CPM Shop Machinery and Tools 2

Question 1

Per OSHA, what is the maximum allowable gap between a bench grinder's work rest and the grinding wheel?

Accepted Answer

1/8 inch

Answer

OSHA 1910.215 limits the work rest gap to 1/8 inch to keep work from being pulled between the rest and wheel.

Question 2

When switching from a 1/4-inch to a 1-inch twist drill in the same mild steel, how should drill press spindle speed change?

Accepted Answer

Decrease it

Answer

Larger drills have higher surface speed at the same RPM, so RPM must be reduced.

Question 3

What is the standard tap drill size for a 1/4-20 UNC thread?

Accepted Answer

#7 (0.201 in)

Answer

A #7 drill gives about 75% thread engagement for 1/4-20 UNC.

Question 4

On an engine lathe, where should the cutting edge of a turning tool be set relative to the workpiece?

Accepted Answer

On the centerline

Answer

Setting the tool on center gives correct rake and clearance angles and prevents rubbing or digging in.

Question 5

Before mounting a vitrified grinding wheel, what simple check detects hidden cracks?

Accepted Answer

Ring test

Answer

A sound wheel tapped lightly gives a clear ring, while a cracked wheel sounds dull.

CPM - Certified Plant Mechanic Practice Test