How do you make reverse engineer for teeth of spur gear?
I wonder how you copy the teeth of spur gears? I have the actual gear and I just have a caliper to measure.
Accepted answer
Digital measurement: it is another useful resource to approach the problem when you do not have adequate measurement tools.
You can take a photograph (as flat as possible, with little perspective distortion) and place a color sheet that contrasts very well under the gear to be able to digitally enhance the image.
If you introduce this image into a CADD sketch you can scale it so that it is approximately in true magnitude. To this end, you have measured a diameter that you can use as a reference, as well as some object whose dimensions you know precisely (such as the caliper with which you made your measurements) that will help you finish adjusting the scale (you can put references in two perpendicular directions to average as best as possible).
You can improve images (sharpen their edges and improve contrast) in Internet utilities, such as PhotoScape.
Once you have a CADD sketch with the photo fitted, you can find the theoretical center of the gear, draw base, outer and inner circles, observe curves of the teeth and compare what you get with the theoretical formulas to try to determine if it fits safely. in some of the cases.
Kind regards
3 Other answers
There are too many variables. Calipers would be completely inadequate for the job. There are gear tooth pitch gauges that would be required. Even then the task is somewhat subjective.
https://www.mcmaster.com/products/gauges/gear-tooth-pitch-identifiers/
You can get a little closer to the problem if you measure the outside diameter of the gear (De) and count the number of teeth on the gear (Z).
Then you can apply some of the formulas that relate these two parameters to the module of the toothing or to its diametral pitch (both are ways of specifying teeth).
I attach a table with the basic formulas and I leave you a link to a page that has equivalences between these systems (module, diametral step, etc.).
When you obtain your quantities you will be able to see if they fit into any of the cases shown in the tables on this page (https://www.engineersedge.com/gear_pitch_chart.htm).
If you do a little research on the internet, you will find pages that tell you which tool to use to make each type of teeth and other information of practical interest.
Kind regards!
PS: Remember that this is just a first approximation, and that you should confirm it with the appropriate measurement methods and tools, as Bob indicated.
PS: so that you do not feel that I am indicating something not used in practice, I am attaching images of a transmission (with teeth much more complex than your case) that was determined digitally, despite being almost completely destroyed.
