To Derive or not to Derive my Sketch

I know everyone is probably busy preparing for their annual pilgrimage to SolidWorks World next week so in lieu of me staying put this year in frozen West Michigan I thought I would share a commonly forgotten command I was reminded of the other day while training a few future SolidWorks power users.

The command I am speaking of is the Derived Sketch command.

So lets take a deeper look at what exactly is a Derived Sketch for those who do not know, how we create one and finally a look at a few tips and tricks to consider when using them.

What is a Derived Sketch you ask?
A Derived Sketch is simply a copied sketch that maintains the link to the original. Change the original, the Derived copy changes as well...plain and simple.

How does one create this linked copy of wonder?

Well it's not that difficult but it does require you to select items in the correct order. You must first have both the sketch you are going to copy and the reference plane or face you would like to derive the sketch on selected. Once both items are selected simply go to Insert and choose Derived Sketch and poof - your sketch appears on the plane or face you had selected. The Derived Sketch acts as a single entity and needs to be fully located by adding dimensions or sketch relations.

So How do I Derive when to use such a great SolidWorks command and what other tips can come in handy?

1. This probably sounds like a no brainer but take advantage when you want multiple sketches to stay linked to one another. I'm sure everyone knows that you can copy and paste sketches using traditional windows copy/paste. But I've seen people not realize that method of copying sketches maintains no associative link. Therin lies the need for Derived Sketches.
2. Don't use Derived sketches when the geometry you are creating is condusive to sketch or feature level patterns.
3. Take advantage of reference geometry in the original sketch. You can't add additional geometry into the Derived Sketch so maximize the use of reference geometry in the original and it will come along for the ride in the Derived Sketch. The reference geometry will be useful for locating the Derived Sketch with dimensions and relations.
4. Finally, if you run into a situation where you want to delete a feature that uses the original sketch but keep the feature that uses the Derived Sketch, be aware of what will happen if you attempt to delete that original sketch. SolidWorks will give you a warning message when deleting the original sketch (see the below image). Probably not a big deal to underive the sketch if you only have one derived sketch in a model. But if you've derived multiple sketchs from that original I would probably recommend keeping the original sketch and just hiding it.

Here are a few examples of how you might use the Derived Sketch command in SolidWorks.

Here is an example of Lofted Bowl. The Red Sketches are the original sketches and the Green Sketches are the sketches I Derived from the red. Adjusting the shapes of the red sketches will now automatically update the green ones so my lofted bowl stays symmetric.

Here is an example where I have Derived a sketch (green sketch) onto a different reference plane to create the same mounting plate on each end. Again, advantage is I can change the red plate and have the green now automatically update.

I hope this tidbit of insight into the Derived Sketch command is useful. Enjoy!