Massive issues with Involute Gears

[azalanono]

Hi. looooo.
First, timing belt gears (T-Shape is excellent. But you should increase the size of the letter very much, it is almost unreadable.

What I noticed today is a massive problem with Involute Gears.
I created two "default" gears, then I changed the number of teeth on one gear from 15 -> 40. So far it works.

Now the problems start:

• Because the little gear doesn't look well, Iset undercut = true. Works. After hitting F5, I get a nice profile. So I try the same on 40T gear. Very hidden I find "Not enough points given". After increasing numpoints to 16, it worked.
  -> Why can't the number of points automatically increased in this situation?

• To get nicer tooth-heads, I wanted to add a head_fillet. I started with 15T gear and enter 0.10 ... -> "Fillet not possible" So I reset to 0.00 and the error vanishes again. -> Something is rotten here.

• Double Helix is also fine. But as you know, 3D printers have sometimes difficulties in the edge of the "V", where beta angle is reversing.
  -> Suggestion: Allow entering a gap width. So the gear actually is two combined gears with a little cylinder in between, who's height can be set. So malformed teeth (from printing) have there free space, but are still treated as one gear (so one gear can be rotated without the risk of lost angular relation to each other by the Gear Connector.

• Combine gears is wonderful, but needs some more functionality.
  Often you need gears adjusted to finally get a required distance between shafts. This is usually done by shifting the profile(s) to get not too much backlash. Is this currently possible? I can't find anything for that.
  I also cannot find anywhere the calculated distance between shafts (centers of gears) to play manually with shifting the involute until I get the required shaft spacing.
  -> Would be great if at least the calculated shaft spacing would be shown.
  -> Would be excellent if I could enter the wanted shaft distance and either one or both of the gears for involute shifting. If both gears are marked, both involutes will be shifted until the result is fine. If only one gear is marked, that one's Involute will be modified.
  -> It would be ultimate if I can select i.e. two cylinders and their distance and angle will be used to set the gear Connector, including a possibly necessary shifting.

[looooo]

Because the little gear doesn't look well, Iset undercut = true. Works. After hitting F5, I get a nice profile. So I try the same on 40T gear. Very hidden I find "Not enough points given". After increasing numpoints to 16, it worked.
-> Why can't the number of points automatically increased in this situation?

I am not sure if undercut makes sense for gears with 40 teeth. The undercut functionality is working best with low number of gears. But anyways I set the default numpoints to 20.

To get nicer tooth-heads, I wanted to add a head_fillet. I started with 15T gear and enter 0.10 ... -> "Fillet not possible" So I reset to 0.00 and the error vanishes again. -> Something is rotten here.

this was a regression, should be fixed

Double Helix is also fine. But as you know, 3D printers have sometimes difficulties in the edge of the "V", where beta angle is reversing.
-> Suggestion: Allow entering a gap width. So the gear actually is two combined gears with a little cylinder in between, whose height can be set. So malformed teeth (from printing) have there free space, but are still treated as one gear (so one gear can be rotated without the risk of lost angular relation to each other by the Gear Connector.

Maybe create an additional issue for this. Maybe someone has time to work on this.

This is usually done by shifting the profile(s) to get not too much backlash. Is this currently possible? I can't find anything for that.

shifting is possible for involute gears. parameter "shift".

I also cannot find anywhere the calculated distance between shafts (centers of gears) to play manually with shifting the involute until I get the required shaft spacing.

https://github.com/looooo/freecad.gears/blob/master/pygears/computation.py#L22L51

Would be excellent if I could enter the wanted shaft distance and either one or both of the gears for involute shifting. If both gears are marked, both involutes will be shifted until the result is fine. If only one gear is marked, that one's Involute will be modified.

maybe create an issue for this. Maybe someone has time to implement this.

I have to admit, that the gear connector is not the best way to proceed. For more modern freecad-versions there are better concepts to place gears (Part containers). Maybe there is a way to automate the placing of gears with this concept.