Although they are SOLIDWORKS focused, the methodologies discussed here should be relevant to any feature-based CAD software. This article is a companion piece to a presentation given at SOLIDWORKS World 2019, which can be accessed here in both the PowerPoint and recorded presentation featuring live demonstrations of many of the techniques described.

Establishing a Model Plan

I’d like to present a simple workflow (see Figure 1) that, in the absence of a more sophisticated strategy, can serve as a basis for creating a robust CAD model.

As much as possible, features should reference back to the reference geometry and initial sketches that are planned out after a clear outline for the model has been established. The success of this process also hinges on performing checks during the modeling process—correcting and reorganizing as you go to make sure your work remains conformant to the plan.

Hand sketching an outline as shown in Figure 2 is a highly recommended prerequisite before you begin the modeling process. This sketch attempts to define the overall shape of your model and a few key parameters that will be driving the model’s design objective. It’s much better to figure this out at this stage rather than after you already have a lengthy feature tree.

To create your sketch, all you need is pen and paper (and, as you can clearly see from Figure 2, you don’t have to be an artist). A quick smartphone picture will digitize the sketch for your records. Unless you are completely confident that you have a clear mental picture of the end result in your head, don’t skip this step!

From the hand sketch, think ahead to what major features will make up your model. This will help guide the structure for sketches and reference geometry that will be created in the next steps.

Create reference geometry and initial sketches (see Figure 3)—these are the planes, axes and sketches that will be used to create the majority of the part features. Creating the appropriate geometry requires “thinking backwards” from the features you are planning to generate. Having more reference geometry than you need is fine, as extraneous or unused reference geometry or sketches can be deleted toward the end of the modeling process.

Primary features are features that make up the bulk of the overall shape of the model and would never be suppressed or removed from the design. These features must relate only to the reference geometry and initial sketches. Perhaps the most important rule for moving forward in the model is to never redefine anything that has already been defined in the initial sketches and reference geometry.

Primary features will typically consist of an initial base feature, plus up to a handful of other features that constitute the overall part profile of the model (see Figure 4).

Secondary features may relate to the initial reference geometry and base sketches, or to primary features (see Figure 5). To determine if a feature falls into the secondary feature category, ask yourself, “Would I ever want to suppress or remove from this from the design?” If the answer is yes, the feature is likely secondary. Secondary features typically include things like cutouts, pockets, holes and bosses.

Detail features are features that you could easily suppress or remove to make a low detail version of the model. This includes threads, small fillets, chamfers and text (see Figure 6).

Sticking to the Plan

It’s easy to have a plan—the real challenge is sticking to it when things get tough!

This modeling methodology hinges on two things: organization, and careful and selective use of references and relations.

I highly recommend the use of folders to help with organization.

Having the right type of features placed in their respective folders provides an inherent self-check to help ensure that you are conformant to the model plan. The folder structure also makes it manageable to navigate massive feature trees. Once you are comfortable with the standard process, you can deviate from such strict folder names to a method that works best for you.

While the shaft example has only 27 features (see Figure 7), a much longer feature tree doesn’t need to take up any more vertical space when using folders.

Some users may prefer to label individual sketches/features rather than use folders—another valid organization method.

Dynamic Reference Visualization can be enabled in SOLIDWORKS by right-clicking the top of the FeatureManager design tree as shown in Figure 8. This is a great tool to periodically check and ensure that your relations and dependencies are going according to plan.

Once the Dynamic Reference Visualization tool is enabled, features automatically highlight their references, so you can quickly validate whether the dependencies are correct. As you can see in Figure 8, the primary feature points back to only base reference geometry, whereas features further down the tree in the details folder may point back to both secondary and primary features.

Unfortunately, it’s easy to pick up relations by accident! To help myself focus on relating as much as possible to my base sketches and geometry, there are two tricks I like to use. Both methods revolve around hiding the part display, so that it’s only possible to reference the initial sketches and reference geometry—you can’t easily pick up a relation to something you can’t see!

My preferred method when trying to avoid accidental relations is to hide the underlying body—either by right-clicking and choosing the eye icon to hide the body, or by using a shortcut to hide bodies. To do this, hover the mouse over the part and press the Tab key on your keyboard. Then, show the initial sketches and reference geometry that you want to reference. Add your features and once you are done, hover over the area where the part was and press Shift+Tab to show the body again (see Figure 9).

Adding features using this method will result in features being placed at the end of the feature tree, which can be freely reordered upstream at will since they will only have dependencies to your early base sketches and reference geometry.

If you do need to pick up a reference to existing geometry, you can quickly show the body again while modeling. The objective is not to completely avoid using references—secondary and detail features will inevitably need some references to other features. The objective is to put careful thought into what relations you add, and, for me, hiding the body forces me to really consider each decision—and ask, “Do I really need to show the body to pick up a reference, or do I have enough information in the base sketches/reference geometry?”

The second approach is to simply roll back in the feature tree to how it was before the initial features were created as shown in Figure 10. Sketches or features you create at this stage can then be reordered down the tree if desired. If you are using the suggested folder structure, it may be necessary to toggle to Flat Tree View (CTRL+T keyboard shortcut), which organizes features in strict chronological order—temporarily ignoring folder display.

The downside of the rollback bar approach is that there is no fast toggle in the event that you do need to reference existing features.

Another thing to watch out for is accidental defining parameters that are already defined in your initial sketches or reference geometry. Unfortunately, SOLIDWORKS makes it very easy to do this! A common offender is the “blind” end condition on an extrude or extrude cut, which adds an additional feature dimension. If it is being used for a primary feature, the length of the extrude should already be defined somewhere in your initial sketches or reference geometry. Using an alternate end condition such as “Up to Vertex” or “Up to Surface” allows you to reference a sketch point or plane, respectively.

This way of thinking is what will help prevent having only portions of your design updating during a model change—and it is worth taking the time to correct issues like this immediately as they are encountered to stay conformant to the modeling plan.

In summary, I recommend creating a hand sketch or model outline in advance of creating your CAD model. Establish the key parameters that will be driving the design and use those to construct initial sketches and reference geometry. Reference back to these sketches and reference geometry exclusively to define your primary features—don’t redefine any parameters!

