In this lesson, we'll create multiple step roughing passes. After completing this lesson, you'll be able to used 2D contour for roughing and finishing tool paths, analyze the ramp cut versus a lead in cut, and demonstrate how to create finishing tool paths. In Fusion 360 we want to carry on with the design optical pickup finishing. The first thing that I want to do is I'm going to select set up one and note that the coordinate system is located in the bottom. Now for my own personal preferences, I want to rotate this around and then I'm going to use the view cube in the upper corner between the back left and top to reset the position of my home. Then I'm going to use the drop down to set current view is home with fit to view. This means that if I make any adjustments to the position, I can always click that home view. We can also use named views by right clicking on the name view folder and creating a new named view based on how we want to view of part. But right now just simply resetting home is going to give me everything I need. In this lesson, the operation that we're going to do is finish cutting the outside of our part. So we're going to start with a 2D contour. We want to select our tool and in this case we're going to go into our machining three axis cloud library, and select tool number 10, a half inch flat end mill. Then we want to go to our geometry and select the bottom edge of our part. This is going to be cutting the outside of our part using our 2D contour. For our height, the only adjustment I currently want to make is setting a negative value 0.5 for the bottom height offset. Because our coordinate system has Z pointing up, the more down that we go on the part below the bottom of the part, we're using a negative value. So in this case, adding some to the bottom of the height, we need to use a negative value. To machine this part, I'm going to assume that the bottom has already been faced, the four holes have been drilled and tapped, and it's bolted down to a fixture plate. This is going to allow me to control tolerances on the entire part. Now again, we don't have any detailed drawing, we don't have specifications that we need to follow. But as a general rule, I like to try to cut all the geometry, either based off of positions such as the whole positions. Or I like to cut everything from one side whenever possible. Now using a fixture plate and having the bottom faced and drilled and tapped to those specific locations can allow me to control this. Next, we want to move on to our passes. Inside of here we have several different things that we can control such as whether or not we want multiple finishing passes, if we want to use roughing passes or multiple depths. For right now, I'm going to leave everything as default and not turn these options on because I want to generate an operation and then I can make those adjustments. From here I'm going to do a quick simulate just to see what the tool is doing. So it's going all the way down and it's working its way around cutting that contour. Now this is generally not a problem until we get into this rounded corner. So the tool has got a fairly consistent load on the outside of the part, but once we get into this corner we're loading a lot of the tool and this is going to create a lot of chatter, heat, and tool deflection even though we're using a 1/2 inch tool. So I want to make sure that I create some roughing passes and then I use multiple step downs. So first I'm going to turn on a roughing pass, I'm going to set this a bit smaller than 0.475, I'm going to do quarter inch and set one step over. I'm going to to say, okay, and now I've got a roughing pass and a finishing pass. However, it's still going to engage a large amount of material on that corner. The next thing that I can do is I can make adjustments by creating multiple depth cuts. Again, this value is not going to be okay for us. I'm going to use a larger value of a quarter inch and I'm going to say, okay. Now it's going to regenerate this going down a quarter inch and it's repeating that finish pass at each level. These are obviously adding a lot of different steps to this operation. One thing that we can do is make sure that we have our leads on all finishes and that we can finish only at the final depth. We'll say okay, and now we only have that finished pass at the final depth, which does save us a bit of time. Let's go ahead and simulate this before we make any other changes. So now we're still engaging a lot of material in that corner, but we are only doing it at a quarter inch depth. So again, this is not great for the tool simply because what we end up doing is adding a lot of heat to that tool and causing some deflection. One way that we can get around this is by making an adjustment to use a ramp cut. So I'm going to come back and instead of doing multiple depths, I'm going to come back and use a ramp cut. This is going to go down at two degrees with a maximum ramp step of two inches. And then it's going to have a clearance height of 0.1. I'm going to say, okay, and allow it to generate and then let's simulate this operation. So now it's coming down and what it's doing is it's ramping down two degrees while it's making that cut. This means that it's constantly moving its way down, all the way around the part until it gets to the end, then it does it again for the finish cut. Now there are not specific rules in place that say you need to use one option over the other, but notice that when we use multiple depths we can finish only at the bottom. When we take a look at using our ramp, we are going to be using the ramp finishing for the entire thing. One thing that I want to consider when we're using a ramp is to add more roughing passes. So I'm going to add to roughing passes and allow it to calculate this. And once again, I'm just going to do a quick simulation. I'm going to speed this up so that I can go down and now you can see we're taking care of those corners were not engaging as much material. And because we don't have all of those steps along the way, we're actually doing it a little bit quicker. So this is a great way for us to play around with just a single operation, like a 2D contour and see what each of those options does. From here, let's make sure that we do save this before we move on to the next step.
