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Archive for June 4th, 2008

What is a block? Well, a block is something I wish my Dynamics of Machinery teacher had used many years ago, while he was trying to explain to us the way different mechanisms were supposed to work.  It would’ve been so much easier to understand with SolidWorks and blocks, but, alas, he had no SolidWorks or blocks, so we had to make do with his dinky drawings on a blackboard and the awkward ways in which he rotated his arms and head, trying to, somehow, use his own body to suggest the movement of the mechanism. Trust me, when you’ve seen a middle-aged man contorting like a four link mechanism, you’ve seen it all! And it isn’t exactly pretty.

In SolidWorks, a block allows you to group together different entities of a sketch, so that they move as one with respect to other entities inside the sketch, while always preserving the dimensions and relations between them. By using sketch relations, blocks can then be connected with other blocks in order to create layouts for assemblies, model 2D mechanisms, and even model pulleys and gears. Blocks can also be saved by themselves, independently of the sketch in which they were created, to use them later in a different sketch. Even better, you can automatically create assemblies from these layouts or mechanisms you create with blocks. In the assemblies created this way, each block is made into a part that contains all the sketch entities that conform that block, and special mates, called LockToSketchMate, are automatically added to keep the sketch geometry constrained to the part geometry. If several blocks were nested into one, then that one block is created as a subassembly and the nested blocks as parts. Neat, huh?

Modeling mechanisms with blocks is really fun and rather easy too, it requires only a little planning and keeping in mind that the entities that are grouped inside a block will not move with respect to each other, but as one with the rest of the block. I’ve included here another one of my DIY movies on working with blocks. I hope it’s a bit clearer than the previous ones!  I think you’ll find working with blocks easy and fun.  If you are a teacher or a student, you may want to try modeling the different 2D mechanisms inside your textbooks to better understand how they work, and if you have a little time, you may even want to create the solid parts for your mechanism, based on your sketches. Have fun!