Gear System Generator

[Dimple Belousson]

Thiscalculator generates the .DXF and .SVG files for making external spur gears, rack and pinion sets, and internal spur gears. DXF files are accepted by most machines that cut 2D shapes such as CNC wood routers, laser cutters, waterjets, and CNC plasma tables. A DXF is also the starting point for various CNC machines that require CAM software. Standard spur gear calculations, graphics, and .DXF files have never been more accurate, accessible, or easy. Involute tooth form only. Clocks use the cycloidal or triangular tooth forms.

To calculate a spur gear, simply decide and input your tooth count, gear module, and pressure angle and the online spur gear DXF generator will do the rest. A spur gear calculator uses these parameters to generate the involute tooth form that's the right size and shape to take into your CAD software, or straight to a CNC router or laser cutter.

The live output lets you visualize your spur gear to ensure you have the right fit and to manage the undercut and gear size, while the .DXF and .SVG outputs will fit into your CAD software or graphics software. If you're looking to make the right gear blank for your gear, you can use our free Gear Dimension Calculator to find the key dimensions of your external spur gear.

Spur gears can be used in a wide variety of applications. Having a DXF or SVG file for your gear is the first step to building your new gear project. After you have your 2D model of your spur gear, you can use this file for a range of applications.

One of the more common mistakes we see in simplified gear software is the lack of undercut in small tooth count gears. This can make gears bind or function poorly. We also see low resolution involute shapes that could function better if they had the correct geometry with sufficient data points defining the involute.

Being members of the American Gear Manufacturers Association (AGMA) and having manufactured gears in most plastics and metals, the details count. So we put the same attention to detail and mathematical skill to work for everyone. For measuring and inspecting gears, using a Measurement Over Pins Calculator is one of the best methods to ensure your gears are perfectly in-spec.

Pro-Tip! Notes for the wood shop or anyone using an endmill to make the cut:

The bit size is a very important consideration! Depending on your software, if the cutter is too large it will either over-cut the root and weaken the tooth, or leave a radius and not finish the involute profile or undercut. When using your CAD program, compare the cutter diameter to the gear's root space to make sure it's small enough and has some clearance

Spur gears transmit power through parallel shafts. The ratio of tooth count between two gears changes the relative speed of those gears by that ratio. Spur gears can increase or decrease the speed of a mechanical system, increase or decrease its available torque, or change direction from forward to reverse.

The module of a gear controls its size. Module is the ratio of the reference diameter divided by the number of teeth; so that a gear with a larger module will have a larger diameter. Small module gears (0.1-0.5) are found in watches and clocks, while larger module (1+) may be found in machine transmissions. More here

Gear Generator is unitless: if you wish it's inches, cm or millimeters. DXF opened in AutoCAD will have the same value for D/P as it is set above. Gears in SVG are measured in pixels, which is the value multiplied with the scale (Pixel per Unit) as it is displayed on the right side.

Gear Generator is a tool for creating involute spur gears and download them in DXF or SVG format. In addition it let you compose full gear layouts with connetcted gears to design multiple gears system with control of the input/output ratio and rotation speed. Gears can be animated with various speed to demonstrate working mechanism.

Why this tool was created? Just for fun. I'm working on a hobby project, a scale construction machine, which needed some spur gears, and I quickly made a simple spur gear creator script in Javascript with SVG output. As it was done, I couldn't stop, and I added more and more features, and finally I got this tool. It was a pleasure to code the whole thing, I'm a bit sad it is already done.

Notes about browser compatibility: all new major browsers are supported (i didn't tested IE), but unfortunately Chrome can't render SVG circle correctly. The winners are: Opera for the best performance (shame on me, I never use it) and Firefox for the best looking SVG render.

I'm trying to build a self-regenerating door lock as a side project in college and i'm having some difficulty accurately calculating the gear trains output (in rpm), the purpose of this gearing system is to operate a AC generator. Any help at all would be much appreciated!

I've estimated that a torque of about 1.12 Nm will be used to turn the door handle down 50 degrees. This torque will be transmitted through the shaft which is attached internally to a one way gear. The one way gear is attached to both a fly wheel and the gear train.

