metric/imperial

Can a drawing be created in metric-then part way thru be converted to
drawing with imperial? Or must it all be done in one then converted?
Reply to
Greybeard
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I do something simular..I insert or draw and item and the use the scale command, selecting what I want scaled and use "(/ 1 25.4)" for the amount to scale:
Command: scale Select objects: c Specify first corner: Specify opposite corner: 4 found Select objects: Specify base point: Specify scale factor or [Reference]: (/ 1 25.4) 0.0393701
Reply to
R Wink
thank you. I just tried it out and it works just fine.
Reply to
Greybeard
You can, but AutoCAD only understands drawing units.
If you start drawing with inches as the drawing unit and then want to switch to millimetres as the drawing unit, you will have to scale everything up by 25.4 so that an object that was 1 unit (inch) now is 25.4 units (millimetres).
You need to be aware that each time you scale up and back, you run the risk of introducing small errors. The more you do this, the worse it will get because there will be rounding and it all adds up.
Reply to
Ian A. White
If you use "25.4" or it's inverse "10/254" there will be no measurable error, even after thousands of rescalings. They are exact.
Errors will happen if you try to use ".03937" or any similar decimal as the inverse because they are not exact.
Reply to
Jim Patrick
I see what you mean-I will do it in the base unit and then do a final scaling using 25.4-then save both versions. My thanks to you for the help.
Reply to
Greybeard
The SCALE command can make the "conversion" at any time. ___
Reply to
Paul Turvill
Well, I have had survey information get screwed up and that was only scaling up and back by 1000 to go from metres to millimetres and back.
The particular boundary ended up being scaled a few times and before long errors started creeping in. After that it became standard practice to do the boundary in metres, then copy it and scale the copy up. If it needed to be altered because of new survey data, the original boundary was modified, then copied and the copy scaled with the previous boundary deleted.
Reply to
Ian A. White
Something's fishy. You're either A) Running an add-on that intercepts the scale call, B)Running a boundary about 30 times the size of the solar system, or somebody's finger slipped on the keyboard.
Autocad uses signed double precision floating numbers (AKA (64bit IEEE reals), where one bit is the (+/-) sign, 52 bits are the mantissa (0 thru 4,503,599,627,370,496) and 11 bits are the exponent -1023 to +1023. On a 4 km boundary the accuracy is 0.000000001mm.
Autocad has many faults; but math precision is not one.
__ A very old (1983?) drawing of the solar system demonstrating the huge dynamic range inherent in the 64-bit math.
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Reply to
Jim Patrick

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