Zoom Scale vs. Viewport Properties

[drewcon18]

Im having a bit of a scaling problem in AutoCAD. I create my drawing at 1:1 in model space. Then I create a viewport in the paper space (layout tab). Normally I would set my scale factor by right clicking the viewport and selecting properties. Within the viewport properties I can set an appropriate scale, say 5:1. However, I recently discovered that this scale was ever so slightly off in my printed drawings. I searched the forums on here and found that you can also set the scale by double clicking within the viewport (mspace) and using the zoom function. This corrects the problem, but resets my scale factor within the properties tab to about 5.2155:1. Where is this offset coming from? What is the difference between these two methods of scaling? I would appreciate any help that could be provided.

 

[DonPhillips]

I typically set the viewport scale by using zoom and yxp where y=1/scale and xp is relative to paperspace. For a scale of 1"=4', it would be 1/48xp.

Then when you plt, you plot paperspace also at 1:1.

Don Phillips

http://worthingtonengineering.com

 

[borgunit]

DonPhillips is correct. Be careful when plotting to fit or if your paper has margins to contend with. These throw 1:1 scaling off.

"Everybody is ignorant, only on different subjects." — Will Rogers

 

[vlh75]

I presume that when you in mspace within the viewport you have used the realtime zoom. In realtime zoom, the zoomed scale factor is not necessary incremented by a round number. There is nothing wrong setting the scale factor by changing the viewport scale factor. You could have set something else wrongly e.g. plot scale not set to 1:1 or mess up the metric/imperial unit.

 

[drewcon18]

Thanks for the info guys. The problem turned out to be a combination of two things: The margins set up for the plotter and the actual calibration of the plotter. I appreaciate the help.

 

[cfee]

Don Phillips ( & borgunit's) answer is THE correct one.
You can set the scale value of the viewport using either of the 2 methods, Don's or by clicking the v-port going to properties, and selecting one of the standard scales from the drop-down list, but when you get back ro P-Space and are ready to plot, 1:1 is the only right answer (not plot-to-fit), just as borgunit has stated. If your t-block slips past the edge of the plottable area of your paper (plotting at 1:1) THAT's where you have to make an adjustment matching your 1:1 T-block to your printer margins.
Good luck !
C. Fee

 

[chicopee]

Perhaps your plot setting with the plot dialog box was not set exactly 1:1 assuming the paper size and the drawing limits were correct. Another problem is that within that same plot dialog box, the plot area was set on extents instead of limits. When you scaled your drawing within that viewport, the limits in PS should have been set to the drawing border and not to the size oof the paper.