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Need Help with scales for working in Meters


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What CadTutor said.

 

This whole thread is what I have to explain over and over again to every client and in every course I have. It is annoying and stupid and you'll get the hang of it after a while.

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What could AutoDesk do to make life simpler for those working in metric units?

 

When modelspace units are set (as for insert units) AutoCAD should be smart enough to realise that this also affects viewport scales in paperspace and automatically compensate for the difference so that when a scale of 1:50 is selected, it would zoom to the correct scale irrespective of whether you are using metres or millimetres.

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Create the option to display the Layout in meters.

 

That could work too but I actually like the fact that paperspace is in millimetres. If you want text to be 5mm high, you just give it a height of 5.

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That could work too but I actually like the fact that paperspace is in millimetres. If you want text to be 5mm high, you just give it a height of 5.

 

Yeah, I see what you mean. Perhaps no matter what Autodesk could do, we wouldn't really be satisfied :thumbsup:

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What CadTutor said.

 

This whole thread is what I have to explain over and over again to every client and in every course I have. It is annoying and stupid and you'll get the hang of it after a while.

It's amazing how many people, even Autocad vetrans that think the terms "drawing in full units", drawing full size" and "drawing 1:1" all mean the same thing (no wonder newbies get confused).

It is probably a strong point in Autodesks favour that a drawing unit can be anything you want it to be, but in a paperspace layout Autocad only knows two units inches or millimeters - who would measure paper in lightyears, and what size is Foolscap or Letter in units of a yard. Personally I draw in full units at full size at 1:1

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In my experience, most don't think about it at all. It seems like they take a stab in the dark each time they create a layout and never stop and think about what they are actually doing.

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True, like the ones that do everything in meters, but measure and input everything to 3 decimal places, and then have to start playing with scales in layouts

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What CadTutor said.

 

This whole thread is what I have to explain over and over again to every client and in every course I have. It is annoying and stupid and you'll get the hang of it after a while.

 

Wow, now that's the panacea I was looking for, I think I completely understand

 

Here's my recap summary, experts please chime in if I stray anywhere... it's a bit long but I would appreciate your feedback, I'm running all this though my head as a newb so please be gentle o:):

 

- Autocad has two types of template files, ISO based (metric) and Imperial based. There are eight files in all covering every combination of [metric/imperial, color dependant plotstyle/named plotstyle, 2D/3D]

- I imagine every dwg file in existence today has its roots somewhere in those files

- For metric files, paperpace always treats drawing units as millimeters ALWAYS

- For imperial files, paperpace always treats drawing units as inches ALWAYS

- That means a 1:1 viewport scale ALWAYS draws modelspace units as either mms or inches

- This also means that the fields in dimension styles, text styles ( ie: "arrow size", "offset size", "text size", etc...) are in mm or inches ALWAYS

- Initially I thought I could change model space drawing units. For example I was convinced I could tell Acad "Hey Acad change those mm drawing units to meters". First I tried UNITS and fiddled with Insertion scale...wrong, way wrong (misled by internet). Then I tried -DWGUNITS ...wrong again

- I kept looking at modelspace for a solution, but the real answer lay in paperspace. Modelspace remains unitless ALWAYS. You cannot tell modelspace anything

- You can tell paperspace how much each of its millimeters or inches equals to in terms of drawing units

- You do this by creating new scales with SCALELISTEDIT

 

example: I open acadiso.dwt and decide to draw in meters, ie: I want each drawing unit to represent 1m. Well I can't tell modelspace its units are meters (it's unitless remember?) but I can tell paperspace each of its mm equals .001 drawing units (or alternatively 1000 paper units = 1 drawing unit). So that's what I do, I create a new scale and label it something like "1:1 (m)" to remind me it works in meters

 

Similarily I can create other scales like

"1:50 (m)" ..... 50,000 paper units = 1 drawing unit

"1:100 (m)" .... 100,000 paper units = 1 drawing unit

 

