Zheng3 Penny Ballista

by zheng3, published

Zheng3 Penny Ballista by zheng3 May 22, 2012

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Zheng3 Penny Ballista by zheng3 is licensed under the Creative Commons - Attribution license.

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Oye! Oye!

Brenda the articulated battle tardigrade has been released into the wilds of 3D printing!

Join the Horde to be among the first humanoids to learn about the next epic project from Zheng Labs!

We now return you to your regular model description.

This nefarious device can easily launch a U.S. penny across a room when printed at 1:1 scale.

It's the first upgrade many Seej players seek when they need a little more oomph than the Zheng3 Penny Catapult can provide.

Seej is an open-source tabletop wargame based around 3D printing. Rules for Seej are at s33j.net

Do you need this in your arsenal? Yes. Yes you do.

Penny not included!


Construction is really simple! Needlenose pliers are recommended, but not strictly necessary.
You'll need two elastic bands to complete this ballista. Tie a single band through the bore on one of the two D-shaped locking keys. Repeat the process with the other locking key.
Feed the end of one band through the rectangular bore on the ballista's left post. Insert the tenons of the locking key into the square mortises on the post to lock the band in place. You'll be tempted to repeat the process with the other side, but don't give in. It will save you precious minutes of frustration.
Unlike the Zheng3 Penny Catapult, these locking keys should be a snug fit. If some settling of the plastic during printing has made the mortises too small, trim the tenons a bit with your blade of choice.
Center the nock on the knot that connects the two rubber bands. Make sure that the penny's cradle is facing forward.
Feed the end of the band that's been locked down through the rectangular bore on the nock. Tie the free end of the band to the second band. Now feed the free end of the second band through the outside of the rectangular bore on the right post and loop it through the second locking key.
The nock has a wee nub on its underside. Slide this nub into the ballista's firing groove; it will improve accuracy.
Load a penny into the nock, pull it back, and fire away. Be safe!
Seej is a tabletop wargame based around 3D printing. Check out http://www.s33j.net for rules and more information.
Or just jump right in and download the Seej Starter Set: http://www.thingiverse.com/thing:24013
You can also search Thingiverse for Things with the seej tag.

Be sure to check Zheng3.com for updates. If twitter's more your thing than follow Zheng3 at https://twitter.com/Zheng3_Jim
Flagrant stagecraft alert: There's a piece of hookup wire holding the nock in firing position for dramatic flair.
Thing-O-Matic users may want to check out the Zheng3 Short Stock Penny Ballista, which will fit on a 120x120mm build platform: http://www.thingiverse.com/thing:23545/
EDIT 6/1/12: There's a new STL that fixes some flipped normals and weird N-gons on the locking keys. If you're having problems printing the previous version, try the clean model. ReplicatorG is pretty forgiving, but other slicing software may be less so. Good luck. We're all counting on you.

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Comments deleted.

Hi, can you make a version with a wedged slot like the Micro Ballista?

WARNING; This design is pure rubbish. If you somehow manage to build it the holder doesn't fit a penny and if you try to shoot it simply falls out. When you do manage to shoot the damn thing the holder flops all over the place and the penny goes like 2 feet even with the band pulled back hard. Don't waste your time and material printing this.

I'm sorry this design didn't work out for you. I wish you peace and love in 2017, my friend.

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how do i even put it together

looks good and yet to print

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Printed this, really not happy with it. The half-moon pieces that are supposed to have the rubber band wrap around them don't fit in the slots, even after filing or cutting. The penny doesn't stay in the shooter, and the launcher usually flips up when firing. Only got one successful launch, and it was with a dime.

I had the same problem.

There were a couple problems with this particular one. I am currently designing another one. I have version one done. My least favorite part about this one is that the penny always falls out when I am shooting. Also the things on the ends were not fitting in. My modified version is much bigger, goes much farther, and also has a better holder so you can hold the penny in while you are drawing back. Once I am done I will post it as a remix. I also want to point out the simplicity of this design as I was able to make my new one which is similar in shape, in tinkercad. Make sure that when you shoot don't point down or the penny will fall right out

About to print any advice

every time i pull it back the penny just falls out

Which Program should I open this into? I can't seem open it in sketch-up.

For 3D printing, STL files are usually opened up by your choice of slicer software. Some examples are Slic3r, Cura (both free) and Simplify3d (not free).

You can open them in Sketchup by installing the STL plugin and then importing. This will allow you to make modifications to the 3D model although there are some issues and limitations with this.

Can you split this to separate files please the launching pad bit failed and don't want to have to print it all out again????

Open the file in CURA, right click on it and choose 'split parts'. Now you can remove bits you don't want to print.

sadly i dont have money to launch :,(

I can print it for you

same here it cost to much to print for me :(
(i don't have a 3d printer)

I can print it for you

Cant u print the ammo:)?

Could you offer the pieces as separate files? I can't figure out how to break them down because my printer keeps messing up one part but not the others, so I don't want to keep doing full reprints of all four peices

bro there is a split button in you slicer software.

so um, why is the penny not included?


