{"product_id":"differential-gear-educational-model","title":"Differential Gear - Educational model","description":"\u003ch2\u003eMy Educational Mechanical Examples Series\u003c\/h2\u003e\u003cp\u003eThis model is one of my educational mechanical mechanism examples on 80mm x 80mm base plates.\u003cbr\u003eYou can find all models of the series in this collection =\u0026gt; \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/makerworld.com\/collections\/15048577-my-educational-mechanism-models\"\u003e[Mechanical Mechanism Examples]\u003c\/a\u003e\u003c\/p\u003e\u003cfigure class=\"image image_resized\" style=\"width: 61.78%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/2025-11-13_a0fbbb25e21458.png\"\u003e\u003c\/figure\u003e\u003ch2\u003eThis model\u003c\/h2\u003e\u003cp\u003eThis is an educational model of the Differential Gear.\u003c\/p\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/941bbe33-a058-4555-8a9b-e45f824b0775.webp\"\u003e\u003c\/figure\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/c8e79c7e-18f9-4005-8ad7-fd25c9879515.gif\"\u003e\u003c\/figure\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"media\"\u003e\u003coembed url=\"https:\/\/www.youtube.com\/watch?v=9IkXLrJ5vaU\"\u003e\u003c\/oembed\u003e\u003c\/figure\u003e\u003ch2\u003eBrief Description\u003c\/h2\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 48.32%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/52902aa6-b9e1-4774-9037-e4deab3f2f06.png\"\u003e\u003c\/figure\u003e\u003cp\u003eThe most typical application of a differential gear is in the axle of an automobile. The driving wheels of a car are rotated by the engine’s power, but the key problem that the differential solves is that the left and right wheels do not always rotate at the same speed. When a car turns, the outer wheel must travel a longer distance than the inner one, meaning it must rotate faster. The differential gear allows this difference in wheel speed while still smoothly transmitting power from the engine.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003eIn this model, the crown gear at the bottom acts as the power input, while the two side disks serve as outputs. The rotation of the crown gear is transmitted through a spur gear to the central gearbox, causing the entire gearbox to rotate. When when both sides experience equal resistance or no resistance, the disks rotate together at the same speed as the gearbox.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003eHowever, when one of the disks is subjected to greater resistance, its rotation slows down, while the other disk speeds up.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003eTo understand why, try rotating the two disks in opposite directions: in that case, the gearbox itself does not rotate. If one side is turned faster than the other, the gearbox begins to rotate proportionally to that difference. This behavior is the origin of the name “differential” gear.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003eThe key point is that, from the gearbox’s perspective, the two side gears always rotate at equal speeds but in opposite directions. Therefore, when the gearbox rotates, the average of the left and right wheel speeds exactly equals the rotation speed of the gearbox. As a result, by rotating the crown gear and driving the gearbox, the differential mechanism makes it possible to transmit power while controlling the average rotational speed of the two output shafts, even when their speeds differ. \u003c\/p\u003e\u003ch2\u003eCase\u003c\/h2\u003e\u003cp\u003eThis model is compatible with the case included \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/makerworld.com\/models\/1983088-educational-gear-examples-1\"\u003ein my first set\u003c\/a\u003e.\u003c\/p\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/ad29ce6c-e9c4-44e2-892b-27ad7f7f6b4f.webp\"\u003e\u003c\/figure\u003e\u003cp\u003e \u003c\/p\u003e\u003ch2\u003ePrinting\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eUse the models named \u003ci\u003e\u003cstrong\u003e???-printable.stl \u003c\/strong\u003efor printing\u003cstrong\u003e.