Drilling Flashcards by shawn Burleigh

What is a sensitive drill press used for?

-Small, precise work
- usually v belt driven
- Typically holes up to 1/2”
- drill chuck only

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Sensitive drills do not have?

Power feed or coolant pumps

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What type of chuck is typically found on sensitive drills?

Drill chuck

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What is different about a upright drill press then a sensitive drill-press?

Meant for drilling 1/2”-4”holes
Geared head to permit slow spindle speeds and high torque
power feed
accepts tapered shank drill bits
has coolant pump and reservoir

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What is a hand drill best suited for?

Holes up to 1/2” and do not require precision.

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What drill should be used when disassembling is not desirable?

Magnetic base

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What can be done with a mag base drill?

Ability to drill, tap and ream large holes

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What size and type of chucks can mag base drill take?

Three jaw chucks

1/2” and 3/4” chucks

Some Models have a #3 Morse taper in the spindle

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When must you secure mag base drills?

When drill is mounted anywhere other then flat.

Don’t use to much pressure when drilling. It could cause the magnet to detach

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What is a radial drilling machine used for?

Drill holes in very large workpieces that are hard to position manually under the spindle of a regular drill press.

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What are the two ways drill presses are sized?

Distance from column to tool

Largest diameter of workpiece that can be centred under tool.

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What is a drill sleeve?

A drill sleeve makes up the difference between the drill bit and drill press spindle.

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When is a drill socket needed?

A drill socket is used when the tapered shank of the drill bit is larger then the tapered bore of the drill press.

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What is a drift used for?

To separate the tapered tool from the spindle.

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What are the features of a power tapping attachment?

When downward pressure is released the tapping attachment reverses.

Adjustable clutch slips of tap bonds

Tap is held in floating head so it can self align

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What is used to reduce misalignment when reaming?

Floating reamer holder

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What are three main holding devises?

Vises-standard, Angle

Clamping sets-c clamps, B-blocks

Jigs

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What are the 3 parts of twist drills?

Point

Body

Shank

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What are two types of drill bit shanks and advantages?

Straight-less expensive, up to 1/2”

Taper- over 1/2”, hold power is much stronger.

Morse taper about 5/8 per foot of taper

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What is the purpose of the flutes in a drill bit?

Carry chips out of the hole and a passage for cutting fluid.

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The diameter of a drill bit is measure across what?

Margins(narrow raised section that runs along the flute)

What does the point of a drill consist of?

Lip or cutting edge-extends from chisel edge to the margin.

Chisel edge-portion remaining between the flutes

Lip clearance-heel must be lower then cutting edge for the drill to advance into material.

What are some specialty drills and uses?

High helix drills-deep holes in softer material

Core drills-used to enlarge existing holes

Oil hole drills-deep holes where it would be difficult to deliver cutting fluid to tip

Straight fluted drill-soft materials

Step drill-drills and counter sinks(counter bore) at the same time

Mason drill-drills concrete and stone

Centre drill-drills centre point for lathe

What are the 4 drill sizes?

Fractional-1/16 to 4”

Number-#97(.0059) to #1(.228)

Letter-A(smallest) to Z (largest) picks up where number range left off. (.234 to .413)

Metric-.04 to 80mm

What is a drill gauge for?

Accurately checking drill size.

How big should a centre punch or pre drill be?

Just larger then the chisel edge.

What are four methods for transferring holes?

Clamping-secure plates together drill all holes at the same time. Twist drill method-if second hole is smaller use this method. Drill just the tip into second piece and un clamp Transfer punch Transfer screw- use when piece is already threaded

Typical angle of screw head?

82 degrees

What is one difficulty when machine tapping?

Chips not clearing causing taps to break.

What two taps work best for clearing chips when machine tapping?

Spiral fluted tap-chips pull out top Spiral point (gun) tap - chips fall out bottom

What is cutting speed? How is it measured?

Cutting speed is the rate the cutting tool moves through the piece. Meters per minute (m/min) or surface feet per minute(sfpm)

What’s the difference between cutting speed and spindle speed?

Cutting speed is the rate the tool moves through the material in a straight line Spindle speed is rotation value (rpm)

Rpm imperial =

Cutting speed x 4 / diameter of drill

Rpm metric =

Cutting speed x 320 / diameter of drill

Feed rate is measured in?

Inches per foot (IPF) Millimetres per foot (MPF)

Over size hole?

Cutting tips not the same size

Drill dulls quickly or a bell mouthed hole?

Point angle is not even Cutting speed to high Feed to high Chipped cutting edges To much clearance

Drill does not feed into material?

Not enough clearance angle (8 -12 degrees is ideal) Chisel edge to wide

60-90 degree drill point?

Drilling soft materials

118 degree point angle?

General purpose

150 degree point angle

Hard materials

Discolouration

Cutting speed to high Not enough coolant

Drill chatter

Set up not rigid enough Pilot hole to large

Squeals and jams

Worn margins Excessive heat Inadequate chip removal

Bell mouth hole

Point angle uneven Cutting lips e even length

When drill big holes with a hand drill it is important to only drill the pilot hole and your main size. Stepping up the hole will cause the large bit to______?

May bind or break if not held perfectly steady

How big should the pilot hole be when drilling?

Just a little bigger than the chisel edge. If the pilot hole is two big the drill begins to chatter.

Three methods of transferring holes when drilling are?

Twist drill method - clamp the two pieces together and use the first hole to guide the bit. Drill only as deep as the point then I clamp the pieces and finish the hole. If you are going to tap the second hole make sure you reduce the drill bit size to the tap drill size Transfer punch method - clamp both pieces together and use a transfer punch to transfer the holes. Transfer screw method - if the holes are blind you can insert transfer screws into the hole and hammer the plate to be drilled on top.

Counter sink bit chatters?

Feed pressure to light

Spindle speed for a counter bore bit in a drill press will be approximately ________ of the speed you had to drill the hole?

1/4 the speed

When does the chisel edge on the top of the drill bit need to be thinned?

When the chisel edge gets to wide from multiple sharpens. Chisel edge should be as thin as possible.

Helix angle chart for twist drills