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Change Units inch to metric in the middle


chewy

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Hi guys,

 

I'm picking up autocad using autocad 2010 version.

 

Lets say a drawing's unit is mm, and now I change the unit to inch.

I know if we just change the unit at beginning, all the lines of the drawing will be base on that unit.

 

How bout if we change the unit to another along the way?

will the drawing's measurements such as angle and annotation dimension be affected too?

 

I know it's sound silly to ask this. But I was curious about it will it create huge changes or some changes we can't notice it easily?

 

Thanks in advance!

chewy

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I would think that changing units midstream, an inherently bad idea, would cause changes that might not be easily noticed and could result in unintended errors re: accuracy.

 

Just my personal opinion. I've actually never changed units (imperial to Metric or vice-versa) mid-course although I have done a drawing displaying alternate units (see Dimension Styles).

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I tend to not use Imperial units at all, but I switch between using meters and millimeters once in a while. So, I'm adding a caveat to what I am about to say, since it might be different with imperial units.

 

Agreed with Remark that it should really not be done, decided on a unit from the start and go with that. If you for some reason need a drawing (the actual drawing, for dimensioning it's different) in two systems, I would have two dwgs.

 

That said, if you do change the units, as far as I know, nothing big will happen, as in the stuff that you have drawn will not change. What will change is the measurements of the lines, the dimensioning and ofc when you do a new line, you'll have to enter the lenght differently.

 

Note though, that the lines will not scale to fit the new units. As for me, if I first draw in millimeters and then switch to meters, a line drawn as 15mm will now be 15meters.

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I do the layout of an Agricultural Show, and all the trade stands are in multiples of 10 feet. Apparently, the canvas tents only come in Imperial dimensions. One year, the organisers tried to metricate the stands making a 6m stand instead of 20 foot as previously, and every one noticed. They were complaining about the missing 4 inches.

 

So now I draw up the stands in Imperial measurement, but take off the setting out coordinates in metric. To help me swiftly change from one system to the other, I have set up a scaling line, based on 0,0, so I can scale everything by reference. Works a treat.

Scaling.jpg

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Inches to Millimeters

1 25.4

2 50.8

3 76.2

4 101.6

5 127.0

6 152.4

7 177.8

8 203.2

9 228.6

10 254.0

11 279.4

12 304.8

13 330.2

14 355.6

15 381.0

16 406.4

17 431.8

18 457.2

19 482.6

20 508.0

21 533.4

22 558.8

23 584.2

24 609.6

25 635.0

26 660.4

27 685.8

28 711.2

29 736.6

30 762.0

31 787.4

32 812.8

33 838.2

34 863.6

35 889.0

36 914.4

37 939.8

38 965.2

39 990.6

40 1016.0

41 1041.4

42 1066.8

43 1092.2

44 1117.6

45 1143.0

46 1168.4

47 1193.8

48 1219.2

49 1244.6

50 1270.0

 

All the above are correct you should never change units mid job etc, but if you have to, scale away chart above helps as does the cool image posted above by eldon (very smart).

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How about fractions of inches to millimeters?

 

:? Maths not my strong point strangely enough ...:D

 

There's a nice Units Converter on the Autodesk website under Services & Support/Units Converter (cannot post link as am new here)

 

How about using quickcalc ?

 

To convert fractions of an inch to mm

 

Using AutoCAD’s QCALC, enter the as a sum dividing the bottom into the top.

i.e. 3/32” = 3 divided by 32 = 0.09375”

press enter

This converts the fraction to a decimal.

 

Now go down to Units conversion and complete the from and to values to inch and mm (as required)

As you complete these to sum is calculated

2.38125

 

Hows that ?

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Well my point wasn't to have you produce another conversion chart. Sorry if I mislead you. But thank you just the same for the additional information.

 

Your welcome but I haven't my man, its just an example of how to use AutoCAD’s QCALC to do just what you wanted fractions of inches to millimeters.

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as above you shouldn't change units once started but it doesn't do anything. If you draw a line 1" (1 unit) long then change the units it remains 1 unit long. AutoCAD will just report that it is now 1mm long.

 

If your question is "I have an imperial block I need to insert into a metric drawing", you wouldn't do it by changing units.

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Thanks guys,

 

So it's always best not to change the units during the progress of drawing. And accuracy is a concern when come to actual project.

 

And if I draw a rectangle of 20 ft by 10 ft now I change the unit, it will just become 20mm by 10mm. I get it thanks!

 

 

If your question is "I have an imperial block I need to insert into a metric drawing", you wouldn't do it by changing units.

 

What should I do if I encounter this situation?

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To answer your last question when inserting a block the user is given the option to scale it in the X, Y and Z directions. Normally AutoCAD will assume that the scale that is applied to X will be used for Y (for 2D drawings). The user is free to scale disproportionally if desired. The block can be scaled up or down.

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EASIEST & BEST METHOD TO ACHIEVE WHAT U R AFTER

 

open a blank drawing.

go to tools>options>user preference> & under 'insertion scale', set 'source content unit' to 'milimeter' & 'target drawing unit' to 'inches'. Also make 'insunits' value '1'(inches) and

than bring in this exisitng drawing there using insert comand.

 

than for the dimension purpose go ot dimension style> selct style & clock 'modify' & than in primery units change the unit format to architectural

 

to bring in the blocks from drawing done in laternate unit, you need to do the same thing.

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