3D Printing: Ultimaker Build Notes


Some build notes from my Ultimaker build experience…..

Overall, it took me roughly 4 days to build the Ultimaker. The first two days were a couple of long stretches and the last two were much shorter. Tuning the device to yield usable prints has taken a bit more time, too, and I still have a long ways to go.

At left is a print made using the default firmware with relatively default settings in ReplicatorG. Stringy as heck, but otherwise quite good! Software and hardware tuning are reserved for another article.

This is some random build notes from the build and roughly correspond in order to the assembly instructions themselves.

By and large, assembly was relatively straightforward. The only real disaster I had was with the cooling fan used on the extruder. When I tried to mount it, it shattered — literally disintegrated into dozens of pieces — in my hand.

The Ultimaker arrives in a surprisingly small, heavy, box. No surprise; wood is heavy and the Ultimaker is largely a wooden box with some very crafty electronics built into it. Frankly, the laser-cut wood based construction is, in and of itself, a bit of a hobbyist kit revolution. Wood is cheap and very strong, yielding kits that can be quite precise, extremely durable, and still remain accessibly affordable.

Random notes below the fold…

The Ultimaker assembly guide starts here. It is mostly excellent — really, really, well done, in fact — but there are a couple of rough spots. Having written such step by step guides myself (though about 2 orders of magnitude fewer steps!), I found it amusing — though very occasionally frustrating — that the details sorta become more and more vague as you move through a section. Overall, really, this is a very very well done kit!


The Ultimaker ships with just about all the tools you’ll need. However, the supplied 2mm hex driver was wimpy and I had stripped mine at about the 70% assembled point. It is possible to “repair” by carefully sawing off the tip to expose some un-worn tip. However, a far better solution is to go down to your local metric-carrying hardware store and purchase a handful of 2mm drivers/tips.

You’ll definitely want a pair of thin needle nose pliers on hand. There are a couple of steps that require sticking a nut on a bolt in very out-of-the-way places, sometimes behind other stuff.

Included with the kit is some ~3/4″ wide blue Scotch 2090 tape that is used both during assembly and to cover the bed for purposes of printing. For the bed, grab some 3″ ScotchBlue 2090 Tape as it only takes 3 strips to cover the print bed, leaving two seams in the printing area of the bed (the seams cause noticeable lines in the bottom of your prints).

Make sure you have a fine flat file or fine grained sandpaper on hand. There are a number of steps that involve inserting wood tab A in wood slot B. If it is at all tight, sand down the tab a little bit to make it slide in easily. You don’t want it to be loose, but you really need to make sure the various wood parts fit together completely!

Assembly Notes: Frame

I assembled a Revision 3 Ultimaker. Notes will go stale with future revisions.

As noted in the instructions, you’ll really want to sand the burn marks off the one side of all the cut wood bits.

– When installing the limit switches, there is no need to tighten them. They all have to be calibrate at the end. The very end after you’ve aligned the extruder.

– When tightening the switches, there are no nuts. It is a metal on plastic threads affair and it is easy to strip the threads in the switch. Do not over tighten!

– When putting the frame together, make sure all pieces fit together snugly and uniformly tight. Don’t use the screws to pull things together. This is where you’ll likely need a bit of sanding/filing to ensure that everything fits without forcing. This is to ensure that the frame is square. If it isn’t, you are in for a world of hurt calibrating the printer later!

Assembly Notes: X-Y Motors

This was pretty straightforward, if a bit persnickety. In particular, keeping the three layers of wood, the motor, and the belt all aligned properly when attaching to the frame was quite the challenge.

– For the Y motor, make sure you get the wires behind the motor when you are mounting it! It is a pain to do so after the fact. There is slightly more of a gap between the wood bits and the rear wooden wall than the motor and the wall.

– It is easier to tackle one screw first than to try and deal with all four screws at once. Once you have one screw a turn or so into the motor, it’ll hang while you move wires about, re-align things, and verify the belts are still in the right spot.

– Don’t bother tightening down the X or Y motors. Both will need to be loose when you are assembling the axis and tightened afterwords.

X-Y axes

This was the step that both had me occasionally questioning my sanity and the first step where the assembly guide was slightly lacking. The warning at the top indicating that it is a tricky step is no joke.

