MakerBot Industries

Vertex generator by ssured

Ever since I watched Michael Felix create a massive dome using connectors printed on a MakerBot, I have been fascinated with the MakerBottable possibilities when you consider MakerBot elements in combination with other elements (rods, ropes, sticks, stones, wires, springs, lasercuts, etc.). Thing 9560 really caught my eye — an OpenSCAD tool for creating wire-frame models of geometric figures.¹

Thingiverse Web Warrior Marty McGuire proposed a next leap in the comments: imagine joining this tool with another “papercraft” tool to allow you to skin your object.² Ssured and WilliamAAdams have been tag teaming on these platonic solids — so maybe one or the other of them will take this tool even further. Or maybe you, O Reader, will post one first!³

Vertex generator by ssured

Based on thingiverse.com/thing:9359 and thingiverse.com/thing:9203 this script allows to model any vertex. Special thanks for WilliamAAdams' work on OpenScad 3d math! You can use this script to print vertices for creating any wireframe model. The script can accept vectors for all directions the edges have to go. Cut your edges and you have your solid wireframe model. For fun and pleasure, and for all math enthousiasts, all regular solids are added to the script. See the script for details on how to generate the vertices.

This thing brought to you by

1. Toothpick geodesic domes, anybody? [↩]
2. From geometric model to enclosure! [↩]
3. Marty also mentions this interesting paper from CMU last year by Max Hawkins that looks to be compelling reading for someone looking to jump in to this topic. [↩]

What is the real cost of MakerBotting? Nick Starno, MakerBot Engineer decided to find out. He did some SCIENCE and made this handy chart so you can plan things out. You’ll notice that the electricity cost is at $.15 in this equation. That is a little bit more than we pay for it here in NYC, but we thought we’d adjust up in case your electricity is more. You’ll notice that the timing of the centimeter cubes is all the same, even though there are different infill settings. That’s because “cool” was turned on, which makes small layers take 15 seconds so they get a chance to cool. Even with solid infill, it needed to be slowed down to make each layer take 15 seconds and so they are all the same time! In the settings, these each have 1 shell so each model has two perimeters. The time noted here did not include warmup time. Using the new Print-O-Matic functionality in ReplicatorG, this was printed with a .4mm nozzle and a .3mm layer height and 30mm/sec feedrate.

We are proud of our plastic. We get the best plastic possible with great tolerances and we make it as cheap as we can! If you’ve done your own experiments in regards to power usage and costs. Drop us a note in the comments!

Check out this Crunchgear video of John Biggs getting scanned! You’re coming to the party right? It’s not a LAN party, it’s a SCAN party!

In last week’s Robot Hospital, I was remiss in mentioning the test piece I used to demonstrate that Skeinforge issue.  So I just wanted to give credit where it’s due, and spotlight this useful calibration print by the tireless MiseryBot.

This is a really nice calibration piece, and it should be helpful for many issues other than the one I mentioned.  It can also bring out other skeinforge bugs, as you can see from the main item photo.

And of course, it’s brilliant at demonstrating the “extra shells” bug — print one with 2 extra shells, and you’ll see see that the narrowest X’s and O’s are unfilled — then print one with zero extra shells and it’s hunky dory.  Remember that next time you’re printing an item with very thin walls and they’re coming out hollow!

And don’t forget to check in tomorrow afternoon for this week’s episode of Robot Hospital!

Wall Thickness Calibration Test Piece by MiseryBot

THIS THING IS FAMOUS! Shows up at 1:54 on this episode of Robot Hospital: youtube.com/watch?v=shpt1hD4z7Y This thing can be used to see what your skeinforge settings and bot will do for certain wall thicknesses: 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2 The OpenSCAD is included in case you want to try other thicknesses. The image has the "as designed" thickness in green, the measured straight wall thickness "as printed" in red (for my bot, of course), and the measured cylinder thickness in purple. My bot is set up with 0.25mm layer thickness and W/T of 2.0 for theoretical wall thickness or 0.5mm. For reference, I am using the MakerBot 0.4mm nozzle, but that really does not come into play. Slightly related to: thingiverse.com/thing:7114

This thing brought to you by

Curling

As printed plastic parts cool the different areas of the object can cool at different rates. ¹  Depending upon the parts being printed, this effect can lead to warping and curling.  Although PLA has a much lower shrinkage factor than ABS, both can warp and curl, potentially ruining a print.  There are some very common ways to deal with this potential problem, the most notable being a heated build platform.  However, sometimes that might not be enough.