My goal is to get an output of about 100 rpm to operate the generator. My question is what factors must i include in the calculation? do i need to include things such as the weight of the gear train and how do i factor in the fly wheel? Thanks!

SO coupling the shaft to the alternator with a one way clutch and a say 4:1 speed up gearbox gives you about what you want. One stage of the epicyclic gearbox in many battery electric drills may be about right. These may have multiple stages to get higher ratios.

Flywheel does not alter energy delivered but can modify user handle-feel and rate of delivery - eg if a flywheel is spun up by a 1 way clutch it may spin down over 1+ seconds and deliver energy at a less peaky rate.

Bonus: Obtaining energy from the opening or closing door is liable to be rather more productive if suitable to purpose. The door can eg have a spring closer and drive the alternator on one or both halves of open/close cycle. Energy taken from this source is liable to less noticed and easier to obtain in greater quantity.

Cheap plastic hand crank alternator.Mechanical efficiency is usually poor.Note gear ratio is probably higher than apparent as another gear is probably not shown. ie their alternator spins MUCH faster than yours. The plastic Z-ish shaped piece in the flywheel acts as a one way clutch/pawl.

From Wikipedia

Since I have defined the centres and pitch diameters of the gears, I would have thought this would be enough information for the gear generator tool to be able to create gear designs. But instead I'm prompted to manually enter the desired gear ratio (this should be the ratio of the two cylinder diameters). To make things worse, I can't seem to make the gear ratio value linked to any other parameters, so I can't set it to be equal to the ratio between the cylinder diameters.

I want the gear ratio to be defined by the cylinder parts, because the gear ratios in the mechanism are dependent on other geometry, so if I change one part, I need the gear ratios to update accordingly.

Something else I noticed is that the gear generator features only remove material from the cylinders, and don't add material, so if my cylinders are the diameter of the gear pitch diameter, I won't get the ends of the teeth. instead the teeth will be truncated / shorter than required. A workaround I used is to increase the diameters of the cylinders, but this just seems a bit unnecessary. I do understant where this would be preferable behaviour, but is there no way of changing this for cases like mine?

I really appreciate any help as I am using this for the first time, and for a personal project. I am beginning to think that defining gears from pitch-diameter-cylinders is not the normal way of operating, but I thought that was a very intuitive way of doing it so it's quite surprising to me if that's the case.

Strain wave gearing (also known as harmonic gearing) is a type of mechanical gear system that uses a flexible spline with external teeth, which is deformed by a rotating elliptical plug to engage with the internal gear teeth of an outer spline.

Strain wave gearing is commonly used in robotics[3] and aerospace.[4] It can provide gear reduction but may also be used to increase rotational speed[citation needed], or for differential gearing.

The basic concept of strain wave gearing (SWG) was introduced by C.W. Musser in a 1957 patent[5][6] while he was an advisor at United Shoe Machinery Corp (USM). It was first used successfully in 1960 by USM Co. and later by Hasegawa Gear Works under license of USM.[citation needed] Later, Hasegawa Gear Work became Harmonic Drive Systems located in Japan and USM Co. Harmonic Drive division became Harmonic Drive Technologies.[7][8]

The strain wave gearing uses the elasticity of metal. The mechanism has three basic components: a wave generator (2 / green), a flex spline (3 / red), and a circular spline (4 / blue). More complex versions have a fourth component normally used to shorten the overall length or to increase the gear reduction within a smaller diameter, but still follow the same basic principles.

The wave generator is made of two separate parts: an elliptical disk called a wave generator plug and an outer ball bearing. The elliptical plug is inserted into the bearing, forcing the bearing to conform to the elliptical shape but still allowing rotation of the plug within the outer bearing.

The flex spline is shaped like a shallow cup. The sides of the spline are very thin, but the bottom is relatively rigid. This results in significant flexibility of the walls at the open end due to the thin wall, and in the closed side being rigid enough to be tightly secured (to a shaft, for example). Teeth are positioned radially around the outside of the flex spline. The flex spline fits tightly over the wave generator, so that when the wave generator plug is rotated, the flex spline deforms to the shape of a rotating ellipse and does not slip over the outer elliptical ring of the ball bearing. The ball bearing lets the flex spline rotate independently to the wave generator's shaft.

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