– Stack up all the parts in assembly order. No, really, do this now. The belt claws are each composed of 5 stacked bits of wood that fit tightly around a bit of pipe. Keeping it all straight is critical.

– Make very sure you understand the orientation of the claws on the rods before sliding anything into place. It is very easy to get wrong (I did so 3 times on 2 of the 4 axis; derp). They aren’t kidding when they say to go ahead an align the belt in the clamp during assembly instead of doing it later! It is much much easier during assembly than after the fact.

– Don’t even think about tightening down any of the various pulleys at this time. Alignment is a whole different adventure awaiting in the next step and any tightening now will be a waste of time. You can tighten down the X-Y motors and their corresponding pulleys at this time as the only alignment is to ensure that the belts are nice and tight.

Assembly Notes: Extrusion Head

This was the step where I met with the Fan Disaster. It was also the step where the contents of my kit most differed from the instructions. In particular, I ended up with two bottom plates (8B); one without any bits attached to it and one wit the push-in fitting already in place.

Overall, the head is really quite an interesting and — frankly — awesome bit of design. With some tricky bits.

– When pushing the tube into the push-in fitting, it won’t back out. If you push it in too far, keep going and try again. You really do need the tube to stick out as much as documented and no more! Keep in mind that when you add the “horseshoe”, you’ll actually be backing out the tube by a little bit! Yes, this step is tricky.

– When choosing which hole to shove the wires and extruder into in the aluminum block, pay careful attention to both the photos and also have a look at various Ultimaker specific fan shroud designs on Thingiverse. You will want to replace the fan shroud that came with your Ultimaker as one of your first print jobs. Or, in my are….

– The head cooler fan that came with my kit was defective. Or, more specifically, it was made from a bad batch of plastic (irony) that left it incredibly brittle. When I tried to attach it to the head, it ended up shattering in my hands. Thus, I ended up with no extruder cooler and turned to Thingiverse to find a 40mm compatible fan shroud that I could use. I ended up designing a custom one derived from an existing design with a focus on printability even with the lack of a fan. Full story for another day.

– Sticking the X-Y head slide rods into the machine is really tricky. Be patient and take it slow. And, again, don’t bother tightening anything down too much. However, you can tighten down the belt clamps and I’ve found that on my Ultimaker, it really doesn’t matter how tight they are as they don’t overly tighten the long axis belts. In fact, I’m going to print some belt tensioners as I’m getting a bit of slop in the x-y axis.

– Aligning the extrusion head is very tedious, but take the time to do it right. I found that tightening down the pulleys at one end of the long axis belts first, then aligning everything and tightening down the other end was easier. It is made more tedious in that sometimes you can get everything aligned only to find that the pulley set screws are in an inaccessible position! Often, this can be remedied by either changing the length of the spacer object used for alignment or by aligning on the other end of the axis.

Assembly Notes: The Z Stage

This is definitely the stage that will call for a bit of sandpaper. There is nothing in these steps that is particularly tricky, but there are several steps within where the result can be a bit awry. For example, the right Z-stage arm on my ultimaker is slightly out of alignment, leading to the front right corner of my build stage being too low.

There are also a couple of bits in this step where I couldn’t help but think some design revisions were definitely in order. Noted inline.

– When putting the arms around the two slide bearings, make sure that the arms are fitting around the bearings tightly. You’ll probably want to use a bit of the sand paper to round off the corners in the slots that the bearings fit into. Just a bit.

– The “Drive Nut Assembly” is the one piece that seems almost shoddy on the entire assembly. The metal ovoid nut just doesn’t fit in the wood in a way that seems to stay stable. It likes to move around bit. In use, it doesn’t seem to matter, but it was certainly quite concerning during construction! Later, it becomes apparent why there is play in this part, but I still don’t think there needs to be this much play!

– When putting it all together, you’ll notice that the left side doesn’t screw into the back like the right side does. This is actually a critical part of making everything fit onto the 3 vertical bars without having to have everything perfectly and exactly aligned (which wooden based assembly makes impossible). This will be important in a later step.

– When mounting the bed on the wooden frame, go ahead and screw down the spring loaded spacer screws pretty far. Not so far that the spring is destroyed. When leveling the bed, it is much easier to raise the bed than adjust the Z axis top stop switch.

