First Days With A 3D Printer

My boys and I have had our eyes on 3D printing technology for awhile now.  We’ve noticed many news stories ranging from 3D printed prosthetics helping humans and dogs to ‘beaming’ a wrench up to the International Space Station.  Impressed by the geek factor and hoping to learn something with my kids, I picked up a Printrbot Simple Metal.  Not only is it relatively affordable, but Make Magazine rated it the 3rd best printer in terms of print quality. It’s also driven by open source software.  The basic printer works with PLA plastic filament, which is non-toxic and bio-degradable.

3D Printing

What follows is roughly our first steps and experiences with our 3D printer.

Step 0) Unbox, of course. Brook Drumm, the inventor and owner of Simplebot, has a great series of instructional videos to help get you started.

Remember the first time you experienced that “new electronics” smell? It’s a unique blend of fresh cardboard, molded plastic, and unfettered possibility.

Step 1) Install Repetier and connect it to the printer via a USB port.  Repetier interacts with the 3D printer, allowing you to control the temperature setting on the extruder, feed filament, change the position of each of the X, Y, and Z motors, and so on.  It also integrates with Slic3r, open sourced software that generates G-code based on your printer settings from STL files.  Repetier then feeds to G-codes to your printer in sequence to create an object, layer by layer.  STL files are a common format for 3D objects published on sites like Thingiverse and YouMagine.

We were successful!  It was thrilling to click a button on screen and see our new printer react by moving the print tray or extruder arm back and forth.

Step 2) Add blue tape to the print bed.

This step was a little bit unexpected.  There are varying opinions about the best way to protect your print bed while at the same time allowing your 3D printed object to have something it can bind to.  We started with 3M painters tape from Walmart.

Step 3) Calibrate the auto-leveling probe.  This one-time setup task is explained by an instructional video.  You pass commands to the printer through Repetier to query its probe height and change/save new settings.  The probe is manipulated by as little as a hundredth of a millimeter, but increments of about a tenth of a millimeter are fine until you’re close.  Test each setting by printing a Cube model g-code provided by the Printrbot website.  If your probe is set too high, the filament won’t adhere to the print bed and ends up being a squiggly mess.  The closer you get, you’ll start to see multiple layers of the filament binding more closely together, creating an almost flat, smooth surface.  Get too close, however, and the extruder starts pushing through the plastic, creating what we called “boogers” and “spider webs.”

After many attempts, we finally got a fairly nice looking cube.  It seemed to bind to the print bed tightly during the print and the criss-cross pattern inside the cube seemed to render cleanly.

Step 4) Print something!  Go to Thingiverse and find something fun.  You’ll download an STL file, which is recognized by Repetier.  Before working with the STL model, you’ll need to import the configuration settings provided by Printrbot for the built-in Slic3r software.  From the Object Placement tab in Repetier, you can Add the STL file and scale it to your desired size.  “Slice with Slic3r” takes anywhere from a few moments to a few minutes, depending on the 3D model and computing power.  We’ve gotten in the habit of warming up the extruder before running a new job so we can clean up any excess filament.

We didn’t realize that the Slic3r settings needed to be specified and our first print turned out comically bad.  I was getting a little nervous at first, but had to keep my cool to impress the kids.  Once we had the Slic3r settings in place, we actually printed a double helix model that didn’t look too bad.  However, it had a lot of spider webs and boogering, so we went back to the support forums.  After much pondering and observation, I realized that our probe was set too low and the extruder was actually pushing through the still-hot plastic.

Raising the probe and extruder level caused the first layer of filament to bind loosely to the blue tape. After a few layers the model would become dislodged from the bed, ruining the print.  The simple solution is to scrub the blue tape when first applied with acetone (finger nail polish remover).  This removes wax from the tape surface and any finger oils you might have left when applying the tape.

If you’re still experiencing boogers or spider webs, play around with the Slic3r extruder temperature settings. We’re having pretty good luck with 205 for the first layer and 200 for other layers. Anything within 195 – 210 is supposed to be reasonable. 

Step 5) Mod your printer.  It’s really cool being able to use a device to create something to benefit itself.  Programmers are used to creating and sharing handy software to make their lives easier. It’s pretty amazing being able to grab and print a model for a fan shroud, filament arm, corner pads, and dozens of other improvements.

We really like the open source feel of the maker community. Our next goal is to create something fun or useful and provide it back to Thingiverse.

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