Oh! Cool. I'll let you know how this comes out. Cant wait to annoy my coworkers. =)

@IoFabLab I had the same problem. I just loaded the STL into Cura and right click > split parts.

I'm having trouble printing everything together...the penny holder keeps breaking free...what's the best way to separate each item and print them on their own? I want to try printing this piece "flat". Thanks

Hey zheng3, is this copyrighted? I would like to use and distribute it.

Is Creative Commons - Attribution use this: http://www.thingiverse.com/thing:23464/attribution_card

Zheng3 Penny Ballista
by zheng3

Does it have to be printed at 100%?

Just printed this and I think you should make it so the penny carriage stays on track, other than that, it's pretty damn cool!
Thanks for sharing!

This is a great idea, but few improvements will go a long way towards the easy construction and firing of this device. Please take these points as constructive criticism, since I admire your work and the fact you're sharing it with us.

  1. Enable the nock to go into the tunnel without leaving it. I don't have the proper technical names, so I'm sorry if it's unclear, but the fact that the nock can just leave the tunnel at any timepoint is really annoying, and also detracts from the accuracy.
  2. Create hooks or other similar add-ons on the nock, to tie the bands there. Tying them around the nock itself is particularly bothersome and prone to mishaps.
    I would do the alterations myself, but as I have no skill with 3D designing, all that's left for me to do is give advice to others :)
    Again, thank you for sharing your work!

Thanks, those are excellent ideas. I'll take them into account for the next iteration.

Soon to be leaving thingiverse because of Makerbot's behavior towards open source.
Details: http://www.fabbaloo.com/blog/2014/5/25/has-makerbot-crossed-the-line-for-some-yeshttp://www.fabbaloo.com/blog/2...

Thanks for this ballista I just printed it. Tommorow I will get the rubber bands and we´ll see if it works

I printed the ballista and it looks great. The problem I am having now is that I cannot figure out how to attach the rubber bands. I have them both connected to the half-round pieces but I can't figure out how to connect the two rubber bands without offsetting the penny holder. It says to center the holder on the knot but that doesn't seem to work out. Am I really supposed to tie the two rubber bands together? Wouldn't some type of hook have worked?

Did you ever figure out the rubber bands? I just printed this thing and can't figure it out either....

Can you upload just the parts as files? When I printed, only the crossbow came out correctly.

Looks like you designed this for US elastic bands. NL bands are larger and almost impossible to fit in. FYI, NL bands are 8mm wide and 1mm thick. (might be the same for the whole of europe, don't know that)

It is possible to get these bands in, but I damaged the band during insertion. So I hope it will hold up during use.

Has anyone tried printing the pennies to shoot with this?

I know this is a late post, but i have the file right here: http://www.thingiverse.com/thing:1320911

Fake ammo for penny weapons

Had a problem printing, the carriage for the penny broke free from the pad. Can you post the file as individual pieces?

 I can't fit all of the pieces in the 140 mm by 140 mm area on my Up! Plus. Is it possible to get a zip of the separate pieces so I can print them out separately?

You might want to take a look at the Short-Stock ballista. It's made for a 120x120 platform.


I think MeshLab or Netfabb basic (both free as in beer) should let you break up the STLs into their component parts until I can get around to making that zip for you.

Zheng3 Short Stock Penny Ballista
by zheng3

 Thanks. I saw the short stock just after this and am printing it now.

For this Seej game, are rubber-band powered, penny-tipped battering rams allowed?

Yes! See Core Rule #2 at http://www.s33j.nethttp://www.s33j.net

As long as your opponent agrees to play against you with whatever strange device you bring to the table, it's legal.

When i was creating the gcode for this with slic3r, it came up with the error "This model has overlapping or self-intersecting facets" and "the input file was not marnifold near edge 122.000000-121.000000." When i printed it then it started printing from the layer above the front arch of the ballista. Any idea why this is happening? I printed the catapult the other day and its fun as hell, so i'm dying to get this one printed! Thanks!

EDIT! There's now a model that works with slic3r! There was some nonmanifold geometry around the bow that made slic3r choke but ReplicatorG let through.

I left the original version in place because if it ain't broke, don't fix it. Slic3r users should download zheng3_penny_ballista_slic3r.stl.

FYI both models have sections that are inside out (normals facing the wrong way) Also something weird about the D shaped keys.

You can fix them by sending them through http://cloud.netfabb.comcloud.netfabb.com
What are you using to make the models?

Thanks cyclone for bringing that to my attention. I've fixed the normals and tracked down the funky n-gons in the locking keys. It's now zheng3_penny_ballista_clean.stl

I left the older versions up for continuity.

I'll look into it. I've been using ReplicatorG to generate my gCode... maybe's it's a little less touchy than slic3r for this model.

Great thanks! i tried the shorter version of the ballista too and had the same issue.

I really wanted to print this but it is just barely too large to print without scaling on my 120mm x 120mm Thing-O-Matic heated build platform.

Here you go:


Let us know how it turns out!

Zheng3 Short Stock Penny Ballista
by zheng3

When I go to generate code it says it is still too big but I think it should actually print. I'll let you know how it comes out.

Thingiverse needs more office-weapons. :)

I'm workin' as fast as I can, cap'n!