Posted on 15 Comments

xBot Medium – A new printer is baking!

Wow, been quiet for a while, and guess what, I’ve been busy working on completely new printer build, using the best I could find from the Open Source world and added on features I’ve been missing, like true autolevel and front hinged printbed in addition to the back mounted Z-stage on the Ultimaker machines.

  1. Ultimaker as primary source
  2. Design goals and specifications
  3. What can be improved on this package
  4. Dimensions of the xBot Medium next to Ultimaker 2+
    1. Dimensions
    2. Build Volume
    3. Printer and Printing Properties
    4. Materials
    5. Requirments
    6. Print Surface
    7. Controller Type
    8. Motor
    9. Firmware
    10. Powersupply
    11. Chamber
    12. LCD and SD
  5. Compatibility
  6. Fine Touches
  7. What’s next?

Note: Please note that some details has been changed during the design and buildphase. 

Ultimaker as primary inspiration

There, I said it. Ultimaker machines. This means I’ve been inspired by the Ultimaker 2 Open Source panels and did a complete workover to make it all match my needs. In all honesty it looks like a normal Ultimaker frame at first look, but when digging in the main left-over features are the hidden nuts and slot in system by the individual plates. Even those are placed totally different, so it’s only really the concept used. And of course the material used; 6mm Dibond.

Of course; the construction method is one of two things making the Ultimakers what they are, so it would be silly to change these for something else!

Design goals and specifications

The second thing making Ultimakers the best, is how they have, in my opinion, the best XY design of all Open Source printers on the market. They do not risk skewing the axes when changing direction and have build in self-adjustments.

In my optics it’s the best as it’s rock solid, simple to design and setup and requires next to no calibration or maintenance. You can move the printers around all day long, hook it up and print without any adjustments.

I even shipped one of my Ultimaker 2+ machines (clones) across the country. The buyer opened the box, hooked it up and printed right away. No calibration or adjustments needed! Even did the same trick a few weeks later, so yea, they really are rock solid and requires next to no calibration. Except for bed level!

The way the XY is incorporated into the very sleek case with hidden nuts, makes all axes very sturdy, which contributes to the unmatches printing quality of these printers.

During the designface I managed to make room for 48mm deep Nema 17 motors, which meant we can use high quality 0.9 degree steppers (17HM19-2004S) now! Previously we could only get 40mm motors where all 0.9 degree motors (I have ever seen) has very high Inductance mH, which really must be under 4mH to get acceptable performances.

All in all it just makes for an incredible appetizing package with both functionality and visual design at the fore.

What can be improved on this package?

There’s not much to change on the physical level, but the Z axis has always been the achilleius heel of the Ultimaker printers. It’s only fixed at the rear side and while the the Z rods has moved up in size from 8mm to 12mm, which improved a lot, the stability is just not as good as it could be.

I’ve previously fixed the Lead-screw at the top, which helped stabilize the Z some, but the leadscrew is not meant for this kind of usage. Especially bad if using a poor quality lead-screw which isn’t all straight.

I also created a method of using an Anti-backlash nut. Later on in the UM2+ and UM3 machines something similar appeared in the form of the T8*8 Delrim nut.

The Brass version of Anti-Backlash nut has become very cheap and more popular as it’s a drop in replacement to the normal Brass nut.

I’m a big fan of these Brass Anti-backlash nuts as they are cheap, drop in replacements and they compensate for both bad quality you might have in your lead-screws (and backlash nuts) and for the wear the nuts especially are going to be subjected to over time. Using regular nuts the gaps between the ridges steadily increase with wear and tear, leading to inaccuracies, especially when using z-hop, but the spring compensates for this kind of wearing down.

I’ll be using 3 of these Brass Anti-backlash nuts for the xBot Medium

To truly overcome this challenge I wanted to add 2 extra Z motors with additional z rods at each front corner, for a total of 3 Z-motors and 4 Z-rods, to make it more stable and also to build in the option for true auto-level function.

