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Printrbot PLUS Build with Timelapse and Notes

The Printrbot Kickstarter was a heck of a ride.  After almost 7 months of waiting, our Printrbot PLUS finally arrived.  We've not had much time to work with it since the build, unfortunately, so we'll have to do a post about its performance another time.  For now though, we have a timelapse video of the build and some notes about the build process.

In the spirit of Printrbot, we took this build to the living room coffee table.

We've worked with quite a few printers, and even as experienced builders this build was a beast at 7.5 hours (assembly only, not including calibration, configuration, or any test printing).  This was one of the longer builds among the printers we've used (more than twice as long as the MakerGear Mosaic).  The factors that contributed most to the long build time were the complexity of design, the finishing required on many of the parts, the organization of the kit, and the format of the documentation.  I'll admit that some of the build time was me making mistakes that may have been avoidable, but we'll get to that.

We had several missing parts, as we'll discuss later, but for the purpose of the timelapse we plowed through the assembly as though those parts were there.

Design

The design of the Printrbot PLUS does an excellent job of decreasing cost, which seems to have been a primary design focus.  In our opinion, the appealing price tag has come at the cost of user experience.  Our experience was very much echoed by the users that commented in this thread over in the Printrbot Talk Forum.

On the whole, this was one of the more difficult build processes among the printers we have experience with, primarily because of design features that we found unintuitive to assemble.

Some of the laser cut parts appear to be symmetrical, and seem like they could have been symmetrical, but are not quite.  Using these parts backwards means disassembling larger assemblies and going back many steps, in some cases wasting zip ties that came with the kit.  Most of these parts are marked with an arrow to indicate which side faces the front of the printer, but at these stages in the build it was difficult to tell which side of the printer was the front.  Perhaps a better design feature would have been markings to show where parts mate with each other rather than showing their orientation relative to the completed unit.

We were disappointed in the number of tools required.  The documentation didn't address the tools that would be needed, which included several screwdrivers, hex keys, several pliers, some vice grips (in our case, as a stand-in for larger pliers), snap-ring pliers (pliers can be used if you don't have them, but it's uncomfortable), drill bits to ream parts, blades to trim parts, clips or scissors to snip zip ties, wood glue, extra zip-ties (only if you make mistakes).

There is exactly one piece that needs to be glued in place, even though the same kind of joinery used in the rest of the printer should have been able to be employed here.

 Part Quality

Many of the parts needed various forms of cleanup.  This is something we've seen occasionally from RepRap kits, but never to this extent on the more commercial printers.  For the most part the laser cut pieces fit together well, but there were a few that were tight enough that they required shaving down with a blade to mate properly, or needed holes drilled out to finish incomplete cuts (there was only one of these) or to widen holes to accept the hardware meant to fit through them.  Likely this is a result of overestimating the kerf of the laser cutter or cutting on one that had a smaller kerf than the cutter used to design the printer.

Note the stringing between the teeth of the gear and the z-wobble in the teeth of the smaller gear at the top.

Almost all of the cast parts needed to be cleaned up with a blade, many needed to be reamed to accommodate the parts they mate with.  Likewise, the printed parts needed similar cleanup, holes reamed out, stringing cut off, bits shaved off, etc.  The stringing was worse than we expected, and occurred in ways we haven't seen before, but we also understand how many orders they had to get out and how little time they needed to devote to each print.  Some of the printed parts also had a tendency to delaminate when screwing into or through them (even after some reaming, though apparently not enough), or when reaming them.

Kit

The kit itself was less well organized than other kits we've worked with.  Most kits have tended to have parts separated by type (all of a single part bagged together, for example, separate bags for all of each length of screw), or separated by build stages (all hardware for each assembly bagged together, for example all of the hardware needed for the x-carriage).

This kit had most of the hardware (nuts, screws, springs, etc.) in one bag, which made it more difficult to find the parts as you need them, especially given how many different (but close) screw lengths there are in the kit (another aspect of the design that was frustrating).  Grabbing the wrong part by mistake was a common occurrence because of how similar some of the screw lengths were, and because screw lengths are interchangeable in some places but not others.