1. Use a heated build platform.  A heated build platform helps keep the lowest levels of a print warm as the higher layers are printed.  This allows the overall print to cool more evenly.  A heated build platform, sometimes abbreviated as HBP, helps tremendously with just about any ABS print and large PLA prints.
2. Print with a raft.  Rafts are a printing option in ReplicatorG and Skeinforge.  They’re basically a large flat lattice work of printed material underneath the lower-most layer of your printed object.  They’ll also help reduce warping and curling by allowing your printed object to adhere better to your flat build surface.  Other variations on this are to print with a larger raft and/or a thicker raft comprised of more layers.
3. Calibrate your starting Z height.  A good first layer makes all the difference.  If your starting Z axis height is too high, the extruded filament won’t be able to make a good bond with the platform.  If you think your Z axis starting height is too high, try lowering it by 0.05mm increments until you find a good first layer.
4. Get the right build surface.  Some people have experimented with different surfaces such as steel, titanium, glass, different kinds of plastic, different kinds of tape, and foam board.  However, I find both ABS and PLA seem to stick really well to hot or warm Kapton tape.
5. Clean your build surface.  ABS and PLA stick better to a clean build surface.  Keep it clean of dust, pieces of old prints, and any other debris.
6. Print slower.  Printing slower allows finer detail, better adhesion to the build surface and lower layers, and gives the printed part more time to cool evenly.
7. Print cooler.  Printing at a lower temperature isn’t always an option.  Ideally, you should be printing at the lowest temperature required for extrusion and that allows good interlayer adhesion.  However, trying lower temperatures isn’t for the faint of heart.  Printing at a too low a temperature could cause harm to your extruder motor or extruder.
8. Eliminate drafts or enclose your robot.  Forrest Higgs found that having his 3D printer too close to an open window caused very uneven heating across his build surface.  This in turn caused the side of his prints closest to the window to curl.  Since keeping the window closed wasn’t an option for him, he compensated for the window drafts by adding a heat lamp.  Cupcake and Thing-O-Matic owners might have an easier time of eliminating drafts by simply enclosing two or three of the sides of their robots.  It will also have a fortunate side effect of helping to control fumes.
9. Design with mouse ears.  Zach Smith’s solution was to add little discs to corners of an object to help those corners stick to the platform.  These essentially serve as “mini-rafts” to give those corners more surface area and better adhesion without having to print an entire raft.
10. Design with aprons to hold down corners.  Forrest Higgs suggested adding “aprons” around an object to be printed, while that object was being printed on a raft.  These low thick pieces of plastic help keep the raft flat and help prevent any curling or warping from affecting the desired printed object itself.
11. Design with surrounding thermal walls.  While Forrest Higgs’ apron approach provides a mechanical advantage of essentially holding down corners with a chunk of plastic, Nophead has added thin surrounding walls to his designs to act as baffles to keep warm air around the printed object as it moves around.  He’s postulated that a very thin surrounding wall could have the same beneficial effect as printing inside an enclosed build chamber.  Interestingly, it seems that Nophead suggests that designing objects with more rounded corners might also help avoid curling and warping at those corners.
12. Reduce infill.  When printing a model you can chose to print it hollow, completely solid, or some percentage between zero and 100.  However, as Nophead points out even the plastic inside a model exerts a force on the entire printed object as it cools.  It stands to reason that the more plastic you have, the more those pieces of plastic will pull against themselves and the build surface as they cool.  By reducing infill there will a reduced amount of internal tension as the object cools.  Reducing these internal forces by printing with a lower infill ratio can help reduce curling and warping as well.
13. EDIT:  Sand the Kapton.  Charles Pax has suggested that sanding a Kapton tape build surface will increase the surface area, making it easier for the molten plastic to stick.
14. EDIT:  ABS surface.  Some have suggested essentially painting the build surface with liquid ABS.²  This is has the same effect of laying down a big flat raft.

If you’ve got some suggestions, tips, or tricks that you use to fight warping and curling, please leave a comment below!

1. Photo courtesy of backpackphotography [↩]
2. ABS dissolved in acetone or ABS glue [↩]