Once you have created secondary features and detail features, try to reference back to the initial sketches and reference geometry as much as possible —hiding the body and showing these sketches is a useful trick to force this. Expect that you will need to show the body again to reference primary features with certain relations and create new sketches for your smaller details. Periodically check the Dynamic Reference Visualization tool and make sure that features don’t have excessive amounts of dependencies.

Planning a Project

Everything discussed so far pertains to individual part modeling, but if you are tasked with planning out a full project or assembly model, it’s worth doing some additional high-level planning. Below are my major considerations when approaching a new project.

Design Inspiration/Research

Design inspiration and research is a crucial step whether you are brainstorming a new idea or working within strict specifications, and I believe it’s always worth doing some healthy research and trying to create a design inspiration collage (as shown in Figure 11). I always gravitate toward Microsoft OneNote, where I paste in pictures of various design ideas and annotate the aspects that interest me.

Hand Sketch and Preliminary Model

After choosing some parameters for my design, I return to paper to create hand sketches that will determine the overall structure of my assembly. Often it is also worth taking the time to build a preliminary concept CAD model, which can help you pick a winner from several competing designs (see Figure 12).

These preliminary models provide a bare-bones level of detail— enough to get the information needed to make a decision on how to move forward.

When creating the hand sketch and/or preliminary model, start to think of the logical splits for parts and subassemblies as you move into tree structure planning.

Tree Structure Plan

Developing a tree structure or “design tree” before you embark on your detailed modeling can reduce a host of issues. It should certainly be a requirement for working in a collaborative environment, as the separation between subassemblies is what enables concurrent design. Only one person can have write access to the top-level assembly at a time (or any other part/component), so breaking up the model into logical subassemblies enables multiple users to be working on separate regions as shown in Figure 13.

SOLIDWORKS Treehouse is a stand-alone application that allows you to plan new assembly tree structures, and even create the necessary assemblies, subassemblies and part files associated with them. Treehouse isalso usefulforretroactively viewing an assembly tree structure. If you don’t have access to Treehouse, using Microsoft PowerPoint, Visio, or another similar flowchart tool can produce effective plans.

Model Requirements

After defining a tree structure, it’s important to define the purpose of the models and what their “inputs and outputs” need to be. This means establishing design requirements for subcomponents as you would typically do for a full design—perhaps using specifications obtained from your preliminary model.

Although it’s not always possible, ideally requirements would be specific enough that each component becomes decoupled (effectively a “black box”),which is the best-case scenario for collaboration. Having enough data from the preliminary model to be able to set a detailed requirement like “Motor subassembly must fit into a 50 mm x 50 mm x 75 mm bounding box, and mate with standard 4 x 100 mm bolt pattern.” This reduces back-and-forth questions between designers and allows more progress to be made before integration into top-level assembly is required.

Level of detail is another important parameter that should be established—for example, what are the models being used for? Purchased vendor parts may be represented with a very low level of detail, while models for photorendering or CNC manufacturing need additional attention.

If you’ve followed along the modeling methodology presented previously, then you should have the best of both worlds—an easy way to vary the level of detail of your models by controlling the suppression of your “detail” features.

Part Numbering

There are many methods and systems for part numbering and entire books have been written on the subject. As it pertains to CAD, it’s important to have a system tohelp ensure that files have unique identifiers and won’tget overwritten by other parts (see Figure 14).

Here is one example system: use a descriptive part name during the preliminary design phase, and a reserved serialized number for release. This is useful because you may not be sure exactly how many parts are needed during the preliminary design phase, and is also an inherent way to differentiate prototype versus release files.

Sometime during the preliminary design phase and tree structure plan, reserve a sufficiently sized block of part numbers. This can be as simple as having a shared spreadsheet (shown in Figure 15) where users reserve ranges. It can be worth reserving some extra slots for parts that could be used for future revisions, upgrades or repairs.

Once the parts are ready to be released, rename the file with the reserved part number and convert the descriptive name into the part description. This is also a great time to fill out any other relevant file properties that may be useful on the bill of materials.

Note also that SOLIDWORKS PDM Professional supports automatically generated part numbering, which can streamline this manual process.

Project Timeline

The best laid plans won’t help if you don’t hit the deadline! For larger projects, it’s worth establishing a project timeline—usually as one of the first actions (see Figure 16). If you’re new to generating a timeline, you may not be sure what to realistically estimate. Thankfully, you can modify or “rebaseline” the timeline as you gain a more accurate picture of when you will likely be finished.

The best part of using a project timeline is that when you are tasked with a new project, you’ll have a historical basis that will help you to make a much better estimate of how long the next project should take. It’s also a great tool for proving that additional resources are required. One of the most popular tools for project planning is Microsoft Project (which produces Gantt charts as shown in Figure 16), but even marking down some critical estimated dates on a calendar can do the trick!

Summary

This article presented an example modeling methodology, relevant SOLIDWORKS tips, and basic project planning techniques. Every industry is different with their own unique requirements, so please consider this as simply one of many valid possible approaches.

I believe the most important thing is to adopt some form of system for modeling and project planning. By employing a system or methodology, you will be able to track your progress and make incremental refinements and improvements in the future.

I hope this article and the processes outlined will give you something to fall back on and allow you to take the complexity out of history-based CAD! If you enjoyed this article and would like more detail, then I recommend that you check out the recorded version of the associated presentation.

• ‘Impossible’ Modeling Challenges Solved by CAD Power Users
• ’Impossible’ Modeling Challenges Part 2: Dynamic Straightening of a Bent Wire in CAD
• ‘Impossible’ Modeling Challenges Part 3: (Un) Bend a Square Profile in Multiple Directions
• ‘Impossible’ Modeling Challenges Part 4: Reverse Engineering (Surfacing and Direct Editing)
• ‘Impossible’ Modeling Challenges Part 5: Volume Limit Mate (Keep the Prisoner in Jail)
• ‘Impossible’ Modeling Challenges Part 6: Volume Control

Background

Every professional 3D CAD software has some type of functionality for unbending models. For example, SOLIDWORKS has native capabilities for flattening bent sheet metal parts. One of the criteria defining a sheet metal part is the fact that any bend is performed in a direction perpendicular to the thickness of the part.

