Decoding Abbreviations on a Technical Drawing

[SillyOldDufferModerator @sillyoldduffer]

My current project has me looking at a drawing that uses a lot of abbreviations. Things like: M3x4DP, 8PF, R30, CS, 10PCD, 3RM and DAA.

These I've decoded, I hope correctly, as:

M3x4DP – Drill and tap M3 4mm deep
8PF – 8mm Push Fit
R30 – 30mm Radius
CS – Countersink
3RM – 3mm Ream
10PCD – 10mm Pitch Circle Diameter

Can anyone help with DAA please? It's applied to some holes.

Thanks,
Dave

[SillyOldDufferModerator @sillyoldduffer]

[AjohnwParticipant @ajohnw51620]

Drill After Assembly maybe – idiotic way of noting it if it is.

John

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[Enough!Participant @enough]

Delete As Appropriate?

[John Stevenson 1Participant @johnstevenson1]

I think that should read help needed on a NON technical drawing

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 16/08/2016 20:41:49:

My current project has me looking at a drawing that uses a lot of abbreviations.

…

Can anyone help with DAA please? It's applied to some holes.

.

Dave,

Here is a long list of things that it probably doesn't mean

http://www.acronymfinder.com/DAA.html

If you could post a copy of the relevant section of the plan, it might help

… Ajohnw might well be on the right track; but it's a guessing game.

MichaelG.

[MWParticipant @mw27036]

Yeah, i think you picked the short straw with that one, this draftsman loves his lettering.

Ever the considerate gentleman, he forgot to include a key to his M-JMB0. As he may have termed it.  

Michael W

Edited By Michael Walters on 16/08/2016 23:09:44

[CirclipParticipant @circlip]

What is the drawing?

Many of the Jon-Tom drawings have abbreviations on them, problem is, the separate engine drawings are part of a book which contains ALL the abbreviations on one of the front pages of the book.

Regards Ian.

[JasonBModerator @jasonb]

It's not one of Elmers (Not Jon-Tom) and the key to his abreviations are on the JT site and others anyway.

[JasonBModerator @jasonb]

It's Julius De Waal's drawing of Stew Harts Potty Engine. Now just to find where he has shoe horned in that DAA!

Why not just use Stew's drawings thay don't have these odd abbreviations.

EDIT it is drill after assembly, refers to pins in the crank, this is mentioned in the text and shown better on Stew's drawing. Julius' drawing also misses out the important part that the crank should be made from one long length of bar and then cut after loctiting and pinning. How Stew did it

 

Edited By JasonB on 17/08/2016 10:16:05

[AjohnwParticipant @ajohnw51620]

It's a pretty disgusting set of drawings clearly not drawn by a pro draughtsman.

I should know I did several years of it and producing something like that would have been a good way of getting the sack.

John

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[MuzzerParticipant @muzzer]

COIK = "clear, only if known", itself a COIK. One of my dad's favourites.

Incidentally, on page 3 there are some notes on abbreviations (RTFM!!):

PF=PRESS FIT, RM=REAM, DAA=DRILL AFTER ASSEMBLY, PCD=PITCH CIRCLE DIAMETER, SA=SUB ASSEMBLY.

I suspect this explains the issue. This probably arises from trying to cram so much stuff onto one page.

[Jon GibbsParticipant @jongibbs59756]

Posted by JasonB on 17/08/2016 10:02:09:

It's Julius De Waal's drawing of Stew Harts Potty Engine.

Sends you bozz-eyed just looking at them, let alone trying to follow 'em!

…and all to save a page or two of paper – surely not worth it?!

Jon

[Nick WheelerParticipant @nickwheeler]

Posted by Jon Gibbs on 17/08/2016 13:57:44:

Sends you bozz-eyed just looking at them, let alone trying to follow 'em!

…and all to save a page or two of paper – surely not worth it?!

Jon

Especially annoying when the pretty rendered pictures have a whole sheet to themselves.

[Ady1Participant @ady1]

Perhaps he'll offer a refund to those people who are dissatisfied

[KWILParticipant @kwil]

If the drawings had been a set of "proper" drawings and not a hotch potch of CAD "cleverness" all would no doubt been a lot clearer

[Martin ConnellyParticipant @martinconnelly55370]

Here's another abbreviation for applying to note 1 on the drawing. WTF

Martin

[AjohnwParticipant @ajohnw51620]

Posted by KWIL on 17/08/2016 14:51:57:

If the drawings had been a set of "proper" drawings and not a hotch potch of CAD "cleverness" all would no doubt been a lot clearer

It's a mix of pretty good and extremely bad but having said that a lot of model engineering type drawings are a bit off for some one who has earned a living in drawing office. In the dim and distance past though some work was awful. It took years to standardise on which projection to use and several were usually taught right into the 70's.

The rules are pretty simple really. A general arrangement that does show all bits with each part numbered. The 3D views aren't to bad for that.

