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xBot Medium – Look at materials (custom BOM)

In this post I’ll start describing what is needed to actually build the xBot-Medium printer.

I’ve set up a xBot-Medium Github Repository where the files can be found for this project. As I havn’t finished it yet, all the files aren’t there, but they will be! Only the .STP files for the Dibond frame pieces and some a few for printed parts are missing, so it’s pretty much complete allready.

This 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 post.

xBot Medium materials can be categorized like this:

    1. Parts for Dibond frame
    2. Custom lengths of quality steel rods
    3. Custom metal/steel parts
    4. Custom aluminium parts

1) Parts for Dibond frame

The frame for the xBot Medium is made out of 6 pieces of Dibond pieces. We actually have 8 pieces when counting the Front Door and the Rear Z-Rod Cover, but these two are part of the Top and Front Dibond pieces respectively, as you’ll see here.

Note: Parts might deviate from designs on this page. Always refer to the xBot-Medium Github Repository for the current version


Most items of interested are noted on the piece.

I’ve intended one the two GX16 to the left to be for the Wire harness for the Carriage. The other one for BLTouch or other sensor.

The four GX12 4-pin, two to either side, are meant for Belted Extruder v4.

Above the GX12 holes to the right are cut outs meant for a Titan Extruder or similar, which people can finish on their own if needed.

USB cutout is meant for a Panel Mount USB B Female socket to USB Micro B 5 pin male cable. Ie, giving you USB access to the board from the rear of the printer.


The bottom accomodates a host of cutouts to accomadte our various pieces of machinery and electrical stuff to make our printer.

The mountholes for powersupply is based on Meanwell HPR-450-24 which is a quality 18.8a low profile supply with temperature controlled fans, so it shouldn’t make unduly noise.

Aside from this, you’ll find cutout for 14×3.2cm Chamber heater and mountholes for SSR for the heated bed and of course for our Duet WiFi and Duex expansionboard.

I’ve designed special 3D printable mount parts for the controllers, which incorporates fixpoints for box/shield/fans or similar for the controller.

Lastly we have room for our 3x Z 280mm motors various Z rods and the Optional 3x Z-Max endstops.


The front piece contains the Rear Z-rod Cover and the various mountpoints for the door.

At the lower part there are optional cutouts for a front facing USB for power, but an adapter for the rear USB panel mount could also be mounted here.

We also have room for a manual rocker switch to turn LED on/off.

Finally there are 2 holes for m3 screws placed 80mm apart to facilitate mounting of an LCD panel if you use one.


Left panel contains mount points for the Y-Max endstop and a groove for wires from both the Y and X endstop.

We also have mount holes for our Left Motorshield and holes for the optional front left Z-max endstop.

And of course the motor driving the Y axis.


Right panel is the most simple panel of all.

It contains the mountholes for the optional front right Z-Max limit stop and holes to fix the Right Motor Shield in place as well.


The top piece has the Door inserted into the empty space.

I’ll strongly encourage to have the door made as it greatly improves all prints you make regardless of material. Even PLA benefits a lot from an enclosed room with a steady slightly raised temperature.

Aside from the Door, the Top contains mount holes for the X-Min endstop and holes for both the 2x 12mm Z rods and the 2x 8mm Z rods.

2) Custom lengths of quality steel rods

Next up is our list of 6, 8 and 12mm steel rods.

I know it’s tempting to buy some cheap chinese bundle of “chromed steel rods”, but please don’t. They are most often not straight and the tolerance is also off by default.

My impression: it seems they take normal 8mm steel rods and do a put a “coat” of chrome on it, making it neither precise nor particularily durable. My description on how they do it, might be totally wrong, but it’s the impression I have from many bad purchases for rods.

So, go shop at a place where they guarantee a certain qiality standard, namely h6. It’s a standard for tolerances and deviations allowed and such.

