From time to time in this space we like to jump back out of the “deep end” and reiterate basic best practices in 3D parametric CAD modeling that are so often overlooked.
You may recall that in last week's cliffhanger, our intrepid SolidWorks power user, Sol, was asking Sal, his trusty sidekick, if he’d ever had any unexpected feature movement or failure on his models.
“All the time, Sol.”
“Have I ever told you about the BORN Technique?”
“No,” replied Sal, “but the other three movies were great! Say, wait a minute…what does this have to do with SolidWorks, Sol?”
“Sal, Sal, Sal,” sighed Sol. “It stands for Base Orphan Reference Node.”
“Sound technical!” Sal’s ears perked up like a dog hearing the refrigerator open.
“It’s a modeling technique I was taught many years ago, and still can teach us many things about modeling today. Remember what I’ve told you so often?”
“This isn’t about cleaning the coffee pot at night again, is it?”
Shaking his head, Sol replied, “I mean about the goal of parametric feature-based modeling being more than capturing the look of the part and capturing the true behavior – the design intent – of the part. For instance, when you need to add a new feature to a part, what faces or edges do you reference?”
“Whatever is closest or handiest, I suppose,” replied Sal sheepishly. Suddenly a look of clarity came over his face. “I think I see where you’re going with this. This is why sometimes when I change a feature, or delete one, I can affect others.”
“Yes, exactly!” Sol picked up on Sal’s train of thought. “Now, there is nothing wrong with feature relationships…they can be powerful and useful in capturing that design intent. Remember we discussed showing and using the default planes and origin points in models last month?”
“Like you’re about to show me in Figure 1, Sol?”
“How do you do that every month, Sal? Anyway, the BORN Technique dictates that it often makes sense to reference all new features back to those static, predictable datums, or to a similarly stable base feature, instead of nearby faces and edges.”
“This is also why you’re always telling me to keep that base feature so simple.”
“Yes, exactly!” Sol repeated.
“Boy oh boy, Sol, where do you learn all this great stuff?”
“Graphics Systems’ SolidNotes blog, my friend. Graphics Systems’ SolidNotes.”
By: Sam Hochberg, Applications Engineer
For another article by Applications Engineer Sam Hochberg, click here to read about Animating Rotary Motion in SolidWorks.