Jan.10, 2013

When assessing 3D printers, build space provided by the manufacturers can be easily compared. However other data, such as print speed, quality, cost provided by the manufacturers are difficult to compare, and it is even more difficult to compare printers that employ different technologies.

Specifically, it is difficult to get clear metrics that will allow the following to be compared:


Speed – Manufacturers provide print speed specifications for their machines in a variety of ways. Some talk in terms of layers per minute, some provide information about the speed that the printer head can move, some provide no data at all.


Quality – Manufacturers provide very little quantifiable information about the quality of the output of their machineseither in terms of accuracy or precision.


Cost – Manufacturers either have their own range of materials or recommend a range of materials for their machines. The pricing for these materials differs acrosstechnologies and suppliers (e.g. SLA machines require resin that is sold on the basis of volume, FDM machines require a filament that is sold on the basis of weight or length).

This white paper "Comparison of Object Printers", written by Shane Ryan, with contributions from Phil Bonham-Pritchard and & Dr Jafar Jamshidi, proposes a test (The Rho Test) that solves these problems by providing the following comparable standard outputs:

Rho Speed –A single number(ρS), a higher number indicates a higher speed.

Rho Quality – Three numbers expressed as percentages:

  • ρQS – This reflects the accuracy of the size of the printed object -100% represents a perfect size
  • ρQG – This reflects the precision of the geometryof the printed object -100% represents a perfect geometry
  • ρQF – This reflects the surface finish of the printed object -100% represents a perfect surface finish

Rho Cost –A single number(ρC), a lower number indicates a lower print cost (this output must be provided with a currency).

This paper addresses the problem, the solution, the test method, how to prepare and execute test and how to calculate the output. This test method can help users to assess 3D printers and find the right one to best match individual or organization's needs, budgets, and operating style.To read the full paper, download it here.





Posted in 3D Printers


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