在Python里应用Openscad实现3D建模之3D螺纹建模初探3

在Python里应用Openscad实现3D建模(修改简化版)-4

–SolidPython学习笔记3

• –form https://github.com/SolidCode/SolidPython

参考Parkinbotshortcuts.scad做了部分修改使得代码更为简洁易读

以下是对solidpython的readme的学习笔记(其中的部分code进行了简化)：

3D螺纹建模初探3

絮絮叨叨

• 到目前我们已经分析了3D螺纹建模的2个解决方案：扭出来和糊出来（好恶俗的名字。。。）
• 从以上的分析中我们应用PY代码初步实现了标准化的（符合ISO261）3D螺纹
• 接下来我们探讨目前最为流行的方案，并进一步实现定制

方案三：垒出来 Solution Three: Sweep polyhedrons

• 该方案是目前thingiverse上最为流行的方案包括：
  • NUT JOB | Nut, Bolt, Washer and Threaded Rod Factory by mike_mattala - Thingiverse
  • Poor man’s openscad screw library by aubenc - Thingiverse
  • Screw Library by syvwlch - Thingiverse
  • screw_thread.py
• 该方案首先创建一个多面体，然后螺旋堆叠出来一个巨大的多面体
• 这个方案不太好懂，以上几种方案中第一和第二个方案（较早）的螺纹建模（姑且叫衰人（Poorman）方案吧）是一样的，而Poorman的作者aubenc提到了更早的第3个方案
• 以下就是

衰人方案:

scad代码：

module full_thread (ttn,//ttn=round(length/P)+1;圈数
                    st, //P
                    sn, //sn=floor(Dmaj*pi/fs);fs=pi/2  sengments  圆段数
                    zt, // zt=P/fn
                    Ifxy, //angle_xy=360/fn;
                    or, // Rmaj
                    ir //Rmin
                   )
{
  if(ir >= 0.2)
  {
    for(i=[0:ttn-1])
    {
        for(j=[0:sn-1])
        {
         pt = [[0,0,i*st-st],
                 [ir*cos(j*angle_xy),     ir*sin(j*angle_xy),     i*st+j*zt-st       ],
                 [ir*cos((j+1)*angle_xy), ir*sin((j+1)*angle_xy), i*st+(j+1)*zt-st   ],
              [0,0,i*st],
                 [or*cos(j*angle_xy),     or*sin(j*angle_xy),     i*st+j*zt-st/2     ],
                 [or*cos((j+1)*angle_xy), or*sin((j+1)*angle_xy), i*st+(j+1)*zt-st/2 ],
                 [ir*cos(j*angle_xy),     ir*sin(j*angle_xy),     i*st+j*zt          ],
                 [ir*cos((j+1)*angle_xy), ir*sin((j+1)*angle_xy), i*st+(j+1)*zt      ],
                 [0,0,i*st+st]];

            polyhedron(points=pt,faces=[[1,0,3],[1,3,6],[6,3,8],[1,6,4], //changed triangles to faces (to be deprecated)
                                     [0,1,2],[1,4,2],[2,4,5],[5,4,6],[5,6,7],[7,6,8],
                                     [7,8,3],[0,2,3],[3,2,7],[7,2,5]	]);
        }
    }
  }
  else
  {
    echo("Step Degrees too agresive, the thread will not be made!!");
    echo("Try to increase de value for the degrees and/or...");
    echo(" decrease the pitch value and/or...");
    echo(" increase the outer diameter value.");
  }
}

• 我们看一下生成的螺纹的截面：

• 可以看出仍是个伪标准螺纹，我们在下面的scad代码中修改一下
• Or = Rmaj + 1 / 8 * H
• 应用布尔运算修改

衰人方案ISO标准修订版之scad代码

use <shortcuts.scad>;
use<Nut_Job.scad>;
Dmaj = 10;
P = 1;
H = .866 * P;
$fn = 36;
length = 10;
Rmaj = Dmaj / 2;
Rmin = Dmaj / 2 - 5 / 8 * H;
Od = Dmaj+H/4
projection(){
    Ry(90)
        I(){
            U(){
                Tz(.5*length)Cy(r=Rmin, h=length);
                screw_thread(Od,1,30,10,PI*5/18,0);
                };
            Tz(.5*length)Cy(r=Rmaj, h=length);
        }
}

