How to Change the Scale of an Autocad Drawing

Printing a drawing at a specific scale

AutoCAD typically deals in millimetres, but Ordnance Survey data available in Digimap is provided in metres. The instructions below explain how to re-scale a drawing from metres to millimetres.

Set the correct map units

Open the DWG file downloaded from Digimap in AutoCAD.
Type 'units' in to the command bar and press enter, the Drawing Units window appears:
Using the dropdown in the 'Insertion Scale' section select 'Meters' if not currently set.
Press the OK button to close the window.

Change the model file from metres to millimetres

AutoCAD now knows that each unit in the map is 1 metre in the model. However, printing in AutoCAD is based on ISO paper sizes using millimetres so in order to print at a specific scale you need to convert the model from metres to millimetres.

Press Ctrl + A on your keyboard to select all elements in the drawing.
Type 'scale' in to the command bar and press enter.
AutoCAD will ask 'SCALE Specify base point:', type '0,0' (without the quotes) and press enter.
AutoCAD will ask 'SCALE Specify scale factor or [Copy Reference]', type '1000' (without the quotes) and press enter. You may need to press the zoom extents button to view the data.

This will have changed the drawing from metres to millimetres.

Creating a print file at a specified scale

In the main AutoCAD map window select the 'Layout1' tab at the bottom left.
On the layout page, delete the existing Viewport to give you a blank page. Do this by clicking once on the black box that highlights the extents of the Viewport (it will change to blue to indicate that it is selected), then press delete.
This will leave you with a blank page.
Change the paper size to the one you want to print. Do this by right clicking on the 'Layout1' tab and select 'Page Setup Manager' from the popup menu.
In the Page Setup Manager window select *Layout1* and then 'Modify'.
Select the Printer and Paper Size, and check that the 'Plot scale' units are set to 1:1:
Select 'OK' and then 'Close' on the Page Setup Manager window if it is still open.
Your sheet will now be set to whatever size you chose on the dialog above (we used A3).
Select the 'Layout' tab at the top of the command ribbon:
In the 'Layout Viewports' section select 'Rectangular' to create a new viewport:
To add a new Viewport to your page click once on the page in the top left hand corner inside the dotted line (the dotted line indicates the print margin of your selected printer), move your mouse to the bottom right hand corner of the page and click again.
You should now have a full page Viewport with the map displayed:
Select the Viewport by clicking once on its border so that it glows blue.
The scale of the currently selected Viewport is displayed in a drop down in the bottom right corner:
Click on the dropdown arrow to expand the list of scales and select 'Custom...' from the list:
The currently available drawing scales are displayed:
Select 'Add...' to add a new scale, and complete as required. 'Paper units' are the units on the finished print out, 'Drawing units' are the units within the AutoCAD model. So to add a custom scale to print at 1:10,000 complete as shown below:
Once completed, click 'OK' to close the window, and again to close the 'Edit Drawing Scales' window.
Select the Viewport again so that it is highlighted in blue.
The current drawing scale will be displayed in the scale selection drop down:
Your new custom scale will be listed, select this and your drawing will now fill the Viewport at the selected scale:
You can now print your map at the specified scale.