Machining the Second Placement

This chapter directly follows on from the previous one since we will start right where we left off before. Now that we have completed all the milling operations on the first placement (the first setup), we can focus on the second placement by implementing all the remaining operations that will result in the final shape of the part.

What we are about to do is clearly depicted in the following figure:

Figure 10.1: The second placement

The partially machined stock has now been flipped and installed onto the fixture we mentioned in Chapter 8. With this second placement, we will machine the opposite side of the part. We will now cover every remaining cutting operation one by one.

The goal of this chapter is to introduce more complex operations than those found in Chapter 9, leading you closer and closer to a real case scenario with an ever-increasing level of complexity. We will also try to analyze minor details that may...

Technical requirements

In order to follow this chapter and get the most out of it, you should have read all the previous chapters and have a clear idea of the milling operations introduced in Chapter 6 and Chapter 9.

Since we already covered several ways of calculating the cutting parameters, we won’t focus on how to get them anymore; therefore, you should already be capable of calculating the parameters and choosing the right tool yourself. Of course, it is also possible to simply copy and paste the tools and the values used here.

Face milling

The first milling operation we should set up is, once again, face milling; in this case, we have to remove a layer of 1.5 mm on the top of the stock. We won’t cover this operation here since it is identical to the first one we introduced in Chapter 9; therefore, we may keep using the same tool and the same cutting parameters.

After the first facing, we should find something similar to this:

Figure 10.2: Face milling

As we can see, the diagram displays both the cutting tool and the generated toolpath for the first face milling I implemented. We already know every setting from Chapter 9; therefore, I won’t bother you with a recap of what we did last time. However, this time I changed something in the settings. Let’s try to discover what I changed just by looking at the toolpath:

• First of all, we can find an entry point close to the origin of the coordinate system, highlighted by the red cone pointed downward ...

Implementing a roughing operation using adaptive clearing

Now that we have machined the top of the stock, it is time to move on to a roughing operation on the complex shape of our part. The goal of this operation is to remove most of the material around it and leave just a tiny bit for the next finishing operation.

Long story short, we have to create something similar to a South American pyramid:

Figure 10.3: Steps on the side of our part

As you can see, there are multiple steps all along the sides of the part. The bigger the steps, the faster this roughing operation will be. However, please remember that a finishing operation is not capable of removing much material; therefore, we should find some sort of sweet spot between optimizing the roughing passes and the finishing passes. For this operation, we will aim for each step to be 2 mm.

Before starting with the command and settings, we should ask ourselves what the best tool to pick is and whether...

Milling a hole

It is now time to implement a machining strategy for the big hole at the center of our part. It’s quite a big feature since it is a pilot hole for an M36x4 thread with a diameter of 32 mm. With such a diameter, it is impossible to use a drill bit; therefore, we have to create a milling operation instead.

In order to reduce tool changes, we are going to use the same tool already used for the previous operation. This type of tool is suitable for many different milling operations. There are multiple commands inside Fusion 360 to mill a hole; for example, we may go for another Adaptive Clearing operation.

However, I want to introduce you to as many commands as possible; therefore, we are going to use a command that we can find in the 2D Operations set called Bore. This command is specifically used for machining cylindrical or conical features and is perfect for our case:

Figure 10.13: Bore

Once launched, you’ll see a familiar...

Finishing the part using a morphed spiral

As we saw in Figure 10.5, there are several options for finishing, some of which have many traits in common and are sometimes even interchangeable. The idea behind them all is to implement multiple cutting passes very close to each other. The smaller the distance between these cutting passes, the better the overall surface finish.

For our example, I think that one of the best operations we can pick is Morphed Spiral. This command creates an adaptive path all around the part and is capable of machining complex shapes with steep surfaces.

As usual, before launching the command, we have to choose the right tool to use. When finishing a complex 3D contour (like in our example), a ball nose end mill is one of the best possible options. However, this type of tool would be a bad choice for us, given our shape and our three-axis machine. The reason is pretty simple: our part has flat surfaces!

As you can see in the following diagram, on the...

Thread milling

The last operation we have left to complete the part is threading the central hole with an M36x4 profile.

During the previous operation (in the Milling a hole section), we already machined the pilot hole, which has a diameter of 31.97 mm.

We should also already know the theory behind threads since we already covered a similar operation in Chapter 5; however, this time we’ll cover the process in a bit more detail and try to explain a few potential issues we didn’t mention before.

Thread geometry

In order to machine threads, we have to know them! To find all the information needed for our thread, we can discover ISO thread tables online.

When searching the web for thread tables, we have to make sure that we are looking at the right type of thread. Internal and external threads have different dimensions, and confusing one for the other will result in a wrong thread profile.

In the following table, we can find the data for an M36x4 internal...

Summary

Congratulations, we have now finished the section on milling! I’m sure that we had a good time together creating our machining strategies from scratch.

In this chapter, we faced several advanced milling strategies: we used one of the best milling operations that Fusion 360 has to offer, which is Adaptive Clearing, then we found out why it is important to find a sweet spot between roughing passes and finishing passes, and how tweaking retract movements or milling direction can increase productivity.

After that, we took quite a deep dive into thread milling, where we tried to uncover every possible parameter needed for proper machining and we found out how to check whether the selected tool was up to the task.

This was probably the most difficult chapter to understand due to the geometries and the challenges proposed; however, I promise you that the hardest part is now over.

It is now time to leave milling behind and finally move on to a new manufacturing technology...