Why friction ridges?

[Noodles140]

Why do we have both Technic Pin 4459 with friction ridges

and Technic Pin 3673 without friction ridges?

I ask because most (all?) technic frames that use pins end up fully braced so that the friction ridges are not necessary. A well braced frame can use 3673 type pins only without comprising the structural integrity.

Is it to allow easier construction? i.e. limiting technic bricks on partly constructed frames from spinning around?

Noodles

[Bfahome]

Friction pins allow for controlled rotation. If you want something to be able to turn without flopping all over the place.

Smooth pins are for spinning things, like wheels. The lack of friction allows easier turning.

Same goes for the half pin/half plus rod pieces.

[Brickthing]

Along with the lack of friction ridges that Bfahome explained, pins without friction fit looser than friction pins or axles. This means that if you have a beam with frictionless pins at either end, connected to another longer beam, the two beams will still be able to jiggle slightly, making frictionless pins inappropriate for building stable frames.

[Noodles140]

Quite right.

I was thinking them from a purely structural frame building POV, which is quite near-sighted.

But of course, on reflection, the friction ridges are very useful for things like doors, dozer blades, crane arms etc. where having something stay open slightly, or move more slowly is required.

Thanks for the replies.

Noodles

[Jetro]

Actually, the friction ridges you show in the picture are a pain in the royal behind. Fortunately they were removed and a much smaller friction ridges were used instead. The old pins with friction ridges are devilishly hard to take out of a pin hole.

compare old Technic, Pin with Friction Ridges Lengthwise and NO Center Slots

with new type Technic, Pin with Friction Ridges Lengthwise

[Dryw Filtiarn]

As some above already explained, the friction pins haven't been invented for nothing. If you want to see why, just try a somewhat larger technic model, but rather then using the usual friction pins, use the gray frictionless ones. You will very likely notice that the model isn't as sturdy after all.

[merman]

I am still curious why the roof of the cabin of 8258 Crane Truck uses some frictionless pins... very strange...

Edited December 5, 2009 by merman

[Anio]

I am still curious why the roof of the cabin of 8258 Crane Truck uses some frictionless pins... very strange...

http://www.eurobricks.com/forum/index.php?...st&p=566793