-hand edge, stand it on its end, and that's where you draw what you can see, in the gap it just left.
Gone Away05/09/2011 23:20:31
829 forum posts
1 photos
Posted by Steve Garnett on 05/09/2011 21:51:41:, I have to say that if you are going to produce drawings 'after the event' of smallish pieces, it's way easier to do this in first angle than third,

If the drawings are being produced in North America, that simply isn't true. The US and (mostly) Canada are, and have been, pretty much exclusively 3rd angle and don't have the 1st/3rd history that I understand has existed in the UK and many parts of Europe.
 
It is way easier for North American draftsmen and engineers to see things in 3rd angle - it's the way they've been trained - and foisting 1st angle on them is not likely to be well-received. And if the drawings are to be used for manufacturing purposes in North America, giving it to them in 1st angle would be a recipe for disaster. They simply have no background in it.
 
If the drawings are being produced and parts manufactured in the UK or perhaps elsewhere in Europe, then first angle may be viable.
 
(The 1st versus 3rd dialogue simply doesn't exist in North America).
 

Edited By Sid Herbage on 05/09/2011 23:24:19

Steve Garnett06/09/2011 10:32:36
837 forum posts
27 photos
Posted by Sid Herbage on 05/09/2011 23:20:31:

If the drawings are being produced in North America, that simply isn't true. The US and (mostly) Canada are, and have been, pretty much exclusively 3rd angle and don't have the 1st/3rd history that I understand has existed in the UK and many parts of Europe.
 

 
I think you may have missed the point I was making - this isn't about how you were trained at all. It's simply about how you handle the part when visualising it. One 90 degree turn to the right is way easier to do than a 270 degree one! It's a short twist in the direction your hand actually wants to go in. Same thing with your left hand.
 
And we never had a first/third angle history here at all. Until the Americans insisted on doing it differently, we simply used first angle, and there was no issue about it. And whilst I haven't researched the history of this very thoroughly, I suspect that the American decision to use 3rd angle was as much to do with simply wanting to be different as anything. Doesn't make it better, though... In fact I look at it very much like the VHS/Betamax videotape thing - Betamax was technically better, but VHS won out by marketing, etc. Admittedly there isn't anything inherently 'better' about either drawing standard - it's just that when you look at how it came about (which is essentially what I described), it perhaps makes more sense as to why we use it.
 
There's a good chance that we've been doing drawings longer like this than the Americans have, as well. After all, it was in the UK that the Industrial Revolution started...
Gordon W06/09/2011 11:10:08
2011 forum posts
Sorry I keep repeating this, but. It does not matter what projection is used, so long as all views are clearly labelled. Many drawings are made using any and all projections, some things can't be drawn just using 1st or 3rd angle.
Trumpet / Flugel06/09/2011 15:06:45
8 forum posts
I seem to recall a fairly recent thread in which there was some debate about whether some artricles in MEW on the subject of engineering drawings and the interpretation of them would be of interest.
 
As an untrained hobbyist engineer I would appreciate any contributions from skilled and experienced engineers / draughtspersons which would help in the basic interpretation of drawings. Besides the differences between first and third angle there are other aspects such as the standardisaton of dimensions which often cause me to scratch my head.
 
In another life I work as a trumpet player. It's great to be able to play by ear, but to become really competent being able to sight read music is a given!
 
Any help would be much appreciated.
 
Peter.
NJH06/09/2011 15:20:12
avatar
2314 forum posts
139 photos
Peter
 
I recommend Workshop Practice Series No 13 - Workshop Drawing by Tubal Cain
 
available here. ( I mean from myHobbystore)
 
It should answer many of your needs.
 
regards
 
Norman
 
 
Gone Away06/09/2011 18:37:42
829 forum posts
1 photos
Posted by Steve Garnett on 06/09/2011 10:32:36:
 
I think you may have missed the point I was making - this isn't about how you were trained at all. It's simply about how you handle the part when visualising it. One 90 degree turn to the right is way easier to do than a 270 degree one! It's a short twist in the direction your hand actually wants to go in. Same thing with your left hand.

Steve, I was responding to the comment that I quoted "if you are going to produce drawings 'after the event' of smallish pieces, it's way easier to do this in first angle than third,"
 
If you've been exclusively trained in 3rd angle it isn't going to be easier to do it in first angle whatever gyrations you perform. If you are just being trained, one or the other projection systems may be perceived as easier to learn but there are as many advocates for 3rd angle being easier to "see" as there are 1st angle.
 
And frankly, all this turning such-and-such 90 deg then twisting your head around here etc that people come up with leave me a bit cold. Sure, beginners receive that kind of advice early in their training but I've never seen professionals (engineers, designers or draftsmen) resort to those gyrations. They simply look at the part and visualise it. And when drawing a part, if they want a view on a particular side they just put it "where it goes" according to the projection system they use.
 

And we never had a first/third angle history here at all. Until the Americans insisted on doing it differently, we simply used first angle, and there was no issue about it.
 
I left the UK in 1968. At school I was taught technical drawing and at university, engineering drawing. I both cases the emphasis was equally divided between 1st and 3rd. Industry at that time was similarly divided. That's what I meant about the history. I wasn't referring to ancient times.

 
And whilst I haven't researched the history of this very thoroughly, I suspect that the American decision to use 3rd angle was as much to do with simply wanting to be different as anything. Doesn't make it better, though...
 
Absolutely. And I didn't imply that. I was simply making the point that there is only one defacto standard in NA - 3rd angle. - and anyone wanting to produce drawings with NA labour or for use in NA plants would be asking for trouble to go with 1st angle. And Riley did state that he worked for a US manufacturer (although he was unclear where the drawings would be produced or used).
 
 

There's a good chance that we've been doing drawings longer like this than the Americans have, as well. After all, it was in the UK that the Industrial Revolution started...
Please believe me Steve, I wasn't trying to get into a NA vs UK peeing contest.

God I hate this editor!

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