This is a question that comes up frequently. We all have our ownopinion– often based on our industry and our companies needs.
What makes a good technical drawing a great technical drawing? I’m interested in hearing your views.
Isaccuracyimportant? Or is it a given that all drawings should be correct? Should drawings be done to a standard? Is it more important that your drawing are done on time, or within the budgeted hours? Does the CAD part of the job matter? If the information you need to communicate is on the page – that’s good enough right?
I asked the same question in theAUGI,Autodesk,CADtutorandMCAD Forumsand I had somefantasticresponses.
Here are a few that really caught my eye. You can read my summary of the answers at the end of the post.
Here is a great response fromDoug Barense On G+
Thoroughness, Readability and Accuracy, in that order.
https://plus.google.com/u/0/104641315693902919761/posts/AtAye7Ck9vc
And these in the AUGI CAD Manager’s forums:
From Tedg:
- Drawings need to be created to good drafting standards, lineweights, clarity, accuracy, to a given Cad Standard.
- Only enough detail for the purpose of scope and/or deliverables (ie: concept, 35% review, issued for bid, etc.).
- Keep within time/budget if possible, if the scope outweighs the budget; bring it up to the PM before you go over budget.
- Don’t over-dimesion! Dimension in one location like the plans, and reference them on details and sections, easier to change once instead of chasing them all.
- All disciplines’ drawings should match if possible, at least have the same building orientation. Of course there are exceptions like Civil will have grid north and Arch, Struct, MEP would have Plan North.
From Jaberwok:
Accuracy,Standards,Layout,Spelling.
Here’s a thought provoking response from DeanSaadallah on the Autodesk forums:
No set is perfect and a professional office providing the service should help manage a client’sexpectationsof this item
A client deadline should never be missed: do what it takes to meet itandensure it’s a complete and accurate set
http://forums.autodesk.com/t5/CAD-Managers/What-makes-a-great-Technical-Drawing/td-p/3567228
Charles Bliss left this neat and succinct list on MCADforums:
Rule #1: The drawing should convey enough information to create the correct part without asking any questions.
Rule #2: The drawing should not have any ambiguity that leads to making too expensive of a part. This usually means the correct use of GD&T, proper finish call outs etc…
Rule #3: Add call outs to improve clarity. (leave nothing to chance)
http://www.mcadforums.com/forums/viewtopic.php?f=3&t=13051
This question as raised some great debate on CAD tutor forums. My favourite is his quote from Cecil Spencer, which was written in 1956 and supplied by ReMark:
[Our Drawings] must be so clear and complete that every one of the users arrives at exactly the same interpretation
http://www.cadtutor.net/forum/showthread.php?71629-What-makes-a-great-Technical-drawing/page2
I had this response from Jim Trujillo via Email:
‘Never, never let any outside force e.g. engineering, marketing ever have any input in establishing drawing content. What you will get are a lot of self proclaimed experts vying to justify their existence, without any thought as to the consequences.
I assume that comment istonguein cheek Jim (But I know how you feel!)
Summary
Here is myattemptto sum up all of ourthoughts.
‘What makes a greatTechnicalDrawing?’
Thoroughness
Technically correct, accurate, complete, consistent and unambiguous.
- Check the brief (a lot – and at all stages of the drawing process).
- Check your measurements.
- Check your spelling.
- Leave no questionsunanswered.
- Leave nothing for someone else to sort out or work out later.
- If an extra hour spent checking the drawing pushes you over budget, it is still worth doing to ensure that no mistakes leave your office.
- Don’t make the same mistake twice.
Brevity
Have you put too muchinformation onthe page? Less is more.
- Only put on the drawing what needs to be on the drawing.
- If you can get the point across with awrittennote – do that.
- If you can get the point across with a hand drawn sketch – do that.
- If a 3D model is going to be required to fully understand and explain the design – do that.
- Don’t draw/model anything twice (Don’t leave yourselfhavingto make the same edit in multiple places).
- Don’t overdimension.Dimensionsare an instruction – not a label.
Clarity
Will everyone who reads the drawing have the same interpretation? Does the drawing leave anything open to misinterpretation?Technical drawing is amethodof communication – It’s a language.
- Follow your National/Industry/Company CAD Standard.
- Imagine yourdrawinghas been dropped on the floor, stomped on, screwed up, had coffee/grease/lubricant split on it and thenphotocopied. Will the drawing still be clear and easy to read?!
- Plan your drawing set in advance. Lead the reader through the set of drawings with call-outsandreferences.
- Plan each drawing in advance, make sure that the layout is clear and logical – don’t be afraid of white space.
- Don’t assume that the reader will understand your favourite abbreviations, hatches or lines colours.Includea legend or notes to explain non industry standard annotations.
- Be certain that each drawing is easy to understand and easy to read.
Consideration
Fit for purpose drawings, on timeandon budget!
- The drawings shouldn’t leave any ambiguities or include any extras that will make the end product cost more that was expected.
- Understand what it is your customer (the end user or users)needs from the drawings.
- Understand what your client (your Boss) wants from the drawings.
- Mange expectations of what you canrealisticallydeliver.
Thanks very much to all who participated. Thecommentssectionis still open if you think of anything I’ve missed.
