{"product_id":"educational-gear-examples-1","title":"Educational Gear Examples 1","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\/DSM00000001983088\/design\/2025-11-13_a0fbbb25e21458.png\"\u003e\u003c\/figure\u003e\u003ch2\u003eThis set\u003c\/h2\u003e\u003cp\u003eThis set includes educational models of:\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eSpur gear\u003c\/li\u003e\n\u003cli\u003eHelical gear\u003c\/li\u003e\n\u003cli\u003eRack \u0026amp; Pinion\u003c\/li\u003e\n\u003cli\u003eInternal gear\u003c\/li\u003e\n\u003cli\u003eScrew gear\u003c\/li\u003e\n\u003cli\u003eBevel gear\u003c\/li\u003e\n\u003cli\u003eWorm and Worm wheel\u003c\/li\u003e\n\u003cli\u003e Crown gear\u003c\/li\u003e\n\u003c\/ul\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/2e16b0f5-b834-4d70-8a70-4f738531a343.webp\"\u003e\u003c\/figure\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/c84608f2-655a-4aa0-9726-ed89cea0239c.webp\"\u003e\u003c\/figure\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/a2c51af8-d468-412b-a260-9958e9890854.gif\"\u003e\u003c\/figure\u003e\u003ch2\u003eIntroduction Video\u003c\/h2\u003e\u003cfigure class=\"media\"\u003e\u003coembed url=\"https:\/\/www.youtube.com\/watch?v=elEaZYwKxLQ\"\u003e\u003c\/oembed\u003e\u003c\/figure\u003e\u003ch2\u003eBrief Descriptions\u003c\/h2\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 23.45%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/9f8171d4-3150-4023-bc20-f51d468b2ecf.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eSpur gear\u003c\/strong\u003e is the simplest and most common type of gear, which is used to transmit rotation and power between two parallel shafts. It has a cylindrical shape, and its tooth trace is straight and parallel to the axis. When one gear turns, it makes the other gear turn in the opposite direction. The number of teeth determines the speed ratio between the two gears. If one gear has more teeth, it will turn more slowly but with greater torque. This model shows the most common type of spur gear, which is called as “involute gear.” Its tooth profile is made up of an involute curve on the outer side and an epitrochoid curve near the root. These shapes are naturally produced when the gear is cut by a rack-shaped cutting tools. So, involute spur gears are easy to manufacture and inexpensive. Only the involute portion of each tooth is used to transmit motion between gears. The epitrochoid portion does not contact with the other gear. When the number of teeth is small, the tooth shape is cut deeply near the root as seen in the smaller gear in this model. This is called an undercut, and it helps prevent the teeth from colliding with the other gear but it also makes the teeth thinner and weaker. Spur gears are simple, efficient, and widely used in machines, such as clocks, vehicles, and industrial equipment.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.54%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/0afe9f2c-1eae-45d6-8841-a08463e39f6a.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eHelical gear\u003c\/strong\u003e can be thought of as a \"twisted spur gear\". Two meshing helical gears have the same helical angle, but in opposite directions (one right-hand, the other left-hand). More precisely, a standard helical gear is defined so that its \"tooth-normal\" tooth width and angle are the same as those of a standard spur gears. As a result, its \"axis-normal\" view of a helical gear shows thicker teeth than a spur gear with the same size. Because the teeth engage gradually along the helix, contact and separation occur progressively along the axis. This provides smoother meshing and quieter operation than spur gears. On the other hand, the angled contact also generates an axial thrust force, which must be absorbed or supported by bearings or other suitable supporting structures. Because of their quiet and smooth operation, helical gears are often used in automobiles and industrial machines.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.26%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/80fa640c-ac09-4de5-b47e-61361988c879.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eRack\u003c\/strong\u003e can be regarded as a spur gear with an infinite radius. Its tooth profile is exact trapezoidal, which consists of linear lines except for the root part that does not contact with the other gear. A rack can mesh with a standard spur gear, which is called the \"\u003cstrong\u003epinion\u003c\/strong\u003e.\" In fact, standard spur gears are often manufactured by cutting a cylindrical material with a rack-shaped cutting tool, whose tip is slightly elongated to make the root clearance. The rack and pinion mechanism is used to convert rotational motion into linear motion, as seen in steering systems and machine tools.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.27%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/327f8dfc-63ed-4758-b0e7-17fbc8c2afb7.