For more complex shapes, users need to install and use specialized add-ins that serve various industries like Logopress3, BlankWorks, ExactFlat or 3DQuickForm.

Typically, power users who do not need this functionality on a daily basis will not have invested in such add-ins. When facing such a challenge, however, they will need to find a solution using the built-in functionality of the software.

What about attempting to unbend a bent I-beam?

The Challenge

For an in-depth study of this problem, the powerusers from the SOLIDWORKS Forum competed in The 4th SOLIDWORKS Power-User Challenge (SWPUC).

This proved to be one of the most popular challenges so far, with over 3,800 views, 81 viewers and 12 participants. Some of the competitors provided several solutions.

The users were asked to:

1. Download and import a Parasolid file containing the model shown in Figure 1.
2. Calculate the unbend length.
3. Create an unbent body.
4. Link the lengths of the bent and unbent bodies, as measured on the neutral fiber.

To simplify the problem, the following assumptions were made:

• The neutral fiber goes through the center of the profile.
• An approximation of 0.001mm can be made between the lengths of the bent and unbent bodies.
• Extra consideration is given if no equations are used.
• FeatureWorks cannot be used for reverse engineering the model.

For a more in-depth explanation of the challenge, please watch this video.

Solution

Step 1: Create a sketch representing the neutral fiber of the part.

The participants proposed several solutions for this step:

1. Manually draw and constrain a 3D sketch (see Figure 3).

Note: This technique can be fast if the user knows how to apply relations in a 3D sketch. In this specific case, the workflow is significantly simplified if, after placing one point of the sketch in a correct location, the user takes advantage of the concentric relations that could be applied to the arcs.

2. Slice the model per bend (see Figure 4).

2.1. Create cutting entities (planes or sketch lines).

Note that due to the simple geometry, two 2D sketches can be created fast using SOLIDWORKSConvert Entity tool on the bend edges.

2.2. Use the Split command to create separate bodies for the straight and bend areas.

2.3. Hide the bodies containing bends.

Tip #1: Using the cursor, hover over each body you want to hide and press the Tab key.

2.4 Add Reference Points in the center of each cut face.

Tip #2: To save time, take advantage of the intelligent user interface:

• Pin the command using the handy tack.
• After selecting each face, right-click to create each point.

By doing so, all points can be created in seconds!

2.5. Create a 3D sketch using the Reference Points.

3. Use the Mid-Surface tool to create the symmetry references.

For surfacing powerusers, it was only natural for them to attempt to find a solution using surfaces.

The Mid-Surface tool is mostly used by simulation users when they want to reduce the computing time for their studies by using shell elements instead of solids.

Other users are most likely unaware that such a powerful tool exists in SOLIDWORKS.

3.1. Find the Mid-Surface icon.

The icon is not easily found in the main toolbars. A quick way to add the icon is to use the Command Search functionality. Simply search for the command and then drag the icon onto the toolbar of your choice.

3.2. Create the first Mid-Surface body.

The first mid-surface can be created automatically. Simply select the Find Face Pairs button.

The desired result appears as if by magic.

Tip #3: Isolate with Transparent option to better see the resulting surface body.

At this point, some users might simply draw the 3D sketch for the neutral fiber by using the edges of the new surface body as a reference.

Of course, the surfacing gurus would continue using surfacing tools. They would either use the FaceCurve command to quickly generate the neutral fiber at 50 percent of the surface or create a second Mid-Surface (in the perpendicular direction) to be intersected with the first.

Tip #4: If you use the Face Curves method, start a 3D sketch before starting the command. This will ensure that all resulting 3D sketch entities will be located in the same sketch.

3.3. Create the second Mid-Surface body.

If you decided to continue using the Mid-Surface feature, you are in a for a treat. First of all, since we will have to manually select all pairs of faces, let’s prepare our graphics area for quick selections.

3.3.1. For that, create a New Window and tile the window vertically.

3.3.2. Orient the part in such a way that all the required faces will be selectable in the two windows.

3.3.3. Start the Mid-Surface command and simply successively click on a face from each window. Make sure the pairs are selected in the correct order (let’s say from left to right).

The resulting mid-surface body is shown in green in Figure 19.

4. Use the Intersection Curve to create a 3D sketch representing the intersection between the two surface bodies.

Tip #5: To increase visibility, change the resulting Sketch Color.

Step 2: Use the Fit Spline to approximate the 3D sketch entities into a 3D spline.

This will allow you to use the new sketch relation Equal Length.

Tip #6: To maximize accuracy, use a small value for the tolerance.

Step 3: Sketch a line representing the neutral fiber of the unbent body.

Step 4: Add the Equal Curve Length relation between the Fit Spline and the Line.

Now, the line will always match the overall length of the neutral fiber of the bent I-beam.

Step 5: Create the Unbent Body using a Sweep feature.

Tip #7: You can select the end face as the profile. There is no need to sketch the profile!

Step 6 (Optional): Move the new body for better visibility.

Furthermore, each body can be deleted in turn in order to create two configurations, one for the bent state and one for the unbent state.

For a complete demonstration of this technique, please watch this video.

Other solutions

We liked the no-nonsense approach from the models submitted by Ned Hutchinson, Shaodun Lin, Deepak Gupta, Jaja Jojo, Mati Link, Tom Helsley and Mike Helsinger.

There was very nice use of the new (2017) Equal Curve Length relation and/or equations. Mati also took advantage of the new Offset on Surface tool.

Then we have Rob Edwards’ model, which uses an interesting technique to emulate the Equal Curve Length relation in 2015.

We enjoyed walking through the models submitted by Ryan Dark and Rob Edwards, who used surfaces to determine the neutral fiber. Great approach to simplifying the creation of the 3D sketch.

Dennis Bacon impressed us again with his three solutions. Nice to see techniques, first time introduced in the SWPUC #3, used again with great effect. 

The Winner of the 10th SWPUC

The Winner of the 4th SWPUC was Erik Bilello. He received extra consideration for the originality of his solution, and especially for the fact that his model can be configured to describe the bending process bend by bend. Amazing stuff!

Conclusion

Even when the software does not provide a solution out of the box, powerusers can always find a way to get the job done!

