Create draft during a feature

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Create draft during a feature.

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In this video, we’ll create an extrude with tapered walls.

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In Fusion 360, we want to get started with the supplied dataset drafted spur gear.

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We're going to start by activating the component and taking a look at the timeline.

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We have an initial extrude followed by a second extrude, a fillet, a pattern,

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and then we have some additional features that add more detail to the part.

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We're going to start by rolling back after that first extrude and taking a look at what we have.

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This is going to be the base of the part and if we take a look at the extrude, we can right click and edit the feature,

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and we can modify the taper angle by adding a draft.

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We're going to do this by first using minus and there's already a parameter in here called gear draft.

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We're going to set it to gear draft and say, OK.

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Now if we roll the timeline past that, you'll notice that we begin to have a problem with the tooth.

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And this is because we're drafting up in the Z direction, making the part smaller as it gets taller.

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What this means is that the extrude for that tooth is no longer in the right location.

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We would either need to modify the original sketch used to create that feature or we can modify the draft on that original feature.

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And instead of making it a negative value, we can make it a positive value.

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It's important to understand the implications that changing the draft angle will have.

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It's going to affect the way that the part is manufactured.

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So it's important to have a good clear understanding of how the part is going to be made,

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before you make decisions like which direction you're drafting.

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Let's go ahead and let's modify the second feature.

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And this one for the draft, we're going to begin to use G for gear draft and notice that it’s drafting outward.

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This means that the sketch profile at the bottom is growing as it goes up in the positive Z direction.

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This means that we no longer have that small gap here because the geometry is actually going further into the cylinder.

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We're going to say, OK.

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And now we can roll past the fillet because that won't be affected by the draft and the pattern because we're patterning that feature.

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So all of these elements now have created draft as we're going in the minus Z direction, the part is getting smaller.

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When we're talking about draft on things like gears,

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it's also extremely important to understand how they're going to affect their mechanical properties.

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If we go to Modify and change parameters and take a look at the user parameter for gear draft, you can see that we're using half of degree.

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Half a degree is a very small draft angle.

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But when we're talking about draft, there are some general rules to follow.

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It's always important that you check with whichever manufacturing facility you'll be working with,

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to understand what their limitations are on the manufacturing side and what the requirements are for draft angles.

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Generally for smaller parts that have consistent wall thickness, you can shoot for anywhere between a half a degree to one degree draft.

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The taller the part gets generally, if it's five times the height of the wall thickness, we need to go up a bit more to say 2 to 3 degrees of draft.

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And if you have something like a texture on the outside of a part, generally that's going to require somewhere in the range of 3 to 5 degrees.

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So once again, it's important to understand the final aspects of the design and how they're going to affect these decisions.

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From here, let's go to our Revolve and notice that the Revolve is removing material.

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So this can be changed by modifying the sketch or by using a tool that allows us to add draft.

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In this case, we're not going to be looking at the draft tool just yet.

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Let's roll all the way to the end and take a look at our results.

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You can see that that other Revolve added more geometry to the outside of the part,

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and it also has a small chamfer that's been applied to those corners.

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What we want to do from here is we want to inspect the model.

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We know that we've added draft to the gears themselves.

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So if we take a look at this from the top side and we zoom in,

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you'll notice that we can't see any of the underlying geometry because we drafted outward.

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If we rotate this around and view it from the bottom and we zoom in, we can actually see the walls because they're tapering outward.

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Even that that half of degree we’re able to see those walls knowing that we do have draft.

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There are some inspection tools that we can use.

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Under Inspect, we can take a look at draft analysis.

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We can select the body, we can select the direction.

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In our case, it's going to be the XY plane.

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And we can set our values.

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In our case, since we used half a degree,

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we're going to go from minus half a degree to positive half a degree and we're going to turn off the tolerance zone.

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This allows us to see the areas that have minus half a degree or positive half a degree draft.

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Anything that's green is going to be okay.

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Anything that we have in this region where we see red doesn't have enough draft on it.

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Now there is generally going to be a very specific amount of draft that works.

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And when we change this to high quality, you'll notice that the color banding changes a little bit.

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But in general if we change this to say 0.45 and minus 0.45, you'll notice that now all of those sides of the gears have turned to blue,

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meaning that they have enough draft.

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So if you're looking for exactly half of degree,

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then you need to sometimes reduce that draft angle value to make sure that you're analyzing everything that you need to see.

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And going to, let's say 0.49 is usually enough, or you can include that tolerance zone,

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which will change the way that the colorization happens on the model.

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For this example, let's turn off the draft analysis, go back to a home view and let's save the design before moving on.