{{Techniques infobox
|image           = Tri-joint-thumb.png
|designers       = Popular Mechanics crate advertisement
|date            = 1923
|vitamins        = 
|materials       = 
|transformations = 
|lifecycles      = 
|tools           = [[Wrenches]]
|parts           = [[Frames]], [[Nuts]], [[Bolts]], [[End caps]]
|techniques      = [[Bolting]]
|git             = 
|files           = 
|suppliers       = 
|reversible      = true
}}

[[Category:Techniques]]

=Introduction=
Three-sided overlapping joints, tri-lapping joints, or tri joints join three [[frames]] together rigidly in all three [[https://en.wikipedia.org/wiki/Cartesian_coordinate_system|cartesian]] axes by securing each with a bolt.  This unique joint requires only frames, nuts, and bolts, and is the basic technique for building rigid structures from [[frames]] used throughout Replimat.

=Challenges=

=Approaches=
All possible tri joint configurations are represented in each tri joint, and accessible via simple rotation or reflection.
======Rotations======
=References=
  * [[https://books.google.com/books?id=H9D4l0q96vAC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false|How to Build With Gridbeam]]