Fixed bed 3d printer

z axis - Why aren't fixed build platform 3D printers popular?


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I'm trying to build a DIY 3D printer for myself. I've been exploring many different styles of printers and found this type of printer that has a fixed bed that stays fixed in one place and the whole gantry moves which includes all axes.

  • Why is this so rare?
  • Are there flaws in this design?
  • Will print quality be affected by using this approach?

Check out this video for reference and skip to 10:50:

  • diy-3d-printer
  • z-axis
  • carriage




Why is this so rare?

Such kind of printers usually harder to assembles, calibrate, and maintain because 3 axes machine is a bit more complex than 2 axes. For instance, it's can be tricky to move an entire extruder among all 3 axis and some of such printer's designs may require even dedicated exruder's design like Bowden Extruders.

Are there flaws in this design?

The key disadvantage of such kind designs is complexity with moving of an extruder among all 3 axes. Moving platform by at least one axis simplifies that.

Will print quality be affected by using this approach?

It depends on the exact printer's design, so, potentially you can have issues with ease of assembling and maintenance due to more complicated construction and as a consequence higher risk of low printing quality due design, assembly or configuration mistakes.

On the other hand, if you already have some device with precise enough 3 axis machine, like CNC milling machine, you can upgrade it to 3D printer by installing an extruder, however, it would also require update of software and, probably, electronics.




As a frame challenge, they kind of are. It's just that the optimal, and in some sense only reasonable, design for a fixed build platform that doesn't move on any axis is the delta robot geometry. This design is not the most popular, but it's far from obscure - there are lots of cheap entry-level delta printers available as well as higher-end ones.

What makes delta optimal? Keeping a single gantry (like the Ender 3 has) square with a fixed bed height is hard enough; it requires a very rigid frame and perfect rails/rods. If you want to have a multi-axis motion system over a completely fixed bed, you have a whole extra dimension in which it can be non-square. Mechanically (at least for a plain cartesian configuration) it's like having a gantry that moves between two other gantries, each of which already has concerns about remaining square, and the resulting system might not even end up being planar.

The delta configuration avoids this by not having a 2-axis motion system that's constrained to a particular movable Z height relative to the bed, but instead calibrating the transformation between a constrained motion system with free degrees of freedom and normal cartesian coordinates. Any error can just get calibrated out.

On top of that, delta has an extremely low toolhead mass, allowing extreme speeds and accelerations.



Within the realm of Cartesian machines (eg having orthogonal X, Y, Z axis) consider the sort of design you do see: the Ultimaker-like X-Y stage over a build platform which can drop.

The question is then, why drop the build rather than raise the mechanism?

Likely the reason is mechanical simplicity. The X-Y gantry is the part that moves around quickly and may vibrate. It's also the part that is rather complex and has lots of electrical cables. Making that fixed in the housing is generally a simplicity. In contrast, the built object in a typical consumer printer has lower mass, and the build platform only moves slowly so variation in dynamics from its increasing mass isn't really an issue (increasing build mass typically isn't even really taken into account in designs where the build rides on a rapidly moving Y axis either).

You might ask, what would a machine like this look like if instead of dropping the build you raised the mechanism?

It turns out such a thing does exist, in the form of a clever hack where you run a linear rail up the wall of your hackerspace, mount your entire Ultimaker-style printer on it (less build platform and bottom panel), and tap out the Z control signals such that the printer climbs itself up the wall leaving some towering sort of build on a fixed platform below. Conceivably if you wanted to start there you could also saw off all but the top third or so of the cabinet to leave the X-Y gantry with some rigid frame. But it's a bigger, more expensive product that doesn't work simply by lifting it out out of the shipping box. Apart from very unusual or "proof of concept" builds, it doesn't make a whole lot of sense.

The thing about the 3d printer realm is that you're free to try anything you like. Some ideas work. Some ideas don't. Some that go a little bit against orthodox mechanical design as taught in Mech E. departments turn out to work a bit better than they should fairly be expected to, and make it into products. But generally what is on the market is what has proven to present a good balance between cost and utility.




Why is this so rare?

