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Originally Posted by Andy Baker
(reading back through this, you gotta be a CAD user to really understand what I am talking about here... hopefully, it is clear)
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Then, when I am working in my assembly, I import this gear into the assembled model. UG has a "reference set" feature where I can assign one model in a part to a named reference set. In this case, I have "actual" and "block" reference sets. While working in the assembly, if I turn on "actual" for that gear, I see teeth. If I turn on "block", then it shows a cylinder. In the assembly, I use block reference set most of the time, until I want to make fancy pictures.
This is also nice for dimensioning. All of my detail prints are 1-part assemblies of the part getting dimensions (UG calls it master-modeling). So, when detailing the part, I pull in the "actual" reference set and the print shows the gear teeth. There are other reasons for master-modeling, but this is one advantage.
I am spoiled on Unigraphics. I assume that other CAD systems can do these things. Is this true?
Andy B.
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I'm not sure if CATIA has an equivalent to the reference set. It has other features that might make it irrelevant. For example if I wanted gear teeth to disappear, I could just turn the feature that created them "off". They would still be there but wouldn't show up on any pictures or view until you turned it back on. Maybe the next time I visit you can show me what you mean.
Unless I'm actually creating a gear from the model, I usually don't bother with accurate teeth. Notice I did NOT say I don't bother with teeth. I simulate teeth using a trapezoid sized so the addendum and dedendum are right in relation to the pitch circle. This way I can check for interferences and clearances without a lot of extra data in the model. But it still looks like the gears are "real". Involute splines for the teeth generally aren't needed and in many systems cause the model size to inflate drastically.
I have made gears using a Selective Laser Sintering machine. This creates parts directly from powder using a file generated from a CAD model. These days just about any CAD system will create the required .stl file. For these I did have to model the involutes and they came out great. But I only did so because it was essential to getting the part to come out right.
ChrisH