All without making the machine huge and bulky!

Some challenge, uhh?

Dimensions of the xBot Medium next to Ultimaker 2+

Note/Disclaimer: All info and images of/about the Ultimaker is from Ultimaker 2+ specificatiosn page and the Printer Comparison Page. They belong to Ultimaker and all credits goes to them. I am in no way affiliated with Ultimaker and I solely show the info here to show where I came from.

I have tried making the below table to illustrate and explain the changes and differences between the super nice Ultimaker 2+ and the xBot Medium I’m building.


Ultimaker 2+

xBot Medium


Dimensions with bowden tube
and spool holder:
34,2cm (width) x 49,3cm (depth) x 58,8 cm (height)
(13.5 x 19.4 x 23.1 inches)
11.3 kg (399 ounces)

Dimensions with extruder, bowden tube and spool holder
36,8cm (width) x 50,3cm (depth) x 42,8cm (height with 1,75mm)
Note: Height is up to 20cm more if using 3mm filament

Build Volume

223 x 223 x 205 mm
(8.8 x 8.8 x 8.1 inches)

223 x 223 x 205 mm
(8.8 x 8.8 x 8.1 inches)

Printer and Printing Properties

1x 2.85mm Geared Feeder

Open filament system

180 °C to 260 °C
Olsson’s Block
Up to 4x Belted Extruders v4 and 1x Titan or similar in any combination of 1.75 and 2.85mm

Open filament system

180 °C to 500 °C

E3Dv6 Full-MetalHeated Chamber


PLA, ABS, CPE, CPE+, PC, Nylon, TPU 95A, and PP  PLA, ABS, CPE, CPE+, PC, Nylon, TPU 95A, PP and Breakaway (all materials)


Ultimaker Cura or other Slizer

File transfer: Standalone 3D printing from SD card (included) or USB

Ultimaker Cura or other Slizer

File Transfer: WiFi drag and drop for standalone 3D printing.

Optional printing from SD card if the optional PanelDue is in use.

Print Surface

Heated Bed: 100w (24v 5a) 2mm aluminium heater.

Print Surface: 4mm Borosilicat/Tempered Glass. Optional Fiberplate FlexiPlate etc

Guided leveling of buildplate

Heated Bed: 500w (240hz AC (Mains) via SSR) Silicone Keenovo heater under 5mm milled Aluminium plate.

Print Surface: PEI-Coated Aluminium plate. Optional 4mm Borosilicate glass or Fiber plate etc.

You can use Ultimaker 2 heated bed if you so choose. Same mountpoints.

Full true automatic autolevel.

Controller type

Ulticontroller – 8bit

5x a4988 drivers and 3x PT100 amplifiers.

Controller Duet WiFi – 32 bit

5x TMC2660 drivers.

Thermocoupler Daughterboard for 2 Thermocouplers.

Using Duex2 or Duex5 for full use of autolevel and multiple extruders.


1.8 degree motors for XY.
Single linear motor for Z
1x 0.9 degree motor for Extruder
High quality 0.9 degree motors (17HM19-2004S) for XY from
3x linear motors for Z for true autolevel function
1-5x motors for extruders.
For 1.75mm filament: 17HM08-1204S
For 2,85/3mm filament: 17HM19-2004S


 External Meanwell 24v 15.8 (black brick type) Internal Meanwell 25v 18.9a with temperature controlled cooling.


 Ultigcode/Marlin firmware  RepRapFirmware


 External Meanwell 24v 15.8 (black brick type) Internal Meanwell 25v 18.9a with temperature controlled cooling.


100w Temperature controlled Heated Chamber
Door in Dibond with acrylic window

LCD and SD

 Small LCD control panel with SD card  Optional PanelDue color touch display with SD card.
options: 4,3″, 5″ or 7″


To the best of my abilities I’ve kept it as close to the Ultimaker 2 as I could. This means most things can be directly reused, if you have build a previous UM2 clone, like belts, pulleys, heated bed, finger screws, screws/nuts , XY endstops, all the bearings and the thick 12mm Z rods.