\u003c\/strong\u003e\u003c\/i\u003e\u003cbr\u003eThe models named \u003ci\u003e\u003cstrong\u003e???-assembled.stl\u003c\/strong\u003e\u003c\/i\u003e are provided just to show how they should be assembled.\u003cbr\u003e \u003c\/li\u003e\n\u003cli\u003eUse \u003cstrong\u003ewell-dried PETG\u003c\/strong\u003e to have better dimensional accuracy.\u003c\/li\u003e\n\u003cli\u003eUse \u003cstrong\u003e0.1 mm or 0.08 mm layer height\u003c\/strong\u003e to have smoother surfaces.\u003c\/li\u003e\n\u003cli\u003eUse slow printing speed for overhangs.\u003c\/li\u003e\n\u003cli\u003eSelect \u003cstrong\u003e“Random” seam position\u003c\/strong\u003e to have smoother rotation.\u003cbr\u003eRandomly distributed seam should be easily worn out after some wearing.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eSanding and Filing\u003c\/h2\u003e\u003cp\u003eSometimes, the gears suffer from the stringing effect and\/or elephant foot effect, resulting in a too tight fit to the shafts (they are designed with a 0.15 mm radial clearance). \u003c\/p\u003e\u003cp\u003eIf you see rough surface on the shafts due to stringing, sand off the roughness with a small piece of sand paper.\u003c\/p\u003e\u003cp\u003e\u003cimg class=\"image_resized\" style=\"width: 32.08%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/e3abfcd0-e7ad-4abe-85e6-6965ba474fb3.webp\"\u003e\u003cimg class=\"image_resized\" style=\"width: 31.94%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/fa3a3254-6dd2-4e30-8dd5-2a9c7d5bf1bf.webp\"\u003e\u003cimg class=\"image_resized\" style=\"width: 31.92%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/b5710942-b209-4c4f-9808-6e8e106c0771.webp\"\u003e\u003c\/p\u003e\u003cp\u003eIf you feel the gears do not rotate smoothly due to an elephant effect, widen the hole slightly by using a thin round bar file.\u003c\/p\u003e\u003cfigure class=\"image image_resized\" style=\"width: 75%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/432ebfa1-c26a-49fd-9ca8-d199382cd692.webp\"\u003e\u003c\/figure\u003e\u003cp\u003eWithout those issues, the parts should rotate very smoothly with minimal friction.\u003c\/p\u003e\u003ch2\u003eAssembly\u003c\/h2\u003e\u003cp\u003eNo glue is needed, in theory.\u003c\/p\u003e\u003cp\u003eFirst, put the output bevel gears in the gear box.\u003c\/p\u003e\u003cfigure class=\"image image_resized\" style=\"width: 50%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/1e0cee90-b61c-4214-a5ed-aba937488b5d.png\"\u003e\u003c\/figure\u003e\u003cp\u003eThen, slide the other two bevel gears \u003ci\u003esimultaneously \u003c\/i\u003einto the gearbox from the opposite sides. Once the gears are roughly meshed, you can swallow and align the small bevel gears to their correct positions by turning both output shafts in the same direction at the same time. Temporarily attaching the output disks to the shafts may make it easy to rotate the shafts for the purpose. This will be the most difficult part of assembly. If they do not get in, you can try slightly sand off the back surface of the small bevel gears.\u003c\/p\u003e\u003cp\u003e\u003cimg class=\"image_resized\" style=\"width: 50%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/7fb15058-aa53-4add-b4fd-1627327325d2.png\"\u003e\u003cimg class=\"image_resized\" style=\"width: 50%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/575473fd-c568-43cd-a3ad-1d5be5bbf89b.png\"\u003e\u003c\/p\u003e\u003cp\u003eThen, push the shaft in and fix it with the retaining rings.\u003c\/p\u003e\u003cfigure class=\"image image_resized\" style=\"width: 50%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/d6624956-e0d5-47e3-9833-9f1a29f117c9.png\"\u003e\u003c\/figure\u003e\u003cp\u003eAt this point, check that the two output shafts can rotate smoothly. If the clearances are properly maintained, you should see that when you spin an output shaft quickly and release it, it continues to rotate slightly by inertia. If the rotation is not smooth, inspect the holes for the gear shafts, as well as the thickness and smoothness of the back-surface of the two small bevel gears. It is affected by the precision of the first layer height and the roughness of the bed floor. If necessary, adjust them carefully with a thin bar file or sandpaper before proceeding.