Bucket Crane

thingiverse

This is a bucket crane I designed as part of a bucket crane robo-car project. Check out the complete robo car video at https://www.youtube.com/watch?v=AAIU-lIyx6k. It requires some assembly. You can see the assembled bucket crane (without the parts connecting to stepper motor) in assembled.stl. Print Settings: Printer: ForgerTech 2020 Resolution: 0.3mm Notes: I found it challenging to make the parts fit with Lego axles. You might need to adjust some settings to get a good fit. Post-Printing: Gears connecting to the stepper motor. Gears from the other side. Assembly Instructions: You will need to print the following parts: 2 base 2 lower_arm 1 upper_arm_main 1 upper_arm_pulley 1 upper_arm_fork 1 bucket Two strings of about 1 foot long each, for connecting the upper and lower pulleys. 8 3mm screws of about 10mm length, and 2 of 12mm length. You also need 2 Lego gears with 24 teeth and 10 teeth, 3 Lego axles, 15 mm, 40mm and 65mm. In addition, if you want to use the gears to connect to the stepper motor, you need: 1 stepper_rack 1 gear_rack 1 coupler After printing, you need to glue the upper_arm_pulley to upper_arm_main. Make sure the knobs on the pulleys are aligned. You might need to check the fitting of the holes with Lego axles. Some filing with a needle file might be required to get the axles in. Similarly, I also ran a 5mm drill bit through the holes to make sure the axles can turn smoothly. The most important step is to connect the pulleys with string, so that when the lower arm is turning, the pulley in the base drives the upper pulley to turn as well. The radius of the pulleys has a ratio about 9:5, so that when the lower arm rotates 100 degrees, the upper pulley rotates 180 degrees to up raise the bucket straight up. I first tied the strings around the knobs on the two upper arm pulleys. Then connected the upper arm to the lower arms with the 40mm Lego axle, and connected lower arms to the bases with the 65mm Lego axle. Wrapped the strings around to the base pulleys. Carefully got the two ends through the small gap between the pulley and base. This takes some patience. I used a wire to help get the strings through. After both ends are in, put a 3x12mm screws through the center holes at the bottom of the base piece, to fasten the strings. Use the other 4 screw holes on the base pieces to attach them to your truck or wherever you are attaching the bucket crane. After this, turn the axle at the base, you should see the lower arm and upper arm rising up together. The next step is to attach the upper_arm_fork to the upper_arm_main. Again, a little bit filing might be needed to get a snug fit. I put a small screw through the hole to connect them. Glue will also work. The last step is to put the bucket into the fork. Make sure the bucket can turn freely, or you have to do some filing again. Hope this is helpful.