Also using same Z motors, although the xBot is using 3 of those.

You can even reuse your extruder if you have a Titan or UM2 extruder, allthough I do recommend using my Belted Extruder v4 as it’s way more quiet and performance just as well.

Fine Touches

In the back plate there are holes if you want to use an extruder as in the normal Ultimaker machines. I havn’t sunk the holes all the way through for Titan extruder, but they are marked up on the files, so it’s easy to remidy it.

Same goes for the various Optional settings in other plates like front USB plug, manual LED on/off switch and the two optional mount holes for PanelDue, if you choose to use one.

Instead of full wire draws I’ve opted to use the Aviation plugs in sizes GX16 for the wireharness up to the Carriage for Heater Cartridge, Temperature sensor, heatsink fan and printed object fans. A second GX16 for the BLTouch or some other sensor as well.

I’ve used 4x GX12 4pin Aviation plugs for the 4x top mounted Extruders on the rear side, and also a single GX12 4pin connector, installed in the bottom part of the frame, next to the Chamber heater vent, for the 4 wires up to the heated bed.

Here are 2 photos from a different machine to illustrate how the GX12 plugs will be placed on the rear side. All the wires going through on the photos here, will be replaced with the larger GX16 Aviation connectors.

What’s next?

I have ordered linear motors and parts from Robotdigg, quality steel rods from Dold Mechatronic and have put in an order for the Dibond plates here in Denmark with a private person, so can’t link to him… so now it’s just waiting time for me over Christmas.

The X and Y motors are high quality 0.9 degree motors (17HM19-2004S) from OMC-Stepperonline which can fit in there due to room for 48mm motors compared to Ultimaker’s room for 40mm motors only.

.. or.. Actually I’m busy working on creating documentation for a Github page for this project where alle the relevant files will be publicly available.

I have in fact allready created a Repository for the xBot Medium on Github and started putting various files and info in it, so please stay tuned.

The STEP files for the side panels will not be made publicly available untill I’ve tested them.

Stay tuned, here, maybe on my Facebook channel and on the Github repository as well 🙂

Merry Christmas to everyone 🙂


15 thoughts on “xBot Medium – A new printer is baking!

  1. Hi,

    Cool your next project is coming at the right time. Based on your Ultimaker threat , I have built the U2ext+ and it works really fine. Thanks for your impressions so far. Maybe you should mention in your previous posts, that the current sense resistors have to be changed on the um 2.1.4 mainboard, because of loosing tourge on your steppers.

    So, finaly I hope you bring this project to a final stage…

    Good luck


    1. Are you talking about Ulticontroller or Duet, or Duex in regards to that resistor? I have no idea what you mean with that to be honest, and havn’t had any problems, so maybe it’s intended that way? 🙂

      I did bring the UM to final stage.. I just never did get any feedbacks here, so didn’t want to bother keep writing about it.. a bunch of people kept asking about help ahead of time, which I did instead of writing for anonymous people 🙂

      1. Hi,

        I am speaking about the ultimaker 2.1.4 mainboard from china. In these boards the current sense resistors usually have 0,5 ohm, but if you check the schematics on github, you will see, that they have to be 0,05.

        These resistors say the driver how much current flows to the stepper and limit the current. So, if you use steppers with a higher current amount you will loose tourge. If you want I can send you a link to the um forum, because this doesn‘t belongs dierectly to your project.

        So far, good luck with your project…


        1. Ok. Guess it depends on the manufacturer from whom you buy it. I’ve had several different boards at my desk from China.

          They all functioned just fine with no lack in torque, so if something was up, it didn’t impede the function to any noticeable degree.

