So I need to design a mechanism (image below) but I don’t have all the information I need to complete the design. Take the slot for example, I don’t know the location and the length of it but I have a good idea the size and location of everything else. In the end I also want to experiment with the diameter of the crank and the link length without having to redo a bunch of stuff. Ever had a design challenge like this?
If so your not alone and I hope this post can help you out a bit. I am gong to introduce Top-down design and how you can do this in Fusion 360 today. What is Top-down design you ask? Top-Down Design allows you to create and update one or more components through a sketch.
That’s right, you can create a sketch and create multiple components from that one sketch. So what happened to all the components if I change the size of the sketch? Lets jump into a simple example and find out!!
Create a sketch that has enough information to build the components you need. Be sure to add the necessary dimensions that you might want to edit later to update your model (don’t worry you can add more detail and dimensions as you go along).
Extrude the various profiles to create each component in your design.
With all the components created, we can add joints to test out the mechanism. I use “as built” joint to make assembling much easier (I’m lazy like that).
Now comes the fun part, we need to add a slot for the pin to ride in. To do this we use the Combine tool to cut a void where the pin intersect the back plate. In this case I will check “Keep Tools” to keep the pin around.
Now I can drag the crank around so the pin is in the closest position to the crank. Once in the position I want, I will place another snapshot and use the combine tool again to create another hole in in the back plate.
Now I need to connect the the two holes to make the slot. To do this I will create a sketch on the same back face and draw a line top and bottom to connect the holes. I can then extrude cut the the slot.
Now I can give it a whirl by animating the joint to see if everything works as I had expected.
Changes happen!! Since we did this all from a single sketch I can make edits to some of the dimensions and see everything update…almost like magic.
You can use this same workflow and even use multiple sketches to drive various parts. In the image below I used a front and side sketch to make all the internals of this bike light that I could easily change light quantity, light size, battery quantity and battery size. It will update the battery holder, lens, lights, switch location and more. This is a fantastic way to set up your designs to ensure they will update quickly and predictably.