SOLIDWORKS Mate Best Practice #3: Don’t fight with your Mates

Article by Jim Peltier, CSWE updated May 16, 2013


Welcome back, fellow SOLIDWORKS users for another installment of our SOLIDWORKS Mate Best Practice series.

In the classic Star Trek episode “Amok Time,” Kirk and Spock fight to the death over a mate. Luckily, in SOLIDWORKS, you don’t have to. In fact, you outright shouldn’t. If you try to insert a mate that isn’t going to work, SOLIDWORKS has certain safeguards in place to prevent you from accidentally inserting it. Of course, if your green blood is boiling like Mr. Spock’s, you can choose to fight for the mate, but you can find yourself in a lot of trouble really fast as you’ll see in Rule #3: Don’t fight with your Mates where I fight for a mate and quickly find myself fighting with a lot of other mates:

That subtle tool is pretty handy for finding the mates that are fighting. Now, I didn’t mention it, but when I had that list open, all parts that didn’t have any mates with errors became hidden. This makes it easier to see the problem if you have a shorter chain of parts with errors in a big assembly that’s mostly fine.

You may also be asking yourself why there were so many errors. I mean, it’s obvious to you and I where the problem is, but to SOLIDWORKS it’s not so straightforward because it’s looking at the bigger picture. In my table example, the faces I’ve selected can’t be perpendicular because the middle bar’s orientation is driven by a distance mate to the foot, which is mated concentric to a hole inside the leg, which is mated coincident to the top bar that I was trying to use for my bad mate (and the leg bone’s connected to the hip bone…). If you get stuck in an instance where you can’t “just delete the red one” (a solution that also works in Star Trek), then you can reason your way through the chain of mates until you find what needs to go. It’s still easier than going through the tree and viewing the mates with Dynamic Highlight.

A second tip for today that is somewhat related: don’t just use the default mate that comes up because your deadline is fast approaching. Use the right mate for the job. Don’t use coincident when parallel will do the trick. Otherwise you’ll find yourself fighting mates later on.

If you had a really keen eye, you may have noticed that my table has leveling feet, and since I mentioned that I used a concentric mate for these, you can reason that these should spin freely, which means I shouldn’t have had a “Fully Defined” assembly. I actually broke my next Rule #4: Don’t Mate too Much.

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Jim Peltier, CSWE

Jim has been using SolidWorks since 2001, and has spent most of that time working in the design of industrial automated manufacturing equipment. He has been working as an Applications Expert at Javelin Technologies in Oakville, Ontario since July 2012 and is a Certified SolidWorks Expert (CSWE).