This is rare because machine designers basically copy the designs that work, without trying to innovate too much. As a result of this, Adrian Bowyer's original RepRap design (a travelling type) is currently the most prominent desktop 3D printer design around.

Are there flaws in this design?

There aren't any flaws in the concept for a static bed, after all, it is just a design concept; there are advantages and disadvantages for each type (static, floating and travelling).

Will print quality be affected by using this approach?

The individual implementations will have varying levels of success. Certain designs provide more quality than most due to the rigidity of the frame that is required (e.g. CoreXY) which in turn provides better print quality. Any printer design can produce a good print quality when the machine is well designed and well maintained.


Workhorse Printer - 3D Distributed


3D Printers

Workhorse Printer

Workhorse 3D Printer

Workhorse- Large DIY Industrial 3D Printer Platform

Build Volume – 650 x 350 x 350 mm
DIY 3D Printer Build – Large 3D Printer Kit
Motion System – XYZ Lead Screw / Ball Screw
Machine Kinematics – Fixed Bed / Moving Gantry
Enclosure – Polycarbonate Enclosed
Extruder – Bowden / Direct Drive Extruder
Materials – Filament – FDM / FFF
Controller – Duet3D
Operating System – RepRap Firmware
Design – Open Source
Software– Simplify3D / SuperSlicer
Skill Level – Advanced

Lead Screw vs Belts

The WorkHorse is a large customizable 3d printer platform for designers, builders, and makers. The XYZ Lead Screw motion system is an open-source design that can be adapted to specific materials and applications. In most cases, belt driven 3d printers are better suited compared to lead screw. But this isn’t most cases and the lead screw we selected to drive the WorkHorse isn’t your standard lead screw. We’ve tried a range of different styles of lead screw and had mixed results. We settled with a Igus high helix thread pitch with a 50mm lead.

If you’re looking for an advanced project like building a large 3d printer, the WorkHorse is an open-source design that you can customize for a specific application or project.

Large DIY 3D Printer Build

Lead Screw / Ball Screw Motion System

WorkHorse Printer

WorkHorse Build Resources

  • WorkHorse BOM
  • WorkHorse Documentation

The fixed bedmoving gantry is intended to make the 3d printer more scalable as the bed and z-axis mechanism becomes heavier.

  • Fixed Bed / Moving Gantry
  • X and Y-Axis Lead Screw
3D Printing at RepRap Festival

While most 3d printers use belt driven motion in the x and y axis to increase print speed but loses quality when more weight is applied to the gantry or carriage. The lead screw used on the Workhorse has a high helix pitch with multiple threads to allow increased print speeds while maintaining the quality provided from lead screw and ball screw motion. The system is particularly useful in applications that add more weight to the gantry or carriage. Materials such as clay, chocolate, plastic pellet extrusion or other foods can increase weight that is moved around which results decreased quality or print speeds. Workhorse Printer’s are available to purchase in Machined Component Kit, Hardware Kit or Complete Kit.

Workhorse 3D Printer MRRF 2019
WorkHorse All Lead Screw 3D Printer


Workhorse DIY 3D Printer Carriage DesignLarge 3D Printer Kit

FrameWorkhorse Printer Frame and Gantry Only

We’re experimenting with changing the frame size and switching to a 3030 extrusion profile. We also made the side panels two inches wider to have more room in the electronics / Filament compartment.

Z-Axis Updates

WorkHorse 3D Printer V2 Gantry Plate Z axis lead screw

We finally made a better z-axis lead screw mount.

Z-Axis Lead Screw To Gantry Plate Mount

Download 3D Model

workhorse large 3d printer build 3d printed lead screw nut mounts

The old version of the lead screw nut mounts were 3d printed. They would crack over time so the version is now made from aluminum.

Custom 3D Printer Parts

The Workhorse X-Carriage design is a heavy duty solution for lead screw driven motion that uses MGN12H linear rails and 20×40 or 20×20 aluminum extrusions. 

