STANDARD TAPERS 906 STANDARD TAPERS

Transcription

1 906 STNDRD TPERS STNDRD TPERS Standard s Certain types small tools and machine parts, such as twist drills, end mills, arbors, lathe centers, etc., are provided with taper shanks which fit into spindles or sockets corresponding taper, thus providing not only accurate alignment between the tool or other part and its supporting member, but also more or less frictional resistance for driving the tool. There are several standards for self-holding tapers, but the merican National, Morse, and the Brown & Sharpe are the standards most widely used by merican manufacturers. The name self-holding has been applied to the smaller tapers like the Morse and the Brown & Sharpe because, where the angle the taper is only 2 or 3 degrees, the shank a tool is so firmly seated in its socket that there is considerable frictional resistance to any force tending to turn or rotate the tool relative to the socket. The term self-holding is used to distinguish relatively small tapers from the larger or self-releasing type. milling machine spindle having a taper inches per foot is an example a self-releasing taper. The included angle in this case is over 16 degrees and the tool or arbor requires a positive locking device to prevent slipping, but the shank may be released or removed more readily than one having a smaller taper the self-holding type. Morse. Dimensions relating to Morse standard taper shanks and sockets may be found in an accompanying table. The taper for different numbers Morse tapers is slightly different, but it is approximately 5 8 inch per foot in most cases. The table gives the actual tapers, accurate to five decimal places. Morse taper shanks are used on a variety tools, and exclusively on the shanks twist drills. Dimensions for Morse Stub Shanks are given in Table 1a. Brown & Sharpe. This standard taper is used for taper shanks on tools such as end mills and reamers, the taper being approximately 1 2 inch per foot for all sizes except for taper 10, where the taper is inch per foot. Brown & Sharpe taper sockets are used for many arbors, collets, and machine tool spindles, especially milling machines and grinding machines. In many cases there are a number different lengths sockets corresponding to the same number taper; all these tapers, however, are the same diameter at the small end. Jarno. The Jarno taper was originally proposed by Oscar J. Beale the Brown & Sharpe Mfg. Co. This taper is based on such simple formulas that practically no calculations are required when the number taper is known. The taper per foot all Jarno taper sizes is inch on the diameter. The diameter at the large end is as many eighths, the diameter at the small end is as many tenths, and the length as many half inches as are indicated by the number the taper. For example, a 7 Jarno taper is 7 8 inch in diameter at the large end; 7 10, or inch at the small end; and 7 2, or inches long; hence, diameter at large end = taper 8; diameter at small end = taper 10; length taper = taper 2. The Jarno taper is used on various machine tools, especially priling machines and die-sinking machines. It has also been used for the headstock and tailstock spindles some lathes. merican National Standard Machine s: This standard includes a self-holding series (Tables 2, 3, 4, 5 and 7a) and a steep taper series, Table 6. The self-holding taper series consists 22 sizes which are listed in Table 7a. The reference gage for the self-holding tapers is a plug gage. Table 7b gives the dimensions and tolerances for both plug and ring gages applying to this series. Tables 2 through 5 inclusive give the dimensions for selfholding taper shanks and sockets which are classified as to (1) means transmitting torque from spindle to the tool shank, and (2) means retaining the shank in the socket. The steep machine tapers consist a preferred series (bold-face type, Table 6) and an intermediate series (light-face type). self-holding taper is defined as a taper with an

2 STNDRD TPERS 907 angle small enough to hold a shank in place ordinarily by friction without holding means. (Sometimes referred to as slow taper.) steep taper is defined as a taper having an angle sufficiently large to insure the easy or self-releasing feature. The term gage line indicates the basic diameter at or near the large end the taper. Table 1a. Morse Stub Shanks per Foot a per Inch b Small End Plug, b D End Socket, a Total, B Shank, C Thickness, E Tang, F Tang Socket Tang Slot Radius Mill, G, H Plug, P Min. ed Hole Drilled X Reamed Y Socket End to Tang Slot, M, N, O a These are basic dimensions. b These dimensions are calculated for reference only. ll dimensions in inches. Radius J is 3 64, 1 16, 5 64, 3 32, and 1 8 inch respectively for Nos. 1, 2, 3, 4, and 5 tapers.

