1 # Sample: creation of simple twist drill bit
3 pload MODELING VISUALIZATION
5 # drill parameters (some terms taken from http://www.drill-bits.cn/drill-bits-quality.asp)
6 dset R 4. ;# outer radius
8 dset Rr 3.5 ;# chisel radius (outer radius minus body clearance)
10 dset b 1. ;# web thickness (approximate)
13 dset H 80. ;# height of the spiral part
14 dset a 3.*pi ;# total angle of spiral rotation
16 dset sigma 118 ;# point angle, in degrees
18 # Create section profile by sequence of Boolean operations
19 # on simple planar objects
20 puts "Creating the drill section profile..."
22 polyline rectangle1 d -R 0 R -R 0 -d R 0 -R R 0 d -R 0
24 circle circle1 0 0 0 0 0 1 R
25 mkedge circle1 circle1
28 circle circle2 0 0 0 0 0 1 Rr
29 mkedge circle2 circle2
33 mkface rectangle1 p0 rectangle1
34 mkface circle1 p0 circle1
35 mkface circle2 p0 circle2
37 bcommon sec rectangle1 circle1
38 # note use of 'fuse' instead of 'bfuse' -- we need to get single face
41 # Construct flute profile so as to have cutting lip straight after sharpening.
42 # Here we need to take into account spiral shift of the flute edge
43 # along the point length -- the way to do that is to make spiral
44 # from the desired cutting lip edge and then intersect it by plane
45 polyline lip d -d/2 0 d -R -R/tan(sigma/2*pi/180)
47 polyline sp 0 0 0 0 0 H
48 cylinder cc 0 0 0 0 0 1 0 -4 0 4
50 trim ll ll 0 sqrt(a*a+H*H)
54 trotate v2 0 0 0 0 0 1 180.*a/pi
63 mkface f0 p0 -R R -R R
64 bsection sflute spiral f0
66 # here we rely on that section curve is parameterized from 0 to 1
67 # and directed as cutting lip edge;
68 # note that this can change if intersection algorithm is modified
70 mkcurve cflute sflute_1
71 cvalue cflute 0. x0 y0 z0
72 cvalue cflute 1. x1 y1 z1
76 # -- variant: replace curve by arc with start at x0,y0,z0 and end at x1,y1,z1,
77 # -- such that tanget at start point is along Y
78 #dset Rflute ((x1-x0)*(x1-x0)+(y1-y0)*(y1-y0))/(2*(x1-x0))
79 #circle aflute x0+Rflute y0 0 0 0 1 Rflute
80 #mkedge sflute_1 aflute vf0 vf1
82 # make rounding in the flute; use circle with radius Rr/2
83 circle cround x0+Rr/2 y0 0 0 0 1 Rr/2
85 mkedge sflute_2 cround vf3 vf0
89 wire w2 sflute_1 sflute_2 sflute_3 sflute_4
92 # cut flute from profile
94 trotate flute 0 0 0 0 0 1 180.
98 # sweep profile to get a drill body
99 puts "Sweeping the profile..."
107 # sharpen the drill (see http://tool-land.ru/zatochka-sverla.php)
110 dset theta a*R/H*sin((90-sigma/2)*pi/180)
111 plane ax1 d 1.9*D "H+1.9*D/tan(pi/180.*sigma/2.)" 0 -1 -1
112 pcone sh1 ax1 0 100*sin((sigma-90)/2*pi/180.) 100
113 trotate sh1 0 0 0 0 0 1 -theta*180/pi
115 trotate sh2 0 0 0 0 0 1 180
116 box sh -D/2 -D/2 72 D D 20
120 bcut body base sharpener
123 puts "Making a shank..."
124 plane pl2 0 0 -40 0 0 1
125 pcylinder shank pl2 4 40
127 plane pl3 0 0 -40 0 0 -0.5
128 pcone tail pl3 R 0 0.5
129 bfuse shank shank tail
130 bfuse shank shank transit
131 bfuse drill body shank
137 puts "Displaying result..."
143 # show section and sweep path
144 ttranslate sec_1 0 0 H; trotate sec_1 0 0 0 0 0 1 a*180/pi; incmesh gg 0.01; vdisplay gg sec_1