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Machining in a Chuck Session 10.

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1 Machining in a Chuck Session 10

2 Lathe Chuck Most versatile and commonly used spindle accessory
Jaws adjustable Three-jaw: jaws move simultaneously Four-jaw: jaws move independently Can handle all operations that can be performed on work between centers

3 Lathe Chucks Must be careful when mounting and removing to prevent damage to spindle and/or chuck Three types of spindle noses found on engine lathes Threaded spindle nose Tapered spindle nose Cam-lock spindle nose

4 Procedure To Mount a Chuck
Set lathe to slowest speed SHUT OFF ELECTRICAL SWITCH Remove drive plate and live center Clean all surfaces of spindle nose and mating parts of chuck Place cradle block on lathe bed in front of spindle and place chuck on cradle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5 Slide cradle close to lathe spindle nose and mount chuck
Threaded Spindle Nose Chucks Revolve lathe spindle by hand in a counterclockwise direction and bring chuck up to spindle (NEVER START MACHINE) If chuck and spindle correctly aligned, chuck should easily thread onto lathe spindle When chuck adapter plate within .060 in. of spindle shoulder, give chuck quick turn to seat it against spindle shoulder Do not jam chuck against shoulder too tightly

6 Taper Spindle Nose Chucks
Revolve lathe spindle by hand until key on spindle nose aligns with keyway in tapered hole of chuck Slide chuck onto lathe spindle Turn lock ring counter-clockwise until hand-tight Tighten lock ring with spanner wrench striking it sharply downward

7 Cam-Lock Spindle Nose Chucks
Align registration line of each cam lock with registration line on lathe spindle nose Revolve lathe spindle by hand until holes in spindle align with cam-lock studs of chuck Slide chuck onto spindle Tighten each cam lock in a clockwise direction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

8 Procedure To Remove a Chuck
Set lathe in slowest speed STOP MOTOR Place cradle block under chuck Remove chuck by following methods dependent on type of spindle nose

9 Threaded Spindle Nose Chucks
Turn chuck until wrench hole is in top position Insert chuck wrench into hole and pull sharply toward front of lathe OR Place block or short stick under chuck jaw Revolve lathe spindle by hand in clockwise direction until chuck loosened on spindle Remove chuck from spindle and store it where it will not be damaged

10 Taper Spindle Nose Chucks
Secure proper C-spanner wrench Place it around lock ring of spindle with handle in upright position Place one hand on curve of spanner wrench to prevent it from slipping off lock ring With palm of other hand, sharply strike handle of wrench in clockwise direction Hold chuck with one hand, and with other hand, remove lock ring from chuck Remove chuck from spindle and store it with jaws in up position

11 Cam-Lock Spindle Nose Chucks
With chuck wrench, turn each cam lock in counterclockwise direction until its registration line coincides with registration line on lathe spindle nose Place one hand on chuck face and with palm of other hand, sharply strike top of chuck Action necessary to break taper contact between chuck and lathe spindle Slide chuck clear of spindle and place it carefully in storage compartment

12 Procedure to Mount Work in Three-Jaw Chuck
Clean chuck jaws and surfaces of workpiece Use proper size chuck wrench and open chuck jaws slightly more than diameter of work Place work in chuck, leaving no more than three times diameter extending beyond chuck jaws Tighten chuck jaws with wrench in left hand while slowly rotating workpiece with right hand Tighten chuck jaws securely using chuck wrench

13 Three-Jaw Universal Chuck
Supplied with two sets of chuck jaws Set for outside gripping Set for inside gripping Jaws marked with same serial number and should never be used with another chuck Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

14 Procedure To Change Chuck Jaws
Thoroughly clean jaws and jaw slides Turn chuck wrench clockwise until start of scroll thread almost showing at back edge of slide 1 Insert jaw 1 (in slot 1) and press down with one hand while turning chuck wrench clockwise with the other

15 After scroll thread has engaged in jaw, continue turning chuck wrench clockwise until start of scroll is near back edge of groove 2 Insert second jaw and repeat steps 3 and 4 Insert third jaw in same manner Some chucks equipped with one set of top jaws fastened on by allen screws

16 Four-Jaw Chuck Used when work must run absolutely true
Each jaw can be adjusted independently Jaws reversible Can hold round, square, or irregularly shaped workpieces securely Work can be adjusted to be either concentric or off center

17 Procedure To Mount Work in Four-Jaw Chuck
Measure diameter of work to be chucked With chuck wrench, adjust jaws to approximate size according to ring marks on face of chuck Set work in chuck and tighten jaws snugly against work surface True workpiece by either chalk method or surface gage method

18 Chalk Method Start lathe and with piece of chalk, lightly mark high spot on diameter Stop lathe and check the chalk mark If even, lightly marked line around work, work is true If one mark, loosen jaw opposite chalk mark and tighten jaw next to chalk mark Continue until chalk marks lightly around work or leaves two marks opposite each other

