Automatic Scaling of Blocks, Images or XREFs
Comments(8) When Autodesk released AutoCAD 2007 I noticed that when I inserted a block or XREF it would sometimes scale up or down in a way I didn’t expect. After a little digging in the help file I found these system variables: INSUNITS, INSUNITSDEFSOURCE, & INSUNITSDEFTARGET.
According to the help file, INSUNITS “specifies a drawing-units value for automatic scaling of blocks, images, or xrefs inserted or attached to a drawing.” If you set INSUNITS to 0 (zero) you can use INSUNITSDEFSOURCE and INSUNITSDEFTARGET to control automatic scaling of blocks, images, or XREFs.
Values for INSUNITS, INSUNITSDEFSOURCE, & INSUNITSDEFTARGET:
| 0 | Unspecified (No units) |
| 1 | Inches |
| 2 | Feet |
| 3 | Miles |
| 4 | Millimeters |
| 5 | Centimeters |
| 6 | Meters |
| 7 | Kilometers |
| 8 | Microinches |
| 9 | Mils |
| 10 | Yards |
| 11 | Angstroms |
| 12 | Nanometers |
| 13 | Microns |
| 14 | Decimeters |
| 15 | Dekameters |
| 16 | Hectometers |
| 17 | Gigameters |
| 18 | Astronomical Units |
| 19 | Light Years |
| 20 | Parsecs |
For example:
I made a block that contained a single line, 1-unit long. In a blank drawing I set INSUNITS to 0, INSUNITSDEFTARGET to 1 (inches), and INSUNITSDEFSOURCE to 3 (miles). Setting INSUNITS to 0 made it an unspecified value so that INSUNITSDEFTARGET and INSUNITSDEFSOURCE would take precedence. When I inserted the block into the blank drawing, I made sure the scale was set to 1 uniformly (X, Y, & Z were all set to 1). Then I ran a DISTANCE on the line and it measured 63360 units (63360 inches = 1 mile).
When I set INSUNITSDEFTARGET to 1, I told AutoCAD that any block, image, or XREF that is inserted into the current drawing (target drawing) to be measured in inches. When I set INSUNITSDEFSOURCE to 3, I told AutoCAD to treat all blocks, images or XREFs (source drawings) that are inserted into the current drawing as if they were drawn in miles. AutoCAD then does a conversion during insertion.
NOTE: According to the help file, automatic scaling does not happen when the block is annotative.
Scenic Shop’s blog post entitled AutoCAD Imperial & Metric Conversions has some more good information on this topic. Thanks for this Matt!
This isn’t just a shameless plug, but a post I wrote a while ago briefly touches on this. The post was more about drafting & dimensioning in mixed units (e.g. inches & millimeters) though this fleshes it out nicely. I’ll throw a link to this on my blog. Click on my name if you want to read the article.)
Matt,
No problem. I like what you wrote. In fact I will put a link in this post to yours.
Automatic Scaling of Blocks, Images or XREFs…
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Thanks for the information. I could not figure out why my referenced drawings were not coming in properly with ACAD 2009 and it was driving me nuts. I found this through an internet search, and by changing the variables you listed, my problem was solved. Thanks again.
[...] argument against going unitless is that you lose the ability to automatically scale XREFs and blocks that use different units. This is a very powerful feature in AutoCAD [...]
We use unitless insertion scale in our office, come to think of it, I really am not sure why.By the way, we use millimeters, we set blocks to unitless and then set INSUNITS to 4 to insert all the blocks that we need automatically to mm. As you’ve mentioned the INSUNITS variable is quite new to AutoCAD and it was in Acad 2007 when we first experienced discrepancies when we inserted blocks. They were either too small or too big! It was until like you, we discovered the INSUNITS command. We didn’t fully understand how it’s used until iI’ve read your post. Well now I know. Thanks a lot.
Hi Josh I wrote a similar article on my Blog. A lot of users still dont know how to use the units properly.Greetings from SwitzerlandJose
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