For my 100th Open Source project posted here to Thingiverse (Yay!!!!!!), I wanted to make something for the community here that is pure fun. And what could be more fun than something that will fling a gummy bear across the room with enough force to slightly dent a wall (maybe, if you look really really hard?)?
This is designed to use a whole pile of fender washers, some string, some metric bolts, a few bearings, some tape, some wire and a few heat set inserts to create the weapon feared by medieval ant castles throughout Europe!
At any rate, please enjoy, and thank you for liking and supporting all my other work. It means a lot to me that people enjoy the things I create, and your comments and messages over the years have been great encouragement. This ones for you guys!
William of Materials:
1 64mm M8 bolt and nut
1 64mm M5 bolt and nut
5 m3 10mm cone head screw with 2 nuts (non locking)
8 14mm M3 cone head screws
4x 14x5x5 bearings
2x 608zz bearings
2x m8 washers
a metric crapton of M5 fender washers
a 200mm length of threaded M5 rod (or similar English size) and 4 regular nuts
4 nyloc nuts to fit your threaded rod
2 finish washers to act as buhings against the frame
1 small metal ring for sling
2 small pieces of wire, one to make the sling hook and one to make the release trigger
some plastic packing tape to make a sling
some black thread to make a sling
15 M3 heat set inserts
4 10mm M3 cap head bolts
9 rubber stick on furniture feet
Print all of the parts. you will want to end up with 4 of the legs so print that file twice.
- Insert 6 heat set inserts into the base plate. 4 at the corner lobes, and 2 in the two centerline holes.
- Insert 3 heatset inserts into the bottom of each main frame side
- insert 3 heat set inserts into the holes in the lower throwing arm
- bolt the chute to the base plate using 2 of the cone head screws with the tapered end facing towards whichever direction you want the sling to go out of the main frame when you fire. See pictures.
- bolt all the legs to the base using the M3 cap head screws. They are directional
- Fit the flappers to the main frames. The screw head shoulf be on the outside, with the nut on the inside. The flappers should move loosely and fall easily but not be so, loose that they are in danger of falling off.
- Bolt the two side frames to the base plate with the longer cone head m3 screws
- Bolt the two 608zz bolts and washers to the main frame pieces with the M8 bolt, sandwiching the two trigger pieces on either side of the frame. See pictures
- Bolt the spacer to the front of the frame using the M5 bolt and nut.
- Bend one piece of wire to an L shape with 2 loops on either end. one loop will go around the trigger pin, the other loop will go around the screw that holds the two arm halves in place
- Bolt the two arm halves together ith the wire sandwiched in between.
- Insert the other piece of wire into the top of the trebuchet arm and bend at a slight angle. See pictures.
13 Bolt 2 14mm bearings to the side of the arm using 2 longer m3 cone head screws. Use washers as spacers if needed. These bearings act as wheels for the arm on the two frame rails.
14.Insert the two lower bearings in place. I actually ended up using washers and 2 nyloc bolts here instead to resolve an arm tracking issue.
- Insert the threaded rod and then use two nyloc nuts and the 2 finish washers to center it on the frame. The finish washers should lightly touch the frame but not compress it at all. Check that the arm can move up and down the slot all the way with no resistance.
- Load an even number of washers or other heavy objects onto the threaded rod. finish with at least one nut on both ends of the threaded rod. Balance is important here.
- Make a trigger pin out of a metal rod and some string.
- Now construct your sling. When folded in half, the sling should be about as long as the length of the throwing arm down to the two side wheels. The one shown in the prototype is slightly too short. Thread a piece of string thorugh the hole in the end of the trebuchet arm, wrap tape over it to make a pouch, thread another piece of string through the bottom and attach a small metal ring to the other piece of string as seen in the pictures. The metal ring is required to ensure the sling flies off the arm sling pin at the proper point of flight.
You should now be ready to test fire!
Troubleshooting your trebuchet:
If the sling does not seem to open, adjust the angle or length of the pin. My pin is pretty close to ideal so you can use the pictures as a guide. You can also try adding a heavier ring.
If the projectile doesn't go forward, adjust the angle of the pin, or consider shortening the sling.
If the flappers don't fall down, loosen the side screws slightly, or trim them to fit better.
If you accidentally shoot your sibling in the eye, don't do that! Its all fun and games until someone loses an eye, then its just fun!
All the STEP files are uploaded, if you need a different format for some reason, please don't hesitate to ask! also stay tuned for the laser target designator attachment and the picatinny scope mount!
Push Plastics ABS
The arm at least needs to be pretty high, I printed it at 85%
Orange! no wait, Blue AIEEEE