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eInternal\u003c\/strong\u003e gear looks so different from a standard \"external\" gear. Its teeth are teething from the outer circumference toward the center. However, if you look at the shape of the hollow part, you can see that an internal gear can be regarded as a disk-shaped piece with a “gear-shaped hole.” This is exactly correct — the shape of the hole is identical to that of an external gear shape with same number of teeth. An internal gear meshes with an external gear that is placed inside it. This type of gear pair is often used in planetary gear systems, which works as compact speed reducers.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.54%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/e1acb9d5-732a-426a-b81a-f1b6fc94946c.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eScrew\u003c\/strong\u003e gear consists of two helical gears whose axes are in a skew position. It equips with two thick gears in this model but, in theory, the meshing teeth contact at only a single point. So, screw gears are not suitable for heavy-load applications. The helix angles of the two meshing gears in a screw gear may be different in value but they must have the same hand – both right-hand or both left-hand. Screw gears are used when the shafts are neither parallel nor intersecting, and when quiet, light transmission is required — for example, in measuring instruments or small machinery.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.67%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/d21b1eae-3a01-4c33-a70f-cb1dc4aff5a3.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eWorm\u003c\/strong\u003e can be regarded as a rack that is helically wrapped around a cylinder. This model shows single-thread worm, which has only one continuous tooth around the cylinder. A \u003cstrong\u003eworm wheel\u003c\/strong\u003e may sometimes looks similar to a helical gear. However, as shown in this model, it is actually formed by cutting a disk-shaped material with a worm-shaped cutting tool. As a result, the tooth shape of a worm wheel is different from that of a standard helical gear. Worm and worm wheel pair provides a very large gear ratio. Because of this, the transmission of motion is often one-way — the worm can drive the worm wheel but the worm wheel can not drive the worm. This self-locking property makes worm gears useful in hoisting machines, conveyors, and steering mechanisms, where backward motion must be prevented.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.54%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/04e3ccab-2038-4cc9-95d8-dfb66e54b691.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eBevel\u003c\/strong\u003e gear has cone-shaped reference surfaces whose apexes coincide with each other. Their tooth profile looks similar to that of a standard spur gear. However, strictly speaking, the tooth of a bevel gear are not formed by planar involute curves unlike spur gears, but by \"spherical\" involute curves. As shown in this model, when properly designed, two axes of two meshing bevel gears can intersect at any angle, although a right angle is the most common. Bevel gears are used to transmit motion between intersecting shafts, most commonly at a 90-degree angle, as in automotive differentials and machine tools.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cfigure class=\"image image_resized image-style-align-right\" style=\"width: 24.39%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/0b759848-48e3-41e4-9d2b-f2c1bbef8fa1.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cstrong\u003eCrown\u003c\/strong\u003e gears,  also called face gears, can mesh with standard spur gears. Since the circumferential velocity changes with the radius, the tooth profile of a crown gear also varies along the radius. As shown in this model, the top surface of each tooth appears diamond-shaped. Only the outer portion — from the side vertices of the diamond — can mesh with the pinion. The inner portion does not contact the pinion. Crown gears are used to transmit motion between two shafts intersecting at a right angle, for example in instrument mechanisms and light-duty drives. Compared to the bevel gears, it does not require precise alignment of pinion gear along the axis. In this model, the thinner pinion can move freely along the shaft, and you can observe that it meshes perfectly regardless of its position.\u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003cp\u003e \u003c\/p\u003e\u003ch2\u003eCase\u003c\/h2\u003e\u003cp\u003eA \u003cstrong\u003estandard light-weight case for personal usage\u003c\/strong\u003e is included in this model, which is in the background in the picture.