• 当然了还有一种方法就是直接修改多面体参数（比如：Po，Fa）

衰人方案ISO标准修订版之python代码：

from solid import *
from solid.utils import *
import viewscad

r = viewscad.Renderer(openscad_exec=r'/Applications/OpenSCAD.app/Contents/MacOS/OpenSCAD')
Dmaj = 10
P = 1
H = .866 * P
segments = 60
length = 10
Rmaj = Dmaj / 2
Rmin = Dmaj / 2 - 5 / 8 * H
def thread_p(Dmaj=10,P=1,length=10):
    angle_xy = 2 * pi / segments
    zt = P / segments
    ttn = round(length / P)
    p3 = 0
    c = []
    for i in range(0,ttn):
        for j in range(0,segments):
            Po = [  [                   0,                    0, i*P+ P                ],#中轴上
                    #近截面
                    [Rmin*cos( j   *angle_xy), Rmin*sin( j   *angle_xy), i*P+ 1/2  *P + j   *zt],
                    [Rmin*cos( j   *angle_xy), Rmin*sin( j   *angle_xy), i*P+ 3/8  *P + j   *zt],
                    [Rmaj*cos( j   *angle_xy), Rmaj*sin( j   *angle_xy), i*P+ 1/16 *P + j   *zt],
                    [Rmaj*cos( j   *angle_xy), Rmaj*sin( j   *angle_xy), i*P- 1/16 *P + j   *zt],
                    [Rmin*cos( j   *angle_xy), Rmin*sin( j   *angle_xy), i*P- 3/8  *P + j   *zt],
                    [Rmin*cos( j   *angle_xy), Rmin*sin( j   *angle_xy), i*P- 1/2  *P + j   *zt],
                    #远截面
                    [Rmin*cos((j+1)*angle_xy), Rmin*sin((j+1)*angle_xy), i*P+ 1/2  *P +(j+1)*zt],
                    [Rmin*cos((j+1)*angle_xy), Rmin*sin((j+1)*angle_xy), i*P+ 3/8  *P +(j+1)*zt],
                    [Rmaj*cos((j+1)*angle_xy), Rmaj*sin((j+1)*angle_xy), i*P+ 1/16 *P +(j+1)*zt],
                    [Rmaj*cos((j+1)*angle_xy), Rmaj*sin((j+1)*angle_xy), i*P- 1/16 *P +(j+1)*zt],
                    [Rmin*cos((j+1)*angle_xy), Rmin*sin((j+1)*angle_xy), i*P- 3/8  *P +(j+1)*zt],
                    [Rmin*cos((j+1)*angle_xy), Rmin*sin((j+1)*angle_xy), i*P- 1/2  *P +(j+1)*zt], 
                    
                    [                   0,                    0, i*P- P                ]#中轴下
                 ]
            Fa =[   [0,1,2,3,4,5,6,13],[13,12,11,10,9,8,7,0],

                    [7,1,0]           ,[13,6,12],
                    [2,1,7,8]         ,[8,9,3,2],
                    [4,3,9,10]        ,[5,4,10,11],

                    [6,5,11,12]
                ]
            if j == 0 and i == 0:
                p3 = bac(P3(Po, Fa))#1st P3
                # p3 += C("red")(Rx()(Le(.1)(Pr()(Rx(90)(P3(Po, Fa))))))# sector of 1st P3
            # c = 0
                for x in range(0,len(Po)):
                    p3 += translate(Po[x]) (C("red")(Sp(.05)))#Po
                    p3 += translate(Po[x]) (Le(.01)(text(text= str(x),size=.2))) #num of Po
            c += P3(Po, Fa)
            # c += Rx()(C("red")(Le(.1)(Rx()(c))))#run the projection() too slow    
    return p3, c
c = thread_p()[0]


# scad_render_to_file(c, "thr_p.scad")
# r.render(c)
c

这是第一个修改后的多面体

c = thread_p()[1]
c

生成的螺纹

c = Pr()(Rx()(c))

c

螺纹截面