April 21, 2023
Description
Attaching a power drill to this model will create a dangerous amount of spin that could shatter some of the parts. Eye protection should be worn and additional precautions should be taken when observers are a part of its operation. Be overly cautious or just use the pull rod which limits the spin.
This was an iteration on the attempt to create a more powerful and resilient toy for my son after similar toys bought for him didn't last or were underwhelming. A battery powered drill or the included pull rod can the used to spin the propeller. The gearing provides a 4:1 mechanical advantage.
A STEP file has been added if you would like to modify this model in any way. Reference the STEP file and this animation for assembly:
2/17/2023 1:06PM PST Adjusted all orientations for strength and added supports required for printing (minimal required).
2/19/2023 11:26 PST V32: Located some newer versions of the parts. Bottom just includes new chamfers. Top includes new chamfers and slight changes to account for interference with Bottom. Large propeller is more refined and has new chamfers. Small propeller is new to this version and will fit most smaller beds. Rack Gear (aka pull rod, rip cord) offsets the finger hole and adds new chamfers. STEP file includes all changes as well. New parts include v32 in their name.
2/20/2023 8:34 V33: Discovered that the propellers worked well with a drill but not the pull rod. Some changes must have been made after my son stopped playing with it daily. Updated the propellers to work better with the pull cord and updated their print settings. Also added another pull rod with a dovetail split for smaller printers that require it. Recommend that glue be used to permanently combine the two pieces. New parts will have v33 in their name.
Why does the propeller just fall off when I pull the toothed rod?
Make sure you are putting the rod (also referred to as a rip cord or rack gear) in the correct side. For reference, hold the handle with your left hand and pull with your right. The propeller is loosely attached and will fly off when the speed of the shaft becomes lower than than that of the propeller.
How long will this take to print?
Your experience will vary. For my printer with a 0.6mm nozzle and custom settings this took less than 12 hours for all parts.
Where do I attach the drill?
Tighten the chuck around the bottom of the part labeled input shaft. This is the shaft that protrudes from the bottom of the housing and is attached to the large gear. Reference the highlighted area below.
What drill should I use?
I used a yellow battery powered drill with a variable trigger, 3/8 inch chuck, and speeds up to 3000 rpms. Whatever you use, avoid high acceleration by pulling the trigger slowly and also wear PPE. Slow trigger pull will avoid stripping the gears and shattering the propeller while the PPE will protect your squishy bits and good looks.
Why do the shafts wobble?
Ensure the seats for the bearings are clear of seams or globs.
Why is it noisy and grinding?
Attempt to center the rectangular aspects of the shaft on the gears. This will leave a small portions exposed above and below the gear (reference highlighted area below). It will act as spacers to isolate the gears from the outer ring of the bearings.
Will it fly?
Like a bird...that is spinning uncontrollably launched from a trebuchet.
How high will this fly?
I don't have a way of precisely measuring this. Using arbitrary units of measure, it goes high enough to get stuck on your roof, fly over fences into your neighbor's yard, and spin for a couple seconds trying to burrow through your drywall ceiling so be careful.
Is it perfect?
Yes, just like an isotropic radiator and your child.
Can you make a left handed version?
No. Use creative mirroring on the parts when printing if you need to.
How long was this in development?
It took an agile team many sprints to achieve this minimum viable product. A month later, the result was a bug ridden product that was good enough for release. Under the release label "Early Access", bugs were eliminated and refinements too costly for a minimum product were made. Roadmaps predict reaching a stable, fully featured product shortly which will then be ready for further monetization with additional addons.
Whose hand should I use to pull the rod?
If you feel strong, your own hand. If you don't feel strong, hit the gym. If you don't have enough motivation to hit the gym, imagine how glorious the launch could be after some intense lifting sessions.
Are the poor quality of the prints in the photos intentional?
No, my printer spent a week and 2500 miles in the back of my truck during a recent move and needs some troubleshooting to diagnose the artefacts. The prints work but are not Instagram worthy. Try to look past their unpleasant exterior and see the beauty inside.
What setup do you use to take photos?
A bright candle, a table, and an old flip phone.
License:
Creative Commons — Attribution — Share Alike
jbaekey
