A study on the dimensional accuracy of a Qidi Tech X-Max 3D printer (2025)
"The world is filled with 3d printers and materials, allowing people to fulfil the fruits of their creative minds. However, certain projects require the production of objects within tight tolerances, and this can be a challenge for the majority of 3d printers. This paper aims to present a study on the dimensional accuracy and precision of a Qidi Tech X-Max 3d printer, by manufacture of three perforated plastic plates, equivalent to test sieve perforated metal plates, and measurement of these parts on an optical CMM, using a VBA program for calibration according to ISO 3310. This procedure makes it possible to calculate parameters at specific three-dimensional coordinates in the perforated plastic plate, allowing an exact characterization of the printing process. The hotbed surface height will be analysed as these printers are known for having warp issues that could be affecting the accuracy of the X and Y axes. The experimentation process yielded an original method for mechanical leveling of the hotbed."
Concrete Testing Machines - Verifying the upper platen and machine components with 3D printed positioning mechanisms (2024)
"A practical case of substituting the upper platen of a concrete compression testing machine will be presented, where original 3D printed positioning mechanisms are used in the verification of the machine according to Standard NP EN 12390-4:2021. Due to time constraints for this maintenance operation, the dimensions of these first prints were not properly verified and were later found to be out of the specified tolerances. However, machine verification results did, unexpectedly, turn out to be satisfactory and were validated by comparison to a later verification made by an ISO 17025-accredited laboratory. The dimensional inaccuracy was a consequence of the lack of calibration of the printer’s axis and extruder motors, which has been successfully accomplished. In spite of the ongoing difficulties, these tools are worth it for their lightness, simplicity of usage and adaptive design, as well as the low costs and ease of production with a 3D printer."
Aquisição de balanças electrónicas para ensaios no domínio da Engenharia Civil (2012)
"No desempenho de funções como Responsável Metrológico do LREC, fui muitas vezes abordado por colegas com dúvidas na aquisição de balanças eletrónicas. Nesta sequência, serve este relatório para apresentar um método simples e eficaz que permita a qualquer utilizador selecionar a balança adequada às suas necessidades."