Create as-built joints

00:02

Create as-built joints.

00:05

In this video, we’ll create as-built revolute joints.

00:10

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

00:15

The first thing that we're going to do is we're going to create what's called a rigid group.

00:20

To create a ridge a group, we're going to expand our housings and bring back our front cover.

00:24

We're going to select all the components that are going to be stationary,

00:28

keeping in mind that we haven't actually inserted any bearings or other geometry yet.

00:33

But it's important that we understand that only our front housing is currently grounded and everything else is still free to move.

00:40

So if we grab hardware or the back or the front housing or any of the gears, everything is still free to move about,

00:47

and we want to make sure that it stays stationary.

00:50

So in order to do this, we're going to go to assemble and create a rigid group.

00:55

Rigid group is a good way for us to define all the elements of a design that are fixed together.

01:00

In this case, that's going to be our back housing, our front housing, our front cover.

01:06

And it's also going to be our housing mount and all of the different hardware that we're using to bolt the housings together.

01:14

It's important that we remember that we are not going to be including any of the gears in this

01:19

because we need to actually have joints to allow them to rotate.

01:23

So once we've added all of those different rigid groups,

01:26

you can see that now if you grab any of these different elements, they are not moving anywhere.

01:32

Let's select all the hardware, right click and let's Show/Hide.

01:38

We also want to hide the front cover and I'm going to hide the back housing as well.

01:43

The front cover has stayed grounded and that one element is keeping everything else fixed in place with the exception of our gears.

01:51

The gears are going to be in place based on what's called a joint.

01:56

Joints can be applied in two main ways, as an as-built joint which makes use of their current position,

02:03

or as a joint, which makes sure that we select not only the rotation type but also the position of the joint.

02:11

Because we've already used a line for all of our spur gears, we want to use an as-built joint.

02:17

We're going to set the joint type to Revolute and then select the components.

02:22

We're going to start with our 16 tooth spur gear and the front housing.

02:27

Then we need to select the position and then we can say, OK.

02:34

When we rotate around to a front view, now this gear is free to rotate about.

02:39

One thing that I want to do is I want to rotate it so that it's not touching the idler gear.

02:45

I'm going to give it a small gap.

02:47

That small gap is going to be equal to the backlash value that we defined when we created these spur gears.

02:54

If we set that backlash value to zero, then there would be no gap between these gears.

03:00

Now that we've rotated that 19 degrees, we're going to capture its position.

03:06

That's going to be an important step because in order to replicate the gear train motion, we're going to be using what's called a motion link.

03:14

It's not going to take into account any of the geometry of the gear, it's simply going to have a ratio or relationship between the joints.

03:22

Next we're going to go to as-built joint again, continue to use revolute between the first idle gear in the housing.

03:29

We're going to use the center position, say, OK.

03:32

Then we use our right click marking menu to repeat that as-built joint.

03:36

Once again we'll select the idler, the housing and the center of rotation.

03:42

Next I'm going to repeat that using as-built joint this time, we're going to use this idle gear and we'll use the same housing.

03:51

And because that gear is centered in this opening, I can select a circular reference and it'll be fine.

03:58

Note that I'm going to rotate this gear once again making sure that I don't have any overlap.

04:06

You can see that small amount of backlash between the gears.

04:09

Then I'll capture its position.

04:12

Next we're going to rotate around to the back side and we're going to add that as-built revolute joint to the large gear.

04:20

Once again, we're going to go to that same front housing, pick the axis of revolution and say, OK.

04:27

Then one last thing I want to do is rotate that large gear until we don't have any contact and once again capture its position.

04:36

At this point, none of the gears have any relationship with any other gear.

04:41

They only have a rotational relationship with the housing.

04:45

Going to revert that position, and I want to make sure at this point that I save and then I can move on to the next step.