MaybeCube

The MaybeCube is a fully-featured, rigid, high speed, and affordable CoreXY 3D printer with a linear rails motion system.

It can be built in a variety of sizes: the standard size is the MC350, which has external dimensions of approximately 405mm by 475mm by 415mm and a build volume of approximately 225mm x 225mm x 200mm.

The self-sourcing BOM cost of the MC300 variant is approximately £430 with a genuine E3D hotend (or about £400 with a generic E3D compatible hotend), this does not include the cost of filament for printing parts, see spreadsheet. The MC350 variant is slightly more expensive.

Assembly instructions

The "standard" size is the MC350 variant. I have built the MC300 variant for two reasons: to test sizing (if the components fit in the MC300 variant, then they will fit in larger variants); and because I had a quantity of 300mm extrusion and the right size heated bed from an earlier project.

The assembly instructions and the BOM (parts list) for the MC300 variant are here.

The assembly instructions and the BOM for the MC350 variant are here.

Please read all the build instructions before you begin assembly.

The STL files are on thingiverse.

The assembly of the different MC300 and MC350 variants is essentially the same, the main differences are in the printbed. Larger variants have a larger printbed and to support this can optionally have either Z-rods on both sides of the printbed, or a 3-point kinematic bed.

If you would like to build a smaller printer, you may be interested in the MaybeCube's smaller sibling, the BabyCube.

Design Goals

1. Create a high quality engineered 3D printer capable of producing high quality prints
2. Make the MaybeCube more easily usable in home environment (as opposed to garage or workshop)
   • try and make it easy to transport and store the MaybeCube, so:
   • integrated design: everything is enclosed within the printer's frame. This includes the motors, the motion system, the power supply, and the circuit boards. The only exceptions are the spool holder, which can be removed for transport and storage, and the extruder.
   • include base plate so underside of printer is not exposed
   • all protrusions from frame (filament spool, extruder, power connector) are on the right hand side to minimise desk clutter and allow the back of the MaybeCube to be pushed right against a wall
   • all protrusions from the frame can be easily removed for storage
   • clean wiring - route wiring in extrusion channels where possible and minimise exposed wiring
3. Improve ease of assembly
   • Use internal blind joints on the frame
   • printed parts designed so that bolts are accessible and can be tightened when frame fully assembled (that is bolt holes are not blocked by other parts when assembled)
   • divide the main assembly into a number of independent sub-assemblies.
   • where possible printed parts push up right against frame and so "auto-align"
   • facilitate building in different size variants
4. Use linear rails for the x and y axes
   • linear rails are now not much more expensive than linear rods
   • linear rails make design and assembly easier, reducing the need for custom printed parts
   • linear rods are used for the z-axis, since linear rails offer no advantage here
5. Maximise frame rigidity
   • one of my goals is to experiment with high print speeds. A highly rigid frame allows higher acceleration settings
   • use 2040 aluminium extrusion, corner joints are about 4 times more rigid than 2020 corner joints and 2-3 times more rigid than 3030 corner joints
6. Maximise build volume for selected extrusion lengths
   • Z-axis assembly is on the left side of MaybeCube. This means the Z-axis assembly does not impede travel in the Y direction
   • The printhead is quite compact, so does not significantly restrict travel in the X and Y directions
7. Enable a fully enclosed print volume
   • The cubic shape makes enclosure straightforward.
   • A panel can be used to isolate the electronics and stepper motors from the build volume
   • A slide-in front panel can be added
   • A top enclosure can be placed on the frame
8. Try and keep the costs down
   • the aim is not to be as cheap as possible, but rather to avoid unnecessary costs
   • use standard extrusions lengths, as far as possible, so no custom cutting is required
9. Facilitate customisation and experimentation
   • Open source design
   • Parametric design in OpenSCAD
   • The open design of the frame and the easy accessibility of parts means the MaybeCube is fairly easy to customise - most parts can be changed without the need to disassemble large parts of the frame
   • The design of the X_Carriage means it is easy to customise to support different hotends and extruders
   • Support other printhead systems, including EVA, XChange, and, in principle, the Jubilee and E3D toolchangers
   • The independence of the XY motion system and the Z motion system means that in principle the Z motion system could be replaced (with, say, an auto-tramming 3-point leveling system)

Variations

The canonical form is the MC350 variant.

variant	Extrusion lengths	Rail/rod lengths	Approx Build Volume	Bed Size	Exterior Dimensions
MC250	x250 y250 z350	x200 y250 z250	concept variant	180mm	290 x 290 x 370
MC300	x300 y300 z400	x250 y300 z300	185 x 185 x 200	214mm	340 x 340 x 420
MC350	x350 y350 y450	x300 y350 z350	225 x 225 x 235	254mm	390 x 390 x 470
MC400	x400 y400 y500	x350 y400 z400	275 x 275 x 285	310mm	440 x 440 x 520

Comparisons

The following table compares the sizes and build volumes of various CoreXY 3D printers.