– When mounting the Z axis in the machine, it is pretty easy to pull the left side of the bed apart (see the step before last). Be careful. The left side won’t necessarily be totally tight and the play on the nut assembly in the middle means that the 3 vertical axis of motion do not have to be perfectly aligned and everything still works.

– When applying the blue tape, completely ignore the directions that say you should use a razor to make it all nice and neat within the laser cut perimeter. Hogwash. You want the tape to cover the entire bed except, maybe, the last 1/2″ or so of the back. In particular, some of the slicers end up letting the head heat up in the front left or rear left corner. If not covered in tape, it makes a hard to clean up mess. Also, you’ll be replacing the tape every dozen+ prints (or more) and, thus, it is easier to lift off if the tape is overlapping the sides and folded under.

– To clean the blue tape, use a bit of rubbing alcohol. This nicely removes any finger grease and dust that prevents adhesion of the first layer.

Assembly Notes: Material Feed Mechanism

There was nothing particularly tricky about this step. However, make very sure that you have the parts aligned as pictured. It is easy to turn one of the plastic parts around such that it seems like the screws are just out of alignment. If you force it, it will likely break (no, I didn’t force it).

The feed mechanism is interesting and elegant in many respects, but I also suspect it will be the first really major upgrade that I make to my Ultimaker. I would really like a feed mechanism that both combines more consistent push through with something that detects when a jam has occurred.

One tip; if you aren’t sure the filament is feeding, use a sharper and place a small dot on the filament before the feed mechanism. That makes it easy to see if it is moving along (though you might end up with a couple of very small discolored spots in the final print). Alternatively, look in the feeder tube as the feeder mechanism cuts texture into one side of the filament and you can see that moving along, if the feed is working.

Assembly Notes: Mounting the Electronics and Initial Tests

Again, nothing particular tricky in this step. However, only the Z-axis limit switch connections are actually labeled as to which connector on the board is top and which one is bottom. I managed to get both the X-Y backwards. Whoops.

– The Z axis limit switches are easy to configure without power to the unit since the Z axis motor is easy to spin manually. XY switches are also easier to adjust manually, but they also need to be tested while powered. When sliding the extrusion head in XY, it is easier to do so by grabbing and sliding the two claws instead of the head itself. This also puts less torsional stress on the rods and frame.

Once everything is wired up and powered on, with ReplicatorG installed correctly (start with ReplicatorG), then there are some final tests that you will want to run.

After you have configured the limit switches to stop the head/bed appropriately:

– Before powering up the Ultimaker, slide the extrusion head to the middle of the print surface and lower the print bed to about half way.

– In the ReplicatorG control panel, set the XY Feedrate slider to really slow. Hit the X+ button and then manually actuate the limit switch at the front right of the machine. The head should immediately stop moving. If it doesn’t, try hitting the front left switch. If that stops the motion, then you have the X axis stop switches mis-wired to the board. Power everything down and swap the two X limit switch connections on the board.

– Repeat for Y. Y- is to the front of the machine.

– Fire up the extruder to a temperature of ~220ºC and, once warm, manually shove filament through until it starts squirting out the head (don’t push too hard and make sure you unlatch the feeder mechanism’s pressure bolt first). Also try toggling the cooling fan to make sure it works.

At this point, you are ready for your first print. Calibration and tuning can come later.

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3 Responses to “3D Printing: Ultimaker Build Notes”

  1. Konrad says:

    Nice comments. Unless you already did it please consider copying the above or at least linking it to Ultimaker’s wiki. It will be much easier to find it for someone who is going to build a new UM this way.

  2. Clem says:

    The one thing that amazed me when I assembled my Ultimaker was how well things fit together. I had sandpaper ready and it was unneeded during assembly. I also painted the birch parts first and that didn’t cause any problems with parts fitting together (however it did make taking the extruder apart later on a bit hard because the latex paint acted as a light glue when heated by the stepper motor).

    The absolutely most critical part of the assembly is setting the length of the bowden tube where it interfaces with the PEEK thermal barrier. If you don’t get this exactly right (and I think even if you do) you’ll end up having to take the hot end apart which isn’t fun.

  3. Bertho Boman says:

    Thanks for taking the time to write it up.
    I look forward to the next section.

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