Documentation

At the time of our build (and at the time of writing), the only official documentation for the Printrbot PLUS was a part number diagram for the laser cut parts and a set of assembly videos for the Printrbot LC.  The Printrbot PLUS is similar enough to the LC that these build videos are mostly compatible, but the subtle differences were a source of some confusion during the build.  The videos also skipped a few critical steps in the interest of time that caused mistakes that took more time and effort (and zipties) to undo.

The lack of a written set of build instructions or a still photo walkthrough was frustrating because it meant skipping around in the video to find the information needed.  Unofficial assembly instructions and photos on the printrbottalk wiki helped, but were incomplete (they were also not linked to from the official site, which means a user would have to know to look for them).

The electronics connections were not documented well (which heater where, which thermistor where), and not all of the connectors on the board have helpful silkscreen labels.  Electronics connections took more research, some educated guessing, and some trial-and-error, which shouldn't have to happen.  I imagine (and hope) we've just overlooked some helpful resource.

Missing and Broken Parts

Many of the kits shipped had missing or broken parts, as Brook has mentioned in his update videos.  Ours was no exception, but we were taken care of quickly.

We received two extra 8mm bearings in place of a 12mm bearing.  One of the 8mm bearings was defective (not Printrbot's fault), causing some of the balls to spill out upon trying to put it on a rod.  Luckily the extras made this a non-issue.  We were also short several nuts and bolts.  Printrbot was very responsive to these problems and replied to our email within the hour; the parts went out the next day.

There was one issue with what we thought were missing parts that turned out to have not been a kitting mistake, but a design versioning issue.  The printer seems to have been designed for square nuts (and the assembly video shows square nuts in use), but the kit we received used hex nuts.  These worked interchangeably everywhere in the printer except in the assembly that mounts the extruder to the X carriage.

You can see the problem in these photos.  The plate with the square holes is supposed to slide down over the hex nuts as they rest in another assembly.  The problem comes from the corners of the hex nuts sticking out further than a square nut's edges would, colliding with the edges of the square holes in the wood plate.  Hex peg in a square hole.

How the square nuts sit in the unfinished assembly.
The hex nuts in place, the corners extend out further past the edges.
The plate in place, locking the square nuts in place; a very comfortable fit.
The hex nuts in position with the plate resting on top. The plate will not press down without forcing it, risking bending the rails or breaking wooden pieces.

The holes in the plate that slip down over the nuts are square and hex nuts do not fit them.  Others have reported this problem too, so we knew we weren't just missing something obvious.  Upon reporting the missing square nuts, we were told that the hex nuts were  compatible there, a point we disagree on.  You can force them, but this made us nervous. We sourced the square nuts ourselves, as the support person from Printrbot recommended.

We reported the problem to Brook, along with the photos above.  He indicated that forcing it was the solution at the moment, but that he would be updating the design to work properly for future kits.  We're glad to hear it.  Perhaps our plate was cut with slightly tighter holes than others.  We went ahead and used our square nuts.

Our Impressions

While we haven't had much time to work with the printer since its assembly to evaluate its performance, we do have some thoughts on its design as they apply to the end-user assembly experience.

The process for leveling the bed (documented in the Getting Started Guide) involves shims between the bed and the parts that mount the bed to the rails.  It is very difficult and time-consuming to get a precise level dialed in as compared to other printers.  With four attachment points and no springs involved, we also worry that the bed (or a y-axis rod) can be warped (possibly permanently, but definitely temporarily) if a corner is tightened down when the corners aren't properly shimmed.  A warped bed means you don't have a flat surface to print on and a warped rod means your bed won't travel in a straight, level line.  When leveling the bed, we recommend leaving the corner opposite your reference corner slightly looser than the others to try to avoid this potential problem.

Precise and easy bed leveling matters most when printing at high resolutions, when getting going with new materials, or when printing in unfavorable conditions (like varying humidity, which can cause wood printer frames to swell and warp slightly), but it does have an impact on first layer adhesion and print quality all the time.

The lengths of cables in our kit weren't well suited to good cable management, which made it difficult to get the cables out of the way where they won't get snagged and where they look nice.  The power solution is very hacked together, using a PC power supply with adapters and jumpers, but it does work and does probably reduce costs.

We were actually surprised by the hot-end.  It came pre-assembled and seems well designed, was easy to mount, and looks decent.  We're hopeful for its future in the community.

