Aluminum tube construction - question about bolt sleeve

I'm building a trike and plan to use a few bolted connections to allow it to fold up.

I have seen bolt sleeves like this on hang gliders. The tube is swaged on both ends and the bolt can be snugged up with a nylock without crushing the large tube. My guess is that the tube also increases the bearing area and reduces the liklihood of ovalizing the hole. On a hang glider most bolted connections like this are subject to pivoting when the glider is folded.

Is anyone familiar with how these tubes are installed? Are they a commercial product or DIY?

My guess is that one end is flared with something like a modified brake line flare tool, and the second end is crushed by tightening a bolt through the tube. Probably needs an outer sleeve inside the big tube to keep that part of the small tube from expanding when the second end is flared - but that"s 100% speculation.

Attachment 2820

Back in the hang glider day, instructions for installing a tube bushing went like this: "Insert bushing into tube. Cut length so that ~1/8" protrudes on each side. Insert a countersunk screw in each side. Place on solid surface and hit screw with a hammer until tubing flares. Remove screw and finish flare by hammering bushing against solid wood block." No joke.

I have a drawing of a tool for flaring a bushing into a tube, however, the attachment feature doesn't seem to be working at the moment. It consists of a through bolt with flaring dies on each end, tightened to flare the bushing.

Since the bushing is held to the tube by interference, it can still work loose, "egg shape" the tube hole and cause failure of the joint. While it might be okay for a hang glider, a powered machine is subject to vibrations and such that might contribute to bushing working loose.

A bushing that passes through a second bushing placed in the i.d. of the tube greatly increases the strength of the bushing and would be the mimimum I would use. However, a solid insert pressed inside the tube would be my first choice.

I made some tube bushings using the hammered flat head screw method back in the day as Marty mentioned, but there was also a commercial tool available that presumably did a better job. There was also a product called an "instabush", which was two pieces, each with the flare already done, and they were a light press fit together... you'd put one in from each side and tap them together. I didn't use them because they were expensive (I was in college at the time). I searched a couple of years ago for the instabush, but couldn't find anything like it anywhere.

For my homebuilt paramotor, I epoxied a hardwood block into the tube at critical bolt points.

I would get two short pieces of drill rod for the "Anvils" and turn a cup shape as for setting snaps or grommets. Bore a bolt size pilot in each one the with a cut off bolt or pilot sized rod to protect the tube use both of your hands to hold it together and the other one to curl over the tubes. [This is far easier if you have a metal lathe], can be done by bringing the drill rod into a tool held in a vice on the drill press table{caution and protection from tool breakage with this jackass move, but some times stuff must get done} Taking a strip of flat stock 1/8 or less folded in half and fit to the anvils would make them like hammer tongs with the pilot rod to keep from over doing it, this turns into cake work

Do you need the pivot? Check out these extension flag poles, http://tele-pole.com/superior.html Not knowing just exactly the joint your working with I could see this push pin application work well in some take down sections.

Dana has the solution that is used in Graham Lee Nieuports - put a plug of wood in the end of the tube and drill through it.

Cheap, easy, and it works.

Thanks for all the tips - got a few good options to work with.