hand reaming and broaching
TRANSCRIPT
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Reaming andBroaching
Session 9
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Shop Tools and Techniques 2
Hand Cutting Tools
Reamers Used to bring hole to size and produce good
finish
Broaches Used with arbor press to produce special
shapes in workpiece
Multi-tooth tool forced through hole
Lapping Where very fine abrasive powder,
embedded in tool is used to remove minuteamounts of material from surface
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Shop Tools and Techniques 3
Solid Hand Reamer
Made of carbon steel or high-speed steel
Available in inch sizes from .125 - 1.500 inch
Metric from 1 26 mm in diameter
Non-adjustable and may have straight orhelical flutes
Should not be used on work with keyway or
any other interruption
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Shop Tools and Techniques 4
Expansion Hand Reamer
Designed to permit adjustment ofapproximately .006 in. above nominaldiameter
Hollow and has slots along length of cuttingsection
Tapered threaded plug fitted into end ofreamer provides for limited expansion
Cutting end of reamer ground to slight taper
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Shop Tools and Techniques 5
Adjustable Hand Reamer
Has tapered slots along entire length of body
Inner edges of cutting blades have taper so
blades remain parallel for any settings
Adjusted by upper and lower adjusting nuts
Blades have adjustment range of 1/32 in. on
smaller reamers to 5/16 in. on larger ones
Manufactured in sizes to 3 in. in diameter
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Shop Tools and Techniques 6
Taper Reamer
Used to finish tapered holes accuratelyand smoothly
Made with either spiral or straight teeth
Roughing reamer Nicks ground at intervals along teeth
Used for more rapid removal of surplus
metal
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Shop Tools and Techniques 8
Reaming Precautions
1. Never turn reamer backward(counterclockwise), it will dull teeth
2. Use cutting lubricant where required
3. Always use helical-fluted reamer inhole that has keyway or oil groove cutin it
4. Never attempt to remove too muchmaterial (maximum = .010 in.)
5. Frequently clear taper reamer and holeof chips
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Shop Tools and Techniques 9
Reaming a Hole
1. Check size of drilled hole (.004-.005 in.smaller than finished hole size)
2. Place end of reamer in hole and place
tap wrench on square end of reamer3. Rotate reamer clockwise to align with
hole
4. Check reamer for squareness with work
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Shop Tools and Techniques 10
Reaming a Hole
5. Brush cutting fluid over end of reamer
6. Rotate reamer slowly clockwise andapply downward pressure
7. When finished, clean hole and checkwith gage for correct size.
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Shop Tools and Techniques 11
Broaching
Process in which special taperedmultitoothed cutter forced through anopening or along outside piece of work
to enlarge or change shape of hole First used for internal shapes (keyways,
splines)
Now used for external shapes
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Shop Tools and Techniques 12
Broaching
Cutting action performed by
series of successive teeth Each tooth protrudes .003 in. farther
than preceding tooth
Last three teeth same depth
and provide finish cut
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Shop Tools and Techniques 13
Advantages of Broaching
1. Machining almost any irregular shape
is possible
2. Process usually in one pass
3. Roughing and finishing cuts
combined
4. Variety of forms, internal or external,may be cut and entire width of
surface may be machined
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Shop Tools and Techniques 14
Broaching Keyways
Keyways may be cut by hand quickly
and accurately by means of broach
set and arbor press
Broach set covers wide range of
keyways
Equipment necessary to cut keyway
Bushing to suit hole size
Broach size of keyway to be cut
Shims to increase depth of cut of broach
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Shop Tools and Techniques 15
Cutting a KeywayWith a Broach1. Determine keyway size required
2. Select proper broach set
3. Place workpiece on arbor press Use an opening on base smaller than
opening in work so bushing properly
supported
4. Insert bushing and broach into
opening
Apply cutting fluid if workpiece is steel
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Shop Tools and Techniques 17
8. Insert second shim and third shim ifrequired, and press broach through
again This cuts keyway to proper depth
9. Remove bushing, broach, and shims
10.When finished, check broachedkeyway for size with appropriatekeystock
Cutting a KeywayWith a Broach
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Shop Tools and Techniques 18
Lapping
Abrading process used to removeminute amounts of metal from surface
Reasons for lapping
Increase wear life of part Improve accuracy and surface finish
Improve surface flatness
Provide better seals and eliminate need forgaskets
Intended to remove only about .0005 in.
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Shop Tools and Techniques 19
Lapping Abrasives
Natural and artificial abrasives used
Flour of emery and fine powders madeof silicon carbide or aluminum oxide
used extensively For rough lapping, abrasive should be
no coarser than 150 grit
Fine powders run up to 600 grit
Fine work uses diamond dust in pasteform
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Shop Tools and Techniques 20
Flat Laps
Close-grained cast iron laps used for flat
surfaces
Roughing operation Lapping plate scored with narrow grooves
.500 in. apart both lengthwise and
crosswise to form square or diamond
Finish lapping done on smooth cast-iron
plate
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Shop Tools and Techniques 21
Internal Laps
Holes accurately finished to size and
smoothness by lapping
Made of brass, copper, or lead
Three types
Lead
Internal
Adjustable
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Shop Tools and Techniques 22
Lead Lap
Made by pouring lead around taperedmandrel that has groove along length
Turned to running fit into hole
Sometimes slit on outside to trap looseabrasive
Adjust by lightly tapping large end of
mandrel with soft block
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Shop Tools and Techniques 23
Internal Lap
May be made of copper, brass or cast
iron
Threaded-taper plug fits into end of
lap
Slit for almost its entire length
Lap diameter may be adjusted by
threaded-taper plug
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Shop Tools and Techniques 24
Adjustable Lap
May be made from copper or brass
Split for almost full length, but both
ends remain solid
Slight adjustment provided by means
of two setscrew in center section
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Shop Tools and Techniques 25
External Laps
Used to finish outside of cylindrical
work pieces
Made of cast iron or may have split
brass bushing mounted inside by
setscrew
Must be some provision for adjusting
lap