I am looking into fabricating a steel tubing frame that needs to be dis/assembled (applies to many larger furniture like bed, shelving unit, wardrobe, cupboard, cabinet, ...).

What are the variants of the steel equivalent of a butt-joint and their pros/cons?

I have only found information on joints for construction steel (think skyscraper-sized double-T section) so far.

I have not found anything for closed sections in DIY sizes like 20/30/40 mm or 1 inch (easily available in hardware stores).

I am certain there must be something in literature. I might not be searching with the right terms.

Ideally, the connectors would be "invisible", i.e. hidden inside the tubing (square or rectangular).

I am considering welding a bolt to one part and a cap onto the other - one hole for the bolt, and another to enable tightening a nut inside the tubing:

enter image description here

Drawbacks: only one fastener, bolts may be too small, assembly of the nut very "fiddly". Pros: does not weaken tubing (depending on load/bending moment).

Another option:

enter image description here

Drawbacks: profile not tensioned, "snug" fit depends on availability and tolerances of tubing.

I'm also interested in connector-hardware made for this purpose.

  • $\begingroup$ Your first image could suit a 'cam lock' setup? $\endgroup$ – Jonathan R Swift Oct 28 '20 at 9:19
  • $\begingroup$ @JonathanRSwift As in woodworking? I've considered it, but it may need a tubular section to sit in (difficult to weld in), and I have doubts the tensioning works in steel (zinc cast parts?). $\endgroup$ – handle Oct 28 '20 at 9:41
  • $\begingroup$ Pins with taper locks - check those used on tailgates and some scaffolding systems. $\endgroup$ – Solar Mike Oct 28 '20 at 9:56
  • $\begingroup$ You can also get fun magnetic nut spinners to help with the fiddly aspect :) $\endgroup$ – Jonathan R Swift Oct 28 '20 at 12:19
  • $\begingroup$ What about dovetail with a pin? $\endgroup$ – NMech Oct 28 '20 at 19:24

See as an example the frequently used principle in the furniture industry. enter image description here


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