19 Surface Gage Method Place surface gage on lathe bed and adjust point of scriber so it is close to work Revolve lathe by hand to find low spot on work Loosen jaw nearest low spot and tighten jaw opposite low spot to adjust work closer to center Repeat steps 2 and 3 until work true

20 Procedure To True Work in a Four-Jaw Chuck Using Dial Indicator
Mount work and true it approximately, using either chalk or surface gage method Mount indicator, with rang of at least in., in toolpost of lathe Set indicator spindle in horizontal position with contact point set to center height Bring indicator point against work diameter so it registers approximately in and rotate lathe by hand

21 Note highest and lowest reading on dial
Slightly loosen chuck jaw at lowest reading and tighten jaw at high reading until work is moved half the difference between the two indicator readings Continue to adjust only these two opposite jaws until indicator registers same at both jaws Adjust other set of opposite jaws in same manner until indicator registers same at any point on work circumference Tighten all jaws evenly to secure work firmly Rotate lathe spindle by hand and recheck reading

22 Procedure To Face Work Held in a Chuck
True up work in chuck using chalk or dial indicator method Have at least amount equal to diameter of work projecting from chuck jaws Swivel compound rest at 90º to cross-slide when facing series of shoulders OR Swivel compound rest 30º to right if only one surface on work must be faced

23 Lock carriage in position
Set up facing toolbit to height of dead center and pointing slightly to the left Lock carriage in position Set depth of cut by using graduated collar on compound rest screw Twice amount to be removed if compound rest set at 30º Same as amount to be removed if compound rest set at 90º to cross-slide Face work to length

24 Rough- and Finish- Turn Work in a Chuck
Operations are same as turning between centers Should be machined to size in two cuts Usually short workpieces If long workpiece, support must be provided Use revolving tailstock center Steady rest

25 Rough and Finish Turning
Mount work securely in chuck, with no more than three times diameter extending beyond chuck jaws Move toolpost to left of compound rest and grip toolholder short Fasten general-purpose toolbit in toolholder and set point to center Tighten toolpost screw securely

26 Set lathe to correct speed and feed
Take light trial cut an end of work and measure diameter Adjust crossfeed graduated collar to one-half amount of metal to be removed Rough-turn diameter to correct length Set lathe speed and feed for finish turning Take light trial cut at end of workpiece Set graduated collar in one-half amount of metal to be removed Take another trial cut, if correct, finish-turn work

27 PCBN Tools Cost-effective for machining materials from 45 Rc and higher Remove material at high rates Long tool life even under interrupted cuts Characteristics include superior hardness, wear resistance, compressive strength and thermal conductivity

28 Guidelines for PCBN Turning
Machines should have good bearings, tight slides and enough power Proper cutting tool selected to suit type of material being cut and machining operation Follow manufacturer's recommendation for proper speed, feed, and depth of cut Set cutting tools on center, short overhang Use cutting fluid wherever possible

29 Interactive Superabrasive Machining Advisor Software
Used to select PCBN tool and machining conditions To use, operator must know the following: Material hardness, machine horsepower Maximum spindle speed and carriage feed Depth of cut and surface finish Program recommends tool grade, tool edge preparation, tool geometry, speed, feed and type of coolant

30 Part Specifications Workpiece material Machine Tool
1 in. diameter, hardened tool steel Rc Machine Conventional lathe with 5 HP drive to spindle Tool BZN* 8100 tipped insert, CNMA 433 Machining conditions .010 in depth of cut .004 in. feed rate 400 sf/min cutting speed

31 Procedure For Turning the Part
Set machine spindle to correct speed Set lathe for recommended feed per revolution Lock PCBN insert in proper toolholder Fasten toolholder in toolpost and adjust tool to centerline height Use .010 in. plastic shim and set tool tip to outside diameter of part

32 Turn carriage handwheel clockwise so tool clears end of part
Turn crossfeed handle clockwise thickness of shim plus desired depth of cut Engage automatic feed to machine diameter toward lathe headstock At end of cut, turn crossfeed handle counterclockwise to withdraw tool from diameter Return to starting position of cut, reset tool for depth and continue passes until part to size

33 Procedure For Cutting Off Work in a Chuck
Mount work in chuck with part to be cut off as close to jaws as possible Mount cutoff tool on left-hand side of compound rest, with cutting edge set on center Place holder as close to toolpost as possible

34 Extend cutting blade beyond holder half diameter of work to be cut, plus .125 in. for clearance
Set lathe to approximately ½ turning speed Move cutting tool into position Start lathe and feed cutoff tool into work by hand When grooving or cutting off deeper than .250 in, good practice to move parting tool sideways slightly Before cut completed, remove burrs from side of groove with file

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