Drilling
for
Quality
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Why do we need drilling for quality?
• Help the mechanic recognize the characteristics of what makes a quality hole
• Procedures required to drill quality holes
• Use the necessary tools to make a quality hole
• Countersink
• Shop safety
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What is S tres s ?
S tres s - During takeoff, in flight, and landing.
Just sitting on the tarmac with the weight of the airplane causes stress.
Weather, Temperature..
What would happen if holes in the aircraft had some sort of defect?
Do you think these stresses affect the holes / fastener installation?
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S afety
• Leather Shoes (no open toes or high heels) • No loose fitting clothing (ties, shirts or jackets) • Pants to be below the kneecap. • Loose jewelry will be taken off • Long hair will be tied back • No loose fitting gloves, • Beware of loose fitting badge holders (make sure you have a breakaway holder)
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www.elvex.com
S afety
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Drill Motors
Typical Drill Motor
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P is tol G rip Motors
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90 & 45 degree Drill Motors
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Drill B it Nomenc lature
S hank
P oint A ngle
L and
S tep
Margin
Margin
F lute
F lute
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Types
Twis t Double Margin R eamer C ore G un B arrel
C ompos ite
Drill B its and R eamers
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Drill B its and R eamers
Shank Style
Quic k C hange T hreaded Quic k C hange 90 and 45
Degree Motors
Tri-F lat
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Quic k C hange T ype Drill B it S ize Identific ation
R eamer
S tandard Double Margin
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E quivalenc y c ard (S tarrett C ard)
F R ONT B A C K
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Hole Qualities
What qualities are we looking for in
a properly drilled hole?
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Diameter - (Within T oleranc e)
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A ngularity - (S traight within 2 degrees )
90 o
+/- 2 o
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Drill G uides
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B us hing Identific ation
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Drill S tops
# 40 # 30 # 20 # 10 1/4 5/16
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Give an example of a defect
and what could cause that defect
T here are many pos s ible defec ts to a drilled hole
Copyright © 2012 Boeing. All rights reserved.
T here are many pos s ible defec ts to a drilled hole
Overs ize Unders ize E longated E ye B rowed G ouged / B arreled Tapered Drill S tarts Drill R uns Angled R ifled C hattered Over Deburred
Double Hole Mis located Mismatch Misaligned Misoriented E xtra Hole S hort E dge Margin B reak Out C racked / F ractured B ellmouth B urned Deep C ounters ink
Copyright © 2012 Boeing. All rights reserved.
What kind of a defect is this?
A ngled Hole
C aus ed by improper us e of drill guide or more likely
c aus ed by NOT us ing drill guide.
T here are many pos s ible defec ts to a drilled hole
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What kind of a defect is this?
Rifled Hole
C aus ed by the us e of a dull drill bit or too muc h lubric ation being us ed, exc es s c utter run out, damaged
c utter margin or c hips welded to c utter
T here are many pos s ible defec ts to a drilled hole
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E dge Margin - (Drawing c all out or 2X diameter)
Edge margin
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S urfac e F inis h - s mooth finis h ins ide the hole
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What kind of a defect is this?
E ye B rowed Hole
C aus ed by drilling of a c rooked hole then reentering the hole
s traight or drilling a hole that has a pilot on the other s ide.
T here are many pos s ible defec ts to a drilled hole
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What kind of a defect is this? Drill R un
Drill S tart
Not us ing a s harp drill bit, not getting the drill bit
into the pilot hole before pulling trigger or trying
to drill too fas t and mis s ed the target! !
T here are many pos s ible defec ts to a drilled hole
Copyright © 2012 Boeing. All rights reserved.
What kind of a defect is this?
B arreled Hole
C aus ed by the us e of too muc h lubric ant, lube holds
debris in the flutes of drill bit and hones out the hole.
T here are many pos s ible defec ts to a drilled hole
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What kind of a defect is this?
Double Hole
C aus ed by walking of the drill bit, pos s ibly a dull drill
bit. Drilling a c rooked pilot hole, then drilling bac k
through the hole us ing a guide
T here are many pos s ible defec ts to a drilled hole
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What kind of a defect is this?
E xtra Hole
C aus ed by not looking at the drawing for proper
layout, mis loc ated tool or c areles s drill bit plac ement.
T here are many pos s ible defec ts to a drilled hole
What kind of a defect is this?
Unders ized Hole
C aus ed when the drill bit is dull or the inc orrec t drill
bit is us ed.
T here are many pos s ible defec ts to a drilled hole
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R eliefs
Deburr
Chamfer
Fillet Relief
Fillet Relief Washer
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F illet R elief, C hamfer, R adius
R eliefs
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F ilet R elief, C hamfer
R eliefs
F illet R elief, C hamfer, R adius
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Deburring T ools
Weldon
Open Countersink
Flat File
Cogsdill Copyright © 2012 Boeing. All rights reserved.
What kind of a defect is this?
C aus ed by us ing inc orrec t deburring tool or a dull
deburring tool.
C hamfered Inc orrec tly
T here are many pos s ible defec ts to a drilled hole
Not R ec ommended Deburring / R elief T ools
R otary F iles
Mac hinis t T riangle Drill bits R ed Devil S c raper
What kind of a defect is this?
Deep C ounters ink
Mus t s et c ounters ink on s c rap material before going to a/p s truc ture.
Make s ure to loc k the s et ring. C hec k c ounters ink bearing, they do go bad.
(A new Zephyr s mall body las ts 80,500 c ounters inks max.)
T here are many pos s ible defec ts to a drilled hole
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C ounters inks
Shaft
Locking Ring
Cage / Body
Countersink Cutter
Rotating Foot Countersink Pilot
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C ounters ink C utter
Hex Drive or L oc k B olt 100 Deg. B olt
100 degree R ivet C ounters ink
100 Deg. WQ B olt
82/30 Deg. R ivet
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C ounters inks
Pull back Cage / Body
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C ounters inks
Rotate Foot to
change depth
This way to make shallower
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C ounters inks
Rotate Foot to
change depth
This way to make it deeper
The countersink is to be set on a scrap
piece of material similar to the material
that needs to countersink
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Us e of C ounters ink
S et c ounters ink on s ame type of material to be c ounters unk Matc h the c ounters ink pilot s ize to the hole s ize Hold the barrel of the c ounters ink while c ounters inking P rior to adjus ting c ounters ink deeper, always re-c ounters ink the
hole to ens ure the c utting was c omplete
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