Y-Axis Motor Mount

Y-Axis Motor Mount to X-Carriage WorkHorse Carriage

The Workhorse 3d printer is available with custom mods and upgrades. We’ve several custom designed machines for many of our customers. If there is a specific size or requirement you just give us a shout. 

New Heated BedWorkHorse Printer Updates

Download Files

WorkHorse Printer CAD

Lead ScrewDescriptionPart Number
X-Axis 2pcs. x 762mm Long Igus High Helix 10mm w/50mm LeadDST-LS-10×50-R 
Y-Axis 1pc. x 485mm Long Igus High Helix 10mm w/50mm LeadDST-LS-10×50-R 
XY-Axis 3pcs x Lead Screw NutsIgus Lead Screw NutsDST-JFRM009 
Z-Axis 2pcs x T12x2 Trapezoidal ACME Lead Screw w/ Brass Nut 500mm LongWK-Z-T12500
Linear Rails DiscriptionDiscription
1pc. x 450mm Long MGN12H 20mm x 20mm Hole PatternWK-Y-LRMGN12h500
2pcs. x 700mm Long MGN12H 20mm x 20mm Hole Pattern WK-Y-LRMGN12h500
4pcs. x 500mm Long w/ Two Carriage BlocksMGN12H 20mm x 20mm Hole Pattern WK-Y-LRMGN12h500
WorkHorse 3D Printer BOM

Buy WorkHorse 3D Printer Parts

WorkHorse 3D Printer PartsWorkHorse 3D Printer Gantry Plates
Machined HardwarePrice $Source
Gantry Plates 3DDistributed
X- Axis C- Carriages 2pcs 3DDistributed
Y-Axis C- Carriage 1pc 3DDistributed
Y-Axis Motor Mount 1pc 3DDistributed
Y-Axis Idler Mount 1pc 3DDistributed
Hotend Mount 3DDistributed
Z-Axis Motor Mounts 2pcs 3DDistributed
Aluminum Build Plate$135. 003DDistributed
WorkHorse BOM


Buy Stepper Motors

See Stepper Motors

Z-Axis Motor Mounts

Z-Axis Motor Mounts

WorkHorse Printer V2

Workhorse Z-Axis Motor Assembly

Duet3D Firmware Files


We now recommend the Duet 3 Mainboard 6HC electronics by Duet3D.

Build Instructions


Sourcing Parts For Your Workhorse 3D Printer

Sourcing Lead Screw

Sourcing Frame Components

Buying Frame Parts

Frame Assembly

Workhorse Frame Extrusions

The frame is made out of 2020 (20mm x 20mm) aluminum extrusions.

  • 20mm x 20mm
  • 4pcs 930mm Long
  • 6pcs 510mm Long
  • 10pcs 570mm Long
  • 3pcs 808mm Long


20mm x 40mm HFS5 Aluminum Extrusions (Misumi Brand)

4pcs 510mm Long



Frame BOM Part List

Frame ExtrusionsLengthUnitsDiscriptionMisumi Part #
2020 (20mm x 20mm)930mm Long4pcsHorizontalsHFS5-2020-930
2020 (20mm x 20mm) 510mm Long6pcsVerticalsHFS5-2020-510
2020 (20mm x 20mm) 570mm Long10pcsFrame WidthHFS5-2020-570
2020 (20mm x 20mm) 808mm Long3pcsBed SupportHFS5-2020-808
Gantry ExtrusionsLengthUnitsDescriptionPart#
2040 (20mm x 40mm)770. 5mm Long2pcsGantry HorizontalsHFS5-2040-770
2040 (20mm x 40mm) 456mm Long
2040 (20mm x 40mm) 510mm Long4pcs.Z axis Linear Rail VerticalsHFS5-2040-510
Frame ComponentsTypeUnitsDescriptionPart#
Frame Brackets20mm Wide90pcsReversal Tabbed BracketsHBLFSNF5
T-Nuts (Misumi)M475pcsM4HNKK5-4
T-Nuts (Misumi)M5180pcsM5HNKK5-5
T-Nuts (Misumi)M375pcsM3HNKK5-3
Frame PricePrice $
Profile Extrusions$ 122. 29extrusions and brackets w/tax and shipping
M5 x 10 Cap Screws (200pcs)$ 9.99225$
brackets$ 40.32
T-nuts$ 19.32
Total$ 191.92
Frame BOM

