This instructable shows you how to build a simple super strong hydraulic bridge crane using a smalle piece of MDF, a couple of screws and washers and two syringes.
The crane can be either 3D printed, lasercut or cut by hand using simple handtools and is able to lift a given weight 100mm vertically while being fixed between two tabletops or any other stable platform. To see the crane in action click the video below:
Step 1: Materials & Tools Required
Before you start, you need to get hold of the plans. You can download the files for the laser cutter right here (insert link) and if you want to modify the files or save them as STL's for 3D printing, the files are available through Onshape right here:
For this project you need the following materials:
1: A sheet of 200x550x6 mm MDF, HDF or plywood.
2: 4 m3 machine screws, each with 4 washers and a nut.
3: Two 20 ml syringes and a piece of 5mm tubing to connect the two.
4: A piece of string to attach the object you want to lift.
5: Wood glue
6: Water or mineral oil
You will also need the following tools:
1: Either a laser cutter, a 3D printer with a print volume of 18x18 cm or a jigsaw and a drill.
2: Allen key and wrench.
3: A staple gun is handy to speed up the process when gluing the pieces together but is not strictly necessary.
4: A pair of scissors.
Step 2: Assembly
Above you see the .dxf file made in Adobe Illustrator, which is afterwards loaded onto the laser cutter's software. In this document we made all of the required parts three times, just to have some backup pieces.
After you have cut all pieces, please refer to the online CAD document (https://cad.onshape.com/documents/d7b9b97fb8204d75..., as it is gives you freedom to view and rotate each part and the complete assembly.
A few thoughts on building the crane:
1) When gluing the pieces together, start with the middle of the crane and the linkage system.
2) Since the crane is designed to be symmetrical, you can do the two side truss pieces at the same time, as it will take a while to let the glue set up and dry.
3) After the whole crane has been build, you should let it sit for at least one hour to let the glue dry completely before trying to lift anything
Step 3: Lift Mechanism
When the crane framework is built and ready, you need to add some kind of lift mechanism.
Yo can add either a motor or choose to use two syringes as a hydraulic system.
The crane works with both systems, but the small motor is the strongest solution.
Step 4: Adding Syringes
Glue the small half round pieces to the top of one of the syringes and attach it with a M3 screw, washer and nut to the linkage.
Insert the other end of the syringes into the bottom of the crane framework, attach a hose and connect to the free moving syringe .
Fill with water and you are ready to go.
Step 5: Attach Motor
With our test of the crane we went with a small DC motor running from a small 4.5 volt battery pack.
Depending on the size of your motor, you might have to modify part 10 in Onshape so they fit the OD of the motor.
Attach the small fishing spool wheel to the engine shaft (part 11 and 12 on Onshape) and tie a piece of cord to two of the holes on one side of the reel.
Connect the two wires from the battery pack to the DC motor and the shaft should start rotating thereby lifting the boom of the crane.
It doesn't really matter which way the reel spins, but if you want to make it router either clockwise or counter clockwise you simply swap the wires going from the battery pack to the two poles of the engine.
Step 6: Finito
And wallah! Your compact crane is ready to lift stuff like wood glue and other small peripherals.