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。

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 opening | 60 mm | 40–80 mm |
| Finger length | 36 mm | 24–56 mm |
| Object size | 30 mm | 15–50 mm |
| Held object | cube | — |
| Pivot screws | M3 | — |
零件清单
| 零件 | 数量 | 尺寸(mm) | 耗材 | 时间 |
|---|---|---|---|---|
| base | 1 | 42 × 77 × 21 | 11 g | 21 min |
| gear-left | 1 | 27 × 27 × 6 | 2 g | 7 min |
| gear-right | 1 | 27 × 27 × 6 | 2 g | 7 min |
| arm-left | 1 | 23 × 41 × 8 | 2 g | 7 min |
| arm-right | 1 | 23 × 41 × 8 | 2 g | 7 min |
| idler-left | 1 | 20 × 39 × 6 | 1 g | 6 min |
| idler-right | 1 | 20 × 39 × 6 | 1 g | 6 min |
| finger-left | 1 | 11 × 77 × 32 | 6 g | 14 min |
| finger-right | 1 | 11 × 77 × 32 | 6 g | 14 min |
| pad-left | 1 | 4 × 29 × 33 | 3 g | 11 min |
| pad-right | 1 | 4 × 29 × 33 | 3 g | 11 min |
制作方法
- 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。
- 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。
- 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。
- 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。
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