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Create gears - rack and pinion

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Create gears - rack and pinion

How would one go about making a rack and pinion? How do I sketch the teeth to make them match perfectly and how do I know the number of teeth, angles etc? Thank you!

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Re: Create gears - rack and pinion

There are a lot of YouTube videos and Community posts on this subject. Try searching to see if there is something that already answers your modeling questions. There are crude but quick models and more precise but more difficult ones. I believe someone uploaded a parametric involute gear model.

 

Otherwise, to better understand, why do you want to? Gears are typically formed on very precise machinery and there is rarely a  CAD model that is used to define them. Particularly for involute gearing, the parts are typically described only by a chart of relevant parameters for the gear teeth. Prior to CAD, gears were only shown on drawings with a circle to represent the pitch diameter and a circle to represent the OD.

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Highlighted

Re: Create gears - rack and pinion

There are a lot of YouTube videos and Community posts on this subject. Try searching to see if there is something that already answers your modeling questions. There are crude but quick models and more precise but more difficult ones. I believe someone uploaded a parametric involute gear model.

 

Otherwise, to better understand, why do you want to? Gears are typically formed on very precise machinery and there is rarely a  CAD model that is used to define them. Particularly for involute gearing, the parts are typically described only by a chart of relevant parameters for the gear teeth. Prior to CAD, gears were only shown on drawings with a circle to represent the pitch diameter and a circle to represent the OD.

View solution in original post

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Re: Create gears - rack and pinion

Thank you for the reply!

 

I've looked on youtube and forums but I can't find a detailed tutorial to create these gears. I basically want to make a spur gear between two bars so that if one bar is pulled down the other bar goes up, just like putting a gear between your index fingers and rolling the gear (or making a fire with your palms and a stick). I have the measure of the gap between the two bars and I need information to calculate all the numbers that are needed to sketch the gears and teeth. (Im using creo 2.0 btw, is there an addon of some sort?)

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Re: Create gears - rack and pinion

There are several gear companies on the web that offer models of their gears.

If you get the Creo version (pro|e - WF...) you will also get some of the math behind the generation of the involute and all the other parameters that make up gears.

 

If you want to learn how to make gears, you will need to learn the lingo and understand how they determine a "generic gear".  Rack gears are straight walls, no involute.

 

These same gear companies also have extensive data on how to define gears.  Not in CAD exactly, but the parameters you need to encompass are there.

 

This is an example source: http://www.sdp-si.com/products/Gears/Index.php

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Re: Create gears - rack and pinion

Rack gears are the limit case for the involute function with R_base = infinity; they are involute, which is why they can be used to generate involute teeth on other gears.

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Re: Create gears - rack and pinion

To solve that particular problem you need to pick a gear that is smaller than the gap and still have room for the rack gears. There is no method to do this because there are an infinite number of solutions. You can look at gear catalogs to see what parts are commonly available and see what fits.

 

Here's one source: https://www.mcmaster.com/#standard-gears/=18s7mrm

Another: http://www.bostongear.com/products/open-gearing/stock-gears/spur-gears

 

 

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