It’s especially important with tight tolerances as we are using bushings for our X and Y rods and sometimes the cheap chinese rods are simply “too fat” for the bushings to pass over.. conversely it’s no good if the rods are too thin either, or not straight.

I’ve allmost always had problems getting the cheap rods through the flanged bearings we use at the XY ends as well.

I’ve ordered all my rods from Dold-Mechatronik this time around and I must say the quality is truely impressive!

The tolerance is 9um (micrometer) which means accuracy within 0.009mm. In other words these rods are high quality steel rods, ground and polished with a superb finish!

# Pieces



 2x X-rods 8mm in diameter. Each of them 367mm long. They run from side to side.


 2x Y-rods 8mm in diameter and 358mm long. They run front to back in both sides


 The two front 8mm rods for Z axis. 339mm long. Runs near each front z motor.


 The two 12mm diameter and 339mm long rear Z-rods. Placed on either side of the center rear Z-motor.


 A single 6mm diameter 327mm long rod running left to right for our Carriage (thing that carries the hotend and fans etc)


 A single 6mm diameter 301mm long rod running from front to back for our carriage.

3) Custom metal/steel parts

Next up is a few pieces we need to have custom made as well. The most important parts are the 4x steel pieces used to keep the four Z rods in place.

The Motorshields are not just for show though, but are intended to partially keep out the heat from the heated chamber while keeping the XY motors cooler using a temperature controlled 40mm fan under each motor. Doing this as the motors performs best and last longer if we can keep their temperature under 40c.

I’ll most likely design some printed versions of these.

# Pieces



Left motorshield. There is room for 48mm long motors making it possible to use quality 0.9 steps Nema 17 motors!
2 m3 threaded holes in each side of the shield for fastening onto the frame in addition to two spuds at the bottom for fastening onto the Bottom frame part.


Right motorshield. There is room for 48mm long motors making it possible to use quality 0.9 steps Nema 17 motors!
2 m3 threaded holes in each side of the shield for fastening onto the frame in addition to two spuds at the bottom for fastening onto the Bottom frame part.


2 pieces of 2mm thick steel plates to hold the 8mm Z-rods in place. There is a m3 threaded hole in each end of the plates to keep them in place.

Note: If you can’t have some made in 2mm steel, then have them made in 4mm thick aluminium. The files for these are located in the xBot-Medium Github Repository


2 pieces of 2mm thick steel plates to hold the 12mm Z-rods in place. There is a m3 threaded hole in each end of the plates to keep them in place.

Note: If you can’t have some made in 2mm steel, then have them made in 4mm thick aluminium. The files for these are located in the xBot-Medium Github Repository

4) Custom aluminium parts

We have 2 custom aluminium parts we need to make for the Z-stage. The Heated bed and the Z-liftplate.

You can use a heated bed from Ultimaker 2 if you choose, but I personally strongly prefer the option with 4-5mm aluminiumplate and an AC under it.

# Pieces



I’m using a PEI-coated 5mm thick aluminium plate from with a 500W AC Keenovo silicone heater under.
I’m recommending using an AC/mains heater, as you remove the stress from your PSU and electronics, meaning it’s easier to cool and you can do with a smaller PSU than you’d otherwise need or run your existing PSU without noisy fans. Note the temperature sensor sits in the middle of the pad and in my experience it shows about 10c more than the actual surface of the bed. At least for a good while.I havn’t shopped at but they have nice prices on their parts and their Ecocast plates would do perfectly for this as well. (choose CAST from dropdown menu.


The Z-liftplate is a bit complicated due to the 3 motors, 4 support rods, 3 holes for screws to hit the Z-end stops and the 3 point Finger Screws to adjust the bed.
I’ve not made cutouts to make it lighter or similar, as it’s mostly for show anyway, but also because the extra cutting takes more time and so costs more money to make.

That’s it untill next time

You can find all the source files in the xBot-Medium Github Repository.
In the next post we will take a look at the Electronics and Electrical and Mechanical parts.

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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 🙂