Hi!

This is an instructable on a geared crane which we have made for a school project.
The crane is controlled by a small dc-motor, but because of the gearing, it can lift quite a lot.

Step 1: Materials & Tools

Materials

6x M3x22mm countersunk bolts
1x M6x30mm bolt
3x M6 washers
1x M6 washer
MDF sheet 625x600
DC-motor
3x AA batteries + batterycase

1x Switch
20cm Wire
40cm String
6mm shaft, possibly a pencil, minimum 100mm long.

Tools

Caliper
Flathead screwdriver
Sandpaper
Lasercutter
(Glue gun)

Step 2: Lasercut Your Parts

Transfer the DXF file to your lasercutter and cut the mechanical parts of the MDF sheet.
(The files are placed close fit for a plate of 625x600, but if your laser cutter can not handle such large plates you will have to split it.)

It's also a good idea to start out by measuring your DC motor if it does not measure 32.6mm +/- 0.1mm, you must modify the dimensions of the holes for the attachment parts of the engine.

Kran.DXF
Download

Step 3: Preparing Parts for Mounting

-Sand the two major ø32 holes, just enough so the engine fits tight.

-Screw the six M3 screws into the large gear.

-Sand the crane 'arm' on both sides till it fits into the two ø6 holes in the "tower".

Step 4: Assembling the Crane

All parts are put together to form the crane.
The two images shows parts which can be put together as subassemblies, and then afterwards joined to fully assemble the crane.

Step 5: Connect the Electrical Components

Connect the circuit of the engine, the switch and the battery pack as shown in the diagram.

We have had little difficulty in determining how many volts engine must have because there is nothing written on it. By 4.5v crane can lift a maximum 'Ruko-key'.
By 9.0V it pulls so hard, that the subassembly with the gear breaks loose. So if you choose to glue, or in another way fix, the geared assembly, the crane can certainly lift a lot more.