Detailing should consist of each part in a box or at least clearly separated with the same numbers identifying each part. That way there is no need to know what a cross head or what ever is – another common problem with some drawings.

There were some useful conventions when drawing were done in imperial. Fractions +/- 1/64, decimal +/- 0.005. Reamed holes -0 , +0.0005, or as specified. The usual 3 views of all parts or more if needed. A GA might need several sections all labelled and shown the usual way, A-A etc. That could apply to parts as well.

There were ructions when things went metric. For a while +/- 1/64 turned into 0.5mm increments as 0;1 was too fine and moans about 0.5mm being bigger than +/- 0.4. I've no clear idea what happened eventually but get the impression that a lot more specific tolerances were used.

John

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[MWParticipant @mw27036]

Posted by Ajohnw on 17/08/2016 17:14:29:

Posted by KWIL on 17/08/2016 14:51:57:

If the drawings had been a set of "proper" drawings and not a hotch potch of CAD "cleverness" all would no doubt been a lot clearer

It's a mix of pretty good and extremely bad but having said that a lot of model engineering type drawings are a bit off for some one who has earned a living in drawing office. In the dim and distance past though some work was awful. It took years to standardise on which projection to use and several were usually taught right into the 70's.

John

 

I suppose the reason why it took so long for them to centre drawing around "1st/3rd angle projection" was probably because the projections depended on what the part in question looked like, so the answer to "whats the best way to do this" was a variable, it's a bit like asking "whats the best lathe" or "whats the best style of tooling" – answer normally is "well what do you want to make with it?".

Different ways of drawing it had its up and downsides, and therefore several ways of projecting them kept in fashion.

Michael W

Edited By Michael Walters on 17/08/2016 17:55:32

[Raymond AndersonParticipant @raymondanderson34407]

Just had a look at the drawings even though I don't really have any desire to build a model Jesus, could he not have crammed in anymore parts / sections. He must be trying to save the forests methinks !! There is one thing for sure, if any design engineer had given the brother a drawing like that he would have been told what to do with it . I would have been a case of give me a proper drawing, and hang that thing up in the toilet. [ there would be a good use for it there ].

[Steven VineParticipant @stevenvine79904]

Wow, you draughtsmen sure know how to lay into something don't ya.

Apart from Julius's non conventional way that does not adhere to the TD standards you have known and have loved for all these years, I reckon they are quite readable and quite easy to understand. Take part 33 for example: if the 3d image was not there then I would have scratched my head over that for a lot longer than I did. Having the 3d image there I was very quickly able to determine what the drawing for that part was all about. I looked at a few other components on that sheet, and again, all pretty intelligible.

I think the info you need must be all there. Once you get your head around (and into) his methods of presentation you should be ok I guess. Yeah, if they landed on the desk of any serious engineering company then they would be laughed at, I can see that,. But for home hobby use, they look like they would get the job done.

I've been seeing his drawings for quite a few years now, they are all over the internet. I'm sure if I found an error on one of his and reported it, then he would correct it quite quickly. This can't be said for many of the model engineer drawings that are kicking about and which are continually getting sold over and over again with the same mistakes in them, never corrected even though the errors are much talked about.

So, bearing in mind this is a hobby drawing, and apart for the unconventionality of JDWs drawings, what is so bad about them? Why is the drawing in question so disgusting and only fit for bog paper?

Steve

 

 

 

Edited By Steven Vine on 17/08/2016 18:55:50

[SillyOldDufferModerator @sillyoldduffer]

Many thanks chaps – 'Drill After Assembly' makes perfect sense. What a shame I've drilled the holes already: it will be interesting to see how well the parts line up when I try to put them together!

I didn't want to cause embarrassment by identifying the drawing but you've got that right too.

With 47 parts (excluding fasteners), the drawing is certainly very crowded. Where necessary I've dealt with that by redrawing the less obvious parts with qcad. I've found redoing the drawing useful to confirm dimensions and to suss out how to make the thing.

One item of good news about the drawing – I've made well over half the parts without finding any errors.

Looking for answers on the web led me to several different drawing standards. What's preferred by Model Engineers?

Ta,

Dave

[Neil WyattModerator @neilwyatt]

Posted by SillyOldDuffer on 17/08/2016 19:02:46:

Looking for answers on the web led me to several different drawing standards. What's preferred by Model Engineers?

Clarity and freedom from gross errors.

Neil

[SillyOldDufferModerator @sillyoldduffer]

Posted by Neil Wyatt on 17/08/2016 19:06:01:

Posted by SillyOldDuffer on 17/08/2016 19:02:46:

Looking for answers on the web led me to several different drawing standards. What's preferred by Model Engineers?

Clarity and freedom from gross errors.

Neil

That's me stuffed then. I specialise in ambiguous mistakes…

[JAParticipant @ja]

Don't let a drawing become cluttered and don't try to put too much information on one view. In other words use more sheets of "paper".

I have long since ceased to expect model engineering drawings to be "professional" (no longer a criticism).

JA

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