Along the way, participants had the opportunity to experiment with combining advanced tools that were designed for other purposes. I hope you enjoyed discovering some of these tools.

Starring in today’s show:

• Mid-Surface
• Face Curves
• Fit Spline
• Reference Point
• Intersection Curve
• Equal Curve Length relation
• Sweep
• Pushpin
• Right Mouse button
• New Window
• Tab key for hiding bodies/components
• Command Search
• Isolate with Transparent option
• Sketch Color

• ‘Impossible’ Modeling Challenges Solved by CAD Power Users
• ’Impossible’ Modeling Challenges Part 2: Dynamic Straightening of a Bent Wire in CAD
• ‘Impossible’ Modeling Challenges Part 3: (Un) Bend a Square Profile in Multiple Directions
• ‘Impossible’ Modeling Challenges Part 4: Reverse Engineering (Surfacing and Direct Editing)
• ‘Impossible’ Modeling Challenges Part 5: Volume Limit Mate (Keep the Prisoner in Jail)

Background

Everyone knows how to calculate the volume of a solid body using 3D CAD. For SOLIDWORKS users there are several options, including:

• Using the Mass Properties tool
• Using a Sensor
• Using a Custom Property (for a part containing only one solid body)
• Using a Cut-List Item Property (for a solid body)

The Challenge

So far, the reported volume is that of the glass, and not of the fluid that fills the carafe.

If we were to pour a liquid substance in the carafe, let’s say an expensive Cabernet Sauvignon, it is important to ensure that the carafe is accurately graded.

When the level of liquid is known, it is relatively easy to compute its volume. The opposite is less simple, requiring a repetitive cycle of trial and error.

For an in-depth study of this problem, the power-users from the SOLIDWORKS Forum competed in the 10^th SOLIDWORKS Power User Challenge (SWPUC).

They were provided with a model of the carafe and seven measurement lines already inscribed. The challenge was to ensure the lines were located at the proper height.

Step 1 – Fill the Carafe to a Given Level

All solutions had one thing in common: the procedure for filling the carafe to a given level. For that we need to create a second solid body, representing the liquid. The best technique takes advantage of the Intersect tool:

1. Create a horizontal plane at a known height.

2. Run the Intersect tool, using the Create internal regions option, without merging regions.

3. A new solid body is created to represent the wine.

Step 2 – Determine the Level of a Given Volume of Liquid

The participants proposed different solutions for this step. Let’s consider determining the 40oz mark.

Solution #1 – Manually Modify the Locating Dimension of the Capping Plane and Reading the Volume

As you can imagine, this is a repetitive, time-consuming exercise.

Solution #2 – Use Instant3DMode to Quickly Adjust the Locating Dimension of the Capping Plane and Read the Volume Sensor

Step #1: Create a Volume Sensor for the wine solid body.

Notice the volume units are not expressed in the type of unit you want. That is because of a known bug: SPR# 588882: Units in sensor are not consistent when editing/updating the volume sensor. 

Fortunately, the fix is simple, just edit the document units and re-select the unit for the volume.

Step #2: Correct the measuring units.

Step #3: Ensure Instant3D is on.

Step #4: Double-click on the capping plane to reveal its dimension.

Step #5: Drag and release the Instant3D handle of the plane dimension.

Notice that, as you drag the handle, you can move the cursor over the ruler to ensure precise measurement modifications.

Step #6: After each drag and release of the Instant3D handle, register the value of the Volume Sensor.

Repeat Steps 5 and 6 until the reported volume of wine is within an accepted tolerance.

Tip: Zoom-in to the handle to perform more precise adjustments.

It takes about 30 seconds to get the volume of liquid within an acceptable range.

Solution #3 – Use a Design Study to Automate the Trial and Error Process

The previous two solutions were labor intensive, requiring repetitive user input. What if we were to ask SOLIDWORKS to do all the work for us?

Step #1: Right-click on the Motion Study on the Status Bar and select Create New Design Study.

Step #2: In the Variable View, add a variable parameter.

Step #3: Select the Plane dimension and name it “Level”.

If you have a licence of Simulation Professional or Premium, follow steps 4 to 7. If you do not have a licence of Simulation Professional or Premium, follow steps 8 to 11.

With a Simulation Professional or Premium license, you can use Optimization functionality along with Goals to quickly obtain the desired result.

Step #4: From the Goals dropdown, select the Volume Sensor. If needed, you can create the sensor at this time.

Step #5: Set the goal to have the Volume = 40 oz.

Step #6: Establish the range for the Volume Variable.

Step #7: Click Run.

The study quickly converges to the optimal result:

Note that the result can be further refined by narrowing the range.

If you do not have a licence of Simulation Professional or Premium, follow steps 8 to 11.

Step #8: Add the Volume as a Constraint. Set it to Monitor Only.

Step #9: Set the variable Level as a Range with Step between 3” and 4” with a step of 0.1”.

Step #10: Click Run.

Step #11: Examining the final results it is clear that the optimal volume can be found for a level of wine between 3.5” and 3.6”.

To increase precision, narrow the range and re-run the study.

Winners of the 10^th SWPUC

This was one of the most popular Power-User challenges so far. With 3161 views, 88 viewers, 84 replies, and tens of solutions, it was really hard to select a unique winner.

In the end, we recognized all the original solutions submitted by:

Todd Blacksher, Andreas Rhomberg, Scott Stuart, Brandon Graham, Muhammad Aamer, Bill Toft, Michael Fernando, Krzysztof W., Dan Pihlaja, John Stoltzfus and Elmar Klammer.

Conclusion

It’s easy to determine the volume of an existing solid body. It is more challenging to determine the level of a known volume of fluid poured in a given shape. For that, a trial-and-error procedure is needed.

SOLIDWORKS has an excellent tool for automating such trial and error processes, called Design Study. It can be used for a wide range of purposes, not only for computing volumes.

For example, if you love basketball, watch this video for another exciting application of design studies.

• ‘Impossible’ Modeling Challenges Solved by CAD Power Users
• ’Impossible’ Modeling Challenges Part 2: Dynamic Straightening of a Bent Wire in CAD
• ‘Impossible’ Modeling Challenges Part 3: (Un) Bend a Square Profile in Multiple Directions

Background

While SOLIDWORKS is the most popular 3D CAD software, it is not the only one. We live in a CAD world that offers engineers and designers many software packages with which to work. Collaboration among various companies using different CAD system is the norm, not the exception.

