Core-XY Cube

Here is my printer build. It has a print volume of 305x209x219 and everything tucked inside a box of 490x420x450

It uses 2M of 40x20 'v'slot and 12 wheels.
The remainder of extrusion is 20x20 Bosch pattern that I had from a local company.


This build first started out as a mendel style printer i.e. a Y axis bed and the X axis rising with the Z.
A mendelmax 2 direct copy, in fact. Funny that the Mendelmax 3 now uses 'V' slot.
It was just coincidence that I found Openbuilds V slot via Ooznest UK as an alternative to the MM2's Igus linear motion gear.

This design saw a few CAD iterations as I built the frame into an enclosure ...

A visit to the TCT show in Brum' and a look round a few pro printers led the way to a cube design more in the UM style - elevating Z moving XY

This 'V' slot is such a pleasure to design with as a structural member and guide rail in one with so many ways to motorise motion.
There were a few design variations - fixed motors-moving belts, moving motors-fixed belts, one motor, 2 motors.
The overall design was there but lacked a certain je-ne-sais-quoi (as we say in English)

Then I saw Openbuilds familiar Carl Feniak had converted a printer from H-Bot to Core-XY motion, citing; "The ability to run drive belts inside the 'v' slot . . .something, something"
I decided that CoreXY was the quirkiness that this printer lacked.
I liked the idea of fixed X & Y motors and tucking the belt inside the extrusion and that gave me a direction. . . Offset belt path Core XY

Running the belts inside the V slot required a little chopping out for the pulley with a grinder-


I tried a method of using fixed bearings with spinning shafts/ pulleys but found it transmitted a lot of noise thru the frame-

So I went for 2 605ZZ 5x14x5mm bearings per belt as running idlers-

I don't have access to workshop machining, only jigsaw/ angle grinder/ pillar drill so used M5 c'sk screws as axles in hand cut Alu plate.
I opted to put the belt return path to the front of the printer so leaving the rear clear for the Z axis parts.
The 'v' slot to the right of the above picture is the front. It was an offcut so used it for the structure.
There's 2 20x20's side by side at the same height to the rear to complete the look.

I had already bought the SCS10 bearings and 10mm ground shaft so I put that to use on the Z axis. Otherwise I would have liked to use 'V' slot there as well.

The Z platform was made from some H section Ali framing extrusion that was down the side of my shed. The lead screw is a TR10x2 with a delryn nut.

I like my cables tidy. The cable chain arrangement was inspired by something that Bits-from-bytes once did-

The extruder is airtrippers direct drive bowden mounted on rubber mounts. The bowden originally ran inside the cable chain which worked but I ultimately ran it outside to reduce friction on the filament.

I made my own wheel plates up to suit my requirements.

There a 4 Alu blocks which hold the bearing idlers. They are M5 csk screws thru the block with a washer/nut/washer/bearing/washer/bearing/washer/locknut. The block screws onto the 'v' slot of the moving X axis. Like the motors; one side points up, the other down.

The wheel plates were first just mounted on the extrusion corner clamps, then I changed the rear idler blocks so that the plate screws into that too to stiffen it up.


I don't like wasted space. Every last millimeter was hard fought-

Even the hot end wire had to be just so . . .

The X carriage is 2 plates sandwiched on spacers

The wheels mount to the rear plate along with belt clamps, wire terminals and X endstops, the front plate holds the Hotend assembly and cable connections.

A couple of tips-
It's worth thinking in advance how you are going to adjust everything square and parallel and then lock it there in a build like this-


For cheapskate nut inserts; if you grind the edges of a M5 nut it will slip down the 'V' slot. Put the ground edges facing in.

Be warned that it can bite a lump out of the inside of the channel if you overtighten it which may be a problem if you intend to move the nut around to adjust something. Better to use a proper insert.

Thats about it for the moment, I may add more. There's an AutoCAD 3D model and a parts list attached.

It's all run well for a year now.
It does have the odd resonant frequency here and there on the acrylic covers. 1/32 microstepping on the stepper motors have much improved things.(Marlin firmware has come a long way in supporting CoreXY since I started all this)
I have some 'astrosyn' damped stepper mounts to fit one of these days and I may get round to replacing the worlds cheapest idler bearings with something more reputable too

There is a movie which is a compilation of build photos

At 10 minutes long, it's a little boring. My first attempt with Windoze movie maker.

There's a shorter descriptive video

Which is no Oscar winner either.

I hope I can inspire others in the way that others have inspired me. Thanks to all who share their knowledge.