Monthly Archives: July 2013

Marshmallow Mangonel on the Printrbot Simple


downloadWhen I designed the Penny Catapult to fit on a Replicator1, assuming that printers were only going to get bigger. But the new crop of smaller, inexpensive printers coming down the pike requires a Seej engine that can be printed on a smaller build platform.

Enter the Marshmallow Mangonel. It’ll still throw a penny, but includes a second throwing arm designed for non-coin projectiles; marshmallows, gumballs, magnets, whatever you’ve got lying around that needs to be parabolized. You can find the Mangonel and its bigger brethren in the Seej Engines category in The Forge.

If this is your first exposure to Seej, head over to s33j.net and grab yourself a starter set. Get printing and then get your tabletop wargaming on.

Penny Ballista Fail


download Still using the demo spool of recycled ABS supplied to me by Filabot. When this print doesn’t fail it creates a Penny Ballista that’ll easily launch Abe across the Oval Office.

I left my Replicator1 unattended for a few minutes and came back to this. This fail isn’t due to any flaw in the filament– if you look closely you can see that the texture of the filament’s very even. Unfortunately, robots don’t do what we want them to do, they do what we tell them to do, and the slicing step of this print went to Wallyworld at some point.

I’ve been having this problem with some models sliced in MakerWare lately; it doesn’t seem to want to add a solid bottom layer to some prints. So I hopped back to ReplicatorG and it sliced just fine; see my previous post.

Penny Ballista with Filabot Recycled ABS


download I’m about halfway through the demo spool that Filabot shipped out to me a few weeks ago so I could test their ABS recycling program.

The spool’s given up all pretense of maintaining its orange color and has now faded completely to ABS Natural. This is intentional on Filabot’s part because they’ve sent me what they call an extruder purge– basically a spool created while cleaning a color out of the Filabot.

Earlier I speculated that the recycled ABS was more brittle than other ABSes, but I found that to be a quirk of a short stretch of the filament. I did get a little more powdering and snapped filaments than usual for a while, but a few meters into the spool the problem went away.

This type of problem is consistent with other rolls of ABS I’ve used in the past and as far as I’m concerned it’s just part of hobbyist 3D printing. All ABSes are not created equal and there’s going to be some gremlins along the way.

This ballista will easily launch a U.S. penny across the room using a single rubber band, and I’ll betcha it’ll crack your fancy triple-pane thermal windows or ding your stainless steel fridge. Be careful with this thing and don’t shoot the cat.

Flagrant stagecraft alert: There’s a twist tie holding the nock in firing position for the photo.