Thread "raw" end_finishes add extra loops and has inconsistent length

[MatthiasJ1]

ref     = Cylinder(1, 1, align=(Align.CENTER, Align.CENTER, Align.MIN))
fade    = Pos(2.5) * TrapezoidalThread(2, 0.5, 20, 1, end_finishes=("fade", "fade"))
square  = Pos(5)   * TrapezoidalThread(2, 0.5, 20, 1, end_finishes=("square", "square"))
chamfer = Pos(7.5) * TrapezoidalThread(2, 0.5, 20, 1, end_finishes=("chamfer", "chamfer"))
raw     = Pos(10)  * TrapezoidalThread(2, 0.5, 20, 1, end_finishes=("raw", "raw"))

[gumyr]

This is by design. "raw" is a unfinished thread end - that is fast to create - that ensures there is enough extra thread such that all of the other end types can be constructed from it. "raw" is used when the user will fuse the end of the thread into another object (like the head of a screw) where it won't be a problem or when other operations will be performed on the read to trim it to shape.

[MatthiasJ1]

The constructor specifies:

pitch (float): thread pitch
length (float): thread length

The constructor is called with:

length = 1
pitch = 0.5

Therefore, that should create a thread of length 1 with 2 turns. What we get:

• Square and Chamfer are correct.
• Fade technically does not comply: 1.5 turns and length 0.8. The algorithm could be tweaked to be consistent with the specification, although in its current form it is close enough to still work as intended (especially since the output is smaller, not larger than intended).
• Raw: Completely contradicts the arguments: 3 turns and length 1.8. Thats 50% more turns and almost 2x the length that was specified!

One of the following should be generated for raw ends (ideally have both be two separate options with raw ending on the centerline or border of the thread):

If some internal algorithms require additional thread length, they can easily increase the length of the thread to get extra raw thread to work with. Or if it needs to be an end_finishes, it should be something like "_raw_extended_for_internal_use" and have "raw" follow the spec since it has use as a user-facing option.