Core-XY printer build from Rat Rig V-Core Mechanical Kit


I have been posting about this on the Octoprint Forum but I think this is the better place to discuss this. I have a Prusa Mk3 which I build from the kit late last year and I am mostly happy with it but I very much dislike the looks of it and I have hopes 3d printing can go much faster. I have read and watched videos about the hypercube and the core-xy mechanics of the printer. It seems to have the potential to print a lot faster due to lower mass on the mechanical side in combination with a 32 bit controller. I have ruled out using China build core-xy kits, mostly cause I would just use the mechanics anyway as hotend and electronics are apparently of sub optimal quality. So here is what I have set as my main components to use.

  • Rat Rig V-Core Mechanics kit incl steppers but printed parts done myself from PC or PET
    It comes from the EU, no customs and VAT drama, looks solid and well made. All parts available as Fusion 360 design. Easy to customise.

  • E3D Titan Aero (Aqua at a later stage)
    Low build height and compact direct drive, never had bowden and it would be less mass but direct drive just gives me a better feeling. A bowden drive would be easy to implement for testing purposes if needed.

  • Duet 2 Ethernet
    Looks like a very well made piece of kit, very comprehensive documentation and fast 32 bit platform. Great web gui and potential to use a very nice screen if needed. Build in ethernet is a must (wired, not WiFi), easy to extend with expansion boards and temperature probe interfaces if needed.

  • E3D Mains powered 300x300 bed
    Just faster, more efficient than driving it from a DC PSU, removes the need of a massive 24V PSU

I have heard horror stories about the v-groove linear system, all of which referred to removing play or have to little play causing flats on the rollers. The V-Core has by the looks of it rather nice way of adjusting the play with eccentric nuts. I would try the v-groove system to start with but have the option of linear rails in mind. Also since its a nice cubical case I would like it enclosed once the first few months of testing resulted in a printer that has become “less fluid” in design when most parts have proven to work well.

I have not yet made up my mind about the following parts:

  • End stops or no end stops
  • Capacitive, inductive, BL-Touch or Pyr0-Piezo (hoping to buy a beta kit) bed leveling
  • Dumb steppers or steppers with closed-loop (in the long run)
  • Print surface, hard to get PEI coated spring steel, glass or some other solution
  • 0.9 degree or 1.8 degree steppers in the long run.

I will order all the hardware later this week, just trying to see where to buy the stuff to buy most where there is stock available. E3D is pretty bad with delivery times these days.

Any input is welcome, especially about the points that are still floating unsolved or undecided.

Have FuN!

PS: This is a learning project without the expectation for it to work perfect right away but with the general idea to get into 32 bit Duet 2 controller and core-xy for future expansion into larger print volume and tool changers for water soluble support and other tool heads. The RailCore II would have been my choice if it was available as kit in the EU but thats not the case.

Woops… its all ordered except the heated bed and bed leveling… gone for 0.9 degree steppers with 61.5oz (0.43Nm) to start with. hopefully have all on the desk in approx 7 working days :smile:

Have FuN!
Jan P.

Finally found a temporary solution to the new heated bed. I have gone for a 24V silicone adhesive heat pad. Took me some time to find a 300x300mm 24V heater. Its just temporary cause I want to get an E3D 230V bed. Included a inductive proximity switch for good measure in the order.

They have a lot of stuff reasonably priced.


The 1st shipment has arrived, Ooznest has send me the Titan Aero, Duet 2 Ethernet, a flat pack NMEA17 for the Titan Aero, 4x 0.9 degree NEMA17 steppers and a bunch of cables for the steppers.

That will keep me busy for a few days I guess…


I have done some basic configuration of the Duet 2 Eth now with the help of the recommendations in the manual and the RRF Config Tool.

Titan Heater, termistor and fan are working, X/Y steppers move as expected for a Core-XY and the Z steppers are working in sync. Did not yet fully assemble the Tita Aero, I need the mount ready for 1st otherwise I have to open and close the stepper mounting many times which I prefer to avoid. I am using a Phoenix Contact 24V 5A PSU which I had laying around, It’s well big enough as long as I don’t have a heated bed connected.

Here my test setup so far. The fan connection is not yet final.

Have FuN!

Update regarding my build:

The Rat Rig V-Core kit took over two months to ship. There was apparently a chain of unfortunate events on the Rat Rig end causing the delays. In fairness they have communicated well and despite my experience I would order from them again any time. The Kit itself came well packaged and undamaged. The extrusions have been really well cut to length and the end where square !!! The quality was very very good and did not require any reworking on the extrusions at all. Here to content of the box.

The extrusions just needed a bit of a wipe and some shavings had to be brushed off. The build as such is also pretty simple. Do read the instructions to the end BEFORE you build. I did not and found out I had the wheels assembled wrong. When building make sure you have the frame top and bottom build 1st and make that proper square. Take your time for that, that is THE most important pert that has to be precise to avoid issues later on. The double t-nuts give enough wiggle room to adjust everything 100%.

Some more pics…

The belt drive is easy enough done, there is no detailed instructions in the manual but the Fusion 360 model shows it all clearly. The idlers are not always on the smooth side, some people think that’s an issue but I think they are big enough diameter that there is no issues from that. The wheels are very easy to adjust to work play free jet not to tight. A few thing I have designed for this printer on Thingiverse.

Bed Heater Cable Strain Relieve

PSU Box with extrusion mount:

My temporary spring mount:

Will be redesigned once I have my aluminium tooling plate.

My temporary Duet 2 mount:

Work in progress hotend mount:

Do not yet use the latter, it is not ready for release yet, still improving the mount and include Piezo sensors, print cooling fan etc…

I am using an inductive probe for now, works OK but in the end it has to be piezo cause of precision and because I want to be able to use glass and metal surfaces.

I did run the Auto Bed Levelling with my Prusa sheet and here is the very 1st layer put down without any prior adjustments etc…

The Duet 2 is set up in a way that it uses the Probe as Z-Min endstop but I also have a switch at Z-Max to be able to drop the bed fast once the printer is powered up without the need to home to z-min 1st.

If anybody has questions or suggestions please reply here !

Have FuN!

Still in progress stuff:

  • Mains Bed Heating
  • Spring Steel Sheet 320x320x1mm
  • Aluminium tooling plate 340x340x6-8mm approx, final size not yet set
  • Print Cooling Fan
  • Piezo Probe
  • Printer enclosure
  • Electronics enclosure

If anybody knows where to get the spring steel sheet with or without PEI please leave a ling, thats what I am really stuck with. But no crowd funding plz.


1 Like

How about the Wham Bam system? It’s a bit pricey, but from what I’ve seen it’s reasonably priced compared to other mag bed solutions. You might be able to order just the spring steel sheet and the PEX (comparable to PEI, it seems) coating.

Not only have you made the right choice, but it’s also very profitable in the long run.

Great detailed build snoozer, how’s it printing now?