# Thread: understanding drawing scale and scale factor

1. ## understanding drawing scale and scale factor

Registered forum members do not see this ad.

Hi:
I am a newbie AutoCADer and am having some problems getting the hang of applying the drawing scale to my assignment. I understand the scale factor that is applicable to the printing only and that AutoCAD doesn't care about the units used...but something is not clicking here and I'm sure it is pretty simple. My assignment requires me to draw 3 simple structures at 1/8" scale on 11X17 paper. Each house is 20' long with 10' walls and each is done in absolute, relative, and polar. I actually completed the work with all 3 formats without specifying the scale or paper size, just to get familiar with the commands. But now that I am trying to set the dimensions correctly, I cannot replicate my work because I'm getting lost in the way things are defined. Any help would be appreciated. I am using AutoCAD 2005, also have a 2002 version to which I can defer.
Thanks everyone!

2. Scale factor (as used by AutoCAD) is always a reciprocal of the drawing scale.

AutoCad uses the unit one as the base unit.

For example, if you wish to plot a mechanical drawing at a scale of 1/2” = 1” the reciprocal of 1/2 is 2/1 which is 2. Therefore the scale factor is 2. If this drawing was to be plotted on a 11 x 17 piece of paper the limits would have to be 34,22. Text would be .25 high and other settings made for this scale to be plotted properly.

Another example would be an architectural drawing plotted at a scale of 1/4” = 1’-0”. Changing feet to inches so the units are all in inches gives us 1/4” = 12”. Dividing both sides by 12 which is the same thing as multiplying by 1/12 we obtain 1/48 = 1. The reciprocal of 1/48 is 48. The scale factor then is 48. If this drawing is plotted on a 11 x 17 piece of paper the limits would have to be 816,528 (68’,44’). Text would be 6” high (.125 times 48 = 6). Other settings would have to be made for this scale to be plotted properly.

Another example would be a metric drawing made full size. 1 = 25.4. Dividing both sides of this equation by 25.4 we get 1/25.4 = 1. The reciprocal of 1/25.4 is 25.4/1. The scale factor therefore is 25.4.
Text (originally .125) then would be made approximately 3 high (.125 X 25.4 = 3.175). Text (originally .25) then would be made approximately 6 high (.25 X 25.4 = 6.35). Other settings would have to be made for this scale to be plotted properly

The scale factor of a drawing should be determined and utilized during the time of drawing set up.
The proper scale factor is extremely important because it makes sure that text (height, etc.), dimension values (dimscale), hatch patterns, limits, and linetype scale (ltscale) are plotted at the proper size.

Samples:

A drawing scale of 1” = 1” has a scale factor of 1
A drawing scale of 1/2” = 1” has a scale factor of 2
A drawing scale of 2 = 1 has a scale factor of .5
A drawing scale of 1 = 60.0’ has a scale factor of 720
A drawing scale of half size (metric) has a scale factor of 50.8

3. why on earth would someone want to "draw to scale" in Autocad ?
surely the whole point about computers/CAD is that we can get away from that old drawback of paper.
In CAD, the space is "infinite", everything should be drawn at 1:1 ~ viewports are where any "scaling" factors should come into play

and here starts another argument

4. Originally Posted by hendie
why on earth would someone want to "draw to scale" in Autocad ?
surely the whole point about computers/CAD is that we can get away from that old drawback of paper.
In CAD, the space is "infinite", everything should be drawn at 1:1 ~ viewports are where any "scaling" factors should come into play
and here starts another argument

http://www.rosegill.com/Bullpen/SoapBox/Illusions.html

This is from the owner of Engineered Software, the maker of PowerCADD ( a mac only CAD app.).

5. Originally Posted by f700es
I don't think they have a smiley for what I'm feeling after reading that !

6. Originally Posted by hendie
Originally Posted by f700es
I don't think they have a smiley for what I'm feeling after reading that !
Everyone here needs to visit that site and just take a look at the way they act. It's no wonder there anti-apple sites all over the net, with attitudes like that. It just kills me. These users throw off on AutoCAD in about everyother post. They try to make fun of us drawing 1 to 1 yet when a cross platfrom program like VectroWorks or SketchUp draws 1 to 1 it is ok..

Got into a internet arguement with one of their users on another forum a couple of years ago after he said that we could not do solid fills, had no accuracy, could not export to illustrator (or anything else for that matter), unstable program and other un-founded remarks. Evern called me a liar when I posted some screen images of things that he said Acad could not do. I'll put Acad up against just about anything.

another smily for them...

F7

7. Originally Posted by f700es

http://www.rosegill.com/Bullpen/SoapBox/Illusions.html

This is from the owner of Engineered Software, the maker of PowerCADD ( a mac only CAD app.).
A joke surely? No one can still hold views like that - at least not if they live in the 21st Century. I have to say that this sort of view is propagated by people who find the transition from drawing board to computer rather confusing. They feel much more comfortable working with an electronic version of their old tried an trusted manual tools. Their loss - new technology means new tools and new tools means new method and new method leads to new opportunities.

It's a brave new world but some are just a little bit scared to jump.

8. ## re:

David, I wish that was a joke but it is not. Browse through the their/his site and see. www.engsw.com
I am also sad to say but these guys are only about an hour away from me here in NC, USA.

Pretty pathetic to me :evil:

9. End of the day you need accuracy,and drawing to scale the old way is just not feasable.

Small minded Souls. I love macs for their simplicity, but hate them for the lack of cross platform programs.

Tell me, isnt Archicad a 1-1 program?

G

10. Registered forum members do not see this ad.

Originally Posted by gcp310
End of the day you need accuracy,and drawing to scale the old way is just not feasable.

Small minded Souls. I love macs for their simplicity, but hate them for the lack of cross platform programs.

Tell me, isnt Archicad a 1-1 program?

G
Not sure about Archicad but it probably is. Just about every CAD/3D application I can think of does 1:1. To me it is just another example of the "Mac - I'm better than you attitude". I work with 2 mac users and they both have this attitude that since they us macs their designs are automatically better .

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts