- FMA
- The Fabricator
- FABTECH
- Canadian Metalworking
Categories
- Additive Manufacturing
- Aluminum Welding
- Arc Welding
- Assembly and Joining
- Automation and Robotics
- Bending and Forming
- Consumables
- Cutting and Weld Prep
- Electric Vehicles
- En Español
- Finishing
- Hydroforming
- Laser Cutting
- Laser Welding
- Machining
- Manufacturing Software
- Materials Handling
- Metals/Materials
- Oxyfuel Cutting
- Plasma Cutting
- Power Tools
- Punching and Other Holemaking
- Roll Forming
- Safety
- Sawing
- Shearing
- Shop Management
- Testing and Measuring
- Tube and Pipe Fabrication
- Tube and Pipe Production
- Waterjet Cutting
Industry Directory
Webcasts
Podcasts
FAB 40
Advertise
Subscribe
Account Login
Search
Bedeviled with the details
Balancing realistic detail with rational modeling discipline
- October 8, 2009
- Article
- Shop Management
A recurring theme in 3-D CAD modeling is design intent. What is the reason for creating the model?
Generally, the goal is some combination of visualization, virtual prototyping, and preparation for manufacturing. The trick is to satisfy those goals within a time budget.
Realistic Cost
Consider the shoulder bolt shown in Figure 1. It is dimensionally exact and includes the proper thread pitch and profile, knurling around the head, and exact hex key cutout size. This model is suitable for use in manufacturing this item. A machine shop could use this model directly for CNC programming.
It took me no time at all to model this part. I downloaded it from an online hardware store (http://www.mc master.com). If you want to fetch your own copy, use part No. 90298A615.
An expert CAD jockey starting from scratch could easily spend a couple of hours creating this model. If the goal is manufacturing, then this effort would of course be justified. In my practice, I more often use fasteners like this in an assembly for other reasons—primarily for visualization and generation of a bill of materials.
Speed Demon
For those purposes, the model shown in Figure 2 is more appropriate. I created this part in about 30 seconds by revolving a sketch of the profile of the shoulder bolt.
Why is Figure 2 "better" than Figure 1? One possible answer is shown in Figure 3a and Figure 3b. Compare the rebuild time my workstation reported (a 64-bit quad core, state-of-the-art monster). The realistic part took 3 seconds. The slug dummy rebuild time was too quick to detect by the timer software.
So, even though it took me very little time to download the realistic model, if I use more than a few of those fasteners in a CAD model of an assembly, then I'll be paying a time penalty as I wait for the model to update. Time is money. Quick CAD work is good CAD work.
Hasty Pudding
Another great use for 3-D CAD models is the generation of instructional videos for assembly personnel as well as the production of illustrations for manuals. The bolt shown in Figure 2 lacks so much detail that it would seem amateurish in those situations.
In Figure 4a we've edited the revolved sketch to include a semblance of threads. They are not true helical threads, but as you can see in Figure 4b, the casual observer won't be able to tell. The addition of a hex key tool hole and a chamfer results in a more finished appearance for the component. The rebuild time is now up to 0.05 second, which is still very efficient.The component shown in Figure 4b has insufficient detail for manufacturing, but it does have enough detail for entertaining visualization. Because that is my design intent in this example, I'm happy.
Gerald would love to have you send him your comments and questions. You are not alone, and the problems you face often are shared by others. Share the grief, and perhaps we will all share in the joy of finding answers. Please send your questions and comments to dand@thefabricator.com.
subscribe now
The Fabricator is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The Fabricator has served the industry since 1970.
start your free subscription- Stay connected from anywhere
Easily access valuable industry resources now with full access to the digital edition of The Fabricator.
Easily access valuable industry resources now with full access to the digital edition of The Welder.
Easily access valuable industry resources now with full access to the digital edition of The Tube and Pipe Journal.
Easily access valuable industry resources now with full access to the digital edition of The Fabricator en Español.
- Podcasting
- Podcast:
- The Fabricator Podcast
- Published:
- 04/30/2024
- Running Time:
- 53:00
Seth Feldman of Iowa-based Wertzbaugher Services joins The Fabricator Podcast to offer his take as a Gen Zer...
- Industry Events
Pipe and Tube Conference
- May 21 - 22, 2024
- Omaha, NE
World-Class Roll Forming Workshop
- June 5 - 6, 2024
- Louisville, KY
Advanced Laser Application Workshop
- June 25 - 27, 2024
- Novi, MI
Precision Press Brake Certificate Course
- July 31 - August 1, 2024
- Elgin,