Introduction
The tipper attachment lets your Rover carry a load and tip it out. A tray is hinged to the front of the robot clip, and a micro servo at the back lifts the rear of the tray through two pairs of arms, so the load slides out over the front. The robot clip wraps around both ends of the Rover's body.
Before you start:
- Use a standard (positional) micro servo, not a continuous rotation one. The servo turns to an angle and holds it, and that angle sets how far the tray tips.
- Tell the arms apart before you start. They are marked on the side: LL (lower arm left), LR (lower arm right), UL (upper arm left) and UR (upper arm right). The lower arm right is the one with a slot for the servo horn on one face.
- Build the left side first. The nut for the left lower arm goes inside the servo box, so it has to go in before the servo does.
Drag to rotate, scroll to zoom
Interactive 3D BuildOverview
The Finished Tipper
The robot clip wraps both ends of the Rover. The tray hinges at the front, and a servo at the back lifts it through two pairs of arms. Drag to look around, scroll to zoom, then step through the build.
What You'll Need
Parts:
- 8x M3 x 10mm Screws
- 8x M3 Nuts
- 2x Servo Mounting Screws (from the servo's accessory bag)
- 1x Servo Horn Screw (from the servo's accessory bag)
- 1x Single-sided servo horn (from the servo's accessory bag)
- 1x Micro Servo (positional)
The build uses seven of the M3 screws and seven of the nuts, so you'll have one of each spare.
Tools:
- Phillips Head Screwdriver
- M3 Allen Key
Thingiverse
Printables
Makerworld13D Print Your Parts
- 1x Robot Clip
- 1x Tipper Tray
- 1x Lower Arm Left
- 1x Lower Arm Right
- 1x Upper Arm Left
- 1x Upper Arm Right
2Attach the Lower Arm Left
- Find the servo box on the robot clip. It sits at the back of the clip, open at the top and on the right-hand side.
- Hold the lower arm left (LL) against the outside of the box's left wall, with its thicker end over the hole in the wall and the LL marking facing out.
- Put an M3 nut into the nut trap on the inside of the wall, then screw an M3 screw in from the outside, through the arm and into the nut.
- Check the fit: stop as soon as the screw is snug. The arm needs to swing freely, so back the screw off a little if it binds.
3Attach the Upper Arm Left
- The upper arm left (UL) is L-shaped. Its short foot goes against the inside face of the free (thinner) end of the lower arm left.
- Press an M3 nut into the hex trap on the foot of the upper arm, then screw an M3 screw in from the outside of the lower arm, into the nut.
- Check the fit: both arms should still pivot freely.
4Install the Servo
- Lower the micro servo into the servo box from above, with its output shaft facing out of the open right-hand side and its tabs against the outside of the box, as shown.
- Fix the servo to the clip with the two servo mounting screws through its tabs.
- Push the single-sided servo horn onto the shaft, but don't screw it on yet. Calibrate the servo first (see the next step).
5Calibrate the Servo
- Before attaching a servo horn to a servo, you need to make sure the servo moves in the correct range.
- Plug the servo into the right port and run the calibration code.
- Upload the code and attach the servo horn to the servo so it is in the correct position when the servo is at 0. The picture shows that position: the horn points straight back along the clip.
6Attach the Lower Arm Right
- Fit the lower arm right (LR) over the servo horn, with the slot on its inner face over the horn and the LR marking facing out. Don't move the horn while you do this, or you'll undo the calibration.
- Fix the arm to the servo with the servo horn screw, through the hole in the arm and into the servo shaft.
- Check the fit: the lower arm right should point the same way as the lower arm left.
7Attach the Upper Arm Right
- Join the upper arm right (UR) to the free end of the lower arm right in the same way as the left side: the foot of the upper arm goes on the inside, with an M3 nut in its hex trap, and the M3 screw goes in from the outside.
8Prepare the Robot Clip
- At the front of the robot clip are two upright hinge ears. Press an M3 nut into the hex trap on the inside face of each one.
9Attach the Tipper Tray
- Lower the tipper tray onto the clip so the two holes at the front of its sides sit outside the clip's hinge ears.
- Screw an M3 screw in from each side, through the tray and into the nut in the hinge ear.
- Check the fit: the tray should swing up and down on the hinge without catching. Loosen the screws slightly if it's stiff.
10Prepare the Tipper Tray
- Tip the tray forward on its hinge so you can reach underneath it.
- Near the back of the tray, two ears hang down from under its raised rear section. Press an M3 nut into the hex trap on the inside face of each one.
Final assembly
11Final Assembly
- Lower the tray back down and line up the top hole of each upper arm with the outside of the tray's rear ear on that side.
- Connect the upper right and upper left arms to the tipper tray with an M3 screw from the outside of each arm, into the nuts.
- Check the fit: with the arms in the calibrated position, the tray should sit flat on the clip.
Fit and Test It
- Push the robot clip down over the Rover so its curved ends wrap around the front and back of the Rover's body, with the tray's hinge at the front (the ultrasonic sensor end) and the servo at the back.
- Plug the servo into the right servo port on the back of the Rover. Match the brown wire to the - on the port icon.
- In the Code Editor, set the right servo to 90. The tray should sit flat. Then set it to -10 to tip the tray, and back to 90 to lower it.
It's a positional servo, so the value sets the angle the servo turns to and holds. The tipper activity below uses 90 as the resting position (tray flat) and -10 to tip out the load. Values in between tip the tray part of the way.
Troubleshooting
- The tray doesn't sit flat at rest, or doesn't tip far enough: the horn is on at the wrong angle. Take the servo horn screw out, lift the lower arm right off the horn, and re-seat the horn one notch around before refitting the arm.
- The servo buzzes and the arms don't move: a joint is too tight. Loosen the M3 screws at the joints and the hinge a little, so every part swings freely by hand.
- The left and right arms don't move together: check both upper arms are screwed to the tray and both lower arms point the same way.
- The servo turns but the right arm doesn't: the horn screw is loose, so the horn is spinning inside the slot. Tighten the servo horn screw.