SOLIDWORKS can import various file types, in either native or neutral format. If you want to see all type of files that could be imported by SOLIDWORKS, simply go to the File menu and select Open, then select the file type (Figure 1.)

Figure 1

More details about the type of files that could be imported or exported by SOLIDWORKS can be found in the SOLIDWORKS Help file (Figure 2).

Figure 2–Importing and Export File Version Information for SOLIDWORKS 2018 SP4.0

In practice, model data is usually transferred from one CAD software to another by the use of neutral formats such as STEP, IGES, SAT, Parasolid and more.

The Challenge

A neutral file usually contains only the body data. The features that generate solid and surface bodies are not preserved. As a result, when the model is loaded into SOLIDWORKS, the only features listed in the FeatureManager Design Tree are Imported features, one for each body.

The power users from the SOLIDWORKS forum were presented with the following case study:

A 3D Printing Bureau receives a neutral file that generates the model shown in Figure 3.

Figure 3 - Imported model, full of cut-outs

The customer wants a 3D Printout showing the way the model looked before all the cut-outs were added.

Figure 4 - End goal: Remove all the red faces.

In the end, the model should look like the one shown in Figure 5.

Figure 5 - A travel back in time, before any cut-outs were added.

If such a model had been created natively in SOLIDWORKS, the user would simply rollback the features in the FeatureManager Design Tree to travel back in time before any cut-outs were created. With an imported model, we do not have this luxury. The challenge is to perform the most elegant reverse engineering procedure for achieving the same goal.

Notice that I did not write “to fill the cut-outs” but “to remove the cut-outs.” Filling the gaps would add to the model, which would not be real reverse engineering.

Fortunately, SOLIDWORKS is built on the Parasolid kernel, which ensures that most faces in a model behave like pieces of cloth “cut” from a larger patch of fabric. There is magic inside SOLIDWORKS that allows for each face to “untrim” itself up to the original patch from which it was cut. For algebraic faces—planar, cylindrical, conical, spherical, toroidal—SOLIDWORKS can precisely extrapolate the untrimmed result. For the rest, it will be precise until the boundaries of the original patch are reached. After that, it will “guess” the rest of the shape or simply stop in case of singularities.

If you are not yet bored by these explanations and would like to be exposed to more information about topology and geometry inside SOLIDWORKS, I strongly suggest taking a Surface Modeling course.

There were 73 replies to the 8^th Weekly Power-User Challenge on the forum, containing various solutions. When you combine the versatility of SOLIDWORKS with the collective talent in the SOLIDWORKS Community, the results are always astonishing.

Reverse Engineering Features vs Fillers or Bridging Features

It is tempting to use features like Extrude, Sweep, Loft, Boundary or Fill Surface to fill the gaps. Some of them are really good in enabling the user to contain the curvature continuity across multiple faces. The truth is that such features will never recreate the original geometry but only approximate it.

Users who require precision learn how to use pure reverse engineering tools like Delete Face and Patch, Untrim, and Delete Hole.The question is what can be done with only three tools.

Most of the Fillers and the Reverse Engineering Tools can be found in the Surfaces toolbar on the CommandManager (Figure 6).

Figure 6 - Fillers enclosed in blue, Reverse Engineering tools in red.

Solution

In this article I will present a solution that is close to ideal. This user maximized the use of the information contained in the imported model, getting close to a pure Reverse Engineering solution.

In order to reduce the amount of work, it was assumed that the model was symmetrical about the Right Plane. Thus, the user could cut the part in two, work on half of it and later mirror the body to return to the full model.

It is worth noting that SOLIDWORKS has a useful tool for checking the Symmetry, as shown in Figure 7.

Figure 7 - Symmetry Check

In this case, the model is not 100 percent symmetric, but this is the assumption we made.

Step 1 – Delete as Many Cut-outs as Possible on Half of the Model

Simply use the Delete Face feature, with the Patch option checked (Figure 8) to remove the cut-outs on half of the model. The selected faces will disappear. The rest will grow based on their own original patch of fabric until the “holes” are removed.

Figure 8 - Delete Face and Patch

Notice that not all cut-outs could be removed with this feature. It is a great tool for simple topology, mostly for faces that are completely contained inside other faces. As you can see in Figure 9, there are areas where fillets of various radii are interrupted. SOLIDWORKS can untrim those faces but cannot determine where the untrimmed faces should meet in order to create a valid edge between them since there are an infinite number of solutions.

Figure 9 - This model has area with complex topology, where Delete Face cannot patch the cut-outs.

Important Tip

It might be hard to select all faces that are not visible if the Display Style is Shaded or Shaded with Edges. In this case, I recommend using Hidden Line Visible style, in conjunction with the Lasso selection mode (Figure 10). That would enable the selection of all faces, hidden or visible, inside the lasso.

Figure 10 - Lasso selection in HLV mode

After step 1, the model looks like the one in Figure 11:

Figure 11

Step 2 – Remove Half of the Solid Body

There are several ways to achieve this. Since the Right Plane is the Symmetry reference, we will use it as input in a Cut With Surface feature.

Figure 12 - Cut With Surface feature

After step 2, the model looks like the one in Figure 13:

                Figure 13

Step 3 – Delete the Rest of the Cut-Out Faces Located Along the Thickness of the Model.

As shown in Figure 9, there are two complex cut-outs that could not be patched with the Delete Face and Patch feature. It is time to turn the solid body into a surface body by using the Delete Face without the Patch option. In Figure 14, the viewport was split in two in order to show the faces-to-be-deleted from both directions.

Figure 14

After step 3, the model looks like the one in Figure 15:

Figure 15 - Time to do some surfacing.

Step 4 – Remove All Possible Gaps Using the Delete Hole Feature

One of the features that is less documented in SOLIDWORKS is the Delete Hole. It is similar to the Untrim feature with Internal Edges option on but offers more control over which gaps will be removed from a surface.

The most intuitive mode to access it is by pre-selecting one edge for each gap and pressing the Delete key on the keyboard. The gaps containing the selected edges will simply disappear. The surrounding face(s) will grow back based on the original patch of fabric.