3 908 STNDRD TPERS Table 1b. Morse Standard Shanks per Foot per Inch Small End Plug D End Socket B Shank S Hole H Plug P Thickness t Tang or Tongue T Radius R W Keyway L Keyway to End K

4 STNDRD TPERS 909 Table 2. merican National Standard Drive with Tang, Self-Holding s NSI/SME B at Line (1) Total Shank B Shank Line to End Shank C Thickness E F ll dimensions are in inches. (1) See Table 7b for plug and ring gage dimensions. Tolerances: For shank diameter at gage line, ; for hole diameter, For tang thickness E up to 5 inclusive, ; 6, For width N tang slot up to 5 inclusive, ; 0.000; 6, For centrality tang E with center line taper, (0.005 total indicator variation). These centrality tolerances also apply to the tang slot N. On rate taper, all sizes per foot. This tolerance may be applied on shanks only in the direction which increases the rate taper and on sockets only in the direction which decreases the rate taper. Tolerances for two-decimal dimensions are plus or minus 0.010, unless otherwise specified. Tang Radius Mill G H Socket Tang Slot Min. Hole K Line to Tang Slot M Shank End to Back Tang Slot P Radius J Drilled Reamed N O

5 910 STNDRD TPERS Table 3. merican National Standard Drive with Keeper Key Slot, Self-Holding s NSI/SME B at Line (1) Total B Shank Tang Socket Line to End C Thickness E F Radius Mill G H Radius J Min. Hole K Line to Tang Slot M Drill Ream N Tang Slot Keeper Slot in Shank Keeper Slot in Socket O Shank End to Back Slot P Line to Bottom Slot Y X N Line to Front Slot Y Z N ll dimensions are in inches. (1) See Table 7b for plug and ring gage dimensions. Tolerances: For shank diameter at gage line, , 0; for hole diameter, +0, For tang thickness E up to 5 inclusive, +0, 0.006; larger than 5, +0, For width slots N and N up to 5 inclusive, , 0; larger than 5, , 0. For centrality tang E with center line taper (0.005 total indicator variation). These centrality tolerances also apply to slots N and N. On rate taper, see footnote in Table 2. Tolerances for two-decimal dimensions are ±0.010 unless otherwise specified.

6 STNDRD TPERS 911 Table 4. merican National Standard Nose Key Drive with Keeper Key Slot, Self-Holding s NSI/SME B (1) B C Q I I R S Min Max for all sizes D D a W X N R S T U V M N O P Y Z a Thread is UNF-2B for hole; UNF-2 for screw. (1) See Table 7b for plug and ring gage dimensions. ll dimensions are in inches. E is greater than one-half. drive key R is less than width R keyway. Tolerances: For diameter hole at gage line, +0, 0.002; for diameter shank at gage line, , 0; for width slots N and N, , 0; for width drive keyway R in socket, +0, 0.001; for width drive keyway R in shank, 0.010, 0; for centrality slots N and N with center line spindle, 0.007; for centrality keyway with spindle center line: for R, and for R, T.I.V. On rate taper, see footnote in Table 2. Two-decimal dimensions, ±0.010 unless otherwise specified.

7 912 STNDRD TPERS Table 5. merican National Standard Nose Key Drive with Drawbolt, Self-Holding s NSI/SME B at Line a Drive Key Screw Holes Center Line to Center Screw D UNF 2B Hole UNF 2 Screw D R Sockets Drive Keyway R Line to Front Relief T Relief U Relief V Draw Bolt Hole d a See Table 7b for plug and ring gage dimensions. from Line B UNC-2B L Drilled Hole E Shanks Drawbar Hole Thread P Counter Bore G ll dimensions in inches. Exposed length C is minimum and maximum for all sizes. Drive Key D screw sizes are UNF-2 up to taper 400 inclusive and UNF-2 for larger tapers. Tolerances: For diameter hole at gage line, , for all sizes; for diameter shank at gage line, , 0.000; for all sizes; for width drive keyway R in socket, , 0.001; for width drive keyway R in shank, , 0.000; for centrality drive keyway R, with center line shank, total indicator variation, and for drive keyway R, with center line spindle, On rate taper, see footnote in Table 2. Tolerances for two-decimal dimensions are ±0.010 unless otherwise specified. S Line to First Thread O 60 Chamfer J R Drive Keyway S Center Line to Bottom Keyway E

