PG193-242Shop 2 Drills Vices Belt Drives etc

Name three common holding devices.

Vises, step clamps, parallels.

When are ladder-shaped rests used?

For large or irregularly shaped pieces.

What condition defines a proper clamp setup (h1 vs h2)?

h1 should be slightly greater than h2.

What condition defines proper clamp length (a vs b)?

b must be longer than a.

How should thin materials be supported during drilling?

With wood or soft metal backing.

Why sandwich very thin sheet metal?

To prevent deformation and improve accuracy.

What is used to secure cylindrical parts?

V-guides with clamps.

How many contact points secure a cylindrical part properly?

Three points.

When is a vise best used?

When the workpiece has sufficient surface contact area.

Why must vise contact surfaces be parallel?

To ensure safe and secure holding.

What should be placed under a workpiece in a drill press?

Blocks to protect the table.

What is the main advantage of a radial drill?

It allows multiple holes without moving the workpiece.

What type of work is a radial drill best for?

Heavy and large pieces.

What is a key feature of an upright drill?

It drills along a fixed axis.

What must be moved on an upright drill to drill multiple holes?

The workpiece

Spindle Speed (Drilling Speed) formula ?

N = V * 12

______

pi D

N = spindle speed (RPM)

V = cutting speed (surface feet per minute)

D = drill diameter (inches)

What does belt transmission allow?

Speed changes via pulley ratios.

What is the formula for pulley speed?

V2 = V1 * D1 / D2

What does V₁ represent in the pulley speed formula?

Speed of the drive pulley.

What does V₂ represent in the pully speed formula ?

Speed of the driven pulley.

What happens when the driven pulley is smaller than the drive pulley?

Speed increases.

Why are gloves not worn while drilling?

They can get caught in moving parts.

How should chips be removed when using drills ?

with a tool, never hands.

What is the most common drill bit problem?

Overheating

What causes overheating?

Excess speed or poor lubrication.

What is the purpose of cutting fluid?

Cooling and lubrication.

What happens if the relief angle is too small?

Faster dulling and weaker cutting edge.

What is negative relief?

Improper angle causing poor cutting and friction.

How do you prevent off-center holes?

Use a center punch and pilot hole.

What tool can help re-center a hole?

Round-edge chipping chisel.

What causes oversized holes?

Unequal drill lips.

How much larger can a hole become due to eccentricity?

Double the eccentricity.

What direction should force be applied with an adjustable wrench?

Toward the adjustable jaw.

Should you push or pull a wrench?

Pull

When does a hacksaw cut?

On the forward stroke.

What materials can a hacksaw cut?

Metal and plastic.

What determines hacksaw blade fineness?

Teeth per inch (TPI).

What is a pipe wrench primarily used for?

Turning threaded pipes.

What is the key safety rule when using pliers?

Pull, don’t push.

Formula for Feed Rate?

Feed Rate = Feed per Revolution × RPM

Measured in inches per minute (IPM)

Too fast = broken bits

Too slow = rubbing instead of cutting

This controls how pulley systems change speed.

Belt Drive Speed Ratio

V₁, V₂ = speeds

D₁, D₂ = pulley diameters

Big pulley driving a small one? Speed shoots up. Reverse it, and things slow down.

Hole Size Error (Eccentricity) Formula?

Hole Diameter = Drill Diameter + (2 × Eccentricity)

When your drill isn’t perfectly centered, the hole grows larger than intended. A tiny misalignment doubles its impact. Precision here is unforgiving.

Tap Drill Size (for threading holes) formula?

Formula (inch threads): Tap Drill Size = Major Diameter − (1 / Threads per inch)

Example:

1/4"-20 thread →

= 0.250 − (1/20) = 0.200 in

If you’re cutting threads, the hole size matters

Drill Point Geometry (Angles)

Standard drill point angle: 118°

Hard materials: 135°

Relief angle: ~8°–12°

Too steep or too shallow, and cutting efficiency collapses.

Clamping Geometry (Stability Principle) formula

Not always written as a strict formula, but it behaves like one:

h₁ > h₂ ensures downward force

b > a ensures stable leverage

Think of it like balancing a seesaw. If the geometry is wrong, the workpiece becomes unpredictable.

Cutting Speed Relationship

Larger drill → lower RPM

Smaller drill → higher RPM

Because the outer edge of a big bit travels farther per rotation.