Atlas

Atlas is a load-cell calibration rig for the Carbon L1 printer. The rig is designed to mount into the printer. The printer is able to push and pull against the springs in the rig to exert its full range of force (+/- 2250 lbf). At maximum compression and tension, the rig is capable of exerting up to 3000 lbf against the printer. The force datastream on the reference load cell in the Atlas rig gets compared to the force datastream of the printer’s onboard load cell to ensure that both datasets match.

Spring stiffness calculations using both Newtonian force methods and energy methods of modeling. These calculations proved that the spring setup, when properly preloaded, yielded double the equivalent stiffness of the original stiffness of the springs alone.

Lightweighting was performed on the large billet to ensure that the rig could still be carried by hand. MIC 6 aluminum plate was selected as the material due to its low residual internal stress. Due to the part’s flat and thin profile, the low residual stress meant lesser likelihood of warping after milling.

In order to prevent friction between parts from affecting the load readout of the cells, oilite bushings were inserted into the midplate.

Proper geometric dimensioning & tolerancing (GD&T) callouts were made on the technical drawing to ensure the fit and function of the rig within the tolerant range. By controlling critical dimensions like the “schunk” interfaces (the four circles that lock into the printer), the machinist is able to create the part to specification to ensure the rig always works as intended.