METRIC TO FRACTIONAL CONVERSION

[SUNDEMON]

hi,
I am having problems creating a drawing that lets me specify distances metrically, later to be converted to feet and inches. I see many FAQs on the subject, but none that seem to directly address my specific problem. I'd appreciate it if someone could offer a little guidance.

I'm working in the US from metrically dimensioned architect's plans. Into these I will have to place items that are manufactured in feet and inches, so a lot of coversion is required. I was hoping to specify distances as written on my plans (metrically), and convert to US measurements further on.

Originally I set my units to decimal/millimeters, and created a dimension style that showed the metric measurements as primary units, and displayed feet and inches (scaled to .3937) as an alternate. When I offset a line a given distance and dimensioned it, everything appeared fine. But when I switched dimension styles to fractional ones, I found that I was actually working x 2.54 too large. I tried scaling my entire drawing by .3937, but the dimensions stll weren't working as I had expected.
Now I'm totally confused.

Any suggestions, gudance, or concise info sources on the subject?

thanks,
sd

 

[SUNDEMON]

persistence pays...

I figued it out, finally, also refined my keyword search.

thanks anyway, however, I'm always interseted in useful info.

sd

 

[MikeHalloran]

We design inch parts for metric boats, sight unseen, all over the world. CAD files may go back and forth many times before everyone is satisfied with the design. In that environment, small scaling errors can cascade until nothing fits. Example: .3937 is only approximately the inverse of 2.54. You can see where repeated conversions will take you.

Better to use the 'cal function to scale keyboard input as you're entering it.

Example: You're entering a distance that's 50 mm, but the drawing is in inches. So where you might otherwise do the conversion and type in an inch equivalent, you would type 'cal <space> 50 / 25.4 <enter>.

Of course, it doesn't work everywhere, so you need to keep a calculator handy.

It's also a good idea to always use the exact conversion factors instead of approximations, and to hang them on the wall so everyone uses the same factors. I couldn't make sense of one designer's drawings until I realized he thought there 26 mm in an inch. Try unraveling that mess.

-Mike-

 

[Navarc]

You could make a new dimension style for the fractional dimensions using a scale factor of 25.4 (or whatever's appropriate)in the Measurement Scale box under the Primary Units tab in Modify Dimension Style in the Dimension Style Manager dialog box. Just a note, if you want the inverse of 25.4, use 10/254 to get rid of the decimal point in the denominator.

 

[kenallmighty]

i have been using an easier method other than the 'cal command. i just use parenthesis as if you were programming in lisp, i.e.

Command: offset
Command: Specify offset distance or [Through] <Through>: (/ [COLOR=black yellow]1000[/color] 25.4)

just be sure that the [COLOR=black yellow]input units[/color] are millimeters.

Absolute zero has nothing on me!!