51

.95396 •95752 .96110 .96468

.96828

.97186 97546

52

•99354

53

68

97546 97906 .98268 .98630 .98990 .99716 .99716 1.00080 1.00444 1.00808 1.01174 1.01538 1.01906 54 1.01906 1.02272 1.02638 | 1.03006 | 1.03376 1.03744 1.04114 55 1.04114 1.04484 | 1.04854 1.05226 1.05596| 1.05970 1.06342 56 1.06342 1.06716 1.07090 1.07464 1.07840 1.08214 1.08592 57 1.08592 1.08968 1.09346 1.09724 1.10102 1.10482 1.10862 58 1.10862 1.11242 1.11624 1.12006 1.12388 1.12770 1.13154 59 1.13154 1.13538 1.13924 1.14310 1.14696 1.15082 1.15470 60 1.15470 1.15858 1.16248 1.16636 1.17026 1.17418 1.17810 61 1.17810 1.18202 1.18594 1.18988 1.19382 1.19776 1.20172 62 1.20172 1.20568 1.20966 1.21362 1.21762 1.22160 1.22560 63 1.22560 1.22960 1.23362 1.23764 1.24166 1.24570 1.24974 64 1.24974 1.25378 1.25784 1.26190 1.26598 1.27006 1.27414 65 1.27414 1.27824 1.28234 1.28644 1.29056 1.29468 1.29882 66 1.29882 1.30296 1.30710 1.31126 1.31542 1.31960 1.32378 67 1.32378 1.32796 1.33216| 1.33636| 1.34056 1.34478 1.34902 1.34902 1.35326 1.35750 1.36176 1.36602 1.37028 1.37456 69 1.37456 1.37984 1.38314 1.38744 1.39176 1.39608 1.40042 1.40042 1.40476 1.40910 1.41346 1.41782 1.42220 1.42658 71 1.42658 1.43098 1.43538 1.43980 1.44422 1.44864 1.45308 72 1.45308 1.45754 1.46200 1.46646 1.47094 1.47542 1.47992 73 1.47992 1.48442 | 1.48894 | 1.49348 1.49800 1.50256 1.50710 74 1.50710 1.51168 1.51624 1.52084 1.52544 1.53004 1.53466 75 1.53466 1.53928 1.54392 1.54856 1.55322 1.55790 1.56258 76 1.56258 1.56726 1.57196 1.57668 1.58140 1.58612 1.59088 77 1.59088 1.59562 1.60040 1.60516 1.60996 1.61476 1.61966 78 1.61956 1.62440 1.62922 1.63406 1.63892 1.64380 1.64868 1.64868 1.65356 1.65846 1.66338 1.66830 1.67324 1.67820 801.67820 1.68316 1.68814 1.69312 1.69812 1.70314 1.70816 81 1.70816 1.71320 1.71824 1.72332 1.72836 1.73348 1.73858 82 1.73858 1.74368 1.74882 1.75396 1.75910 1.76428 1.76946 83 1.76946 1.77464 1.77984 1.78506 1.79030 1.79554 1.80080 84 1.80080 1.80608 1.81138 1.81668 1.82198 1.82732 1.83266 85 1.83266 1.83802 1.84340 1.84878 1.85418 1.85960 1.86504

70

79

1.86504 1.87048 1.87594 1.88142 1.88690 1.89240 1.89792 87 1.89792 1.90346 1.90902 1.91458 1.92016 1.92576 1.93138

1.93138 1.93700 1.94266 1.94832 1.95400 1.95968 1.96540 89 1.96540 1.97112 1.97686 1.98262 1.98840 1.99420 2.00000

90 2.

Refer to page 262 for explanation of table.

TABLE FOR USE IN COMPUTING TAPERS

IN the table on pages 260 and 261 the quantities when expressed in inches represent the taper per inch corresponding to various angles advancing by 10 minutes from 10 minutes to 90 degrees. If an angle is given as, say, 27 degrees and it is desired to find the corresponding taper in inches, the amount, 0.4894 may be taken directly from the table. This is the taper per inch of length measured as in Fig. 6, along the axis. The taper in inches per foot of length is found by multiplying

27/2

4894

FIG. 6. Taper per Inch and Corresponding Angle

the tabulated quantity by 12, and in this particular case would be 0.4894" X 12 = 5.8728". Where the included angle is not found directly in the table, the taper per inch is found as follows: Assume that the angle in question is 121 degrees, then the nearest angles in the table are 12° 10' and 12° 20′, the respective quantities tabulated under these angles being 0.21314 and 0.21610. The difference between the two is 0.00296, and as 1210 is half way between 12° 10′ and 12° 20′ one half of 0.00296, or 0.00148 is added to 0.21314, giving 0.21462" as the taper of a piece 1 inch in length and of an included angle of 12 degree. The taper per foot equals 0.21362" X 12 = 2.5634".

TABLE FOR DIMENSIONING DOVETAIL SLIDES AND GIBS

THE table on page 263 is figured for machine-tool work, so as to enable one to tell at a glance the amount to be added or subtracted in dimensioning dovetail slides and their gibs, for the usual angles up to 60 degrees. The column for 45-degree dovetails is omitted, as A and B would, of course, be alike for this angle.

In the application of the table, assuming a base with even dimensions, as in the sketch Fig. 7, to obtain the dimensions x and y of the slide Fig. 8, allowing for the gib which may be assumed to be inch thick, the perpendicular depth of the dovetail being § inch, and the angle 60 degrees, look under column A for inch and will be found opposite this that B is 0.360 inch, which subtracted from 2 inches gives 1.640 inches, the dimension x. To find first get the dimension 1.640 inches, then under the column for 60-degree gibs (where C is inch), D is found to be 0.289 inch, which is added to 1.640, giving 1.929 inches.

In practice this dimension is usually made a little larger, say to the nearest 64th, to allow for fitting the gib.

MEASURING EXTERNAL AND INTERNAL DOVETAILS

THE accompanying table of constants is for use with the plug method of sizing dovetail gages, etc. The constants are calculated for the plugs and angles most in use; and to use them a knowledge of arithmetic is all that is required. The formulas by which they were obtained are added for the convenience of those who may have an unusual angle to make.

As an example of the use of the table, suppose that Z, Fig. 9, is the dimension wanted, and that the dimension A and the angle a are known. A glance at the formulas above shows that Z A - D. Then the constant D corresponding to the size of plug and the angle used is subtracted from A and the remainder equals Z. For instance, 4", the plug used 3", and the angle

if A

Ꮓ

=

AD 4"

=

=

30 degrees, then