Model Space and Sheets

This is the idea that trips up almost everyone new to CAD, and it is worth getting straight before you try to print anything.

You draw in the model, at full size. A wall 4400 mm long is 4400 units long. Always. Whatever it will eventually print at.

A sheet is a piece of paper. It is measured in paper millimetres, and it holds your title block, your notes and your border — plus one or more viewports: windows that look into the model and show it at a chosen scale.

The split keeps two different questions apart:

• How big is the thing? — that belongs to the model.
• How big does it print? — that belongs to the scale, either the drawing's or an individual viewport's.

And here is the payoff. Because they are separate, the same model can print at 1:50 on one sheet and appear again at 1:10 as an enlarged detail on another — without being drawn twice, and without the two ever disagreeing.

Prerequisites

• A drawing with something in it — see Drawing Basic Shapes.

Where sheets live

Along the bottom of each drawing: Model first, then each sheet, then + for a new one.

You do not have to use sheets at all

A new drawing starts with no sheets — just Model. You can print the model directly and never make one.

Add sheets when you need a laid-out, titled, multi-scale drawing to issue to somebody.

Making a sheet

Click + after the sheet tabs, or choose Sheets ▸ New Sheet.

What you get. The sheet opens with one viewport already on it, showing the model at the drawing's scale, on the current paper size.

What changes about drawing. On a sheet, everything is measured in paper millimetres, from the paper's lower-left corner. A border you draw at 390 × 277 really is 390 mm × 277 mm on the printed page.

That is why title blocks and notes are drawn on the sheet rather than in the model: they are paper-sized things, not real-world-sized things.

Setting the paper

Right-click the sheet's tab ▸ Page Setup, or Sheets ▸ Page Setup.

This sets the sheet's paper size and orientation, and how it prints — colours (black, greyscale, or as drawn), lineweights, and transparency.

There is no print scale to choose here, and that is deliberate: a sheet always prints its paper at 1:1. The scaling already happened, inside the viewports.

Viewports

A viewport is a window on the sheet that looks into the model, showing it at a scale you choose.

Sheets ▸ Viewport (VP), then pick two corners. It is available on a sheet only — there are no viewports in model space.

Working through a viewport

• Double-click inside a viewport to work on the model through it. Its outline turns amber and the rest of the sheet fades back, so you can see which mode you are in.
• Double-click outside to come back to the sheet.

Your scale is protected from accidents

This is a small design decision with a big payoff:

• Zooming zooms the whole sheet, so a viewport's scale can never change by accident. A stray scroll or pinch cannot quietly misprint your drawing.
• Panning slides the model inside the viewport — unless the viewport is Locked.

To change a viewport's scale on purpose, set it on the status bar while you are inside it, or in the Properties panel. The panel also holds its rotation, Locked, On, and its size on the paper.

Tick Locked once the view is right, and panning will not move it again.

Worked example: an enlarged detail

The classic reason for a second viewport.

1. On the sheet, start Viewport (VP) and press S, then type the scale you want for the detail.
2. Drag out its two corners.
3. Double-click inside it, and pan to the part you want to show.
4. Tick Locked in the Properties panel so it stays put.

Each viewport keeps its own scale, so the detail now sits beside the general arrangement on the same sheet — both driven by the same model geometry, so neither can go out of step with the other.

Hiding a layer in one viewport only

Sheets ▸ Viewport Layers hides layers in the selected viewport alone — tick the layers to hide. The same control is the Properties panel's Layers button when a viewport is selected.

While you are working inside a viewport, the Layers panel gains an In viewport column for the same job.

This is how one model makes many drawings: the structural sheet hides the services layers, the services sheet hides the furniture, and all of them stay correct because there is only one set of geometry underneath.

Annotating: in the model, or on the sheet?

Both work. Which to choose depends on what the annotation is about.

• Dimensions of the thing itself are usually best in the model, so they follow the geometry when it moves. Use annotation scales so they come out the right size on paper.
• The title block, revision table, general notes and border belong on the sheet — they describe the document, not the building.

Dimensions can also be placed on the sheet and still measure the model through a viewport, which is convenient for a one-off note on a detail.

Fields (Annotate ▸ Field, FLD) let a title block fill itself in with the file name, date and sheet name — see Attributes and Fields.

Printing

• Sheets ▸ Print Sheets prints or exports several sheets at once.
• File ▸ Print (Ctrl+P) prints whatever you are currently looking at.

See Plotting and Printing.

Next Steps

Next: Plotting and Printing