AutoCAD Tips & Tutorials

Dealing with gaps

Gaps can be frustrating. You want to hatch an almost-closed object, but it doesn't work. You may want to join lines, or close an arc or an elliptical arc to remove the gap. Finally, you may want to join polylines. Here are some tips about dealing with gaps.

First, and foremost, if you don't want surprise gaps while you draw, always use object snaps when drawing. If you need to draw to the endpoint of a line, don't eyeball it, use the Endpoint object snap.

Hatching

If you need to hatch an open area, use the DIST command to find out the length of the break. Then start the HATCH command. If you don't see the Gap Tolerance section, click the right-facing arrow at the lower-right corner of the Hatch and Gradient dialog box. This section controls the HPGAPTOL system variable, which you can also specify on the command line.

Enter a number larger than the gap. Then place the hatch by clicking the Add: Select Objects or Add: Pick Points button. However, these two methods of placing the hatch don't always work the same way. Sometimes one button won't work at all or won't give the right results. In this example, only picking points worked properly.

By selecting objects	By picking points

However, in the example below, selecting objects gave acceptable results, picking points displayed this dialog box and wouldn't hatch at all.

Therefore, before giving up, try both options! Also, in some cases, you can fill with a regular hatch, but not with a solid.

Joining objects

You can use the JOIN command to eliminate gaps. The command requires lines, polylines, arcs, or elliptical arcs. (However, it combines splines and helixes if they touch each other, but are separate objects). Although AutoCAD's Help on this command doesn't explain this, the objects must be on the same linear, circular, or elliptical path. Therefore, JOIN works best for objects that you broke with the BREAK command and were therefore once one object.

A nice feature of JOIN is that you can close arcs to make circles and elliptical arcs to make ellipses.

Joining polylines

The PEDIT command has its own Join option. Start the PEDIT command and at the first prompt, choose the Multiple option and select both objects. Then use the Join option. At the Enter fuzz distance or [Jointype] <5.0000>: prompt, enter a number larger than the gap to close it, and end the command.

Use the Jointype suboption to specify how the gap is closed. The Extend method extends or trims segments to the nearest endpoints. The Add method adds a straight segment between the two nearest endpoints. The Both method tries to extend or trim, but if it can't, adds a segment.

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