Prep question 7

Scaling objects to a given size. 

Plus a useful way of using construction line command's offset option.


Email info@inhousecadtraining.com for your file Ref 1Q11


Open the file ACA1-06.dwg. Scale the bottom desk which has a width of 1200 so that this width becomes 1600 using the left hand corner of the desk as the base point for the scale command. Use the calculator to work out the scale factor.

How far would the scaled desk need to be moved to the left,  so that it's right hand edge is the same distance away from the office wall on the right,  as the other desks are away from the wall on the left hand side.


Answer 47.2071


Explanation:-



Consider a 10 unit line which you wish to scale down to value of 5 units. Your scale factor would be 5/10 or 0.5 in decimals. Or you might want to double the size of the line to 20 so your scale factor would be 20/10 or 2.0


So if you have a length of 1200 which you to scale up to 1600 your scale factor will be 1600/1200. Whilst you could use an office calculator for this Autocad's calculator will give a more accurate result. It also has some useful functions such as it's own distance command button. Use this just like the Di short cut and it will feed the distance you pick from 2 points into the calculator. Use the / for divide and work out your scale factor.


Leave the answer in the calculator and move your cursor back into the drawing area because you nee to transfer Windows actions to the drawing from the calculator.


Next use the scale command (SC). Select objects, enter and choose the required base point. Scale actions always radiate out along the x and y axes from the point you pick.

When the command line asks you to specify the scale factor, go back to the calculator and find the "paste value to command line button". Click this and note that your scale factor appears on the command line. move the cursor back to the drawing and push enter to complete your command line entry of the scale factor. You should see the desk change size and it will measure exactly 1600.

To answer the distance question you should use construction line and then it's offset option. (Note that this is not the same as the offset command). Construction line offset option gives you a useful construction line at the offset distance and not a copy of the object.

Set the distance for the construction line offset by 2 points to represent the distance from the existing desks to the left hand wall. The command line will then ask you to select a line object. 


Select the inner right hand wall line and specify a point the left hand side. This will create a construction line at at a distance away from the right hand wall. A distance which you have just set by 2 points. 


There's no need to move the scaled desk as you can just measure the distance required using the short cut Di. ie. From the construction line to a point on the desk. (Use nearest to perpendicular osnap poins)