Drilling

Question 1

Normal Twist drills have an included angle of____ and a clearance angle of ____

Answer 1

Normal Twist drills have an included angle of (118 deg.) and a clearance angle of (8-12 deg.)

Question 2

Centre drills have an included angle of____

Answer 2

Centre drills have an included angle of (60*)

Question 3

True or False:
There are fractional, numbered and lettered drill bits

Answer 3

True!

Fractional sizes are “filled in” by letters and numbers

Question 4

When drilling, what do “happy chips” look like?

Answer 4

Two equal spirals

Question 5

When drilling with a tapered drill bit, is the ‘depth of cut’ measured to the point of the drill bit, or to the shoulder?

Answer 5

Shoulder!

The drill point will not cut the full diameter of the required depth.

Question 6

What are types of hole machining operations? (7)

Answer 6

(1) Drill
(2) Countersink
(3) Ream
(4) Bore
(5) Spotface
(6) Tap
(7) Counterbore

Question 7

What are some instructions for reaming?

Answer 7

Slow RPM
Heavy cutting fluid
NEVER reverse direction
Full depth (tapered)