Frame Assembly

Workhorse Frame Step 1Workhorse Frame Assembly DiagramFrame Diagram Front ViewFrame Diagram Front View


Gantry Motor Plates

Assembling The Gantry Plates

Part List:

  • 1pc. x Gantry Motor Plate
  • 1pc. x Gantry Idler Plate
  • 16pcs. x M5 x 14mm Long Screws
Gantry Motor PlatesGantry Plates2040 Gantry Frame Extrusion Thru HolesY-Axis Carriage 2040 Extrusion Needs M5 Thread (Hand Tap or Get It From 3D Distributed)2040 Gantry Frame Extrusion Nema 23 Motor Mounting Plate Nema 23 Motor Mounting Plate Nema 23 Motor Mounting Plate

Gantry Plates Before Gantry Frame And Motor

Gantry Plates Assembled To Frame

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X and Y-Carriages use 4 M3x6mm Screws

  • X-Carriage (X-Axis) 2pcs
  • Y-Carriage (Y-Axis) 1pc
  • M3x6mm Screws 12pcs (4 for each Carriage)
X-Carriage With Linear Rail

The x-axis carriage screws down to the 2040 Y-axis extrusion and rail. *Note* The y-axis 2040 extrusion must have hand tapped M5 threaded holes.

Y-Axis Assembly

Linear Rails

The Workhorse Printer uses MGN12H linear rails with a 20mm x 20mm Hole Pattern.


  • 500mm Long Z Axis (4pc)
  • 700mm Long X Axis (2pc)
  • 450mm Long w Y axis (1pc) 

Linear Rail Screw:

  • M3x9mm Long Screws 26 per X-Axis
  • M3x9mm Long Screws 14 for Y-Axis
  • M3x9mm Long Screws 18 per Z–Axis

Total M3x9mm screws  138pcs.

Install Y-Axis AssemblyAttached X-Carriage To Linear RailsAssemble Y-Axis Motor Mount To X-Carriage

Motor Mount to Carriage

  • M3x8mm Long Screws 4pcs
Assemble Y-Axis Idler Mount To X-CarriageAssemble Y-Axis Idler Mount To X-CarriageAssemble Y-Axis Idler Mount To X-CarriageAssemble Y-Carriage To Y-Axis Linear RailAssemble X-Carriage Insert

Igus dryspin lead screw nuts do not require lubrication. This is normal for Igus materials. If you have any sounds, vibrations or wear, then the problem is most likely in the alignment and assembly of the mechanical components.

Assemble X-axis Lead Screw Assemble X-axis Lead Screw And X-Carriage Insert Assemble X-axis Lead Screw And X-Carriage Insert Assemble X-Carriage Insert

X-Carriage Lead Screw Nut Insert 2pcs

  • Each Insert uses:
  • M3x35mm screws 4pcs
  • M5x55mm Long
Align & Square Carriage To GantryY-Axis Extruder CarriageScrew Down Y-Carriage To Y-Axis Linear RailY-Axis Carriage Install


Stepper Motors

Heated Bed

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120Z - Modix Large 3D Printers

Modix BIG-120Z

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Modix BIG-3Z 120D Printer

is a unique 3D printer that allows you to print tall objects in one piece, making them stronger and reducing post-processing time. BIG-120Z is ideal for the needs of: visual communication, interior design, art, mannequins, props, entertainment and engineering.


The Modix Big-120Z has similar specifications to all other Modix printers (check here). These are the unique features:

  • Print volume: 600 x 600 x 1.200 mm (XYZ)
  • Machine dimensions: 906 x 1060, 2.000 mm.
  • Machine weight: 160 kg
  • Z-axles HIWIN MGW Linear Rails - included
  • Price includes 12 months warranty and lifetime support. The warranty does not cover degradable (PEI sheet and nozzles) and consumables. For a longer warranty period please contact sales at [email protected].
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