Implemented pitch diameters and module to create a pitch hole

[Maaajaaa]

implements #7, the module hole_pitch differs from hole_through in the fact, that it allows to use standardized hole sizes in three variation (fine, medium, coarse) instead of guessing a clearance (as you do in the hole_through).

[JohK]

Hi,

Thank you for your work!

I have several remarks concerning the implementation that I would like to have resolved before merging:

• In general the clearance parameters are there to adjust the clearance for 3d printers, they are not meant "to guess" the right hole size. With this in mind, also the hole_pitch should have clearance parameters (might be set to 0 by default?).
• The thread of metric screws are defined by lead not pitch (in german both is "Steigung").
• The parameter "type" should be called "lead" and default to medium (most widely used screw...)
• hole_through and hole_pitch really should be one module. ---> hole_through(name, l, cld, h, hcld, lead) ( The head is optional, it is there so you can easily check your model for collisions )

What's your opinion on those points?

Cheers Johannes

[Maaajaaa]

Hi, so here's my opinion about your remarks:

1. Makes sense to me
2. Ok, I didn't know and care about that but thanks for the hint
3. Well I though the types where some kind of sane clearance defaults (I don't know the standard or engineering for that matter that well)
4. Sounds good but I'm not sure how I'd implement the fine, medium and course "types" or rather how to name that parameter

Have a nice day Mattis

[JohK]

Hi Mattis,

have you put some more work into this and want to create a new pull request?

Johk