Introduction
The digger attachment gives your Rover the ability to scoop and lift objects. It clips onto the front of the Rover via the attachment clip. Two arms join the clip to the scoop: the right servo, in the clip, raises and lowers the arms, and the left servo, on the back of the scoop, tilts the scoop. This guide will walk you through printing and assembling the attachment step by step.
Before you start:
- Use two standard (positional) micro servos. Each one is set to an angle, so you calibrate them to 0 before fitting the horns.
- You'll need the Rover and Code Editor during the build. Each servo is set to 0 before its horn goes on.
- The two arms are different. The left arm has pockets for the servo horns on one face. The right arm has round recesses for the M3 screw heads.
Drag to rotate, scroll to zoom
Interactive 3D BuildOverview
The Finished Digger
The digger clips onto the front of the Rover. The right servo lifts the arms and the left servo tilts the scoop. Drag to look around, scroll to zoom, then step through the build.
What You'll Need
Parts:
- 2x Micro Servo (standard, positional)
- 2x M3 x 12mm Screws
- 2x M3 Nuts
- 2x Single-sided Servo Horns (from the servos' accessory bags)
- 4x Servo Mounting Screws (from the servos' accessory bags)
- 2x Servo Horn Screws (from the servos' accessory bags)
Tools:
- 3mm Allen Key
- Phillips Head Screwdriver
- Side Cutters (to trim one horn)
Thingiverse
Printables
Makerworld13D Print Your Parts
- 1x Attachment Clip
- 1x Scoop
- 1x Left Arm
- 1x Right Arm
2Insert the Nuts
- The clip and the scoop each have a servo mount: a box with an opening on the left side for the servo.
- Push an M3 nut into the hex pocket on the inside of each mount's right-hand wall (the wall opposite the servo opening). One goes in the clip and one in the scoop.
- The nuts can fall out until the screws are in, so hold them in place by hand during the next step.
3Attach the Right Arm
- Sit the scoop in front of the clip, opening facing forward, with both servo mounts in line.
- Hold the right arm against the right side of the mounts (the side without the servo openings), with its round recesses facing out. The long straight end goes on the clip and the hooked end on the scoop.
- Screw an M3 x 12mm screw through each end of the arm into the nuts. The heads sit in the recesses.
- Check the fit: the arm and scoop should swing freely on the screws. If they're stiff, back the screws off slightly.
4Install the Right Servo
- Push a micro servo into the clip's mount from the left side, so its tabs sit against the outside of the mount.
- The output shaft faces out to the left, at the back end of the servo (away from the curved hook), in line with the right arm's screw.
- Fix it in place with two servo mounting screws through the tabs.
5Calibrate the Right Servo
- Before attaching a servo horn to a servo, we need to make sure that the servo moves in the correct range.
- Plug the servo into the right servo port on the Rover and set the right servo to 0 in the Code Editor.
- With the servo at 0, press a single-sided horn onto the shaft so it points straight up, away from the clip plate, as in the picture.
6Install the Left Servo
- Push the second micro servo into the mount on the back of the scoop, from the same (left) side as the first.
- The output shaft faces out to the left at the top end of the servo, in line with the right arm's screw on the scoop.
- Fix it in place with two servo mounting screws through the tabs.
7Calibrate the Left Servo
- Plug the servo into the left servo port and set the left servo to 0.
- The horn pocket at the hooked end of the left arm is shorter than a full horn. Using side cutters, trim the second horn's arm off at the first hole so it fits.
- With the servo at 0, press the horn onto the shaft so it points back along the scoop towards the clip, as in the picture.
8Attach the Left Arm
- Leave both servos at 0, so the horns stay where you set them.
- Swing the scoop up on the right arm until both horns line up with the pockets on the inside face of the left arm. The long straight end goes on the clip's servo and the hooked end on the scoop's servo.
- Press the arm onto the horns and secure it with the two servo horn screws, through the arm and into the servo shafts.
- Check the fit: the left arm should sit flat on both horns and parallel to the right arm.
Fit and Test It
- Clip the attachment onto the front of the Rover, with the curved hook around the front end and the plate on top.
- Plug the right servo (in the clip) into the right servo port and the left servo (on the scoop) into the left port. Match the brown wire to the - on the port icon.
- In the Code Editor, set both servos to 0: the arms stand up and the scoop's opening faces up. Then set the right servo to 85 to lower the arms onto the Rover and the left servo to 0 to bring the scoop down flat.
Both servos are positional, so the value is an angle. The right servo moves the arms: 0 is raised and 85 is down on the Rover. The left servo tilts the scoop relative to the arms: lower values tip it forward to empty it. The activity below rests the digger with the right servo at 85 and the left at 0, carries a load at 0 and -20, and tips it out at 10 and -90.
Troubleshooting
- The left arm won't fit over both horns: check both servos are still at 0 and the horns were fitted in the calibrated positions. Re-seat a horn one spline tooth at a time until both line up.
- The left arm won't sit flat on the scoop's horn: trim that horn's arm a little shorter.
- The arms or scoop are stiff: loosen the M3 screws slightly so the right arm swings freely.
- The scoop moves the wrong way or the arms move instead: swap the servo plugs. The clip's servo goes in the right port and the scoop's servo in the left.
- A servo buzzes at the end of its travel: the arms are pressing on the Rover or the scoop is pressing on the ground. Use a value a little closer to 0.