\u003c\/p\u003e\u003cp\u003eThe rest is easy if the parts are nicely printed:\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eMount the spur gear on the side wall of the gearbox with a tab. The tab should fit the notch on the spur gear.\u003c\/li\u003e\n\u003cli\u003eMount the spacer ring on the other side. \u003c\/li\u003e\n\u003cli\u003eSnap the side output disks into the rectangular holes at the ends of the shafts. \u003c\/li\u003e\n\u003cli\u003ePut the crown gear on the base plate and lock it with the retaining ring.\u003c\/li\u003e\n\u003cli\u003eFinally, push the shafts of the gearbox into the bearing on the base plate.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cfigure class=\"image image_resized\" style=\"width: 50%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/386f288e-b8ac-48be-9546-41aa4d31d9fd.png\"\u003e\u003c\/figure\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e\u003cstrong\u003ePOSSIBLE DIFFICULTY:\u003c\/strong\u003e Inserting the side disks and mounting the two shafts onto the bearings can be a bit tricky, because the snap tabs and bearing parts may print somewhat fragile if your filament has absorbed moisture. Be careful not to break them during assembly.\u003c\/p\u003e\u003cp\u003eIn particular, if your print shows stringing, it’s a clear sign that the filament has taken up too much moisture or nozzle temperature is too high. So, dry the filament to get robust print.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003ch2\u003eOther educational models\u003c\/h2\u003e\u003cp\u003eYou may also be interested in the models in my educational mechanical mechanism examples.\u003c\/p\u003e\u003cp\u003eFind them in this collection:\u003cbr\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/makerworld.com\/collections\/15048577-my-educational-mechanism-models\"\u003ehttps:\/\/makerworld.com\/collections\/15048577-my-educational-mechanism-models\u003c\/a\u003e\u003c\/p\u003e\u003cfigure class=\"image image_resized\" style=\"width: 61.78%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001991124\/design\/2025-11-13_a0fbbb25e21458.png\"\u003e\u003c\/figure\u003e\u003ch2\u003eAcknowledgement\u003c\/h2\u003e\u003cp\u003eI got into gears thanks to \u003cstrong\u003eK.$uzuki\u003c\/strong\u003e's amazing \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/karakurist.jp\/\"\u003earticles\u003c\/a\u003e and \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/www.youtube.com\/@karakurist\"\u003eYouTube videos\u003c\/a\u003e. Many of the mechanisms shown in this series came from the introductions on \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/karakurist.jp\/\"\u003ehis website\u003c\/a\u003e. He also makes \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/oishiiosushi.thebase.in\/\"\u003eexcellent gear models\u003c\/a\u003e himself. This series wouldn’t have existed without his inspiration.\u003c\/p\u003e\u003cp\u003eI learned a lot about technical detail of designing gear tooth profiles from \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/involutegearsoft.hatenablog.com\/\"\u003eHaguruma-No-Hanashi website\u003c\/a\u003e. I’m truly grateful for that.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003ch2\u003eLicense (2026-03-13 updated)\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eThe 3D model(s) are licensed under \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\"\u003eCreative Commons Attribution 4.0 International\u003c\/a\u003e. (unchanged)\u003c\/li\u003e\n\u003cli\u003eHowever, the text and images on this page are copyright reserved. (added on 2026-03-13)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003eDesign by osamutake on MakerWorld (license: BY).\u003c\/p\u003e","brand":"Mymadmanlab","offers":[{"title":"Default Title","offer_id":67383346004272,"sku":null,"price":16.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0987\/0809\/5280\/files\/0_edf3ac55-7a37-46a8-82a6-a75c8277a864.png?v=1784502799","url":"https:\/\/mymadmanlab.com\/products\/differential-gear-educational-model","provider":"Mymadmanlab.com","version":"1.0","type":"link"}