\u003cbr\u003eA \u003cstrong\u003epremium case \u003c\/strong\u003eis \u003ca target=\"_blank\" rel=\"noopener noreferrer ugc\" href=\"https:\/\/makerworld.com\/models\/1984007-premium-case-for-my-educational-mechanical-models\"\u003eseparately provided in this model\u003c\/a\u003e, which is in the foreground in the picture.\u003c\/p\u003e\u003cfigure class=\"image image_resized\" style=\"width: 75%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/89ee48df-05af-40cd-bf45-62297b4090e5.webp\"\u003e\u003c\/figure\u003e\u003cfigure class=\"image image_resized\" style=\"width: 75%\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/651c5fb2-41eb-4b8b-a1cd-d1de5f773793.png\"\u003e\u003c\/figure\u003e\u003cp\u003e\u003cimg class=\"image_resized\" style=\"width: 50%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/3382caa0-7f33-4733-ac12-78bd026318fb.webp\"\u003e\u003cimg class=\"image_resized\" style=\"width: 50%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/3f9ca136-b02e-46ea-919c-c6d36cd42beb.webp\"\u003e\u003c\/p\u003e\u003cp\u003eAll the eight gear examples included in this model can fit in a single case.\u003cbr\u003eNote that the crown gear and the bevel gear are facing to each other to save the space.\u003c\/p\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/85bbdf25-bc78-496d-8e5b-23821f5d76a4.webp\"\u003e\u003c\/figure\u003e\u003cp\u003e \u003c\/p\u003e\u003ch3\u003eLid with slots\/ridges\u003c\/h3\u003e\u003cp\u003eI provide two kinds of the lid for the case.\u003c\/p\u003e\u003cp\u003eOne is a simple empty lid. It is easy to put on the case.\u003c\/p\u003e\u003cp\u003eI lately added the other one, which is with slots or ridges to stably support the base plates of the models in the case. It is also useful as a temporal display stand for the printed models.\u003c\/p\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/559381bf-d4d9-40d7-a507-01e02606c778.webp\"\u003e\u003c\/figure\u003e\u003cfigure class=\"image\"\u003e\u003cimg src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/acd98f19-3dc8-45ba-9936-b425d46850d0.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 to show how they should be assembled.\u003cbr\u003e \u003c\/li\u003e\n\u003cli\u003eUse well-dried PETG to have better dimensional accuracy.\u003c\/li\u003e\n\u003cli\u003eUse 0.1 mm or 0.08 mm layer height to have smoother surfaces.\u003c\/li\u003e\n\u003cli\u003eUse slow printing speed for overhangs.\u003c\/li\u003e\n\u003cli\u003eSelect “Random” seam position to have smoother rotation.\u003c\/li\u003e\n\u003cli\u003ePrinting orientations:\u003cul\u003e\n\u003cli\u003eThe long shafts of the worm and the pinion for the crown gear should be printed in a standing position. Add brims to them for safer printing.\u003c\/li\u003e\n\u003cli\u003ePlace the worm so as the flat cross section along the axis facing down.\u003c\/li\u003e\n\u003cli\u003eThe short shaft for bevel gear should be printed in a standing position, too.\u003c\/li\u003e\n\u003c\/ul\u003e\n\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\u003e \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 \u003c\/p\u003e\u003cp\u003e\u003cimg class=\"image_resized\" style=\"width: 32.08%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/640b477d-6f45-4aac-a30a-c30c59aed475.webp\"\u003e\u003cimg class=\"image_resized\" style=\"width: 31.94%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/ccb089d1-fb91-4bcf-9205-ec3e1c119f65.webp\"\u003e\u003cimg class=\"image_resized\" style=\"width: 31.92%\" src=\"https:\/\/makerworld.bblmw.com\/makerworld\/model\/DSM00000001983088\/design\/887e246a-bb78-4ecf-b26a-d5b3884d48e4.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\/DSM00000001983088\/design\/fc008f0b-4d5a-4549-a8af-654652266759.webp\"\u003e\u003c\/figure\u003e\u003cp\u003eWithout those issues, the gears should rotate very smoothly with minimal friction.\u003c\/p\u003e\u003ch2\u003eAssembly\u003c\/h2\u003e\u003cp\u003eNo glue is needed except for the worm.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eWorm: If you feel the shaft of the worm is too loose, glue them by using some super glue.\u003c\/li\u003e\n\u003cli\u003eRack \u0026amp; pinion: Slide in the rack first, before putting the pinion.\u003c\/li\u003e\n\u003cli\u003eInternal: Insert the internal gear first, before the other small gears.\u003c\/li\u003e\n\u003cli\u003eBevel: Insert the shaft for the smaller gear at last.\u003c\/li\u003e\n\u003cli\u003eCrown: The thinner pinion can move along the axis. Be surprised to see that the pinion perfectly fits to the crown gear regardless of the position along the axis.\u003c\/li\u003e\n\u003c\/ul\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\/DSM00000001983088\/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":67375191458096,"sku":null,"price":19.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0987\/0809\/5280\/files\/0_bb81bac9-7cd6-4c4d-bbc4-35697b0858f7.png?v=1784229129","url":"https:\/\/mymadmanlab.com\/products\/educational-gear-examples-1","provider":"Mymadmanlab.com","version":"1.0","type":"link"}