Chapter 6 mentioned that careful use of blocks, external references (Xrefs), and layers can help you improve your productivity. In this section you will see firsthand how to use these features to help reduce design errors and speed up delivery of an accurate set of drawings. You do this by controlling layers in conjunction with blocks and external referenced files to create a common drawing database for several drawings.
Preparing Existing Drawings for Cross-Referencing
Chapter 6 discussed how you can use Xrefs to assemble one floor of ~e apartment. In this section you will explore the creation and use of Xrefs to build multiple floors each containing slightlydifferent sets of drawing information. By doing so you will learn how Xrefs allow you to use a single file in multiple drawings to save time and reduce redundancy. You’ll see that by sharing common data in multiple files you can reduce your work and keep the drawing information consistent
You’ll start by creating the files that you will use later as Xrefs.
1. Open the Plan file. If you didn’t create the Plan file, you can use the 12a-pl an. dwgfile from the companion CD-ROM (see Figure 12.24).
2. Turn off the Notes layer to get a clear, uncluttered view of the individual unit plans.
3. Use the Wblock command (enter W.J at the command prompt) and write the eight units in the comers of your plan to a file called Fl 00 (see Figure 12.25).When you select objects for the Wblock be sure to include the door symbols for those units. Use 0 0 for the Wblock insertion base point.
4. Using Figure 12.26 as a guide insert Unit2 into the comers where the other eight units were previously
If you didn’t create the Unit2 file earlier in this chapter use the Unit2 dwg file from the companion CD-ROM
5 Once you’ve accurately placed the corner units use the Wblock command to write these comer units to a file called Fl ocrz dwg. Again, use the 0,0 coordinate as the insertion base point for the Wblock.
6. Now use File» Save As to turn the remaining set of unit plans in 0 a file called Common.dwg.
You’ve just created three files: Fl oorl, Fl oor2, and Common.Each of these file’> contains unique information about the building. Next you’ll use the Xref command to recombine these files for the different floor plans in your building.
Assembling External References to Build a Drwing
Next you will create composite files for each floor using external references of only the files needed for the individual floors. You will use the Attach option of the Xref command to insert all the files you exported from the Plan file.
1. Close the Common.dwg fill’, 0pl’n a new fill’. and call it Xre f 1
2. Set up this file as an architectural drawing 81/2″ x U” with a scale of 1/16″=1′. The upper-right comer limits for such a drawing are 2112, 1632. Metric users should set up a drawing at 1:200 scale on an A4 sheet size. If you look at Table 3.4 you’ll see that your drawing area should be 4200cm by 5940cm.
You are asked to use a small paper size since it is the most common size available to readers. Normally you would specify a larger size and scale for architectural drawings.
3. Set the Ltscale value to 192. Metric users should set it to 200.
4. Open the Reference toolbar by right-clicking a toolbar and then selecting Reference from the popup menu.
5. Click External Reference Attach on the Reference toolbar or type Xa.J.
The Select Reference File dialog box appears.
6. Locate and select the Common.dwg file.
7. In the External Reference dialog box make sure the Specify On-Screen check box in the Insertion Point group is not checked. Then make sure the X Y and Z values in the Insertion Point group are all O
Because the insertion points of all the files are the same namely 0 0 they will fit together perfectly when they are inserted into the new files
8.Click OK. The Conrnon. dwg file appears in the drawing.
9.Click the External Reference Attach.tool on the Reference toolbar again and then click the Browse button to insert the Floor! file
10. Repeat step 10 to insert the Col-grid.dwg file as an Xref. The Col-grid.dwg file can be found on the companion.CD-ROM. You now have the plan for the first floor.
11. Save this file.
Now use the current file to create another file representing a different floor.
1. Use File> Save As to save this file as Xref-2. dwg.
2. Click the External Reference tool in the Reference toolbar or type Xr.J.
3. In the Xref l-Ianager dialog box highlight Floorl in the list of Xrefs and then click Detach.
4.Click Attach. In the External Reference dialog box, click Browse.
5.Locate and select Fl oor2. dwq.
6.In the External Reference dialog box, make sure that the X,Y,and Z values in the Insertion Point group are all set to O.
7. Click OK. The Floor2 drawing appears in place of Flood.
If you move an external reference fde aher you have Inserted it into a drawmq AutoCAD may not be able to kvj It la er when you attempt to open the drawing If this happens you can use th browse cpt Ion In the External Reference dialoq box to tell AutoCAD the new locauon of the external referenced frle.