My Printrbot LC setup experience (Part I)

This weekend I received my first Kickstarter reward: a Printrbot LC. Over about four hours I did most of the mechanical assembly. Here are my notes.

  • Overall, the quality of the kit is excellent. The laser-cut wood parts are precise and snug, and they happen to smell good (lightly burned wood). Everything was appropriately wrapped and protected in the package, and most parts were there (see below).
  • The power cable for the big power supply was missing. This isn’t a big deal because I have extras around the house.
  • There is a controversy (at least, I picked up from the videos that there is one) about square nuts vs. hex nuts. The videos show square nuts, with a few exceptions where hex are required. However, the shipping kits include only hex nuts, and Brook is adamant they’re largely interchangeable.
    There is, however, a definite need for four square nuts that the kit doesn’t include. LC parts 170 and 171 are designed explicitly for square nuts, and I couldn’t figure out a way to make hex nuts fit. I went to OSH and bought four #6-32 square nuts, and I recommend you do, too. It’s possible I’m confused about this; I have an email out to the company about it.

  • The passive assembly that holds one end of the long tread is held together with a 516”-18 x 1.25” bolt. I assembled it correctly and ran out of room for the lock nut at the end. So on my OSH trip I also got a 1.5” bolt, and that worked. I later measured the kit bolt and discovered it was only one inch long. So check your kit and make sure you got the extra quarter-inch to avoid frustration.

  • There was something in one of the videos about Kapton tape for the thermistor. I’m not sure whether this was missing from the kit or that I’m supposed to get it myself. I went to two stores and nobody had any idea what I was talking about. So I’m stuck there.

  • Likewise, there was something about getting a custom-cut piece of glass. I don’t know whether this is optional or what it’s for.

  • I broke almost every printed part during assembly. I cracked one of the gears (#7) and split another. A bolt broke off inside the extruder body (#1), so only one of the springy bolts is there. I also split part of the extruder body. By the time I reached the last gear in assembly, I was too afraid to mess with it, so now I have a loose-fitting gear that’s probably not going to work. I thought I was being suitably gentle with the parts, but there must be some finesse I need to learn.

  • Pro tip: the clips that hold the short tread (#10) look like they take the very short bolts, but they take the next size up. You’ll figure this out when you run out of short bolts.

  • There is something I’m not getting about the four metric bolts holding the heating element on its mounting board, because the end of one of the bolts hits the zip-tie holding the linear bearings, so I can’t move the board farther than about halfway along that axis. The shorter bolt size doesn’t fit, so this must be the right size.

  • The quality of the printed parts… well, look. We’re at the beginning of an exciting time in personal manufacturing, and I know I’m on the bleeding edge. But these parts apparently need a lot of work after they come off the machine, and even then they’re not going to be as strong as solid pieces of plastic (this is why I split so many parts; they’re made of consecutive layers of material, and the layers are susceptible to separating). That’s just how it is, and it’s not a knock on the Printrbot. Part of me wants to send the files for the printed parts off to a more conventional plastic manufacturer and get super strong, high-tolerance parts that I don’t have to polish, drill, and re-glue. But that would kind of miss the point of this manufacturing revolution that’s starting now.

  • I can tell that this machine is going to be something I get to know really well if I become proficient with printing. By that I mean I’ll be calibrating it and probably readjusting parts frequently. Again, this isn’t a criticism of this model. These kinds of printers are meant to be made of simple off-the-shelf parts and parts that it can print itself. In exchange for not requiring incredibly precise and expensive machining of the parts, you get to calibrate it yourself. It’s a fine tradeoff, but not for someone who thinks “it’s like a $100 laser printer except it prints things instead of paper.” It’s more involved than that.

  • A nice touch is that the assembled machine still fits (length/width) in the shipping box. So I can gather it all up from the spread on the kitchen table and conveniently put it away at the end of the evening.

Part II of this series will be hooking up the wires, plugging it in, and getting it to print its first parts. I expect those parts will be the parts I broke; even if I’ve sufficiently repaired the originals, it’ll be smart to have a second set on hand.

By the way, my kids are pretty excited about this thing. My daughter wants coat hooks for her room. My son wants me to print another printer for him. My youngest daughter is concerned we’re going to print another kid.