Printer	EType	Extrusion lengths	Build Volume	Exterior Dimensions
MC300	2040	300 x 300 x 400	185 x 185 x 200	340 x 340 x 420
MC350	2040	350 x 350 x 450	225 x 225 x 235	390 x 390 x 470
MC400	2040	400 x 400 x 500	275 x 275 x 285	440 x 440 x 520
MC450	2040	450 x 450 x 550	325 x 325 x 335	490 x 490 x 570
BLV MGN Cube	2040	496 x 496 x 560	300 x 300 x 365	576 x 536 x 560
Clock 3	2020	620 x 620 x 800 (est)	300 x 300 x 350	640 x 675 x 875
Creality Ender 5 S1	2020/2040	375 x 440 x 550 (est)	220 x 220 x 280	425 x 460 x 570
Daedalus 1.5	2040	450 x 480 x 590 (est)	310 x 300 x 345	495 x 521 x 600
Denali 200	2020	320 x 320 x 590	200 x 200 x 200	380 x 380 x 620 (est)
Denali 250	2020	370 x 370 x 590	250 x 250 x 200	430 x 430 x 620 (est)
Denali 350	2020	470 x 470 x 690	350 x 350 x 300	530 x 530 x 720 (est)
E3D ToolChanger	2040	Z: 500	200 x 300 x 300	530 x 505 x 500
FuseBox3	2020	310 x 332 x 407	235 x 235 x 235	350 x 372 x 427
HyperCube	2020	340 x 303 x 350	200 x 200 x 155	380 x 343 x 350
HEVO	3030	420 x 410 x 500	300 x 300 x 300	480 x 470 x 500
HevORT 315	3030	410 x 420 x 880	315 x 315 x 340	640 x 480 x 890 (est)
HevORT 415	3030	510 x 520 x 980	415 x 415 x 440	740 x 480 x 990 (est)
Jubilee	2020	409 x 604 x 430	300 x 300 x 300	476 x 604 x 558
RatRig V-Core3 300	3030	440 x 505 x 510	300 x 300 x 300	518 x 583 x 560
RatRig V-Core3 400	3030	540 x 605 x 610	400 x 400 x 400	618 x 683 x 660
RatRig V-Core3 500	3030	640 x 705 x 710	500 x 500 x 500	718 x 783 x 760
RailCore II 300ZL	1515	400 x 370 x 360	250 x 250 x 280	522 x 445 x 496
RailCore II 300ZL	1515	460 x 425 x 445	300 x 300 x 330	572 x 495 x 546
RailCore II 300ZLT	1515	460 x 425 x 745	300 x 300 x 600	572 x 495 x 830
SecKit SK-Go	2020/2040	430 x 440 x 485	310 x 310 x 350	520 x 500 x 500
SecKit SK-Cube	sheet metal	N/A	200 x 200 x 250	405 x 400 x 470
SecKit SK-Tank	sheet metal	N/A	350 x 350 x 400	560 x 530 x 710
SimpleCore 200	2020	350 x 350 x 450	200 x 200 x 180	390 x 390 x 390 (est)
SimpleCore 300	2020	500 x 500 x 500	330 x 330 x 230	540 x 540 x 540 (est)
SnakeOil XY 180	3030	310 x 310 x 500	180 x 180 x 180	400 x 390 x 520 (est)
SnakeOil XY 250	3030	400 x 370 x 550	250 x 240 x 230	490 x 450 x 570 (est)
Ultra MegaMax Dominator	4040		300 x 300 x 695	610 x 530 x 1500
Voron 0	1515	200 x 200 x 200	120 x 120 x 120	230 x 230 x 280
Voron Trident 250	2020	370 x 370 x 500	250 x 250 x 250	410 x 410 x 500
Voron Trident 300	2020	420 x 420 x 500	300 x 300 x 250	460 x 460 x 500
Voron Trident 350	2020	470 x 470 x 500	350 x 350 x 250	510 x 510 x 500
Voron2 v2.4 250	2020	370 x 370 x 430	250 x 250 x 230	410 x 410 x 430
Voron2 v2.4 300	2020	420 x 420 x 480	300 x 300 x 280	460 x 460 x 480
Voron2 v2.4 350	2020	470 x 470 x 530	350 x 350 x 330	510 x 510 x 530
VzBot	2020/2040	530 x 460 x 530	330 x 330 x 400	530 x 500 x 570