8 STNDRD TPERS 913 Table 6. NSI Standard Steep Machine s NSI/SME B per Foot a at Line b a This taper corresponds to an included angle 16, 35, b The basic diameter at gage line is at large end taper. ll dimensions given in inches. The tapers numbered 10, 20, 30, 40, 50, and 60 that are printed in heavy-faced type are designated as the Preferred Series. The tapers numbered 5, 15, 25, 35, 45, and 55 that are printed in light-faced type are designated as the Intermediate Series. Table 7a. merican National Standard Self-holding s Basic Dimensions NSI/SME B ll dimensions given in inches. long xis per Foot a at Line b long xis per Foot at Line a a See illustrations above Tables 2 through 5. Means Driving and Holding a Tang Drive With Shank Held in by Friction (See Table 2) Tang Drive With Shank Held in by Key (See Table 3) Key Drive With Shank Held in by Key (See Table 4) Key Drive With Shank Heldin by Draw-bolt (See Table 5) Origin Series Brown & Sharpe Series Morse Series 3 4 Inch per Foot Series

9 914 STNDRD TPERS Table 7b. merican National Standard Plug and Ring s for the Self-Holding Series NSI/SME B a per Foot a at Line Class X Tolerances for b Class Y Class Z at Small End Line to End L Gaging- Notch, Plug L a The taper per foot and diameter at gage line are basic dimensions. Dimensions in Column are calculated for reference only. b Tolerances for diameter are plus for plug gages and minus for ring gages. ll dimensions are in inches. The amount taper deviation for Class X, Class Y, and Class Z gages are the same, respectively, as the amounts shown for tolerances on diameter. deviation is the permissible allowance from true taper at any point diameter in the length the gage. On taper plug gages, this deviation may be applied only in the direction which decreases the rate taper. On taper ring gages, this deviation may be applied only in the direction which increases the rate taper. Tolerances on two-decimal dimensions are ± British Standard s. British Standard 1660: 1972, Machine s, Reduction Sleeves, and Extension Sockets, contains dimensions for self-holding and self-releasing tapers, reduction sleeves, extension sockets, and turret sockets for tools having Morse and metric 5 per cent taper shanks. dapters for use with 7 24 tapers and dimensions for spindle noses and tool shanks with self-release tapers and cotter slots are included in this Standard.

10 STNDRD TPERS 915 Table 8. Dimensions Morse Sleeves B C D E F G H I K L M Table 9. Morse Sockets Hole and Shank Sizes Morse Morse Morse Size Hole Shank Size Hole Shank Size Hole Shank 1 by by by by by by by by by by by by by by by by by by 6 5 6

11 916 STNDRD TPERS Table 10. Brown & Sharpe Shanks Number 1 c per Foot (inch) Plug at Small End Plug, P Keyway from End Spindle Keyway a rbor Tongue Keyway rbor Tongue Thickness rbor Tongue Mill. Shank B & S b Mach. Standardard Miscell. K S L W T d Stan- D t c c a Special lengths keyway are used instead standard lengths in some places. Standard lengths need not be used when keyway is for driving only and not for admitting key to force out tool. b B & S Standard Plug s are not used in all cases. c dopted by merican Standards ssociation.

12 STNDRD TPERS 917 Table 11. Jarno Shanks Number B C D per foot s for Machine Tool Spindles. Most lathe spindles have Morse tapers, most milling machine spindles have merican Standard tapers, almost all smaller milling machine spindles have R8 tapers, and large vertical milling machine spindles have merican Standard tapers. The spindles drilling machines and the taper shanks twist drills are made to fit the Morse taper. For lathes, the Morse taper is generally used, but lathes may have the Jarno, Brown & Sharpe, or a special taper. Of 33 lathe manufacturers, 20 use the Morse taper; 5, the Jarno; 3 use special tapers their own; 2 use modified Morse (longer than the standard but the same taper); 2 use Reed (which is a short Jarno); 1 uses the Brown & Sharpe standard. For grinding machine centers, Jarno, Morse, and Brown & Sharpe tapers are used. Of ten grinding machine manufacturers, 3 use Brown & Sharpe; 3 use Morse; and 4 use Jarno. The Brown & Sharpe taper is used extensively for milling machine and dividing head spindles. The standard milling machine spindle adopted in 1927 by the milling machine manufacturers the National Machine Tool Builders' ssociation (now The ssociation for Manufacturing Technology [MT]), has a taper inches per foot. This comparatively steep taper was adopted to ensure easy release arbors.