While our comments here on the build process don't shed the most positive light on the printer, the Printrbot PLUS is probably a viable option for those most sensitive to price who are willing to put some time in. For the user who wants a trouble-free build, this may not be the best option, but if you're willing to tinker you might do ok.

Since we're still yet to have logged much time using the printer, we've tried to speak only to the build process and not to operation. If you want more opinions, the printrbottalk forums are a great place to ask questions and find answers.

6 Responses to Printrbot PLUS Build with Timelapse and Notes

  • plexus

    Very nice review. I also backed and built a PB+ and am sitting here printing with it right now. I am also the admin for printrbottalk.com. I am glad the forum and wiki of use to you. I agree with your review however I would caution people that the printer kits that shipped are those to backers from the Kickstarter project. Also a small number of printers were also sold to people outside of the kickstarter project. keep in mind Brook and team had to design, manufacture, pack and ship from 1500-1800 printers. they did so between dec 2011, when the kickstarter project ended, and mid-aug 2012 - call it 9 months. think about what would be involved in doing this. also, Brook's expectation from kickstarter was 50 printers so he and his team were completely unprepared to manage >30x that volume.

    I think they did a STELLAR job.

    That said, its not really a fair review in that the printer kits were hurried out the door. Many kickstarter backers were not happy with the delays and not tolerant or understanding of the volume issue - they just wanted their printers. I believe Brook and team made getting the printer kits out the door the top priority and quality of construction, documentation and other such details were less of a priority. however, they did re-design a number of things and make innovations and enhancements WHILE facilitating manufacturing and shipping.

    Now that the kickstarter rewards are basically fulfilled, I am pretty sure PBHQ (printrbot headquarters) will focus now on providing top notch quality kits and documentation.

    So keep all this mind when reading this review. The kit reviewed was part of the kickstarter backer fulfillment and I believe does not represent the potential of Printrbot moving forward.

  • Alex

    Thank you for your comments plexus.

    You mention that this isn't a fair review because these kits were rushed out the door. I would argue that this is a fair review because it is an accurate representation of our experience with the product. If our experience was similar to that of the other backers, that makes it all the more valid. It's entirely possible that future kits will provide a different experience, but this was ours. The fact that they were rushed out the door is a logical reason for some of the problems we encountered, but at the same time still doesn't change the experience.

    We look forward to seeing what Printrbot will be up to now that their Kickstarter rewards are fulfilled.

  • Steve

    I also have a Printrbot+ and was one of the last to receive a kit. I agree that some aspects of it seem ripe for improvement, but overall I'm very pleased with the kit. What I'm not pleased with is the lack of usable build instructions from Brook. Instead, I had to rely on the excellent set of Wiki posts by Printrbottalk user Badger, though even those omitted some important steps. The included 49-cent power supply, though, is a complete waste and I had to replace it.

    But I did manage and over the past week have calibrated it enough to put out some very nice prints. I spent some time thinking about cable management and found solutions that work well for me.

    This was indeed "my first 3D printer", so I am approaching it from a different perspective than some of you. I agree with plexus that the volume of orders was overwhelming and Brook had a "trial by fire" in volume production. While it certainly could have gone better, I think overall he did well.

  • Tibrol

    I backed this project too and I'm aware that is a "stellar" job as plexus said, but, I'm still waiting my Printrbot PLUS. It's seems that USPS lost the parcel. I've noticed the Printrbot team and I've no answer since the 29th august. They just have to call them (!), I don't understand. Furthermore, many people inquire the team about broken and missing parts. I'm very afraid because I see so much problems...

  • Heri

    Check out the romscraj PortaBee. Way way better build/assembly instructions! http://romscraj.com/carttoo/index.php?route=product/product&product_id=122

    Disclaimer: I am in no way affiliated to them. Just a customer.

  • Roy Emmons
    Roy Emmons on January 26, 2013 at 5:53 am said:

    I have been fighting with my printrbot plus LC for two months and still no good prints. I got half of a igloo built before it stopped extruding. I've tried every temp from 195 to 230 degrees and no luck.
    I've tried light spring pressure to full compressed springs, no luck. At some point it wares a hole in the side of the filament. I then have to pull the filament trim it and start over. 100 times I've done this and still no luck. I do not have a phd in cad-cam but I did build a photo copier out of Legos.
    Is it possible to get a good print without a phd and only a 136 iq?

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