Join John Helfen for an in-depth discussion in this video The Mate/Flush constraint, part of Inventor 2014 Essential Training.
Now that we know how to place parts into an assembly file, we can look at how to connect those parts together using constraints. Constraints are essentially rules within the assembly file, that tell a part where it's positioned, and how it can and cannot move. On the screen you see the universal joint assembly I created, and you first saw it when I first introduced assemblies. Since then, I've made a minor modification. Rather than listing all the parts individually in a single assembly file, I went ahead and created a universal shaft assembly, that is made up of three components.
If you click the plus symbol next to the assembly in the browser, you can see that this assembly is made up of a joint, a second joint. And you can see I'm highlighting in the graphics window when I hover over it. And finally a connecting rod. So it's essentially these three components, here in this center of the assembly. I've also created a universal shaft start assembly, that we can use to begin testing these assembly constraints. In this video, we're going to be focusing on the make constraint. It's the most commonly used constraint.
And it's also the default option. So we'll start there. To access the constraints, you could right-click in the graphics window, and select Constraint from the Marking menu. Or, you can go to the Assemble tab, under the Relationship panel, and select Constraint. I'm going to right-click and select Constraint from the Marking menu. This brings up a Place Constraint dialogue box. It's made up of a few different sections, a type, the selections, the offset, and the solution. In the type section, mate is selected by default. There's also ability go create angle, tangent, insert and symmetry constraints.
We won't cover all of those, but we will cover the most essential ones. Next you have the selection. The selection section just simply allows you to understand what is selected and what isn't. And, it helps you understand that every constraint is going to be made up of two different components, or two different parts that are being connected together. The offset, allows you to set a distance between, for example, two faces that might be touching each other. Below that, you have a preview option, which is checked by default, which allows you to see what the result of your input is going to be.
Next to that, you have an option to predict the offset, and the orientation of a part. Which essentially measures the distance between two parts. And automatically sets the offset distance. And then finally, you have the solution option. Each constraint is going to have multiple options for solution. In this case, mate when two faces are touching each other. Provides a mate solution. The opposite of that is a flush constraint, where the two phases are facing in the same direction, but are in line with each other. As we begin, its important to understand that each solution is going to have different selection capabilities.
Depending on the specific need of that constraint. Right now, we're in the mate solution. And when hover over parts within the graphics window, let's zoom in so we can see it a little more clearly. If we hover over specific components, you'll notice that when I hover over the connecting rod, I get the center axis. If I hover over the face on the end, I can select the entire face. If I select on the circular edge, I'll get the center point of that circle. Or, if I select any straight edge, or hover over any straight edge, you'll see that I can also select edges.
That's different than what you get when you're in a flush constraint. In the flush solution, you only have the ability to select faces, because that's the only thing that you can make flush. We're going to go ahead and focus on the mate solution first. If we select the face on the end of the connecting rod, and the face on the inside of the joint, you'll notice that the preview shows that both faces are touching, and it moves the part into that position. It also automatically moves us into the offset value, so that if we wanted to say this was offset by, for example, by 0.125, you'll notice that if we rotate, you can see that the face is offset from each other, by 0.125 inches.
If we set this back to zero. You'll notice that it updates so that those faces are touching each other. What you'll see here, is we're in the mate solution as I mentioned earlier. The flush, is essentially just an opposite of that. By selecting that, you can see that both arrows are facing in the same direction. Whereas the mate, as you can see from the icon, points in the same direction. And it's just a toggle to switch back and forth between those. So, even though I started with a mate solution, I converted to a flush solution, and the reason for that is, I actually want this to be flush with this face, but the next constraint I add.
Will center the axis through the connecting rod, to the axis through this hole. Now that I have the part in position like I need it, I'm going to go ahead and apply that constraint. I can either right-click and select apply, from the marking menu, or I can select apply from the dialogue box. Once you get the hang of adding constraints, I think you'll find that. A right-click and drag up. To apply the constraint, will allow you to move along very quickly. But, any option is perfectly acceptable depending on what is comfortable to you.
Now that we have that constraint applied, we are in a position to continue applying new constraints. And in this case, I want to apply a mate constraint between the axis of this connecting rod, and the access of the hole. To do this, I'll return to my Mate solution, and I'll hover over the connecting rod to highlight its axis. With it highlighted, if you left-click. It'll turn blue and select that axis. You'll notice that in the dialog box, the selection one has been made.
You can see that the icon is white now, or the arrow is white. You can see that the arrow is white. And we've been moved to selection item two, and it's still red, indicating that some additional selection needs to be made. To do this, I'm going to zoom in a little bit, and I'm going to hover over the hole, that we want this connecting rod to run through. By hovering over the hole, I can highlight its axis, and then left-click to select it. You can see that it's aligned, and if I hit OK.
The dialog gets closed, and the assembly constraints are added. The way you can tell if they've been added, is by simply clicking and dragging on parts. It might be a little hard to see here. But by clicking on this, I can actually rotate this connecting rod, within the hole. You can also tell by moving to the browser, and expanding the part. By clicking the plus symbol next to it. In this case, the connecting rod has a flush constraint. You can, if you hover over it in the browser you can see the two faces highlight in the graphics window.
Or, by hovering over the mate, you can see that the axis of the connecting rod and the axis of the hole are aligned. The next option is to attach this joint to the opposite end, and we're going to do the same process one more time, to make sure everybody understands how exactly to connect these components. This time, we'll right-click and select Constraint from the Marking menu. We'll select the inner face of the joint. And, I'm going to select the end of the connecting rod. Now, you'll notice the face that I want to select, is on the other side of this component.
I could rotate the part, and select the face by rotating it. But I do want to call out another option that comes in very handy, more handy when there's more parts, but I do want to call it out and show it here. And that's the ability to select faces or components, through the part. With my mouse hovered over the spot, where I could select the axis or. Behind it select the face, and that will allow you to cycle through those options and select the face you want, without having to rotate the model. Again, I'm in the Mate solution, so the two faces are now touching.
Which is almost what I want. I want those two faces aligned with each other rather than touching, and that's the flush solution. By selecting the Flush solution. You can see that the model is flipped over. And, if I rotate this into position, you can see that the end of the connecting rod face, is in line with the face of the joint that we want connected. I'm going to go ahead and click Apply in the dialog box. And, I'm now ready to add my next constraint. I'm going to set the solution to Mate.
I'm going to select the connecting rod which will select its axis that runs through it. And, I'll hover over the center of this hole, and select its axis as well. I'm going to go ahead and select OK to apply those constraints, and exit the dialogue box. And then I'll select the hole button on the view cube. This will return us to a home view where we can see the entire part. And, you'll notice that my parts are aligned and connected in the way you might expect. The one item that will, I do want to call out before we move on, because we'll cover this in the next video, is the fact that if I click and drag on this part, you'll notice that it can still rotate, and that's because we haven't applied an angle constraint to it.
We can align these faces, by using an angle constraint, and we'll cover that soon.
The course was created and produced by John Helfen. We're honored to host this training in our library.
- Customizing Inventor's menus
- Drawing rectangles, arcs, splines, and slots
- Moving, copying, and rotating geometry
- Trimming, splitting, scaling, and stretching geometry
- Creating work planes
- Projecting and importing geometry
- Creating extrusions, revolves, sweeps, and lofts
- Adding holes to a part model
- Creating rectangular feature patterns
- Creating iParts and iFeatures
- Using constraints to position parts
- Creating drawing views
- Setting dimensions