Redesigned Gear Depthing Tool

grabcad

DESIGN SUMMARYThe problem I set out to address was that of figuring out the perfect distance between 2 or more gears so that they mesh/work properly once placed on their mounting points. This problem is especially relevant in 3D Printing as usual methods for dealing with said problem, like heavy post process of the fabricated gears, is not possible and unlike metal or mold forming which can be quite accurate, 3D printed gears are guaranteed to not work perfect right off due to printing inconsistencies. So this forces designers to have to play around with the profile of the gears and mounting points until the required fit is achieved, reprinting countless times in the process. This is not only wasteful and and time consuming, but also labor intensive and aggrevating. With the use of the depthing tool however, you simply need to print your gears once, measure the ideal distance with the tool, tweak the profiles of the mounting points then print those once as well. Naturaly this saves the designers lots of effort and material. While the concept of such a tool is not new, my version is made specifically to cater to 3D Printed gears (by upscaling the general tool form from its usual size suited for fine watch making), provide upgrades that make the tool more user friendly and convinient (like micrometer style measuring, adjustable mounting points and lock down mechanisms), as well as introduce revolutionary modularity, allowing the combination of multiple tool modules, so that an entire chain of gears can be tuned, and not just 2-3 like it has only been possible until now.DETAILED DESCRIPTIONI am entering this competition as a post secondary education student, currently enrolled in an undergraduate mechanical engineering course at Brunel University London, England, UK.IntroductionFor my entry I have chosen to completely redesign and overhaul the concept of the gear depthing tool. A gear depthing tool is a tool used in determining the proper distance between 2 gears so that they mesh properly. Theoretically this distance should be the combined 2 radi of the pitch diameters of the two gears, however in practise, the actual proper distance can differ from a few fractions of a mm to a couple mms, due to manufacturing inaccuracies, as well as user prefered backlash/looseness.These kind of tools are usually mostly found in fine watch making, as larger conventional gears either run fine even without perfect meshing, or if required, can be cut deeper. The introduction of additive manufacturing via the use of 3D Printing however, has presented a renewed need for such a tool, as manufacturing defects are much more severe than in conventional metal forming or plastic moulding creation techniques, and cutting the gears further after fabrication is impossible without compromising their integrity. This means that in order to get a perfect meshing you have to trial and error endlessly, wasting time and material in reprinting either the gears or their mounting points until you get the desired fit. My design aims to provide the perfect solution for this issue and bring an easy to use and fit for purpose tool in the hands of 3D Printing users, by introducing a tool you can use to measure the proper meshing distance between two or more gears you have printed, and use that information to create the rest of the parts needed within that context, completely eliminating the need for trial and error and/or reprinting in the process.Redesign description illustrating design creativityWhile keeping in line with the original concept of the gear depthing tool, where you have one fixed mounting point for 1 gear, and a moving mounting point for the second gear, gradually bringing the two together, my redesign provides multiple “quality of life” improvements as well as completely revolutionizes the concept itself, by introducing complete modularity to the entire system. Where conventional gear depthing tools allow only 2 (and on very rare occasions 3) gears to be tuned at the same time, my design functions in such a way that you can connect multiple gear depthing modules into one another, and therefore tune an entire chain of gears that can be infinitely long in size, while at the same time allowing individual and independent tuning of each set of gears within the chain. The modules can connect to one another from both sides, and are offset by 30 degrees from one another so as to not have any issues when gearing down (having a small gear followed by a big gear multiple times in a row).The quality of life improvements include adjustable chucks for both mounting points, so that any axle between 1.5-5 mms can be mounted on them without the need for changing axle receptors, micrometer style measuring, so that the distance between the gears can be recorded accurately up 0.1 mm and grub screw style locking of the driving screw, so that a distance between two gears can be locked down and you can move to the next set of gears, within a chain. The linear motion is achieved via the use of an enclosed screw driving a sleeve, which itself is enclosed on a slider running across linear rails. In this way the length of the entire module stays the same throughout the entire motion of the screw and slider (unlike most conventional gear depthing tools, where the main screw gradually starts protruding from the back as it travels ). The design also allows the user to calibrate it. By locking down the primary grub screw you can lock down the main screw, and by unlocking the secondary grub screw you can unlock the sleeve, and therefore by moving the sleeve itself from the sides, you can reposition the slider relative to the main screw, while the main screw itself stays static (This is well represented in the video linked below). As to the micrometer style measuring system, the main knob on the back of the module that you twist to rotate the driving screw, is divided in 25 divisions, with the main screw having a 2.5mm pitch. This means that for each increment indicated on the knob, the slider has moved 0.1 mms. A gauge marking every 2.5mm increase in distance is located on the top of the left module rail. The minimum distance between 2 gears measured by the module is 40.5 mms (26.5mm if using the standalone measuring end, and you are not connecting the module to another module) with the maximum distance being 123 mms. This gives a full 82.5mm range of measuring adjustment.Printing/ Adherence to specsThe entire module comprised of 17 parts can be 3D Printed on an FDM printer with PLA in one go and within the 120.65x120.65x120.65 volume set by the competition, as evident in Slicer Picture 1 and 2. Printing is to be done at 0.1 mm layer height with 0.2mm thickness (ideally using a 0,2mm nozzle), generating supports with an angle cap of 30 degrees. If printing everything in one go it is recommended to print at 80%< infill, in order for important parts to get required hardness. I have included STL files to print everything in one go, both with and without the end cap, incase you want a standalone unit or a modular piece. I have also included all parts to be printed separately, so that incase an individual part is not printed well, it can be reprinted separately, as well as to allow for the user to customize the colouring pattern he chooses to print the different parts with and also give the opportunity to print different parts at different infill densities, as some parts are fine even when printed at 10% internal density. A 3D printed example printed on a Cetus 3D FDM printer using UP slicer software, can be seen in pictures Real Life Pics 1-5Advanced Manufacturing: Exploration of the impact of 3D printing on your design, shape, structureIn order for the design to be 3d Printable a lot of in context design choices had to be made. Cylindrical parts had to be printed vertically, and with the space limitation that influenced the shape and size of a lot of components. Spiral (screw) features also required vertical printing, and where that was not possible, the screw feature was seperated from the main part and put on an insert to be printed verticaly seperately. Due to the nature of 3d printing, conventional mechanical fixtures used when creating tools of this kind like rivets or pins were unsuitable, and so snap fit connection points had to be created between components requiring fixing. Tolerances between intermoving surfaces also had to be given in line with the printing layer height and thickness of the chosen printer, typically 0.1 mms between linear moving pieces (See Picture named Tolerance 1), and 0.3 mms between radially moving pieces (See picture named Tolerance 2). However 3D printing also provided certain advantages. Pieces that would have otherwise needed to be printed in multiple parts (like the slider/ chuck base) could be printed as one via the use of 3d printing.Overall impression of the artWhile the redesign itself focuses on a functional tool, whose value is mostly counted in its usefulness, artistic considerations were made. Cuts were created where possible to both simplify parts, and give them a sharp nice looking profile, and the part separation was done in such a way to allow for a tri-chromatic pattern to nicely underline the tone of the tool.Please find below linked a video I created, showcasing the assembly and calibration required for an individual module, as well as the operation of a module both in standalone and modular use.