Frame stiffness

The frame is a cuboid with 6 rectangular faces. Rectangles have no inherent rigidity and are subject to shearing. The rigidity of a rectangle is provided solely by the strength of its joints, and these often do not provide sufficient rigidity. A small movement at a joint is magnified into a much larger movement at the end of a 400mm extrusion. There are three main ways to increase the rigidity of rectangles:

1. triangulation, where the a diagonal piece divides the rectangle into two triangles, this is exemplified in truss bridges
2. using a shear plate, this is exemplified in the shear boards used to stiffen wooden framed buildings
3. reinforcing the joints.

The MaybeCube uses 2040 extrusions, these provide significantly more joint rigidity than either 2020 or 3030 extrusions. Additionally the MaybeCube uses shear plates on the bottom, back, and (optionally) left and right faces to stiffen the frame.

The front face of the MaybeCube is the most subject to shearing, since it needs to be open to allow access to the printbed. Two measures are taken to counteract this: 2080 rather than 2040 extrusion is used at the bottom of the face, and the idler mounts at the top are extended to provide some triangulation and reinforcement of the upper joints.

Input shaper test results (MC300 variant with side panels)

Comparison of input shaper test results

Printer	X frequency	X amplitude	X acc limit	Y frequency	Y amplitude	Y acc limit
MC300	114	1,720	51,200	88	4,500	32,800
BabyCube	92	19,000	32,600	87	13,500	44,100
RatRig V-Core3 300	62	47,500	15,300	N/A	N/A	N/A
SnakeOil XY	83	110,000	27,400	56	49,500	12,100
VzBot	93	87,000	34,100	64	35,500	15,900
Voron 2.4	52 & 82	15,400	26,500	38 & 63	11,600	9,900
Voron Switchwire	70	11,000	N/A	48	16,200	N/A
Ender 3	30 & 88	4,100	3,800	32 & 57	19,000	9,300
Prusa i3 MKS+	38 & 58	39,000	N/A	32 & 78	42,000	N/A

These input shaper results give a rough idea of the rigidity of various printers. The acc limit is the value of the max acceleration for the ZV shaper for each printer and axis - it is not that meaningful in itself, but it does form some basis for comparison.

It does seem that the MC300 compares very favourably with the other printers for which I have found results published.

Customisations

EVA module printhead system (version 2.4.2)

In its default configuration the MaybeCube has an E3D V6 hotend with a Bowden extruder. However I've created adaptors so that the EVA modular printhead system can be used. The EVA system supports a wide variety of hotends and extruders. More details on using the EVA adaptors are here.

The STL files are on thingiverse.

In the picture below, EVA adaptors are printed in blue, MaybeCube standard parts are printed in red, and EVA standard parts are printed in black and green.

Printermods XChange quick change tool head

I've created an adaptor for the Printermods XChange quick change tool head. More details on using the XChange adaptor are here.

The STL files are on thingiverse.

Voron Mini Afterburner printhead

I've created an adaptor for the Voron Mini Afterburner (as used on the Voron V0) printhead.

More details on using the Voron Mini Afterburner adaptor are here.

The STL file is here.

E3D tool changer

Currently there is no adaptor for the E3D tool changer, however I think it would be fairly straightforward to create one.

There should be room to dock at least two, and perhaps three E3D ToolChanger Tools in the back of the MC350, this would allow experimenting with the E3D docking system in a framework considerably less expensive than the E3D Motion System.

Jubilee tool changer

The Jubilee 3D printer has a tool changer compatible with the E3D tool changer. I have a proof of concept showing that this tool changer system can be used on the MaybeCube. Note that this is incomplete and still requires an X_Carriage adaptor for the Jubilee plates.

3-point Kinematic Bed

The MC300 and MC350 use a cantilevered print bed. For larger variants it is possible to use a 3-point Kinematic Bed.

Dual Z rods

Alternatively, for larger variants, it is possible to use dual sets of Z-rods to support the print bed.

Pictures

In these pictures the power supply and PCBs are mounted in the back of the printer - I've done this in the development build so that I can easily change things around while I experiment. For the release build, the power supply and PCBs are mounted in the base of the printer.

License

MaybeCube is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0)