13 918 STNDRD TPERS Table 12. merican National Standard Plug and Ring s for Steep Machine s NSI/SME B per Foot a (Basic) at Line a Tolerances for b Class X Class Y Class Z at Small End a Line to Small End L Overall Body B Opening C a The taper per foot and diameter at gage line are basic dimensions. Dimensions in Column are calculated for reference only. b Tolerances for diameter are plus for plug gages and minus for ring gages. ll dimensions are in inches. The amounts taper deviation for Class X, Class Y, and Class Z gages are the same, respectively, as the amounts shown for tolerances on diameter. deviation is the permissible allowance from true taper at any point diameter in the length the gage. On taper plug gages, this deviation may be applied only in the direction which decreases the rate taper. On taper ring gages, this deviation may be applied only in the direction which increases the rate taper. Tolerances on two-decimal dimensions are ±0.010.

14 STNDRD TPERS 919 Table 13. Jacobs s and Threads for Drill Chucks and Spindles Series B C per Ft. Series B C per Ft a a These dimensions are for the 2 short taper. Thread Size D E Dimension F Max. Min. Max. Min. Max. Min Thread a G Plug Pitch Ring Pitch Size Max Min H b Go Not Go Go Not Go c d a Except for 1 8, 1 10, all threads are now manufactured to the merican National Standard Unified Screw Thread System, Internal Class 2B, External Class 2. Effective date b Tolerances for dimension H are as follows: inch for thread sizes to , inclusive and inch for thread sizes 1 8 to , inclusive. c for Jacobs 0B5 16 chuck is inch, length for 1B5 16 chuck is inch. d for Jacobs 1BS chuck is inch. Usual Chuck Capacities for Different Series Numbers: 0 taper, drill diameters, inch; 1, inch; 2, inch; 2 Short, inch; 3, 0 1 2, , , or inch; 4, inch; 5, 3 8 1; 6, inch; 33, inch. Usual Chuck Capacities for Different Thread Sizes: Size , drill diameters inch; size , drill diameters 0 3 8, , or inch; size , drill diameters 0 1 2, , or inch; size , drill diameters inch; size , drill diameters 0 1 2, , or inch; size , drill diameters inch; size , drill diameters or

15 Table 1. Essential Dimensions merican National Standard Spindle Noses for Milling Machines NSI B (R1998) Face column Usable threads ;;;;;;;;; Standard steep machine X See Note 3 taper inch per ft min;; ;; ;;;;;;;;; E M K Slot and key location X.002 total M Z 920 ;;;;;;;;; Max variation D min C ;;;;;;;; ;;;;;;;; ;; ;;;;;;;; ;;;;;;;; L min section Z-Z ;;;; F G from gage line B gage X X.0004 See note 4 ;;; ;;; STNDRD TPERS Optional Key Construction ;;;; G Z F F J Keyseat Key tight fit in slot when insert key is used G H H Preferred Key Construction ;;; ;;;;

