Homebuilt underwater robot

 

Grabber

The grabber is useful tool to retrieve small objects or attach a line to objects located underwater.
GrabberGrabber


The jaws of the grabber are driven by the electric screwdriver. Using electric screwdriver has many advantages:

  1. Easy available
  2. Cheap, cost about 5€.
  3. Powerful - 2.4Nm
  4. Planetary gearbox (low quality)

Because screwdriver is extremely cheap you can consider not to isolate housing! Just buy another one when water damages it. Tests in real environment shows that after a few divings it still works.

Battery part of the screwdriver have to be removed. Model shown on the pictures fits 50mm PVC pipe. Front and back caps are made from Plexiglas. Two simmerings are used as water isolation on front cap.

Electric screwdriver: Torque 2.4Nm, power 6V, Cost 5€.Electric screwdriver: Torque 2.4Nm, power 6V, Cost 5€. Engine without battery packEngine without battery pack Front cap with simmeringsFront cap with simmerings Disassembled engine housingDisassembled engine housing Engine housing: Top viewEngine housing: Top view Grabber partGrabber part Engine and front capEngine and front cap Grabber top viewGrabber top view GrabberGrabber GrabberGrabber Gripper model: Device used to test gripper designs.Gripper model: Device used to test gripper designs. Grabber side viewGrabber side view GrabberGrabber Grabber: Jaws onlyGrabber: Jaws only GrabberGrabber Grabber rear viewGrabber rear view GrabberGrabber Grabber and handGrabber and hand

Details

Grabber DiagramGrabber Diagram

Grabber decomposedGrabber decomposed

Grabber decomposed: Bottom viewGrabber decomposed: Bottom view

Description

Please note, size of the elements is not critical. Availability was the main criterion.

1. Jaws × 2; 10mm Plexiglas
2. Threaded rod Ø8mm × 1; metal
3. Nut assembly × 1
4. Washer × 4
5. Bolt × 4
6. Link actuator arms × 4; aluminum or steel
7. Pivot bush/mount Ø10mm × 2
8. Bearing assembly × 1
9. Simmering sealed front cap × 1; Plexiglas, simmering×2
10. Motor housing; PVC pipe ø50mm × 1, size depends on motor size
11. O-Ring sealed motor housing end cap × 1; Plexiglas + o-ring
12. Nut × 4
13. Compression plate × 1; steel or aluminum, lathe work
14. Washer × 4
15. Studded bar × 4
16. Pivot mount bush Ø8mm × 4
17. Compression plate/mount × 1; steel or aluminum, lathe work
18. Bush × 4; steel or brass (the best)
19. Nut insert × 4

Elements that are permanently connected:

  1. 18+1 (epoxy glue)
  2. 9+10 (epoxy glue)
  3. 5+19 (epoxy glue)

If you are able to use steel as material of the jaws you do not need to use parts 18 and 19. Instead use an ordinary nut.

Corrosion of steel is ignored in this design. Total time in water is relatively short, so paint should be sufficient protection. Another solution is to use stainless steel.

Jaws

In the last step permanently attach sleeves.

How to make jawsHow to make jaws

Dimensions

Grabber dimensionsGrabber dimensions