Discovering More Turning Strategies

In this chapter, we will review the most important turning operations available in Fusion 360, in order to implement all the machining needed to complete a somewhat complex design with several different features to be machined. The part we are about to use as an example may look not so difficult, but actually, it hides several challenges to overcome.

Studying this chapter is very important, as we will introduce several new turning operations, which should enable us to machine 99% of the parts we encounter.

In this chapter, we will cover the following topics:

• Turning Profile (Roughing)
• Turning Profile (Finishing)
• Turning Threads
• Drilling
• Turning Groove
• Turning Part

Technical requirements

The main requirement is you need to have read and, for the most part, understood all the previous chapters since we won’t explain subjects that we have already dealt with.

Also, as before, we are going to use Sandvik CoroPlus to evaluate the cutting parameters and speed up the process; however, CoroPlus is not strictly needed; for the following pages, you can simply copy the same cutting parameters used in the book.

In this chapter, we will continue with the work we did in Chapter 4; therefore, you should have the same setup ready with the facing operation already set.

We will machine the following features out of a stock with a diameter of 55 mm to complete the example part. In the following diagram, you will find all the dimensions you need to define every geometry detail necessary inside the design environment:

Figure 5.1: Part dimensions

From the diagram, we can spot quite a complex geometry. There is a diameter...

Turning Profile (Roughing)

After the first facing operation we implemented in Chapter 4, we should start by setting up a roughing operation to remove most of the material from the stock. One of the best commands for roughing our part is called Turning Profile Roughing and can be found among all the other turning commands:

Figure 5.2: Turning Profile Roughing

This turning operation will generate longitudinal passes, and it is useful to use when removing high amounts of material with powerful tools operating at a high cutting power. Before clicking on the command icon, we will choose the cutting tool we plan to use.

For this roughing operation, I decided to use the following ISO-coded insert: CNMG160616.

Note

Why did I choose to use this tool (CNMG160616)? Because it is good for both roughing and finishing, and most importantly, it doesn’t have accessibility issues like the round insert we used for facing.

The insert will be installed...

Turning Profile (Finishing)

After we have implemented the first roughing operation, it is a good idea to set a final finishing pass to remove only a tiny bit of material and achieve a good surface quality.

Fusion 360 comes with a handy operation called Turning Profile Finishing, which we can find among all the other turning operations in Figure 5.2:

This is a contouring operation that will generate a toolpath parallel to the part profile. Before launching the command, we should know which type of tool we plan to use and which cutting settings will allow us to have the target surface quality we want.

For this operation, we can still use the same tool and shank used in the previous operation. The insert (CNMG160616) can be used both for roughing and for finishing, in fact. Once again, we will let CoroPlus calculate the optimal cutting parameters for the insert and simply copy and paste them. Let’s now launch the command!

The Tool tab

As we should already know, inside...

Turning Threads

In this section, we are about to discover how to machine threads with our lathe, but before jumping directly into the turning command that allows us to machine threads, we need to recap thread theory and check our thread specifications.

As you may recall, our example part features a thread starting from the front face. The first thing we will do is check the thread specifications. The thread we have to machine is an M42x4.5, a standard ISO thread with a coarse pitch.

All ISO screw threads are ruled by the following diagram:

Figure 5.13: ISO thread

Now that we can check the thread drawing, we can explain the parameters we can spot inside the diagram:

• P: This is the thread pitch. For a coarse M42, the pitch is 4.5 mm.
• Dmax: This is the screw’s maximum outer diameter. For an M42, this value must be between 41.937 mm and 41.437 mm.
• H: This is the thread height measured between sharp corners:

...

Drilling

We haven’t mentioned this yet, but a lathe is also capable of drilling. When drilling with a lathe, the drill bit doesn’t spin; it simply moves against the stock, and it is the part that is spinning.

There is one limitation, though: since we use the chuck rotation to remove material, the hole axis must be coincident with the rotation axis. There is no workaround to this limitation; it is the way drilling works with a typical lathe. If our part features multiple holes, we may need to use a milling operation after processing the stock on our lathe.

Another option would be a multi-spindle machine that can perform both milling and turning operations.

In the following pages, we are about to find out how to set up a simple drilling operation. Please note that there is not a dedicated drilling command for turning; the same command can be used when setting up both turning and milling operations. This is the reason why we will encounter few options inside the...

Turning Groove

In our part, there is a circlip groove that we still have to machine. As we can spot in Figure 5.2, there are two different types of grooving strategies we can use: Turning Single Groove and Turning Groove.

What is the difference between the two? With Turning Single Groove, we can specify an edge where we want to perform a groove. And that’s it; almost no other option is available. On the other hand, Turning Groove is a much more powerful command; not only can it be used for groove cutting, but it can also be used as a roughing strategy instead of typical longitudinal machining.

Before starting the command, we already know the tool we have to use and its cutting parameters. The tool we are about to use is coded as: N123T3-0150-0000-GS-1125, which is a specific tool for grooving. For additional information on this tool, you can find the datasheet at the following link: https://www.sandvik.coromant.com/en-gb/products/pages/productdetails.aspx?c=n123t3-0150...

Turning Part

Turning Part is a command that allows us to detach our part from the stock cutting it. As you may imagine, cutting a part from the stock is typically the final operation to perform when turning a part. This type of operation is somewhat similar to grooving, with two major differences:

• When cutting, the cut width is not driven by the geometry of the part. We can cut whatever width we prefer. Of course, a higher cutting width means more material wasted and higher cutting power needed. Whereas, on the other hand, a super slim and super sharp cutting tool will cost more money and will wear in a shorter amount of time. Therefore, we should always aim at a trade-off between the material and the tool cost.
• When parting, our tool needs to plunge inside the stock, up until the rotation axis; therefore, cutting tools are usually longer and slimmer.

For the following example, we will need these two links:

• This is the link for the shank: https://www.sandvik...

Summary

Congratulations! You completed the section related to turning. As you may already know, we didn’t really cover every single command or option available, but we can definitely say that you now know a major part of the CAM module.

As a quick recap, first, we learned how to set up roughing passes to shape our geometry with longitudinal operations. Next, we discovered how to set finishing passes with a contouring strategy.

After that, we discovered how to create a thread and how to drill a hole inside the part. And finally, we reviewed how to create a groove and how to cut the part. With all these operations in mind, we should be ready to set toolpaths for almost every shape machinable with our lathe.

It is now time to move forward from turning and start talking about milling. As we will discover, most of the key concepts will be almost identical, so we can say that the effort spent up until now will earn you a lot of additional knowledge!