# Plate perpendicular to bottom of square brick/plate: is this connection legal?

This is closely related to the question about jamming plates underneath 2x2 round bricks, (and indeed prompted by a comment there), with differences explained later.

It is possible to attach a plate (or tile) to the underside of a square rectangular brick/plate/tile, between the wall and the tubes, like so:

Note how the distance between a brick's wall and its inner tube seems to be the same as the thickness of a plate:

A few observations:

• This connection feels looser (seems to have less clutch) than using a round brick.

• For 1-stud-wide plates, this connection doesn't guarantee a straight angle. The edge of the plate sits loose inside the brick.

• For post-2005 regular bricks (i.e. non-sloped), since they have thinned walls with notches at every stud, the connection is particularly flimsy. A 1-stud-wide plate just won't get any grip at all.

• The walls of rectangular bricks are connected to each other, so bending a wall "outwards" (to jam a plate/tile inside) means bending or stressing the perpendicular walls (as far as I understand the physics of solid materials).

So:

• Is this connection "legal"? (i.e.: Does this connection stress the parts involved?)

• Has this type of connection been used in any official sets?

• I'm guessing the "thinned walls" comment is the key indication that Lego doesn't consider it legal - otherwise they'd have had to preserve the old style of wall. Aug 6 at 14:47
• Would this connection be considered "in system"? it seems the parts are offset by half a plate in two dimensions, and half a stud in the other, which would be in system. Aug 7 at 23:15
• Indeed - the offset is 4 LDUs (half a plate) in two axes. The plate, however, can slide along the third axis. This becomes obvious when using a 2x8 brick: a plate/tile can slide between the wall and the tubes. Aug 7 at 23:25

To answer your second question: The technique was used by Lego in 1976's set 726 (12v Western train with 2 Wagons and Cowboys), to attach the horse's tail.

See page 13 of the instructions:

• Amazing! And look at the old legs used for the horse, too! Aug 11 at 20:24
• I'm not quite sure this is still legal, keeping in mind 46 years have passed since quoted use in 726 set. There are cases where TLG used certain building techniques, but then marked them as "illegal".
– Alex
Aug 12 at 14:38
• @Alex: That's why I didn't venture an opinion on the 'is this [currently] "legal"?' part of the question. Aug 12 at 20:10

Some anecdotal evidence against legality: I have built such connections with rather old plates a long time ago and one of the outer plates failed (the wall breaking off). So it certainly puts the plates under some stress.

Yes, you can use it (for example, to build a robot). It isn't used in official sets.

• Hi George and welcome to Bricks.SE! You have made an assertion but what is it based on? If the technique is never used in official sets then how do you know it to be considered legal by TLG? Aug 11 at 8:49