The Case for Underside Fillet Primitives

[Jude Parrill]

As some of you may have seen, I recently added some underside stud fillet primitives (Here is one such file, where discussion has occurred). Some are wondering whether these parts should exist, and if so, where they should be located (P or S). Here is the thread I promised with my arguments.

The Problem (As I See It):
There are a number of parts in our library which have underside fillets. I recently uploaded some new 4xM and 8xM parts, but more exist. There are more as well. However, there is actually a bit of variety to them. Some are 2 ldu in width, while others (like the ones I worked on) are 3 ldu in width. There are also some medium height ones as well as ones which are full length except at the edges where they are medium height. Some are detailed while others are pretty basic.

Here's a picture which shows some of that variety:


However, there is currently no system for naming or re-using these parts. In fact, most of relevent parts are located in the S directory, and I found no less than 3 sets of these, two of which could probably be combined:
- 6161.dat and 6162.dat use s/6161s01.dat and s/6161s02.dat
- 30072.dat uses s/30072s01.dat and s/30072s02.dat
- 47116.dat uses s/47116s02-05.dat (4 files)

And the question becomes, the next time LEGO releases a new large Brick, will the person who creates the part be able to find and use the correct subparts/primitives for this? Will they simply create another set for their given part? How is one expected to know these parts even exist when there is no mention of them on the primitive reference page?

Why not just put these parts in the S folder?
Because it makes re-using them harder, especially for newer authors who may not know they exist. Really, the S folder should be for part specific subparts which don't and probably never will have any use elsewhere. The P folder is for primitives which either can be used for many parts, or have the potential to be used by many parts.

The Solution (As I See It):
I believe we need to create a new set primitives for underside fillets. When I created mine, I used stud naming convention based on an assumption that later proved to be false. And as Chris has pointed out, these are much more than studs. As such, I believe a new name should be used, and I'm currently favoring "Fillet" although I'm open to suggestions on this. However, assuming we used "Fillet", the naming scheme would proceed as such:

FilletS[h][d]-[optional-identifier].dat
where
S is the width of fillets in ldu. Currently both 2 and 3 ldu width fillets exist, and it leaves the option for further sizes should they come along.
h is used for half-height fillets (I believe 33230.dat on the PT could use these).
d is used for detailed parts (like the ones I currently have on the PT).
optional-identifiers can be used for different variants based on wall collisions. A meaningful naming convention is preferred.


So that's it. I don't think I'm that far out of line on this, but you can let me know what you think.