SO CONFUSED ABOUT SPUR GEAR MATCHING. 3

[Jerome Lowery]

SO CONFUSED ABOUT SPUR GEAR MATCHING.
I am having an extreme problem in figuring out the proper gears for my project
I can calculate the gear ratios with no problem
When I go to find the gears I want to use, THEY DO NOT MATCH!
I import exact CAD drawings from McMaster Carr.
I use a FREE 2D drafting software called DraftSight. AWESOME & 100% free.
When I try to match them up, it dosent work.
I select all of the same gears from their inventory.
I select them all by the same criteria, Keyed Bore with Set Screw.
Did quite some reshearch and it seems as if the word MODULUS is what is important.
I made an Excel spreadsheet to do ths formula to find the modulus.
Can someone please help me in selecting gears that match without a lot of problems.
If I would want to select varous gears with various amount of teeth HOW TO DO IT.
To achieve the target RPM.
Is there a more simple way in selection these gears.
I would really appreciate any and all comments to my problem.
Thank You
Jerome

 

[hydtools]

https://khkgears.net/new/gear_knowledge/gear_technical_reference/calculation_gear_dimensions.html

Ted

 

[JStephen]

In what way do they not match?
McMaster-Carr has CAD drawings for many of their products. There is no guarantee that those drawings are an exact geometrical representation of the product. For example, for an involute gear tooth, I would expect the McM-Carr CAD drawing to be made up of one or more arcs, which, in the judgment of the draftsperson doing the model, are adequately close to the geometry at hand. But certainly not intended for 3-D modeling, either. "For components to mesh correctly, they must have the same pressure angle and pitch/module."- I would think that pretty much covers it.

 

[TheTick]

Mating gears must have same modukus (or pitch).

 

[Jerome Lowery]

Thank you all for taking time out of your day to assist me in my problem.
I really appreciate it.
Thanks
Jerome

 

[Occupant]

The attached picture shows how I used to do this - in this case 13 Teeth, Module 10.0. I imported the data into AutoCAD and then connected the tangent points on the outline to get an accurate representation of the profile. I was never able to find any vendor drawings accurate enough. Seems like a lot of work, but you really have to do only one half of a tooth that way.

 

[gearguru]

In the past we discussed similar problems. Check this thread (and some more, try to search for it):
thread406-64651
There is also a Lisp program which used to work in Autocad at that time. I have no access to any new version of CAD; hopefully the Lisp is still alive in ACAD and it still can accept that old program.
But it would need to convert module to diametral pitch first and probably to use inches instead of mm.

 

[Jerome Lowery]

Again.
Thank all of you for your assistance.
I really appreciate you people to take time to share your knowledge with others.
( ME)