Block Scaling too Large

One of my colleagues reminded me of an age old problem I have encountered several times and never got to the bottom of, when inserting a block it scales to a strange size and doesn’t fit to the page.

This turns out to be yet another setting between the “American Imperial” measurement system and the “International ISO Metric” measurement that exists in AutoCAD.

It turns out that changing MEASUREMENT setting to 1 (metric), from the default of 0 (imperial) only changes the way hatches and linetypes scale and not the inherent way the drawing works. The underlying unit scale of the drawing is governed by other setting. So old drawings created when out-of-the-box AutoCAD defaulted to imperial might still have all the old settings.

DWGUNITS command line options
DWGUNITS command line options

The option in question is DWGUNITS. It appears that the default is 1, which is inches. This is why a block drawn in a drawing using DWGUNITS of inches is inserted into a drawing set to mm scales to a differing scale!

As an aside DWGUNITS also sets linear display precision, which is also set by LUPREC.

The options after DWGUNITS is typed appear in a pop-up command line box for easier reading, they are as follows:

Unit for length:
This is the overriding base setting between metric an imperial, here we note that the original setting was 1 for the block template and we changed it to 3, which is the system we use in the office.

Linear display format:
This changes the output reading for items like DISTANCE from 2000.000(decimal) say to 2.000E+03 (scientific). I find the decimal easier to read so we will select 2 here.

Linear display precision:
This governs the number of decimal points in the output reading for items like DISTANCE. 0 gives a measurement of 2000, 1 results in 2000.0 etc. I tend to leave this at 3, but this is personal preference. (LUPREC system variable also changes this setting, and is also found in the dialogue box after typing UNITS, found under menu –> FORMAT –> UNITS).

Scale objects from other drawings upon insert:
This is the one that makes the drawings scale from one unit set to another. I have left this as YES as it will highlight any other blocks and drawings that might not have been set to mm in the first option. Otherwise the block will be inserted without scaling and the error persists.

Match INSUNITS to drawing units?
INSUNITS is another option to scale BLOCKS on insert. It is best to say yes here so they do match, otherwise errors could occur!

Scale objects in current drawing to reflect change in units?
This one you need to say no to. The reason being is that you have drawn a line that is 2000 units long, and in this case before changing the DWGUNITS this would have been interpreted as 2000 inches. AutoCAD can scale the drawing (which is sometimes useful when say changing from a drawing that was actually drawn in inches to metric) however in this case you want to preserve the “2000 units” as 2000 and just change the unit type from inches to mm.

Then the drawing and block drawn in the drawing will be compatible with other drawings drawn in mm.

Please note that DWGUNITS and UNITS are completely different commands.

Please also note the DWGUNITS command is undocumented in AutoCAD both 2013 and 2014 help, it might be present in previous versions but probably need to go back many years to obtain anything!

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