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Lawson Documentation
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Release status: concept

Lawson is a 3D printer with accurate linear motion and a mechanically stiff frame.
CAD Models
External Link


Lawson is a 3D printer design by Scott Lawson featuring excellent linear motion accuracy and a mechanically stiff frame. Compared to the MendelMax 2, Lawson eliminates the need for custom sheet metal, significantly lowers build cost, and uses higher quality linear motion components for the X, Y, and Z axes. It is easy to source components for the Lawson printer as 95% of the components can be sourced from only two suppliers.


Lawson is a high precision and mechanically stiff 3D printer. Components can be substit uted to tailor the printer for higher accuracy and precision, or to lower build costs.


  • Stiff, rigid frame with no play
  • High accuracy and precision
  • Mechanical components can be purchased from two suppliers, minimizing the reliance on a middleman supplier.
  • Components can be substituted to achieve higher quality or lower build costs, appealing to a wide audience.


Component λ Variant ϵ Variant
Mechanical parts (exc. motors, electronics, screws) 26 26
Printed parts (exc. motors, electronics, screws) 0 17
Hardware Cost (exc. motors, electronics, screws) $443.41 $369.52
Controller Electronics Almost all RepRap Almost all RepRap
Printing Size 200 x 200 x 240 200 x 200 x 240
Motors 4x NEMA-17 Stepper, 1x NEMA-23 5x NEMA-17 Stepper
Pro High accuracy, speed, stiffness Lower cost, high speed
Con Higher cost Lower mechanical stiffness and accuracy


Design Goals

  • All printed components can also be purchased off-the-shelf
  • 95% of components available from two suppliers, to simplify component sourcing
  • High accuracy and mechanical stiffness
  • Component substitution can tailor design for high precision or mechanical stiffness


The total build cost of the Lawson printer is approximately $900 USD. This is the price for all components needed to build a working Lawson printer. Build costs can be reduced by up to approximately $120 USD if printed components are used.

Component Sourcing

To simplify component sourcing, 95% of the components can be obtained from only just two suppliers, Misumi and OpenBuilds Parts Store. Parts that cannot be obtained from these suppliers are:

  • Hotend + extruder
  • Heated bed + Glass
  • Electronics

This gives users the freedom to easily purchase Lawson components themselves, without needing to go through a middle-man supplier selling a kit.


The x-axis is a belt driven linear stage powered by a NEMA 17 stepper motor. The axis is constrained by OpenRail which is screwed into a length of 2020 aluminium extrusion. The x-carriage wheels have eccentric spacers that can be adjusted to prevent excessive friction. The belt tension can be adjusted easily by loosening the belt idler and sliding it left or right on the extrusion. A bowden feed extruder is reccommended over a direct drive extruder because it significantly reduces the mass of the x-carriage, permitting higher acceleration and speed values and reducing resonance.


Overview of the triangular y-axis belt drive mechanism.

The y-axis is a belt driven linear stage powered by a NEMA 23 stepper motor. The axis is constrained by a precision Misumi linear slide. Compared to y-axes in other designs such as the MendelMax 2, this triangular belt configuration permits higher speed and acceleration values, reduces component costs, and simplifies construction and maintenance access. The NEMA 23 was selected instead of a NEMA 17 because it simplifies mounting and has generally higher performance characteristics.

The y-axis belt tension can be adjusted by loosening the screws on the NEMA 23 motor and sliding the motor left or right.


The z-axis is a lead screw driven linear stage powered by two NEMA 17 stepper motors wired in parallel. The z-axis is accurate to ±150 µm over the full travel. The wheels have eccentric spacers that can be adjusted to prevent excessive friction from overconstaint.

Close-up of the z-axis which is constrained by V-slot wheels.

Printable Components

A number of Lawson components can be 3D printed to reduce build costs, with the caveat that printed components are less stiff than their metal counterparts. Unlike many other RepRap printers, all printable components are purchasable, but not all purchasable components are printable. This means that printed components are not mandatory and that individuals without access to 3D printers, or individuals who prefer metal components are able to build a Lawson printer. The use of printed components can save up to approximately $120 USD in build costs.

Optionally printable components are shown highlighted in blue.


Almost all RepRap electronics such can be used to control the Lawson. Electronics confirmed to be working include the RUBMA Board, Printrboard, GEN7, RAMPS, and Rambo board.