Robot Sketchtime!
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I recently purchased my first 3d printer. I felt that it would be useful to post information others have shared with me or things I have noticed as I’ve been experimenting with the printing process. I’m by no means an expert or a definitive source of information.
Hardware
I’m currently using a Makerbot Replicator2. Some information I’ll post is specific to printing on the Replicator2.
The Replicator2 was easy to set up. It comes mostly assembled with several zip ties keeping pieces from moving. The only steps required were to load filament, place and level the build platform, and plug it in.
It’s important to note that Makerbot seems to be in this in-between stage of moving from hobbyist/do it yourself 3d printers to plug and play printing. Even though the printer was easy to set up, a few co-workers and myself have run into hardware issues that we had to fix ourselves. For example my thermocouple (the piece that reads the temperature of the extruder) stopped working. Makerbot sent me a replacement part but the printer had to be partially disassembled and the component replaced and connected to the motherboard. Other issues I’ve seen is a co-worker’s replicator arrived with it’s Z-axis screw dislodged, as well as another co-workers thermocouple breaking similarly to mine.
I decided to keep the printer in a room where sound/smell isn’t an issue. I use the bonus room of my house as my office/hobby room and it’s a good spot for the printer. It does make quite a bit of noise and has a smell when printing (similar to a hot glue gun) so I wanted to keep it out of the way.
I stayed in the room with the first few prints I created. I created very small items at first that only took 20 minutes so it was easy to watch the whole object print. The Replicator 2 actually came with a few example items to print, I like to use the comb (20min print) to make sure the printer is working correctly. Now that I’m doing longer prints (3-4 hours), I purchased a wireless webcam that I can view from my iPhone. This allows me to periodically check on the status of my print.
Software
Here’s a quick workflow explanation of how I get my model to the printer(Using an SD Card).
There’s a few ways to get the model into .STL format. Some programs support the format out of the box. Zbrush has a .STL exporter but it’s not very dependable. It asks for the bounding box dimensions on export, so if the sculpt has been changed in a way that distorts your bounding box you will not be able to maintain a consistent size between exports. It also makes it difficult to print multi-part objects.
I export my models from Modo or Zbrush as an .obj file. I convert to .STL using NetFabb Studio Basic. This program also provides important information like size on each axis, surface area and volume. It has standard analysis tools for checking that the mesh is water tight and repair tools for fixing those errors. I usually check my dimensions and correct the scale before saving my .STL file.
For turning the .STL file into gcode I use ReplicatorG. I’ve never actually used Makerbot’s Makerware, from talking to co-workers and reading various posts I gathered I would run into less issues using ReplicatorG. Here I make sure the object is rotated correctly and on the build platform. I recommend placing any important detail facing up(if possible) since the support structure can add imperfections to the suface. ReplicatorG will generate the gcode in the same location as the .STL file.
I haven’t fully explored all of the gcode settings but here’s some notes on the ones I have:
Use Raft/Support: If this is enabled with no support settings it will simply generate a Raft. This is a grid-like structure that is built below the model. When printing a model with thin strips of surface area I found it useful to use a raft. A raft is always built if any support is created.
Exterior Support: This only places support material under pieces hanging off the model like a ledge. It assumes that hanging pieces between parts are short enough to not require support. When I printed an iPhone case the gap for the switch hole was short enough it could cross it while printing and not require support.
Full Support: This places support material under all surfaces. Most of my art pieces need this since they were not built with 3d printing in mind.
Object infill%: The object is filled with a diamond grid pattern, this percent is just how solid the object should be. Filling the object with <10% will make it extremely light and feel fragile, although i’m not sure how strong it is.
Layer Height: I’ve noticed this is the greatest factor in how long my builds take. The default is .27mm but I believe the replicator2 can go down to .1mm. Just keep in mind smaller number = more detail = longer build time.
After generating gcode I do 2 things. First I run gcode->Estimate inside of ReplicatorG. This will give an estimate of the total build time. Second I use the program Repetier-Host to load the gcode and view the tool paths. It displays tool paths as 3d splines so it’s useful for making sure the print looks acceptable.
Once I’ve checked my gcode I save the .X3G file to the SD card using ReplicatorG. I’ve had files not show up on the build menu of the makerbot before, I’d be interested to know if anyone else has ever seen this.
Various Notes
I’ve never actually gotten a model to slice that was higher than 200k triangles. I’ve tried a few higher but the slicer ran out of memory. I’ve read that the slicer can be changed to store smaller gcode and that it may help. This page covers it: https://groups.google.com/forum/?fromgroups=#!topic/makerbot/J3m3AA7ELLQ
I usually dynamesh in Zbrush all of my models that are complex. It’s the easiest way to make my models water tight and one mesh.
Makerbot recommends using painter’s tape on the build platform. I just picked up some 3M 3” wide painters tape at a hardware store. I typically lay down 2 strips side by side, and 2 smaller strips at the front corners. The smaller strips are to make sure when leveling the the build platform I’m measuring over tape.
I always watch the first few layers print. One print had filament raising up after it was printed, this was because there was too much space between the platform and the extruder and the filament wasn’t adhering to the layer below.
Straight and smooth shapes will print faster, the less the printer has to change direction the faster it will print.
A putty knife works really well for detaching the print from the painter’s tape. I also use small needle nose pliers for detaching support structures, and small metal hobby files for removing small support bits that are difficult to remove.
I’ve found I have to be careful removing support structure from thin areas, its very easy to break thin pieces off. Once I find the pattern the support follows I try to pull it off in a zig-zag pattern.
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