Turning tool and work holding devices

Question 1

What happens if tool is above centre height?

Answer 1

Tool will not cut

Question 2

What happens if tool is below centre height?

Answer 2

Finishing is poor and there will be errors in dimensions

Question 3

What are the 3 types of toolpost?

Answer 3

1. Front Tool Post
2. 4-way Tool Post
3. Quick Change Tool Post

Question 4

Features of front tool post

Answer 4

It can only hold one tool at a time, useful for low batch production

Question 5

Features of 4 way tool post

Answer 5

Can hold up to 4 different tools
Can be rotated and locked into position by an indexing device
Useful for medium batch production

Question 6

Features of quick change tool post

Answer 6

Fast in swapping out tools
Each tool requires a separate tool holder
No packing is required as centre height can be adjusted using the adjusting screw
Useful for batch production
More expensive

Question 7

What are shims?

Answer 7

They are thin metal strips that are fabricated to high accuracy

Question 8

What are sleeves?

Answer 8

Used as an adapter on drill chucks and reaming bits, if the tailstock is bigger

Question 9

What is the use of an insert holder?

Answer 9

To rigidly hold the insert

Question 10

What are the 2 common methods of supporting long and thin workpiece?

Answer 10

Centres and steadies

Question 11

Advantages and disadvantages of a 3 jaw chuck

Answer 11

Advantages:
- Self-Centering, all the 3 jaws move concentrically and simultaneously about the spindle axis, allowing the workpiece to be clamped in the centre of the chuck
- Reversible Jaws, work of larger diameter but shorter length can be machined
Disadvantages:
- Clamping Restriction, clamp round bars or stocks with multiples of 3 sides
- Low gripping strength, tightening force is distributed around the 3 jaws
- Numbered Jaws, to match with the respective slot

Question 12

What are the advantages and disadvantages of a 4 jaw chuck?

Answer 12

Advantages:
- High gripping strength, the tightening force is only applied to the jaw that is tightened
- Clamping variability, able to hold workpiece with regular or irregular shapes
- Reversible Jaws, work of larger diameter but shorter length can be machined
Disadvantages:
- Longer set up time, each jaw must be tightened individually, and work must be measured for setup accuracy before machining