With imperial acad.dwt template:

"1:1 (yd)" ..... 36 paper units = 1 drawing unit

"1:1 (mi.) ..... 63,360 paper units = 1 drawing unit

 

The beauty of this is that annotative objects like text and dimensions display properly, no modifications required, and everything is logical. You just select the correct viewport scale and you're set. Finally, to let the outside world know I'm drawing using meters you select "meters" for insertion scale (UNITS command) this way if you import anything it'll scale up (or down) properly (ie: an object of size 150mm x 250mm will import as .15m x .25m and not 150m x 250m ). It also works the other way in case people import your stuff.

 

I hope I got all of the above correct....

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That's pretty much it - I think you've got it :) just create your own custom scales for metres and away you go! It's not intuitive and it's not very smart (of AutoCAD) but it works.

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...

- I kept looking at modelspace for a solution, but the real answer lay in paperspace. Modelspace remains unitless ALWAYS. You cannot tell modelspace anything

- You can tell paperspace how much each of its millimeters or inches equals to in terms of drawing units

....

Finally, to let the outside world know I'm drawing using meters you select "meters" for insertion scale ...

 

This is pretty much the best condensed explanation I have seen - good job Dan, you got it :)

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That's pretty much it - I think you've got it :) just create your own custom scales for metres and away you go! It's not intuitive and it's not very smart (of AutoCAD) but it works.

 

Your last sentence got me thinking again:P. Some things that initially appear archaic sometimes turn out be very intuitive, a classic example of this is HP's RPN key input on their calculators, initially I was very skeptical (pffft..! reverse what? lol) but once I tried it I got hooked, and I am hooked to this day! Similarily I keep telling myself there must be good reason Autodesk choose

the particular drafting implementation they did. I think one benefit of an infinite and unitless modelspace is that if you want to (like, really really want to) you can draw everything in one massive modelspace ... from the airport layout you're working on in the office to your kid's go-cart project. More importantly, you can make drawing units represent one thing in one area of modelspace and something completely different in another area. For example, you can draw the airport layout using drawing units representing meters and then, in some other location of modelspace, draw the go-cart using drawing units representing millimeters. Nothing forces to use the same for both. So long as your intentions are properly communicated to paperspace for both cases (ie: setting up the correct viewscales using SCALELISTEDIT- see post 50) everything will work out. If you decide to draw everything using the same drawing unit representation (mms or meters) the go-cart will undoubtedly end up looking awful small next to your airport layout, so small you would even doubt its existence. I think the way Acad is setup up is pretty neat since it gives you the opportunity to make all the drawings and geometry that lives inside modelspace equally visible

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I have to agree. Mixed units will not make a CAD tech popular with downstream collaborators.

 

The same, no doubt, would apply to my suggestion to modify the Page Setup’s Plot Scale Factor – especially if it’s sole purpose was a rather dubious advantage of a 1:1 viewport scale factor relationship.

Conceivably, though, some offices deal with drawings based on different Units. Meters and millimeters would be a likely combo. This office may own Block libraries based on Meters – for Model Space insertions, as well as millimeter assets for Page Layout.

AutoCAD only allows one Insertion Scale per drawing. When set for Meters, inserting page layout content will be hampered. My suggestion of modifying the plot scale factor, at least, allows for automated scaling for both Model- and PaperSpace.

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If your drawing needs to get shared with others and there's lots of importing and exporting going on you are absolutely correct, using mixed units is not a very good idea. For stand alone applications (shop drawings used internally for instance) it could have its benefits I think.... seeing everything that lives in modelspace in approximately the same size with a simple zoom-extents command could be a useful feature. For example, in my previous example both the airport layout and go-cart would draw about 2000 units long in modelspace, now replace that go-cart with something more useful like the flooring tiles used in the different areas of the airport and the advantages of this technique become readily apparent I believe

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