solidworks-hitman.jpgI love errors. Those kinds that riddle a FeatureManager Tree with red like the list of a persistent hitman with refined and distinguished taste. Errors can be a disgustingly vicious act and a lovely dinner all tied up together.

Errors force a solution
Or rather, errors force determining a solution. The hitman’s hitman to keep that cool analogy steaming along.

You have to figure out what happened, where it happened and how to prevent or get around it undetected. It’s when your senses are honed and you learn the most.

You could say there’s two laws to follow. One by reduction, one by creation. Kill.

Part 1: The Laws of Reduction

There’s no doubt that by reducing involvement you will avoid certain doom, but when your hand is forced there’s a deliberate approach to take in solving the headaches of multiple errors. In the next model you open you can reduce errors immediately with the following approach.

Reduce Relations
You’ll be adding these either by dimensions, automatically or setting your own. It’s good practice to fully-define sketches, but often there are some that can be eliminated. When you make something collinear, a horizontal relation will be redundant. If a perpendicular relation is used, horizontal and vertical relation become redundant.

If you are working top down you can convert the edges of a rectangular shape that gives you four relations, or you can draw a rectangle that is locked to one corner and the other corner giving you two relations.

It may not seem to matter at first, but when design changes, fixing this becomes crucial.

One concept I use is creating sets of simple rectangles that more complicated sketches are locked to. It’s easier to adjust the rectangle than mess with the complicated pieces.

Reduce mates
This may seem odd since you need a minimum amount of mates to fully-define the location of a component and anything more over-defines it. In some cases I would recommend eliminating mates by creating parts in assemblies and working top-down. (2008 gets rid of the InPlace Mate and fixes the part right away. hoorah.)

If you’re going bottom-up, make an effort to avoid parallel and perpendicular mates as well as mates to a point (vertex) unless you know you definitely need that.

A better way to state this would be to reduce mates to geometry that could change. Right away the three default planes become the best bet to build your model around while skillfully using symmetry and forethought to gain an advantage over future changes.

Reduce People
Take out the right people and the target is much clearer. Better yet, use the right person and the other people are not even a blur in the periphery. I have often times used a spectacular SolidWorks user to set-up each model. This provides consistency and that person can train someone else to strengthen the foundation of the group. Then, they are both creating consistent models to start with as the group grows.

You can start this now, even if you’ve been developing models for a while. Most likely, you or someone in your group is a key person that knows their stuff. Use the following law to make it happen.

Part 2: The Laws of Creation
I put this second, but makes the first even more potent. 3D models can reduce product development time, but there’s always some efficiency lost in processes left undefined. Deadly force in the right spot is the trick. These three can provide that delicate precision.

Create a Process
I bet you never would have thought of this one. Very profound huh? A lot goes into creating a process, but a lot less goes into updating a process.

I would go as far to suggest setting up monthly or weekly tech updates so those involved in the CAD environment have the most current information on new features in software that can be used, processes that can be updated and hardware that can help the company grow. These are also a fun way to get suggestions from uses that are involved in manufacturing, documentation or planning.

Create a Log
Most PDM software keeps a log of check-in/check-out activity. If you can pinpoint a time and day something was changed, you can reduce the time it takes to fix it. I keep daily server back-ups. If a model becomes corrupt or someone has made serious changes that have cause errors, the log can be opened to find when the change occurred and the problem alleviated.

Create a Model Checklist
Every good hitman keeps a checklist. You have to keep the killing separate from the groceries. Creating a checklist is crucial for consistent results in a multi-user environment and even if you work on your own. Here’s a simple example of a checklist for a Standard Installation.

Most likely your’s would be different, but you get the idea. Moreover, this would be a definite must for new users or new employees to adjust to how your group maintains certain aspects of a design philosophy.

There’s nothing in SolidWorks that controls these aspects of modeling. You’ve had to figure out things yourself I bet, which is hard way of learning it. Are these kinds of ‘laws’ actually necessary? Or is it easier to just go at it and deal with wounds you get from mistakes?


Josh is founder and editor at, founder at Aimsift Inc., and co-founder of EvD Media. He is involved in engineering, design, visualization, the technology making it happen, and the content developed around it. He is a SolidWorks Certified Professional and excels at falling awkwardly.