Create joints

00:02

Create joints.

00:05

In this video, we’ll create a revolute joint and we’ll create a motion link.

00:11

In Fusion 360, we want to carry on with our gear reduction housing assembly.

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We've created as-built revolute joints for all the gears in our gear train.

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But what would happen if one of the gears was not in the correct position if we hadn't used align and we wanted to still create a joint?

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Well, we can go to the last as-built revolute joint we created,

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and I'm going to select Delete on the keyboard to get rid of that capture position and to get rid of that revolute joint.

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Then I want to move this gear out of position and capture it.

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So if your gear was brought in and it was not in the correct position, you can still create a joint by going to Assemble and selecting Joint.

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Remember as-built joint makes use of the current position of the component.

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A joint will allow you to select the points on multiple components that you want to align.

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This can be done a few different ways.

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Simple will allow us to select a reference point.

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Between two faces will allow us to select two faces and it will automatically go to the middle.

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Or we can select two edge intersection.

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The first thing that I'm going to do is first set my type to revolute.

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And then for the position, I'm going to start by rotating my gear around.

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And similar to how we used align, I'm going to hold down the control or command key and select that center point noting the orientation of X, Y and Z.

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Z being our blue axis.

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Next I need to select where this is going to go.

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Once again, holding down control or command I'll go to the center point of this opening, noting the direction of the Z coordinate system.

01:54

Once it's in position, note that it's automatically set to 0 degrees and offset values here are all set to zero.

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Even though we manually selected those positions, we could still offset them or rotate them if we wanted to.

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You notice that there is a slight amount of overlap here so we can use the on screen manipulator to rotate their position,

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noting that we want to go to about minus 3 degrees.

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And you'll notice that we're getting more overlap.

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So if we go to a positive 3 degrees, we’re starting to go the other way.

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All of our other gears were about 20 degrees off and it looks like this one is still a bit more off than that.

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When we get to 30 degrees, we’re much closer.

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So I'm going to insert a value of 32 degrees to see if that gets us close enough.

02:49

It's going the wrong way, so we can go backwards to 28 degrees.

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If we're having difficulty at this step, we can say OK, and we can manually rotate this around and capture its position as well.

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Now that we have that new joint added, we want to add motion links between our different joints.

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To do that, we'll go to Assemble and we’ll select something called a Motion Link.

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The main motion link that we want is between our 16 tooth and 48 tooth.

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But we're going to work our way through the gear train system, starting with this joint and moving to our first idler.

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What we want to do is we want to remember that we're going based on a ratio of the gear.

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So we're having a 16 degree or 16 tooth rotation and a 10 tooth rotation in the opposite direction.

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Noting that that is just way too much rotation, so let's flip those numbers around, going 10 and 16.

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If we do that, you can see that the relationship is much better.

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We'll repeat that motion link this time going between these two gears, reversing the direction,

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noting that they're both 10 tooth, so they're going to be the same.

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We'll do that one more time between the two idlers.

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You note that those are both 10 tooth, so those are the same.

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And lastly we'll repeat it one more time going between this idler and the large gear.

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This is going to be 10 tooth in and 48 tooth out.

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But again, we might need to reverse those 48 and 10 and reverse their direction.

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So now if we rotate that large gear, you should see that everything is moving as intended.

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For this, let's go back to a home position and save the design before we move on to the next step.