Tabbed windows & door

[N. W. Perry]

Regarding the Mursten-era door (u8012) and windows (u8019–u8024):

The geometry of these parts is not quite right, and leads to collisions when the tabs are interlocked as intended. I propose this modification, which avoids these collisions, and also those that arise by placing the tab behind a neighboring brick (as seen here). But the real geometry may be a slightly thicker tab that fills the slot better, with the part itself being slightly less than a brick-width in Z (so maybe 18 LDU or so), relying on the part's flexibility to fit behind or in front of a neighboring brick.

This revision also subfiles the tab, for brevity's sake. I use u8021 as an example, but all seven parts would be affected.

[N. W. Perry]

Ah, perfect. I've found exactly the image I needed:
https://flic.kr/p/rxWHUM

This shows me several things:

• The window is the same width as a brick
  
• The tabs lie flush to the back side of the window
  
• The tab does not fill the entire slot, but in fact is about half as thick
  
• An example of each of three ways the tabs are used:
  

1. In a slot
   
2. Behind a neighboring brick (the curved macaroni brick here)
   
3. In front of a neighboring brick, but behind a round 1x1 brick)
   

Options 1 and 2 appear to work without distorting the window (aside from the ubiquitous warping of all cellulose acetate parts that we can see), so our geometry should reflect that. Option 3 is clearly a kludge, albeit an official one, so we should not try to accommodate that.

Rough measurements from that photo show that the tab is actually about 3 LDU thick (the slot is 4), which doesn't really make geometric sense, so I've settled on a 2 LDU tab.

Here is my revision of the u8012 door, along with an updated version of the tab. Pending any discussion here, I'll submit these as fixes to the existing parts as I create them.

---

EDIT:
Wow, things worked out even better than I expected! By having a 2 LDU-thick tab, and by moving the window forward by 2, you can indeed fit in front of a neighboring brick, but behind a round 1x1, while also fitting within the slots. See what I mean:
   

So all of the official "connections" for these parts can in fact be made, without any collisions or having to physically bend anything.

[Philippe Hurbain]

Awesome photo indeed that tells a lot about these old things... JC Tchang (my reference for these parts!) fully agrees Congratulations!

[N. W. Perry]

Awesome photo indeed that tells a lot about these old things... JC Tchang (my reference for these parts!) fully agrees Congratulations!

And my indebtedness to JC Tchang for some of the most comprehensive documentation available for all things LDraw!

(I wonder if you and JC have ever been spotted in the same room together? hmm…)  

[N. W. Perry]

The revised parts are now all on the PT:
https://www.ldraw.org/cgi-bin/ptscan.cgi...ope=header