Timestamps for various topics:

0:00 Minimum requirements for meshing to work at all
7:20 Gear ratio selection restriction
9:07 Binding due to insufficient backlash
12:29 Screw pump working
13:12 Pressure angle tradeoffs
13:45 Effect of shaft-shaft distance on backlash for different pressure angles
14:48 Effect of pressure angle on tooth strength
16:43 Force driving the shafts apart, and effect of backlash on this force
18:37 Failure of WiFi tank drivetrain due to this force
20:12 Conclusions on pressure angle
21:02 Standard values for pressure angle
21:51 Tradeoffs between module and number of teeth
22:58 Larger module is more tolerant for shaft-shaft distance errors
24:26 Undercutting, why it’s necesary, and why it’s bad
26:35 Concentricity error or runout error gives same type of problem as shaft-shaft distance error
28:47 Why m=3 for the screw pump?
31:51 Outer diameter of a gear

Part 3:    • How to model Helical and Herringbone ...  
Full playlist:    • All about gears  

I don’t think any of the files in this video are interesting enough to share. If you would like to see one of the files, leave a comment below.

I have made extensive use of these two references, which treat a bunch more topics that I didn’t discuss here, such as contact ratio, profile shifting, and wear resistance:

https://khkgears.net/new/gear_knowled...

https://qtcgears.com/tools/catalogs/P...

If you have any questions, comments or suggestions please leave those down below.