          There are lots of “fun facts” circulating around and I’ve learned to ignore it all unless or untill I start having problems and go looking for solutions.
          No need to invent problems you aren’t experiencing regardless of wheter you might actually have some ‘wrong’ components or not 🙂

  2. Hi,
    What do you think about a new and maybe better print surface?
    Neoceram is a Ceramic infused glass, designed to withstand up to 800C heat impact. Why it can do that? That’s one of the interesting things. The Neoceram glass doesn’t ‘Expand’ when it heats up, it doesn’t change of shape when heating up, so it doesn’t break, chip, or get damaged by heating/cooling.

    Watch this video…
    Watch this


    1. There are so many surfaces around it’s enough to make anyone dizzy.
      I see this again as one of those inventions solving a problem that isn’t there.. or at least not one that causes problems really.

      Your post seem dangerously close to an advertisement. Might you be affiliated with them Oliver?

      Ultimaker is using some sort of hardened Borosilicat glass and they just don’t chip, while many chinese manufactured plates are indeed somewhat fragile.

      I’m using PEI-Coated aluminium plate in my machines and just listed it as one of my material components for the Xbot printer as well. They don’t break, chip or otherwise gets ruined.

      I have 500W AC heater under it, so it heats rapidly and I can use a smaller PSU than otherwise + not so much current through my electroncis as when using DC bed.

      I’m also sometimes using glass with glue on, when printing Nylon. For glass I just use some old glass from a Printer/scanner. Some people use mirrors as well.

      What I’m trying to say is: I’d never use a ton of money on a custom surface that can break or wear down. Also goes for all the various surfaces you can put on your bed as it just makes up for a running expense. I used PEI sheets some years ago, and they are nice.. but at some point they do break/tear if you make a mishap, so it’s very expensive in the end.

      As a rule: if it’s advertised primarily on youtube, then I ignore it. I want to read and see tests. 🙂 Guess I’m old that way.. liking datasheets and such, hehe.

      1. Hi,

        I don‘t affilate with them. I found this post on an ultimaker forum, where they want to improve the ultimakers l8ke you.
        For me PEI is good enough, but you are creating a new printer and this is maybe a good way to test / improve it with this new surface.
        BTW: I am from germany and Schott fabricates these surfaces and they don‘t cost tons of money 😉
        If you are interested in sheets I can send you some links.


        1. Thanks, but I don’t want to use sheets. Keeping the running expenses down by finding permanent solutions.
          I’m using a pei-coated aluminium plate for my printer.
          When I need a different surface I clamp on a plate of glass or similar.

          1. Hi, I meant the technical sheets 😉
            Could you give a link to your PEI coated plate?

            Maybe I test this next year…


  3. […] post is going to be about the custom parts we need for the xBot-Medium 3D Printer. I’ll list the Electronics and Electrical and Mechanical parts in a later […]

  4. I did put in links to where I had my PEI-coated plates made 🙂
    Here’s a link to my post on printbed for my BeTrue3D Printer:

  5. Hi

    I’m wanting to build a direct drive IDEX system based on a Duet wifi. I’m really struggling to find designs at the moment. You say you can add up to 4 extruders on this. Have I completely misunderstood it, or does this mean we could use your design for an IDEX system? I know you have your own extruder design, but I want to print really really soft filaments (like 60A if I can) so I want a direct drive, unless I went with zesty or something.

    I love the independent z levelling on this. I like your spec too. Is there a reason you didn’t want to go down the rail route? I’m just a bit concerned about all the weight for my direct drives!

    1. Hello Kester and thank you.
      I’m not sure what an IDEX system is?
      The xBot can have multiple extruders mounted, but to be fair, you can mount a lot of extruders on many printes. If nothing else, just by drilling some holes. It’s due to the controller combination I can use as many. If I Duex2 it would make 2 extruders possible where as Duex5 would give me up to 3 more. What I’m trying to say is that you could do this on most printers as long as you invested in the Duet WiFi (or ethernet) and Duex5.

