How I built a RapMan 3D printer from scratch

3D printing technology is growing rapidly—it’s crawling out of its niche marketplace and showing off how useful and cool it can be. Hell, you can even buy a 3D printer at Staples nowadays. To keep on the pulse, I felt it was time for aggressive expansion into this field: We needed our own printer to use in the TechHive labs. I wanted to learn exactly how a printer worked, so I built one myself instead of purchasing a pre-assembled model.

Is building a printer from a kit easy? No, but for me, that’s part of the fun. I didn't know what exactly I was getting into, but I knew I was more than a match for whatever a kit could throw at me—my over confidence was my weakness. Here are some of the trials and tribulations that come with building a 3D printer from the ground up.

Albert Filice
Oh mysterious box, what mysteries do you hold?

Getting organized

Before tackling my first build—a RapMan 3.1 3D printer kit from BitsFromBytes—I peeked ahead to see what my final result should look like. When complete, the printer is cube-shaped. Steel rods make up the edges, and flat acrylic pieces clamp them together using dozens of screws.

Although the RapMan 3.1 has been discontinued for some time, the parts are up to date, and the printer is compatible with all current open-sourced software. Its instructions were long and somewhat vague at places, but that didn't discourage me: When I got stuck, I turned to online forums and IRC chats for tips.

Albert Filice
A portion of the kit, laid out after a couple hours of poking around and minor assembly.

I didn't want to open anything until I needed it, so I laid out all of the pieces and set aside the parts I would need for the first stage of the assembly process—including various acrylic parts and an organizer tray full of nuts, bolts, and various other small pieces—and put the rest away for the time being. I used sticky notes to keep track of the parts, since some of them differed only very slightly from one another.

Albert Filice
Assemble. Label. Repeat.

The build process

Building the printer proved to be more complex than I anticipated. I spent a couple of hours a day over a week tinkering with it, assembling this printer piece-by-piece and adjusting things as needed. The build time and difficulty will, of course, vary from printer to printer.

With the RapMan, I started with the main support body. Assembling the bottom bracket—the base on which the rest of the printer stands—proved to be a bit tricky. This part needs to be perfectly squared in order to assure that the printer is sturdy (so, you know, no pressure or anything). I constantly swapped leveling guides from side to side to mark my progress.

Albert Filice
Grub screws hold the steel rods in place on the bottom bracket.

The top bracket has parts that allow the print carriage—the part that does the actual printing—to slide smoothly. I first had to affix steel rods to the bottom bracket that would support the top bracket, and make sure it was strong enough for me to pick up and move around. Once I had the top brackets in place, I assembled the Z-axis drive shaft, which moves the print bed downward very precisely, and lets the printer lay down layers less than a quarter of a millimeter thick.

Albert Filice
Here I had just fit the top bracket onto the vertical rods supporting it.

All printers have a print bed—the flat surface that objects are printed on—and a print head carriage—the part that moves the extruder in a set pattern during a print. You can see both in the picture below, and putting these together wasn't hard at all. The belts attached to the motors on the top bracket pull the print head in four directions: The motor circled in green moves it in the direction of the green arrows, and the same goes for the magenta motor and arrows.

Albert Filice
The circled motor moves the print head in the direction of the arrows with corresponding colors.

Once the print bed is in place, check to make sure it’s leveled. But don't use a level—just manually move the print head around to various positions. Measure the distance from the nozzle tip to the print bed, tweaking the screws as you go. That way, you can double-check that the print bed is level in relation to the nozzle.

Albert Filice
Three spring loaded screws allow you to accurately level the print bed.

Pain points and getting crafty

The hardest part of the RapMan was getting the extruder assembly just right. The extruder is crucial—it is the nozzle that squeezes out heated filament during a print. I messed this up early on: I had oriented the mount for the extruder assembly the wrong way, so I had to remove it and swap all the pieces around. This was a grueling process. The worst part was that I was so certain I had done it correctly the first time.

Albert Filice
Extruder assembly must be precise.

Don’t be afraid to bust out your inner MacGyver. I somehow managed to over-tighten a bracket and it cracked. Oops. Luckily, I had some super glue and a pair of clamping pliers to squeeze the crack shut.

Albert Filice
Locking pliers clamp the acrylic while the glue dries.

Another pain point was wiring. As it turned out, my kit was missing the cables that connect the stepper motors to the control board. I opted to pilfer some wires from abandoned power adapters, and use crimped butt connectors to rig them up. I ended up using electrical tape to hold the wires down. Printing small designs generally makes the printer shake, which would knock connections loose and mess up the print.

Albert Filice
Tape holds the connections together while the printer moves.

Voila!

Even though I am pretty much done with the build, my work is far from complete. I still have a lot to learn about the printer and the actual practice of 3D printing in general. The more I've used it, and the more I've printed with it, the more I've learned—but there's been lots of tinkering along the way.

Albert Filice
Done and done. The printer is now ready to print.

The overall process of assembling the printer was a lot of fun, but wasn't always enjoyable. There were moments where I wanted to give up. Taking into account the complexity of the kit and the problems with directions and such, you have to be pretty driven to complete the kit. You’ve got to want it.

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