Summary

The intent here was to create an open ended construction toy to let my kids build and experiment with various types of catapults. The design is very similar to TinkerToys.

Parts are all easy to print, no supports necessary. Just clean up the peg holes if necessary so the dowel rods can slip in (the holes are tapered inward to retain the rods.) (Print out 1 before printing a set to see how it fits for you)

I strongly recommend using these rod lengths as a standard (designed to make 45-45-90 triangles so all lengths are useful)

1.25"
3.25"
4.9"
7.25"
10.56"

Uses 5/16" wooden dowel rods: https://www.amazon.com/Dowel-Rods-Wood-Sticks-Wooden/dp/B08HQ6GWK5?crid=HXTWBSJAC6QB&keywords=5%2F16%2Bwooden%2Bdowels&qid=1681407429&sprefix=5%2F16%2Bwooden%2Bdowl%2Caps%2C173&sr=8-4&th=1&linkCode=ll1&tag=links-after-sept2018-20&linkId=5d52d93ed8b8c1c8f09c36db85e7ccf5&language=en_US&ref_=as_li_ss_tl

Velcro Target pictured: https://www.amazon.com/dp/B0923N157Q?psc=1&linkCode=ll1&tag=links-after-sept2018-20&linkId=ddc4cf2cee94c14e64c117d6dbba1695&language=en_US&ref_=as_li_ss_tl

It works well for its job, though the pieces are larger than I had imagined. The only type of catapult I havent been able to construct is a trebuchet.

Parts are all made with PLA except for the TPU damper which exists to prevent the rods crashing into each other.

Ive considered a major a redesign with smaller rods but wood is too flexible at small diameters so Id have you use expensive materials.

Notes for edu purposes: Recommended age minimum is 6+

Catapult (uses a lever & energy from elastic element)
Trebuchet (uses a lever & energy from weight/gravity)
Ballista (projectile on a guided track )
Slingshot (projectile is not guided by rigid elements)

A few things to think about in your design:
How is the projectile guided before being released?
How is the motion of the throwing arm stopped?
What type of lever does the catapult use? (1st, 2nd, or 3rd class)

How do you think these variables affect the distance and arc of the projectile?
Pull back angle. Launch angle. Arm Length. Effort Force.

vocabulary: Projectile (payload). Pivot (fulcrum). Node (connector). Member (a beam). Frame (an assembly of noes & members) Launchpad. trigger.