Build your own 3D Printer: Frames and Linear Motion!

Build your own 3D Printer: Frames and Linear Motion!

Building a RepRap-style 3D Printer without buying a full kit is still the purist’s way to go – it’s the cheapest and most flexible way of acquiring a 3D printer, but there are a lot of chances where stuff can go wrong. In this mini-series i’ll try to cover the most important spots while Luk builds his iTopie i3!

iTopie i3
Herculien Repository and Community

Frames and Linear Motion!

Hey everyone, Tom here, and while i routinely recommend just buying a printer kit if you want to build your 3D printer yourself, it is still very possible to source all the parts yourself and end up with a better printer for less cash, learn about what makes your printer work and truly make it your own by adding some individual touches. But don’t get me wrong, if you’ve never built one, it can be a very daunting task and leave you pulling your hair out as to why certain things just don’t seem to work. And while i can’t help you with every single issue you might encounter, i can try to guide you through the process, and hey, even if you don’t end up building a printer from scratch, maybe you’ll learn a thing or two in the process anyways.

So in these first few videos, i want to cover the basic set of parts you’ll need to build a printer and what you should keep in mind when selecting them. Let’s get right into it and start out with the most influential part of the printer, the frame. There are a few different options here, depending on what kind of printer you want to end up with.

First off, you’ve got the choice between a regular cartesian machine like most printers or a Delta, basically the choice of a kinematic platform of the entire printer. Deltas look incredibly cool and do have a few advantages when it comes to tall machines, but in general, they are a pain to set up, they can be incredibly wobbly if built incorrectly and have a few other artifacts in their prints that might be pretty hard to diagnose and get rid of. So in general, unless you know exactly what you’re getting into, just build a regular cartesian machine.

The most popular types for those printers are the i3- or Mendel90-style sheet frames, which is what i’ll be using in the form of an iTopie i3, from Sébastien Mischler aka skarab, thanks for sending that over, made from a relatively thick MDF sheet, more on that in a second. This style of printer typically has a center sheet that supports the Z-axis, again, X, Y, Z, when looking at the printer from the front, this is your X-axis, this is your Y-axis and this is your Z-axis, when looking at movement of the nozzle relative to the bed, and this is universally true for any CNC machine, if not, it is set up wrong. So back to the frame, the X-axis will sit on top of the Z-axis with this kind of frame and carry the extruder and hotend, unless it’s a bowden setup. More on that in the next video. The y-axis will be the moving print bed, which isn’t optimal, since you’re also lugging your printed part around and increase the drafts around the heated bed should you choose to add one, but it’s good enough and works for normal-sized printers.

Now, the other type of frame are box frames, like used in something like the Herculien, and I’d consider them mechanically superior, but not in so much that the i3 frames would be completely unusable. These box frames are typically made from aluminum machine profiles, like the ones from Misumi or Rexroth, and they are industry standard parts, so they should be available wherever you intend to buy them. These printers typically rely more heavily on printed parts than sheet-based ones, require more assembly, but offer fewer possibilities for inaccuracies in the frame parts since the aluminum profiles are typically cut precisely to length by the seller. You’re typically also going to need more fasteners and especially the expensive T-nuts that allow you to attach things onto these profiles.

While there are some sheet frames like the Mendel90 that you can cut and drill yourself with a jigsaw and a cordless drill, it’s probably smarter to get the frame ready to use, and like this one, CNC routed or laser cut. There are plenty of sellers that offer ready-to-go frame kits. If you do opt for a wooden one, which really isn’t a bad choice especially if you get one that is thick enough or has these back braces that keep the wood from warping, especially if you’re using plywood, it still a good idea to seal it with Primer and a top coat of paint, and i mean, it also makes it look better than plain brown MDF.

The next thing that you’ll need are printed parts, these are entirely dependent on the printer frame you’ve chosen. If you’ve got as FabLab or Makerspace nearby, that might be a good start to printing them yourself or having them printed – also, if you want to machine the frame yourself, that’s the place to go as well. For the standard printers, like the original Prusa i3, you’re also going to find plenty of cheap printed parts on ebay. Free market for the win! Definitely get them printed from ABS, PLA parts will not stand up to the temperatures around your 3D printer, especially those around the hotend or heated bed.

The next thing you’ll need are linear guides, again, dependent on what type of printer you’re building. The most popular one is still the combination of 8mm rods and LM8UU bearing, they’re incredibly cheap, they work well and practically last forever if you’re using the right rods, but they are not the stiffest type you could choose. Again, they’re good enough, just remember to buy proper chrome-plated and hardened rods for them, you can get those on ebay or Aliexpress. The more high-end option are linear rails like the MGN types from HiWin, and since you can screw the rail to whatever surface you’re using along the entire length of the rail, they’re going to be incredibly stiff, but they’re also way more expensive overall, especially the carriages are much more expensive than LM8UU bearings.

So that should have you covered for building the printer frame. In the next videos, we’re going to dive in and look at the parts you’ll need to add motion to the frame and make it an actual 3D printer. Because, at this point, you could still absolutely turn it into a laser cutter or a super-light-duty CNC router.
Music is No Frills Cumbia Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License