Chapter 10: Knowledge Check

Check Your Knowledge: Chapter 10

Quiz yourself using the following chapter review questions to check how well you can recall the material.

Review Questions

1. True or false: Because a lathe doesn’t have rotating cutting tools, it is much safer than machinery like drill presses and milling machines.
2. Use the correct term to complete the sentence. The __________  is the main structural component of the lathe and contains the precision ways of the machine.
3. This is one of the most common work holding devices mounted to the lathe because of its ease of use.
   1. Face plate
   2. Lathe dog
   3. Four jaw chuck
   4. Three jaw chuck
4. This is the most common cutting tool material for turning tools.
   1. Diamond
   2. Ceramic
   3. High speed steel
   4. Carbide
5. How far across should the operator face the part?
6. How many cuts should be taken to bring a part to finished diameter?
7. How far should the boring bar stick out past the tool holder when setting up a boring operation?
8. How should a taper turning operation be set up when attempting to cut a taper of tight tolerance?
9. What is the easiest way to create an accurate radius on a manual lathe?
10. How is the tool touched off when cutting a chamfer?
11. How should a grooving tool be fed into the work when cutting a groove?
12. What is the primary way a threading tool should be incrementally set, at the beginning of each pass, when cutting a thread?
13. How is the tap held straight while power tapping?
14. What type of operation is knurling?
15. How far should a part off blade stick out from the tool holder?

Answer Key

1. False – Nice work! Lathes are often the most powerful machines in a machine shop and require the utmost respect.
2. bed – Nice work! The bed is the main structural component of the lathe. It runs horizontally, and most other components are attached to it. The bed contains the ways of the machine.
3. Three jaw chuck – Correct! A chuck is a work holding device mounted to the spindle nose of the lathe. One of the most common is the three jaw chuck because of its ease of use.
4. Carbide – Correct! Turning tools can be made of many different materials; high speed steel (HSS), cobalt, brazed carbide, cermet, diamond, and ceramic are a few. However, the most common in the machining industry is the carbide indexable insert.
5. The part should be faced to the middle and no further.
   If a facing cut is attempted past the middle of the part, the material will be revolving backwards against the cutting tool, no longer removing material.
6. Turning is generally performed with multiple roughing cuts and at least one finishing cut.
   The roughing cuts are used to remove material at the quickest metal removal rate the job will allow, and the finish cuts are to achieve dimensional accuracy and better surface finish.
7. The boring bar should stick out slightly further than the depth required for the bored hole. Approximately 1/8 “
   The length and diameter of the boring bar are critical considerations when setting up for a boring operation. Boring is generally more unstable than other turning operations and the operator must make a conscious effort to optimize the setup to help reduce the chance of chatter.
8. A taper turning operation of tight tolerance should be set up using a drop indicator and trigonometry.
   All three methods of taper turning, tailstock offset, taper attachment, and compound rest, can be roughly set and machined to general increments. However, if tight tolerances are required, the graduations on the equipment are not accurate enough and more precise means are necessary.
9. A form tool is the easiest method for creating accurate radii on manual lathes.
   A form tool only requires the machinist to plunge it into the work in the specific position in order to create the proper shape.
10. While the carriage is locked, the compound rest is moved side to side while at the same time slowly moving in on the cross slide until the tip of the tool just touches the corner of the part.
    Gently touching off the tool in this method will allow the operator to establish a zero point on the cross slide. Chamfers are generally called out in a linear distance that can then be calculated by setting cross slide infeed while cutting the chamfer with the compound rest.
11. Slowly engage the parting tool into the work. Keep a nice even feed and allow the chip to curl into a spiral shape on top of the tool while applying an occasional drop of cutting oil.
    Grooving tools are delicate and have a tendency to bite into the work aggressively, breaking the tool or causing damage to the work.
12. For all of the roughing cuts, the threading tool should incrementally be set using the compound rest.
    The threading tool being increased by moving the compound rest allows the leading edge of the tool to do a majority of the cutting, creating a predictable chip that is easier on the tool and the thread.
13. The tap is held straight by the operator moving a center mounted in the tailstock.
    The operator needs to keep the center in constant contact with the end of the tap in order to keep it cutting straight. If the operator fails to keep contact, the tap will start crooked creating a thread that is out of tolerance.
14. Knurling is a metal displacement and forming operation.
    Knurling tools don’t do any cutting. The knurl is created when the wheels of the knurling tool are pressed into the work with enough pressure as to displace the work material creating a serration with raised edges.
15. Approximately 1/8 “ further than the radius of the material to be parted off.
    The tool should stick out a little further than the radius calculated for parting, that way that there is clearance between the part and tool holder. However, if the tool is extended too far, there could be excessive flex and lack of rigidity in the setup that might cause chatter or other adverse cutting conditions.