Figure 16 – Just press Delete!

After step 4, there are only two gaps remaining in the surface body.

Figure 17 - Two remaining gaps.

At this point, many users would fill the gaps using the Fill surface command. We will continue to attempt to use reverse engineering features to go back in time to the original shape.

Step 5 –Measure the Minimum Radius of Curvature for the Fillets Around the Gaps

The reason the Delete Hole did not work on the remaining gaps is the topological complexity introduced by the fillets intersecting the gaps. In case we would need to remove and re-create them later, we should first measure them. Since the filleted faces are not cylindrical, the only way to measure their minimal radius of curvature is by using the Check tool.

Figure 18 - Make sure to use the Face Filter to target the relevant face.

Repeat this process for all faces that intersect the gaps. Record the measurements.

Step 6 –Isolate the Faces to Be Untrimmed

At this point, we cannot untrim the existing surface body any further. The connections between faces makes any topological change too complex for SOLIDWORKS to handle.

The solution is a divide and conquer method.

For that, we will make a copy of faces that could be untrimmed if they were isolated from the rest. Use the Offset Surface feature, with 0 (zero) offset.

Figure 19 - Zero offset results in copying the faces in new surface bodies.

After step 6, there are two new surface bodies in the model.

Figure 20 - The original surface body has been hidden for clarity.

Step 7 –Isolate the Inner Face of the Big Round

This step is a perfect example of the divide and conquer method. The inner face of the big round needs to be isolated in its own surface body.

Simply add another Offset Surface with zero offset and copy the face from the main body.

Figure 21 - A forth Surface Body is generated.

Step 8 –Delete the Original Faces of the Pocket from the Main Body

Since we will continue the untrimming on the copied faces, it is time to remove the original faces of the pocket. We do not need duplicates.

Figure 22 - A simple Delete Face with no Patch on. The other bodies are hidden in this screenshot.

After Step 8, the model will look like the one shown in Figure 23:

Figure 23 - All faces are unique at this time.

Step 9 – Untrim the “Curvy” Face of the Big Round

It is time to benefit from our work. Since the big curvy face is a one-face surface body, it could be untrimmed with ease. The scope is to extend it until it interferes with the next part of the fillet.

Figure 24 - Learn to love interferences!

Step 10 – Untrim the Left Face of the Big Round

Let’s repeat the process for the face on the left. We will have a nice interference between two separate surface bodies.

Figure 25

Step 11 – Trim the Two Surface Bodies to Generate the New Edge and Knit Them in the Process.

The mutual trim feature is extremely powerful. Not only does it give users complete control over what is preserved and what is removed, but it also automatically knits the remaining faces into one surface body.

Figure 26 - In this case, it is easy to select the big remaining patches for preservation.

After step 11, the model looks like the one shown in Figure 27.

Figure 27 - Divide and conquer works!

Step 12 – Untrim the Bottom Face of the Pocket

Since we isolated this face as its own body, it can be untrimmed. Notice how the resulted face has four edges. Remember the “fabric” or “cloth” analogy? Each piece of fabric is woven from two threads normal to each other. Because of that, the natural shape of the resulted work is rectangular. It is similar in SOLIDWORKS. We call the two threads Face Curves. Take a surfacing course to learn more about them. You cannot be a master of SOLIDWORKS without fully understanding these concepts.

Figure 28 - Notice the four edges of the preview.

Step 12 is ensuring the big purple face is ready to be part of a mutual trimming operation involving the orange round. But first, we need to untrim the round.

Figure 29 - Main body made transparent for clarity.

Step 13 – Extend Some Faces of the Big Round Using the Same Surface Option

This is the first time in which we cannot use a pure reverse engineering tool. Attempting to untrim the big round would not work due to the topology complexity. Instead of that, we will use Untrim’s cousin, the Extend Surface feature, with the Same surface option on.

Even using Extend Surface, only some face of the surface body can be extended.

Figure 30

Step 14 – Recreate the Missing Bits

We are to a point where we need to use fillers in order to fill the missing bits in the round surface. By employing the use of the Tangency to Face conditions, we strive to be as close as possible to the original geometry.

Figure 31 - Boundary employed as the last resort tool. At least we use Tangency conditions...

After adding a second boundary feature for the other missing patch, the result is shown in Figure 32:

Figure 32 - Time to knit the round face.

Step 15 – Knit the Three Surface Bodies of the Round into One Surface Body

Figure 33 - Be sure to "zip" any gap in the new surface body.

After step 15, the round surface body looks like the one shown in Figure 34. Notice the two undesirable edges.

Figure 34 – These edges have to go!

Step 16 – Remove the Two Edges by Using Delete Face with Tangent Fill

Sometimes we must choose between observing the geometry or the topology. As a teaching moment, I chose to attempt to match the topology of the original model. In order to remove the troublesome edges, I will delete all faces containing them. At the same time, I will generate new faces tangent to the original and the geometry around them. A pretty ambitious project is made easy by the Delete Face with Tangent fill feature.

Figure 35 - Edges be gone!

After step 16, the round surface body looks like the one shown in Figure 36.

Figure 36 - Clean faces, no mid-edges.

Step 17 – We Did the dividing, It Is Time to Conquer

At this time, the pocket geometry consists of two separate surface bodies.

Figure 37

We already know how easy is to use the Mutual Trim to join them into a new body.

Figure 38 - Mutual Trim... pure magic!

Step 18 – Recreate the Small Fillet Using the Measurement from Step 5.

Figure 39

At this time, the pocket is completed. It is time to move our attention on the big body.

Figure 40

Step 19 – Untrim the Surface Body by Selecting the Edges on the Right

Figure 41

At this time, it looks like we can knit the two bodies:

Figure 42

Not so fast! There is an interference here:

Figure 43

So, what do we do when the Knit feature does not work?

Step 20 – Mutual Trim, Of Course

I told you that the Mutual Trim feature is magical. Guess what? It can even turn watertight surface bodies into solid bodies.

Figure 44 – When Create solid option is greyed out, it signifies the presence of other gaps that need to be zipped.

Step 21 – Knit the Surfaces, Zip the Gaps and Solidify the Model

Figure 45 - I was right! There were gaps that needed closing! Also, notice the Create solid option being checked.

