New hinge part - and a standards curiousity

[Tim Gould]

Hi all,


New Hinge LDraw by gambort, on Flickr

I just whipped up the new hinge part this morning (I'll post .dats when I have part numbers) and noticed it's thrown up a little 'issue'.

The real technic holes are actually centered at about 9LDU from the top of the part, rather than 10LDU like we use in LDraw. On this particular part it means that the bit where the technic connector joins the main body has a small (2LDU odd) bridge from the connector to the plate, while in LDraw the bridge can't be there due to the center and radius.

I think that leaving the bridge off is the best option in this case. But it's something I've never run into before.

Tim

[Philippe Hurbain]

Hi Tim,
Probably a stupid language barrier issue, but I don't understand the problem you have. I guess you don't have the parts yet to publish a photo?

[Orion Pobursky]

If you think that it non-functional then leave it off...

[Tim Gould]

Hi Philo,

This illustrates the difference. True LEGO technic parts actually have their hole center slightly higher than system parts (this is discussed in the Stressing the Elements document that floats around). This new hinge part demonstrates it quite clearly since it has a tiny bridge (like the 9LDU part) underneath going from the round part to the plate.

But the LDraw part should keep to the usual standard with center at 10LDU and the bridge cannot appear.

Make sense?

Tim

Code:

0 Demo for Philo
0 Name: Demo.dat
0 Author: Tim Gould [timgould]

0 // Hole centered at 10LDU
1 16 -5 4 -30 35 0 0 0 4 0 0 0 20 Box.dat
1 16 40 10 -30 10 0 0 0 0 -10 0 20 0 4-4Cylo.dat
1 16 40 10 -30 8 0 0 0 0 -8 0 20 0 4-4Cylo.dat
1 16 35 0 -20 5 0 0 0 1 0 0 0 10 Rect.dat

0 // Hole centered at 9LDU
1 16 -5 4 30 35 0 0 0 4 0 0 0 20 Box.dat
1 16 30.5 4 40 0.5 0 0 0 4 0 0 0 10 Box.dat
1 16 40 9 30 9 0 0 0 0 -9 0 20 0 4-4Cylo.dat
1 16 40 9 30 8 0 0 0 0 -8 0 20 0 4-4Cylo.dat
1 16 35 0 40 5 0 0 0 1 0 0 0 10 Rect.dat

[Tim Gould]

It's definitely non-functional. And even worse it would break the standard to include.

Tim

[Orion Pobursky]

We differ from real Lego parts in other ways so this fairly trivial example can just be added to the list.

[Tim Gould]

Yeah definitely. As the title says it was more a curiosity than anything. It's the first time I've ever had to alter a geometry because of one of these differences from reality and I wanted to see what others had done (there are other ways around).

This particular quirk does have some very minor effects on modelling. Most obviously when you put a liftarm next to a brick.

[Orion Pobursky]

Yeah. Technic models can get frustrating not only because you need to know math to model them but the sometime exploit the small amount of "give" real plastic has.

[Philippe Hurbain]

Thanks Tim, got it.
Another way to cheat with reality:

Code:

0 // Hole centered at 9LDU
1 4 -5 4 30 35 0 0 0 4 0 0 0 20 Box.dat
1 4 30.5 4 40 0.5 0 0 0 4 0 0 0 10 Box.dat
1 4 40 10 30 9 0 0 0 0 -10 0 20 0 2-4Cylo.dat
1 4 40 10 30 9 0 0 0 0 9 0 20 0 2-4Cylo.dat
1 4 40 10 30 8 0 0 0 0 -8 0 20 0 4-4Cylo.dat
1 4 35 0 40 5 0 0 0 1 0 0 0 10 rect.dat

Maybe it would be a bit better since round liftarms are modelled with 18 LDU width.

[Tim Gould]

Hi Philo,

Interesting idea. I thought there might be a solution a bit like that. The problem is that the non-co-centricity of the hole is pretty obvious. I'll probably just leave it as is since it's definitely not a functional issue but I wanted to hear other people's thoughts.

And here's another fun game: what should the part be called?

"hinge technic plate 2 x 4 with hole top/bottom" doesn't exactly roll off the tongue

Tim

[Philippe Hurbain]

I'm not so good at coining names... Your proposal looks fine to me, I'd just specify "with Pin Hole" or perhaps even "with Pin Hole Hinge"

And I got the part numbers! Bottom is 98285, top is 98286.