16 Table 1. (Continued) Essential Dimensions merican National Standard Spindle Noses for Milling Machines NSI B (R1998) Size Spindle B Pilot C Clearance Hole for Draw-in Bolt Min. D Minimum Dimension Spindle End to Column E Driving Key F Keyseat F Maximum Height Driving Key G Minimum Keyseat G Distance fromcenter to Driving Keys H Radius Bolt Hole Circle J Size Threads for Bolt Holes UNC-2B K Full rbor Hole in Spindle Min. L Usable Thread for Bolt Hole M (Note 1) (Note 1) ll dimensions are given in inches. Tolerances: Two-digit decimal dimensions ± unless otherwise specified. : Tolerance on rate taper to be inch per foot applied only in direction which decreases rate taper. F Centrality keyway with axis taper total at maximum material condition. (0.002 Total indicator variation) F Centrality solid key with axis taper total at maximum material condition. (0.002 Total indicator variation) Note 1: Holes spaced as shown and located within inch diameter true position. Note 2: Holes spaced as shown and located within inch diameter true position. Note 3: Maximum turnout on test plug: at 1 inch projection from gage line at 12 inch projection from gage line. Note 4: Squareness mounting face measured near mounting bolt hole circle (Note 1) 2.000(Note 2) (Note 2) STNDRD TPERS 921

17 922 STNDRD TPERS Table 2. Essential Dimensions merican National Standard Tool Shanks for Milling Machines NSI B , R1991 Size N Tap Drill Size for Draw-in Thread O Neck P Size Thread for Draw-in Bolt UNC-2B M Pilot R Pilot S Minimum Usable Thread T Minimum Clearance Hole U Size. Distance from Rear Flange to End rbor V Clearance Flange from W Tool Shank Centerline to Driving Slot X Driving Slot Y Distance from Line to Bottom C'bore Z 60 Center K C'bore L ll dimensions are given in inches. Tolerances: Two digit decimal dimensions ± inch unless otherwise specified. M Permissible for Class 2B NoGo gage to enter five threads before interference. N tolerance on rate taper to be inch per foot applied only in direction which increases rate taper. Y Centrality drive slot with axis taper shank inch at maximum material condition. (0.004 inch total indicator variation)

18 STNDRD TPERS 923 Table 3. merican National Standard Draw-in Bolt Ends NSI B , R1991 Size Small End Usable Thread at Small End B ll dimensions are given in inches. Usable Thread on Large C Size Thread for Large End UNC-2 M Size Thread for Small End UNC-2 D Table 4. merican National Standard Pilot Lead on Centering Plugs for Flatback Milling Cutters NSI B (R1998)

19 924 STNDRD TPERS Table 5. Essential Dimensions for merican National Standard Spindle Nose with Large Flange NSI B (R1998) merican Standard Inch Per Ft X See Note 1 Size Diam Size 50 D min Distance from Center to Driving Keys Second Position Spindle Flange B Pilot C Radius Bolt Hole Circles (See Note 3) Clearance Hole for Draw-in Bolt Min. D Min. Dim. Spindle End to Column E Size Threads for Bolt Holes UNC-2B Driving Key F Full rbor Hole in Spindle Min. L Height Driving Key Max. G Keyseat Min. G Usable Thread for Bolt Holes Inner Outer H 2 J 1 J 2 K 1 K 2 M 1 M C M 2 Usable threads K Usable threads Max variation from Line M 1 E min L min section Z-Z K gage X.0004 See note 2 Face Column -X- F G 1 F 1 Drive Key Slot and key location Distance from Center to Driving Keys First Position H Keyseat F ll dimensions are given in inches. Tolerances: Two-digit decimal dimensions ± unless otherwise specified. Tolerance on rate taper to be inch per foot applied only in direction which decreases rate taper. F Centrality solid key with axis taper inch total at maximum material condition. (0.002 inch Total indicator variation) F 1 Centrality keyseat with axis taper inch total at maximum material condition. (0.002 inch Total indicator variation) Note 1: Maximum runout on test plug: at 1 inch projection from gage line at 12 inch projection from gage line. Note 2: Squareness mounting face measured near mounting bolt hole circle. Note 3: Holes located as shown and within inch diameter true position. B Keyseat Key tight fit in slot G 45 J 1 Z 45 J X.002 Total M Z H 1 H 1 2nd Position H 2 H 2 1st Position

20 Size Drill Decimal Equivalent Point when Included ngle =90 Point when Included ngle =118 Size Drill Point on Twist Drills and Centering Tools Decimal Equivalent Point when Included ngle =90 Point when Included ngle =118 Size or Drill Decimal Equivalent Point when Included ngle =90 Point when Included ngle =118 Drill Decimal Equivalent Point when Included ngle = Point when Included ngle =118 STNDRD TPERS 925