Model Overview & Print Notes

A torquetum is a device used for observation and calculation during the Middle Ages. It allows the observer to measure the position of a star or planet in one of three different coordinate systems. One is the observer’s point of view relative to the horizon (both parts closed), the second is relative to the Earth’s equator (the Tabula Equinoctialis is set to the observer’s latitude), and the third is relative to the planetary ecliptic (the Tabula Equinoctialis is set to the observer’s latitude, and the Tabula Orbis Signorum is propped up with the stilus). It seems excessively complicated to use for taking measurements and is probably more useful as an analog computer for converting measurements made by other devices to one of the other coordinate systems without having to perform spherical trigonometry. Some of the adaptations allow for 3-D printing, such as raised lettering and markings, so that the top couple of layers can be printed in a different color by pausing the print and changing filaments. Other changes have been made to accommodate the FDM process and to minimize the need for printing supports. The scale on the Tabula Orizontis has been extended to range from a latitude of 9° N to 90° N, since I live considerably further south than those who designed and built the originals in Europe . This is rather large and will not fit on many print beds. It will fit on a printer like a Prusa XL if you split the Tabula Orizontis (the base). I printed this on a Prusa i3 MK 3S+ by scaling each part by 70%. I still had to split the base piece. I used PLA, a 0.4mm nozzle, and a layer height of 0.2 mm. A larger nozzle or layer height may result in some loss of detail on the markings and symbols. All parts can be printed in PLA. Two perimeters and 15% infill should work fine. I found that using at least 4 layers for the top resulted in a fairly flat and smooth surface. When assembling, do not overtighten the fasteners. The various parts should move freely, except for the hour circle. Ny-lock nuts may be helpful. The only fasteners that should be tight enough to restrict movement are the two on the protractors of the Tabula Orizontis. Once this is set for your latitude, it should not need to be adjusted unless you move the device. The Crista has a triangular protrusion that fits into a corresponding notch in the Turnus. Normally, these two parts would be a single piece. Note that the dimensions are optimized for a full-size print. Scaling down will result in some loss of detail in the text. A 0.25 mm nozzle may be necessary to achieve the best results with the scaled-down version. Someday I hope to get a larger-format printer and make this full size. A bill of materials and detailed instructions are included in the PDF file. If you find any errors, please let me know. Information is scarce since there are very few of these in existence. ## 3D Printing Settings