Warning: some parts may break off and present a choking hazard to children, print and use at your own risk
OTHER BITS NEEDED:
Small self tapper screws x3
3M bolts x2 (or something similar)
MY PRINTER SETTINGS:
• 0.6mm nozzle
• Layer height: First layer 0.6mm, other layers 0.4mm
• Filament: PETG,
• Temp: 230 degrees hot end, 70 degrees plate
• Print parts in orientation shown, no supports, most prints will need some clean up. A few prints have an added brim to assist adhesion (I know these can be added in the slicing software but I tend to like brims in certain locations – ie corners, not just everywhere) some bits that slot together need a fair bit of “trimming” with a sharp knife, 0.3mm tolerances have been added in most places to help bits “slide” together, but the 0.6mm nozzle on my printer probably does not help to make printing an accurate science – see what your printer does and adjust to suit (sandpaper and knife work well).
Specific printing considerations
• “boom” is the crane boom, it has an inbuilt end stop that stops the crane boom being lowered below horizontal, think this is good for kids (this is also the second attempt so has been cleaned up a little) “Boom no end stop” can be raised or lowered through full range. Print the one you want (“boom no end stop” does require supports where touching bed)
• The swivel of the crane is made by joining “crane attach base” to the “bottom swivel”. “Top swivel” is not needed. I have added it to the list of files in case you want a swivel for use in making a Duplo helicopter / turntable etc
• When printing “pulley centre” print 2 copies on opposite sides of your build plate. This gives the print some time to cool in between layers and not melt, then use whichever print looks better at the end. If you have a pretty good blower fan this would not be needed (but it works for me )
• Two copies of” Boom cog x2” are required
Super glue or cyanoacrylate is used throughout as glue of choice. See pictures provided for details of construction. Test fit whole structure before gluing.
- Glue “pulley side” to “pulley centre” taking note that the square shaft key lines up, and circular ‘dimples’ are on the outside of the pulley
- Screw M3 bolt into hole in both “boom cog x2” (it will cut its own thread), then cut the bolt off so it sticks out 3-5mm. (if you don’t have an M3 bolt you can use anything about 3mm in diameter and just push and glue it in)
- Push first “boom cogx2” into square hole in boom and glue in place (a bit of trimming likely needed here)
- Bend ends of boom apart and slide in pulley till the hole in its centre clicks into place onto the bolt sticking out of “boom cog x2” you will notice a little protrusion on the boom which locks into the ‘dimples’ on the pulley. This is to provide a bit of resistance to the pulley to stop it unwinding too easily when lifting loads with crane. It sticks out a little too far on purpose, sand or scape it back until you achieve the level of resistance desired.
- Glue other “boom cog x2” into place on the other side of the boom. Ensure that bolt lines up with centre hole of pulley, and that pulley still rotates (ie don’t get any glue on the pulley)
- Test fit “boom clip 1 and 2”onto the boom cogs. The resistance should be enough that the boom holds up under its own weight on any given position, but not so much that you will pull the cane over every time you want to move the boom, scrape or sand back the little bumps on the inside of the circles as required
- Slide the completed boom onto the “crane attach base” a fair bit of trimming was needed here
- Put little self tappers into the holes provided to lock “boom clips” in place on the base
- Test fit “bottom swivel” into the “crane attach base” sand / scrape till a loose fit is achieved
- Screw self tapper into the base to hold the parts together. The self tapper should be small enough to spin freely in the “bottom swivel” but big enough to grip into the “crane attach base”. If you have trouble just drill out the holes as required.
- Place “hook” into “hook block” slide a small bit of 1.75mm filament into the holes to lock it in place and glue together
- Tie string between pulley and hook, use an little glue on the knots
Job done, enjoy! Post pictures of your completed Duplo crane
Free cad file included in downloads if you want to modify it