      I use 2x 1.75mm filament through the same hotend and change over to 3mm sometimes. I _could_ settle for Duex2, but it would require a good deal of fiddling every time I switched over then.

      You are right to be aiming at using a Direct Extruder when using filament that soft. You CAN do it in 3mm bowden but Direct is best for optiomal result. The stuff I print is 85A.

      I don’t use rails for 4 reasons:
      1) I don’t have any experience in using it, so hard to design something nice with it.
      2) The CrossBot Gantry setup here is just awesome as there is zero skew at any point, making perfect circles etc.
      3) This project was a matter of making something very similar to the Ultimaker2 machines, as people can relate to that design. Ie: people can compare and judge the design and price.
      Mine has same print area, but has 2 extra motors for true autolevel and is only 1cm deeper and 2.6cm wider.. and much lower due to extruder placement, so seems a bit silly to me that Ultimaker hasn’t done it in their UM3 instead of fancy features.
      4) The Ultimaker gantry is hugely popular so many different high quality carriages for hotend etc for free download and usage 🙂

      About weight and Direct drive in this setup.
      If you put in more than one toolhead in this design you are going to be sacrificing some printarea.
      There are some solutions however, but they are still bowden:
      Or this one which is a sort of Direct-bowden ->
      UM2 specific (drop in design, also into mine)

      1. Many thanks for such a detailed reply!

        IDEX is usually just two independent extruders (e.g. BCN3D Sigma, or LeapFrog), as opposed to having two extruders attached to the same X gantry holder (e.g. Vertex K4800, Flashforge Pro and many others), or two filament feeds going to the same hot end (e.g. diamond hot end).

        IMHO, IDEX is the only sensible way to print mixed materials with different temperatures settings. And direct drive IDEX can also give the option of using flexibles with harder filaments, like PETG.

        I already have an Ultimaker style printer (the aforementioned Vertex), but it’s a dual head Bowden, and therefore not much use! If I convert this one to IDEX, the print area would be very small, as you say. So I really need a new box with plenty of space down the sides.

        I’ve had a look at some magnetic switched hot ends, and the flex3drive. But the latter doesn’t respond to emails and some of the stuff on the website looks ‘untouched’ for several years. There seems to have been some dispute with Nimble Zesty which is a licensed version of the same thing and I’m not sure if the hassle with the geared steppers and firmware changes is worth it.

        I was thinking of getting a couple of titan aeros. I know they’re really noisy, but they also seem to be ‘no hassle’ in terms of setting up with the Duet Wifi for IDEX.

        I do like the idea of your bed levelling, in fact I like it all. What do think the print size would be if I tried to make it with two independent titan aeros?

        Sigh, it’s a fun hobby but I don’t have the time to do full designs and also build them up!

        1. I rarely ever print anything but just 1 color/type. I have a Chimera lying around which would be nice for different temperatures

          Diamond is “just” a mixing hotend intended to use with x-times the same type of material with same melting point.

          Am a bit confused by your term of extruder. Seems you mix it a bit with the term hotend? “as opposed to having two extruders attached to the same X gantry holder”.. but I think I know what you mean 🙂

          Titan isn’t particularily noisy. It’s just like any other geared non-belted extruder, and they work very nicely.

          About flex3drive and nimble, yea, Nimble borrowed stuff from flex3drive to test but ended up copying it instead. Or rather, downgrading it, but advertising it as being superior which it simply isn’t. I’ve talked to them and asked about their buzzwords and they simply just couldn’t quantify why it was better or strong etc.

          I wouldn’t know about print size as I havn’t looked into any of these solution at all aside from a curiosity perspective. I’d guess it would at least 5cm on one or both axes, but that’s just a guess.

          If I were to use a remote solution it would be the flex3drive. He is active but working on a new hotend. I think the desolated look is due to a wish to make documentation for all kinds of stuff, which is all but impossible to keep updated – know from personal experience 🙂

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