At this time the model is solid, and the pocket is beautiful.

Figure 46

Figure 47 - Half of the model has been reverse engineered.

Step 22 – Mirror the Solid Body to Complete the Model

Make sure to use the Mirror Bodies option.

Figure 48 - Merge the solids into one solid body.

Job done. Many thanks to the readers who got this far.

Figure 49

Other Solutions Received for this Challenge

Michael Lord has the merit to be the first one submitting a solution. He used the Delete and Patch Face command to eliminate the holes and heal the surrounding faces. That is one of the best tools for reverse engineering in SOLIDWORKS. He used the Fill Surface to close some of the most complex gaps.

Kevin Pymm's first entry also used Fill Surface in one place. He was the first who took advantage of the model's apparent symmetry and saved a lot of time by splitting it in two and working on only half. His subsequent entries avoided the use of the Fill Surface, but they created many little facets in some areas.

Figure 50

Jaja Jojo’s first entry also used Fill Surface.

Roland Schwarz’s first entry proposed a model without holes but also without pockets. The result, an elegant shape, but not the original one.

Paul Salvador submitted several entries that got refined in time. His first acceptable solution was posted June 6 at 12:13 pm. He had good use of Ruled Surface for recreating the original conditions before the fillets were applied. His solution has two more faces than the original model.

Dave Dinius shocked me with his original use of the Move Face command. Initially, it seemed to be a great replacement to the Untrim command. Spectacular! He also helped in revealing bugs in the software. He demonstrated the instability of the Move Face command. Once it is edited (with no change) and rebuilt, several features downstream will fail. Please submit the model to your VAR for getting SOLDIWORKS working on solving this problem. Again, a genial idea that would work well once the software gets repaired. He also graciously provided a detailed play-by-play commentary to his model as a forum message. Thanks for that!

Roland Schwarz’s second submission was a sample of a typical work for a power-user who is not afraid to explore the model by using a sculpting method. Change this, than that… with the ultimate goal to get the job done. He was consequent in using just reverse engineering tools. The end result is a beauty.

I am amazed on how much time he dedicated to this challenge. Take a look at the number of features:

Figure 51

Mark Biasotti’s second entrance is a master’s work of art.

Figure 52

He took advantage of most of the tools available in the surfacing toolbox, including an ingenious use of the Replace Face feature. He was also the first to add comments directly on the features. I love the new Comments Folder introduced in SW 2017!

Figure 53 - Can you imagine how useful having all the designer’s thoughts embedded in the most important features of model could be for your team?

Jaja Jojo submitted a new entry with a fairly small tree. He used Loft and Boundary features for re-creating the fillet, thus adding a certain degree of approximation. To be fair, this is what most users would use in real-life projects.

Steen Winther submitted a beautiful, elegant solution, fully commented. Only 18 features, which could be reduced to 16. He had two extra faces compared to Biasotti's solution.

Figure 54

Krzysztof Wojcik made great use of the Heal Edges command. The result is a great.Read this, if you need more information about this feature: http://www.javelin-tech.com/blog/2012/03/imported-surface-edge-count/

The Winner of the 8^th SWPUC Is Mark Biasotti.

Special mentions to Roland Schwarz, Michael Lord, Dave Dinius and Krzysztof Wojcik.

About the Author

As an Elite AE and Process Improvement Consultant, working for Javelin Technologies, Alin Vargatu is a Problem Hunter and Solver, and an avid contributor to the SOLIDWORKS Community. He has presented 22 times at SOLIDWORKS World and tens of times at SWUG meetings organized by four different user groups in Canada and one in the United States. Alin is also very active on SOLIDWORKS forums, especially on the Surfacing, Mold Design, Sheet Metal, Assembly Modeling and Weldments sub-fora. His blog and YouTube channel are well known in the SOLIDWORKS Community.

If you were to ask what the most important quality of SOLIDWORKS is and expect me to rave about the exceptional ease of use, intuitive interface, rich ecosystem or speed to which I can model most everything with it, my answer could surprise you. Yes, I acknowledge all the above. For me, the biggest advantage, as a SOLIDWORKS user, is being a member of a huge and passionate community of users.

My job title is process improvement consultant for Javelin Technologies in Canada. When I am asked what my job entails, I reply that I am a problem hunter—solutions architect. When a company defines goals for its engineering team like doubling productivity, eliminating errors or reducing repetitive tasks, my role is to hunt for any problem that could prevent them for reaching the goal and then design a custom solution for solving it.

It is true that many problems are similar for most engineering teams, regardless of the type of product they design or industry they serve. For example, large numbers of engineering managers would mention large assembly slowdowns affecting their team. While the symptoms are the same, the causes are, most of the times, unique for each team. Finding these specific causes and tailoring solutions for each customer is art as much as science.

Throughout my years as a hunter, I had the opportunity to add exotic trophies to my collection of challenges experienced by end-users. I found the most interesting ones when the existing SOLIDWORKS functionality could not provide a direct answer to the problem. A new method, technique or workaround had to be designed.

After finding a solution to each problem, I could not refrain from wondering whether an even better solution existed. And, where else could one find brain power capable to solve such challenges other than the place where the best SOLIDWORKS power users are known to congregate? Of course, I am referring to the SOLIDWORKS Forum.

What Are SOLIDWORKS Power-User Challenges (SWPUC)?

… and this is how the idea for SWPUC was born.

Other than having fun solving riddles, the declared goal of SWPUCs has always been to facilitate—through brainstorming—the finding of new techniques and methods for the benefit of the SOLIDWORKS community.

The participants strive to:

• Identify areas where SOLIDWORKS’ functionality needs enhancements.
• Design workarounds to overcome the current lack of functionality.
• Submit new enhancement requests (ERs) or promote existing ERs, relevant to each challenge’s topic

Since May 17. 2017, modeling challenges have been posted on the forum. Each of them received multiple solutions. At the end of each challenge, the users who submitted the best solutions received the title of SOLIDWORKS PowerUser, along with a certificate signed by three peers.

As a side note, the artwork decorating the border of the Power User certificate has a unique story worth its own article. It has been created by one of the top forum contributors, John Stoltzfus, using SOLIDWORKS as the medium.

