Norm and I kicked off July by building a 3D printer, the Printrbot Simple Metal It was the third printer we’ve built, and it was interesting building a printer with a metal frame, but once we got it assembled and did a couple of test prints, we didn’t have time to touch it for a month. I’ve spent much of the last week dialing in the printer, figuring out its nuances, and getting decent prints out of it. We’ll do a Tested In-Depth video with it at some point in the future, but in the meantime, here's what I've learned so far.
First, in the time since we finished the build, the instructions for building the kit version of the Printrbot Simple Metal have been updated. The kit’s assembly instructions have been completely revamped, addressing many of the issues we had during the assembly. Along with good pictures, the newest version of the instructions provides written instructions for non-obvious steps.
I love that the Printrbot makes it easy to make slight Z-axis calibration changes in software rather than hardware.
The instructions for calibrating and making the first print are quite good, and I love that the Printrbot makes it easy to make slight Z-axis calibration changes—a common cause of bad prints—in software rather than hardware. It took two or three false starts, but we were able to print a fan shroud that was good enough to work in two or three tries. Because of the way this type of 3D printing works, it sometimes takes a few minutes for failures to become obvious. To give context, when we built our first printer, the original Makerbot Cupcake, it took almost a week of tweaking to get usable prints.
Once you get past the first print, configuring the software gets a little hairy.
Your printer software lets you place objects on the printer’s build platform, then slice those 3D objects into two dimensional layers. Those two dimensional layers are then converted a series of instructions that describe the movement of the print head and the build platform that the printer can understand, called gcode. The software that Printrbot recommends, Repetier also lets you control the stuff you need to do to maintain the printer--move the print head, the build platform, turn fans on or off, and adjust the temperature of the extruder.
Repetier handles the housekeeping, but gives you multiple options to convert your 3D objects into gcode. Printrbot recommends Slic3r for this task. Configuring Slic3r is tricky. Both Slic3r and Repetier are designed to work with many different types of devices, so you need to do a fair amount of configuration to get them to work with the Printrbot. Some of that is handled by configuration files provided by Printrbot (I had the best luck using the Simple Slow Config), but you’ll also need to tell Repetier about your printer’s printable volume.
I was surprised at the lack of profiles for the Simple Metal that work with different vertical resolutions. Switching the vertical resolution reduces the number of layers that you have to print, which lets you print much faster. While I was able to find a very reliable 0.2mm vertical resolution profile the 0.1mm profiles didn’t work particularly well with our printer. They under-extruded, printing a test cube that had a grid of plastic (think Chex cereal) instead of producing a solid layer of plastic. I love having the granular controls over every variable that this setup provides, so I’m sure I’ll eventually have a 0.1mm profile that’s reliable, but I wish there were better configuration files available for fine, medium, and coarse prints.
I also experienced a few technical problems as I started printing. When we were assembling the printer, we hadn’t locked the hot end into the block well enough. When the printer heated up and the extruder pushed filament through it, the hot end slipped out of the extruder block and dragged through the model and across the build platform. I gouged up the platform pretty badly. Before I realized that the hot end was actually loose, I thought the z-axis sensor had slipped out of alignment and spent some time adjusting it, which was undoubtedly a mistake. Luckily, I was able to cover the damage enough to get good, flat-bottomed prints using blue painter’s tape.
While we’re on the subject of blue painter’s tape, this is the first printer I’ve used in several years that didn’t have a heated build platform (there is a $100 upgrade available though). Typically, users recommend applying a layer of blue painter’s tape to the print bed to help your prints stick and also make them easier to remove once the print is done. If a print breaks loose before it’s done, it’s essentially impossible to recover. At first, I just used whatever tape we had laying around the office, but I had problems with that tape breaking free from the platform and causing the prints to warp. After a quick trip to the hardware store, I had six different types of tape, and eventually found that 3M's Scotch Blue Painter's Tape for Multi-Surfaces #2090 worked really well. I still had some slight warping at the edges of very large prints, but for the most part, the tape stayed stuck to the platform, objects stuck to the tape, and I was able to remove the tape from the prints.
If you’re having adhesion problems, the first thing to do is wipe down the build platform with rubbing alcohol, let it dry, apply your blue painter’s tape, then wipe it down with rubbing alcohol too. The alcohol takes off any leftover manufacturing residues and removes your fingerprint oil. It’s best to get in the habit of wiping down your print surface before every print. Not much sucks more than spending hours on a print only to have it break loose after 5 hours.
I also noticed that the Printrbot is really sensitive to tension on the filament line. If there's any tension in the filament at all, it stops feeding and your print will get messed up. to solve the problem, I put together a simple spindle holder using a couple of pieces of scrap wood and a dowel that I had in my garage, and then printed a couple of filament guides. It solved the problem, but I think I’ll eventually end up making something that holds more than one spindle of filament.
It’s important to note that 3D printing is still in it’s infancy, especially for consumer-priced models like this one. If you’re having other problems, and you will have other problems, this troubleshooting guide will walk you through the most common issues and fixes. In my experience, the most common causes of failed prints are adhesion problems, slicing problems, or poor z-axis calibration. Once you nail those three things, you’ll be able to crank out consistently awesome 3D prints.
I’ve been really pleasantly surprised by what this printer is capable of. It’s $600 assembled or $540 in kit form. After spending a few hours assembling it and a dozen or so hours getting the settings dialed in, I’m getting impressive prints out of it. Best of all, it’s an extensible frame—there are already kits that let you add a heated build platform and upgrade the print head to work with multiple extruders. Because of the way the printer is designed, it wouldn’t even be particularly difficult to upgrade the print volume.
I’ve set up Octoprint on a Raspberry Pi and am now using that to control the printer instead of Repetier. Octoprint is a phenomenal little piece of software that makes the printer essentially standalone—normally, you need to leave a computer hooked up to it while it’s printing. Octoprint lets you control the printer from a browser, check on its progress, and even queue prints. If you have the appropriate camera, you can even watch a live feed of your prints or shoot a timelapse of your build. Next time, I’ll explain how I set up Octoprint and share some timelapses. In the meantime, let us know how you are doing with your 3D printer in the comments below.
Next: Configuring Octoprint and shooting timelapses from the printer's bed.