Mixing models with Metric and English systems of measurements

[GlenWisham]

Procadsters,

I've got an imported step file that appears to be built using the Metric
system of measurements.

I've brought it into another assembly that uses the English system of
measurements. It appears fine.

I do not recall seeing this situation before... and it brings to mind the
lesson of an interplanetary probe that missed Mars.

Will this cause problems down the road if we do nothing?

What is the recommended procedure for converting a step model and it's
assembly from Metric system to the English system?

Words of wisdom are greatly appreciated.


Glen R Wisham
MOEC EW Mechanical Engineering
Space and Airborne Systems
Raytheon Company

805.879.3359 (office)
805.879.3017 (fax)
561.3359 (tie line)
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6380 Hollister Avenue
Goleta CA 93117-3114 USA

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[ptc-157102]

I've had assemblies where parts were mixed and the metric parts came in with
inch sizes (39 inches instead of 39mm). I haven't seen this lately. Creo
should take care of this. The other issue is the accuracy setting. It will
be different.

[ptc-157102]

Another point comes to mind. The properties will be different systems and
need to be resolved for analysis purposes.

[rrich]

There are a couple of ways to handle this. First you must understand how
this happens. Someone creates a step file if part was metric ie 25.4mm dia
and they step it out you will get a 25.4mm so file is internally labeled
metric and your part will be metric. This is correct. This can go wrong
however, someone models a part 25.4mm dia and there drawing units are inch,
now they step it out and the part is 25.4 inches in dia. because the drawing
units were set to inch.

Now you wish to bring in the step file, you have two ways to do this. One
you just open the step file and the part will be created. - this way you
will not create any of your standards needed from your start part ie
parameters, units, layers and such. Doing it this way your drawing units
will be set to what ever the step file was created at inch or metric. The
second way is you have a part that already started and you import the shared
data from file. If you pull a metric part from a metric step file it will
scale properly into your inch drawing you have already started, but if you
pull in a step file of a part that has metric dimensions but was written out
in inches your part will not be the correct scale. Don't worry you can fix
this in pro.

Go to setup and then to units. Lets say your part is currently in inches
but the import you brought in is 25.4 times too large. To fix change your
units to mm and on the next pop up box choose the option to leave dimensions
as they are 25 = 25. This should change your units and not force any
regeneration. Now your part is in mm and everything should be correct size,
but you really want it in inches. So back to setup and then to units and
this time select inch. When the second box comes up this time select the
button for convert dimensions. Now your model will regenerate and when you
inspect the dimensions you will see that your part is now 1.00 not 25.4.

As for assembling parts if you have proper parts ie metric units showing
metric parts you can assemble these directly into inch assemblies and they
should be the proper size or vise verses assembling inch parts into a metric
assembly.

Hope this helps.

Ron