I must be missing something obvious. I want to create a scaled drawing. I make geologic cross sections with drill holes that are 500 to 1000' deep. I would like to set the drawing scale to something like 1"=250'. So a 1000 foot drill hole would be a line 4 inches long on the screen. I have gone to the Drawing Scale List and figured out how to create a new scale, but nothing I try allows me to change the drawing scale from 1:1. I can edit the list, but I can't change the 1:1 default. I have tried right clicking, double clicking etc. It seems that the drawing area stays at the original 1:1 scale. What am I doing wrong? I want to make a drawing where I can give the Line command the coordinates 250,0 and it draws a vertical line 1 inch long. I would appreciate any help. Thanks.
Scale really only matters when it comes time to plot the drawing on paper. In manual drafting you reduce the size of your objects as you drew them on the paper - you scale as you draw.
In CAD, you draw everything full size and scale when it comes time to plot. Theoretically, you needn't concern yourself with scale until then. But, scale does figure in for a few other things as you draw in CAD:
(1) Text size. AutoCAD, CorelCAD, Microstaion, etc, specify text height in object size, not output plot size (which is why annotation scale was introduced). You don't tell CorelCAD to use 1/4" text height, you have to give it a size relative to the real size of the objects you're drawing. Here's where an idea of output scale helps. If you're going to plot at 1"=100', then you would tell CorelCAD to use a 25' text size so it plots at 1/4".
(2) Linetype patterns. Any linetype besides continuous generally consists of repeating patterns. Most are short line segments separated by empty spaces. CAD changes the pattern lengths and spacing based on the scale. Have you ever used a dashed line only to see it plot solid? It looks solid because the solid patterns overlap the empty spaces. The lengths and spacing are controlled by the global linetype scale (ltscale). Setting this to a value compatible with your plotting scale makes the lines appear correct. For example, if the plot scale is 1"=100' set the ltscale to 100 (actually, twice to half the scale would work, 50 to 200). Ltscale can be set at the command line or in the Line Style dialog box: Parameters | Global scale (be careful as you can also scale individual objects which are multipled by the global scale).
OK, so what's all this mean? Well, while you can jump right in and start drawing things, a little upfront work can avoid a lot of headaches later. I generally use this approach when starting with the standard template:
(1) Set units (liner and angular); type & accuracy. While here, also select block insertion units (I prefer dimensionless)
(2) Set the drawing limits. This defines a drawing area large enough to contain your object(s). Set the limits from 0,0 to MaxX,MaxY where MaxX and MaxY create a rectangle large enough for your area.
(3) Zoom Bounds. This will zoom your screen so the entire area defined by your limits is on the screen (this helps avoid drawing objects off the screen).
(4) Guesstimate a drawing scale so you can use appropriate text size and linetype scale. For example: if you want to plot an 800' wide area on 11x17 paper, landscape orientation, then your scale would be 17"=800' or 1"=47.06'. Round to a smaller common scale, 1"=50'. To accommodate margins, maybe pick 1'=60' instead. Set your ltscale in the range of 30 to 120. For 1/4" plotted text size, set drawing text size to 60x(1/4) = 15 ft; 1/8" would be 7.5 ft, etc.
If you draw similar sized objects at similar scales, set up a template (or a series for different scales). and use it to set up your drawing automatically.
BTW - If you turn on the grid and zoom out far enough, the grid will disappear because its pattern becomes too dense. If you use LIMITS and turn on the grid, the grid will only appear within the area defined by the LIMITS. That gives you a visual reference of your drawing area.
Thank you, this clears up a lot.