Sample of a SWPUC certificate.

What Is a SOLIDWORKS Power User?

We asked the winners of the SWPUCs to come up with a definition for a Power User. This is what some of them wrote:

Who Cares about the SWPUCs?

My first answer, somewhat selfishly, would be “my customers.”I actively share any new solution resulted from crowdsourcing on the forum with customers who would benefit from it.

When this question was directed to the forum users, it became clear that the benefits extended to the user community and SOLIDWORKS as a company. Everyone benefits:

• Power Users who participated in the challenges.
• SOLIDWORKS forum participants who find answers to old questions. Most of the problems are relevant to specific groups of users.
• SOLIDWORKS as a company benefits from the limitations identified in the challenges and enhancement requests that are created at the same time.
• The whole SOLIDWORKS community, once SOLIDWORKS implements solutions as per point 4.

This is sample of what users wrote:

The first article in the SWPUC series describes the first challenge and its winning solution.

Challenge 1 – Simulate a “Point Captive on a Face” Mate

A common mating problem in SOLIDWORKS is attempting to limit the movement of a pin in a groove by the physical interactions between the two components.

The blue pin should be allowed to move anywhere in the white space of the groove.

Currently, SOLIDWORKS functionality allows it to simulate the movement of the pin without using a mate. The Physical Dynamics mode in the Move Component command could be use for that.

Physical Dynamics.

The pin should be free inside the groove.

The problem with Physical Dynamics is that it is active only as long the Property Manager for the Move Component command is on. That is not enough for most users’ applications. They want to be able to simulate the movement all the time using mates.

Since there is no volume mate in SOLIDWORKS, the first thing users attempted to do was build a construction face in the yellow part, representing the space where a point on the axis of the blue cylinder could be restrained on. The simplest way to achieve that is by creating a planar surface from an offset contour, with the offset equal to the pin’s radius.

Attempt 1 - Building the "trap."

Back to the assembly, it seems intuitive to believe that applying a coincident mate between a point on the axis of the pin and construction face would solve the problem.

Mate the point on a planar face.

Unfortunately, for algebraic faces, the boundary considered by a Coincident Mate is the full untrimmed surface. For a planar face, that is the whole infinite plane.

The planar limit is infinite in this case.

The good news is that this problem could be easily diagnosticated using the Untrim Surface command.

A simple test: run the Untrim Tool.

The next workaround users tried was deforming the construction face using the Dome, when the face belongs to a solid body, or Freeform feature.

Using Freeform to deform the planar surface.

Unfortunately, the resulting surface is still untrimmable, which would make the point free to move anywhere on the untrimmed surface.

Deforming a planar face would deform its original fabric, without limiting the boundaries to its edges.

If only the deformation would go in one direction only, either above or below the original plane. In that case, we could apply a Limit Mate that would constrain the point on one side of the zero value.

So, what is the solution that works?

It starts with building an untrimmable face. Such a face could be created by using one of the algorithmic type of surfaces which could be produced with tools like Loft or Boundary Surface.

In this example, a plane was created for the purpose of adding a curve to define the new surface.

First step in preparing a non-planar, untrimmable surface.

A simple arc is added, with Pierce relations to the lines of the groove.

The mating face was defined as a boundary surface.

Notice the use of the Selection Manager for defining groups of curves.

Let’s put the new surface to the test using the Untrim feature. This way, it is easy to demonstrate that SOLIDWORS cannot extrapolate the surface any further.

The new surface is not trimmed from a larger fabric.

Returning to the assembly, if we want to ensure the pin does not move up and down on the new construction face, it is worth adding a new construction component.

The origin of the new Link component is mated coincident to the construction surface.

Now, let’s add a second coincident mate to the Link’s origin. This time, we will mate it to the axis of the cylinder.

The final goal has been achieved, A point on the cylinder axis is captive on a surface with edges that are a cylinder radius away from the groove’s faces.

The last step is hiding the construction surface. Once that is done, the cylinder can be dragged anywhere inside the groove. It will never interfere with the yellow plate.

The Pin-in-the-Groove mate has been applied.

Conclusions and Deliverables after the First SWPUC

• • Limitations identified in the current SOLIDWORKS functionality

    • The edges of a face do not represent limits for a Coincident Mate.
    • The underlining (untrimmed) surface is used for defining a Coincident Mate.
    • The underlining surfaces for some algebraic faces do not have limits (planar, cylindrical, conical).

  • SPR Recorded by SOLIDWORKS as a Direct Result of the First SWPUC

SPR 1051495: Add the functionality for Lines and circles to terminate movement of objects mated to them with a coincident mate like the splines

• • The 10^thIdea Voted in the Top Ten at SOLIDWORKS World 2018

Add option to limit Coincident mate to area of face selected for all types of face.

• • Video Demonstration

You can use this link to watch SOLIDWORKS Tutorial: Mating a Free Pin in a Pocket, Real Life Conditions, a video demonstration of this technique.

The Winner of the First SWPUC

John Stoltzfus

Product Development Specialist

Keystone Collections

John Stotzfus has been using SOLIDWORKS since 1997, primarily for Custom Dry Bulk Material Handling Equipment Industry and Custom Fabrication, using Sheet Metal with Assemblies of over 4,000 components.

Since 2014, Stotzfus has used SOLIDWORKS to design custom furniture. For that, he developed an efficient Skeleton Sketch Top Down design approach, which enables changes to be made simply and easily.

Stotzfus is also an accomplished artist who uses SOLIDWORKS to create abstract art.

Stay tuned for the next articles in the SWPUC series, demonstrating more original solutions to “impossible” modeling challenges in SOLIDWORKS.

About the Author

As an Elite AE and Process Improvement Consultant, working for Javelin Technologies, Alin Vargatu is a Problem Hunter and Solver, and an avid contributor to the SOLIDWORKS Community. He has presented 22 times at SOLIDWORKS World and tens of times at SWUG meetings organized by four different user groups in Canada and one in the United States. Alin is also very active on SOLIDWORKS forums, especially on the Surfacing, Mold Design, Sheet Metal, Assembly Modeling and Weldments sub-fora. His blog and YouTube channel are well known in the SOLIDWORKS Community.