机械臂用舵机平行夹爪

一个由单个 MG90S 舵机驱动的小型机械臂夹爪。舵机带动一个 20 齿齿轮,它再反向带动一个相同的齿轮,所以两边夹口一起开合。每根手指挂在两根等长连杆上(平行四边形),所以在整个行程中两块垫片始终相互平行,而不是沿弧线摆动。在 Grip 动画中,齿轮啮合滚动,手指张开、夹住物体、再张开。校验显示齿轮啮合中心距正确,夹口能张开到你设定的大小、闭合到 8 mm 而不相碰,舵机的 2.0 kg cm 在 30 mm 立方体上每侧约产生 3 N,TPU 垫片能绰绰有余地夹住一块小木块。

舵机平行夹爪:可 3D 打印的模型,57 × 139 × 38 mm
Building the model
Loading the 3D view
No adjustable sizes

Ask for the sizes you want to tweak, e.g. “make the width adjustable”.

默认尺寸下的规格

在 Bambu Lab A1 上用 pla / TPU 实际构建测得。拖动上方滑块时,每个数字都会实时更新。

整体尺寸
57 × 139 × 38 mm
零件数
11
耗材
38 g
打印时间
1 h 52 min
打印盘
1
支撑
不需要

工程校验

校验和参数名称直接来自 CAD 引擎,以英文显示。

  • Gears mesh in phasecentre distance m(z1+z2)/2 = 25.00 mm, 20/20 teeth, module 1.25; overlap 0.000 / 0.000 mm3 at rest / turned 17 deg; contact ratio 1.45; backlash 0.21 mm at the pitch circle (0.1 mm flank gap each side)
  • No tooth undercut20 teeth at 1:1 (20 deg) vs 13 minimum
  • Teeth take the servo's stall torque3.2 MPa at the tooth root (Lewis, Y 0.322) for half of 0.196 N m through the mesh; PLA allows 16.7 (teeth printed flat, along the layers)
  • Jaws stay parallel (four-bar closes)frame pivots and finger pins both 31.4 mm apart, arm and idler both 31.7 mm: a parallelogram, so the finger only translates; idler end meets the finger pin within 0.0e+0 mm at 0/20/30/55 deg
  • Jaw rangeopens to 60 mm at 55 deg, closes to 8 mm at 0 deg with the fingers clear of each other and the frame (overlap 0.00 mm3); 55 deg of servo travel
  • Object fits between the open jaws15.0 mm each side round the 30 mm cube when open; the jaws meet it at 20.3 deg
  • Pads close square on the objectclosed pads touch the cube at x = +-15 mm (overlap 0.00 mm3), 29 mm of pad along it; links and frame clear; open, nothing touches it (0.00 mm3)
  • Grip holds the object3.3 N per jaw at stall (2.0 kg cm through 31.7 mm links at 20 deg); friction 3.3 N vs 0.56 N to hold a 19 g wooden cube at 3 g (a quick lift)
  • Pivot pinsM3 screws as pins: finger loads 10.7 N (arm) and 11.4 N (idler); bore pressure 0.76 MPa (keep under ~5 in PLA), screw shear 1.6 MPa
  • Arm root bending0.6 MPa at the 14 x 5 mm hub for 0.098 N m vs 16.7 along the layers
  • Jaw root bending2.9 MPa at the jaw root (grip x3 for a bump) vs 16.7
  • Horn screw drives the gearstall torque on the M2 horn screw 7.5 mm out: 26 N, 3.1 MPa bearing in the gear vs 16.7; the stock horn screw on the spline centres it
  • Servo seated and screwedMG90S tabs rest on the plate, 2x M2 self-tappers 27.8 mm apart; body passes a window 0.3 mm clear (overlap 0.00 mm3)
  • Pad retaineddovetail 2 mm deep, 1.0 mm undercut each side carries the object's weight; slides in from the tip against a closed back end
  • MG90S servo goes in23 poses along its path clear of every part.
  • 30 mm cube goes in40 poses along its path clear of every part.
  • driver: finger pin goes in20 poses along its path clear of every part.
  • driver: arm pin goes in20 poses along its path clear of every part.
  • driver: gear-right axle goes in20 poses along its path clear of every part.

可调尺寸

设置默认范围
Max jaw opening60 mm40–80 mm
Finger length36 mm24–56 mm
Object size30 mm15–50 mm
Held objectcube—
Pivot screwsM3—

零件清单

零件数量尺寸(mm)耗材时间
base142 × 77 × 2111 g21 min
gear-left127 × 27 × 62 g7 min
gear-right127 × 27 × 62 g7 min
arm-left123 × 41 × 82 g7 min
arm-right123 × 41 × 82 g7 min
idler-left120 × 39 × 61 g6 min
idler-right120 × 39 × 61 g6 min
finger-left111 × 77 × 326 g14 min
finger-right111 × 77 × 326 g14 min
pad-left14 × 29 × 333 g11 min
pad-right14 × 29 × 333 g11 min

制作方法

  1. 按你要夹的东西设置最大夹口张开量和物体尺寸,再选手指长度。
  2. 底座、齿轮、连杆和惰轮用 PLA 平放打印,手指顶面朝下,两块垫片用 TPU 打印。
  3. 把 MG90S 放进底座拧紧耳片螺丝,把舵盘拧在左齿轮下方并压到花键上,再用转轴螺丝装上齿轮、连杆、惰轮和手指。
  4. 从指尖把垫片滑进手指的槽里,让舵机回中,用四个 M3 孔把底座装到机械臂上。

打印建议

  • 齿轮和连杆 3 层壁平放打印;装连杆前先确认两个齿轮能一起顺畅转动。
  • 垫片用 TPU 95A、尾端朝下竖着打印,燕尾槽和筋条会更干净。
  • 转轴螺丝拧到贴合即可,不要夹紧:连杆应能靠自重摆动。

常见问题

能用 SG90 代替 MG90S 吗?

按现有设计不行。SG90 更矮,舵盘会落在齿轮下面。底板、开窗和齿轮高度都是按 MG90S 定的,夹持力数值也是用它的扭矩算的。

能夹多重的东西?

堵转时在 30 mm 立方体上每侧约夹 3 N。配 TPU 垫片可以夹住木块或打印的测试方块这类小而轻的零件。不适合夹重型工具。

需要螺丝吗?

需要:M3 螺丝(用滑块也可改 M2.5 / M4)当转轴销,两颗 M2 螺丝固定舵机,四套 M3 螺丝和螺母把它装到机械臂上。

需要目录里没有的形状? 用文字生成 CAD,用你自己的话描述它

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