Skeleton Modeling Part 2

It seems that skeleton modeling has been the popular topic here on my blog, so I decided to go into more detail by showing its use in an incontext assembly. The assembly is a two tank filter system using two identical tanks with unique piping. The system is a completely fictional assembly made only for demonstration purposes.

To Begin:
Open an assembly but don't insert any parts. Select a starting plane (top in this case) and insert a 3D sketch. Draw the skeleton for line 1 of the system to include mounting points and tank constraints. I ended the skeleton on the right plane for length constraint.


Next create the skeleton for line 2. Make the vertical tank lines equal to the line 1 lengths to make the tanks identical. Constrain the end point to the right plane again to constrain the length.


The last skeleton is the discharge tee. Add the sketch lines of a reference plane on the vertex where the tank centerlines are.


Once the skeletons are in place, we can start creating in-context parts. First is the tank. The tank is made with a flush mount at the bottom and an extended flange at the top. Insert it on the reference plane.


Using another reference plane through tank 1, insert the feed line 1 and create the pipe run following the skeleton you created earlier. Use a sweep and cut-sweep to create the pipe. Remember, each contour for the sweep must be on its own sketch. Add flanges at each end.


For feed line 2, insert your new component and escape the initial sketch mode. Instead insert a 3D sketch to create line 2 and follow the original skeleton.



Lines 1 and 2 are defined by separate skeletons and those skeletons can be manipulated in the assembly to modify multiple components. Change some dimensions and go from a tall configuration...

to a short configuration.


Drawings can also be updated automatically when the assembly is updated.


Skeleton modeling has many uses. It can be used in small bits to control feature positions in parts, or in more complicated configurations to control multiple features and components. One warning, though, keep your skeletons as simple as you can. Don't try to put too much into one sketch or you could create errors down line.

Good luck and comments are welcome.
Chris

Inserting a Part into a Part

One of the designers I work with came across a problem and I knew there was a simple solution, but for the life of me I couldn't remember what it was, or rather where it was. My designer needed to add a toolbox item, a nut, to a part. When he added the nut into his part he could position it, but he couldn't change the configuration to the size he wanted. (SW2007) I knew there was a way to do it, but I couldn't remember where the option was. Finally I asked the SolidWorks Forums for help and received it. Janusz Gacek let me know that the configurations are found in the "List External References" link of the RMB menu.

So, here is a quick tutorial on inserting a part into a part and resizing it:

Under the Insert/Part pull-down menu find the part you wish to insert and click Open.

When you set the part into your base part the Locate Part menu comes up and you can position your part the same way you would in an assembly using mates.


Your part will be the size of the last saved configuration. Right click the part and select List External References. Under Configuration Name change the part to the configuration you need. Click OK and your inserted part will re-size.

Skeleton Modeling

Skeleton modeling is a design method that can be used for both single parts and assemblies. The idea is simple. Draw a skeleton sketch, or several sketches that locates the important surfaces and maybe even the base feature sketch. Once you have located all the important surfaces that sketches will be placed, you can begin building your part. With this concept, you want to use either linked dimensions to your feature extrudes and cuts, or extrude up to next/surface. This way, if your part changes size, you can change the skeleton sketch and your features will adjust their position. You may still need to make detail changes (chamfer or fillet sizes, cut or extrude sizes), but the repositioning work will be done for you.

Start with a basic skeleton on the front plane:


Add another arm on the right plane:


Add your required sketch planes at the endpoints of your arms:


Begin extruding and cutting your features:




Your basic part can now be detailed with flanges or other finishing touches:


When your part changes, the skeleton is changed and everything will adjust:


For an assembly, the process is the same. Make a base sketch at the beginning of your assembly that includes axis' and points placed at insert positions. From there you can place any required planes and begin inserting parts and attaching them to your base sketch as well as to one another. Any changes in the assembly size can be updated in the base sketch. This is a very effective method for companies that create dynamic parts from an assembly model. Some companies have reasons to tie the designer's hands and restrict this practice. My company prefers to hang us in the dungeon by our thumbs.