Thread: "Tube Ends" for thicker-walled Tubing?...

Dear "Spark-Makers" ,

I'll be wanting to mount Castors at the bottom of some frame-legs that will be made from SHS-tubing soon, and I want to use some of those "threaded"-type Tube-Ends that you push into the end of the tube, and then screw your Castor's mounting-bolt up into. The only trouble is - the Tube-Ends on offer all seem to have been designed for tubes with only 1.6mm thick walls, whereas I want to use tubes with walls that are at least 2.5mm thick (This is because the extra thickness will make it much easier for me to weld the tube-style legs to the rest of the frame, which will be made of angle at least 3mm thick...)

The crux of the problem is that when they say - for example - that 25 x 25 SHS is available in 1.6mm, 2.0mm, and 2.5mm Wall-Thicknesses, the extra Wall-Thickness extends inwards, so that the external dimension of the tube remains 25mm. It is the internal distance between the tube's walls that shrinks when the Wall-Thickness is increased. So - if a Threaded Tube-End is designed for an SHS with 1.6mm Walls, then it's going to be a very, very tight fit (if at all...) into a 2.5mm-walled SHS, because the hollow opening is going to be 1.8mm smaller in each direction - ie. 2 x (2.5mm - 1.6mm) = 1.8mm.

The two main "players" in the game are "Fallshaw" and "EHI" - the latter being the brand stocked by Bunnings. You might have seen the Fallshaw units in more-industrial-type outlets; they are made in two separate plastic halves, into which a couple of captive-nuts are inserted prior to the halves being held together and then pushed into the end of your tube. In contrast, the EHI product is a single plastic module that is cast around an embedded steel female thread. Having seen both, I think I prefer the EHI's... (sorry, can't get my hands on any useful photos of either...)

Trouble is - both of them (going by the data given on their respective websites), appear to have been nominally designed for insertion into 1.6mm walled Tubes...

So, the question is - have any of you "muscled" one of them - preferably the EHI brand - into a thick-walled Tube? Perhaps with enough applied force, their outermost extremities get "planed" off by the inside-edge of the tube-walls, and hence are able to fit...

Many Thanks,
Batpig.