Self-explanatory. I've noticed that 3/4 pins will not securely attach to System plates with holes in them, due to there not being a groove on the rim like there is in 1/2 width Technic beams etc. But strangely enough, when you put 2 holed plates on top of each other, a full-length pin will clip securely. Is that by design? I find it a bit frustrating, since it'd be pretty cool to be able to use half-length pins on plates and such. It's particularly egregious with part 3176, which could work really nicely as a trailer attachment on a half-pin or something to that tune, but seems like you need to stack 2 on top of each other to make it work, and us a full length pin then. 

39 minutes ago, Xfing said:

Is that by design?

Yes.
That full pin connection comes from overal geometry of system parts. 2 liftarms are thick as 5 plates stacked, so half liftarm is 1,25 plate thick, but thanks to groves it can be attached to 3/4 pins. Plates never had recession for pins to click inside.

Technic plates and frictionless pins (grey, 2L)  date back to the very first Technic sets, the 3/4 pin and half thickness Technic parts are about 20 years newer, so they didn't change the design to accomodate it I guess.  Some parts like 3651 to 32013 did get modified to accomodate the thin/studless parts.

 

3176 is even older, there were no Technic pins, no axles... it's designed to fit studs or let bars hook through it.

Edited December 22, 2024Dec 22 by Stereo

Yeah, I agree with m_longer and stereo. The ratios between pin length and plate thickness are different. 

As far as I know this is only part which has plate thick pin.

On 12/23/2024 at 4:00 AM, msk6003 said:

As far as I know this is only part which has plate thick pin.

welp my man, you would be right!



I never in a million years would have thought this piece's pins were longer than that of the 3/4 pin. And I find the decision doubly weird given how well 4261 works with indented, half-width beams in the first place. There is some up and down give, sure, but too little to notice. 

Edited January 15Jan 15 by Xfing

2 minutes ago, Xfing said:

welp my man, you would be right!



I never in a million years would have thought this piece's pins were longer than that of the 3/4 pin. 

It was released back in 1981 to be compatible with 4262 and other similar parts, which have thickness of a normal plate. 3/4 pin only came in 1996 to help connecting liftarms of half-stud thickness to full-thickness pinholes.

Just now, howitzer said:

It was released back in 1981 to be compatible with 4262 and other similar parts, which have thickness of a normal plate. 3/4 pin only came in 1996 to help connecting liftarms of half-stud thickness to full-thickness pinholes.

Yeah, but 4261 works with no apparent incompatibility with those too. They're meant to be plate-wide too, albeit with indentations. I think Lego should have kept something that would be plate compatible, since as is, without a compatible piece all you can do with holed plates is put axles through them or only put pins through two at a time.