How strong is square tube slip joint when bolted thru ?

[GoceKU]

I'm planning a project that has very strict space constraints, so i need to design it in couple of pieces so i'm considering using slip joints that will be held by bolts. I've never used them, from what i could find the inside piece that slips in should be double the diameter of the tube. The question is can a bolted slip joint hold like a single piece or do i need to use bigger diameter to compensate and any advice on how to make them easiest, the tube i'm planning is 30x50x3mm.

 

[Silverbullet]

What is it being used for. Weight , length , impact. Tow hitches use box tubing , the heavier the steel the better 6 mil x 50 x 50 about. If I were bolting thru I'd make inside spacers to keep size when tightened . That thin a box will bend easy bolting it thru. Welding would hold better if it's an option.

 

[GoceKU]

The plans are for a small flatbed trailer that can come apart and fit inside the boot. I can't stand driving slow on the highway with an empty trailer, it jumps around and is very dangerous, especially at the speeds i'm going, on the way back i don't mind driving slower i'm taking a different road and the load is not heavy just bulky. My thought is make it in couple of sections that can fit in my boot and in couple of minutes assemble it on the spot and use it, my thought on using 30x50 is to use it vertically so it can carry the forces on its stronger side.

 

[Silverbullet]

Humn thinking , could you make it fold and ride on the receiver box. Like a hitch hauler. Don't think it will cause any problem doing what you want. Bolts may not be best pins with cinch clips should work and be quicker to set up n take down. I'd make the male ends a longer part then pictured .

 

[Winegrower]

The Harbor Freight engine hoist uses what seem like fairly thin wall square telescoping tubes with a pin through holes every foot or so. It is rated at 2 tons and had no trouble lifting my 2500 pound lathe.

 

[RJSakowski]

Instead of distributing stress to the entire cross section of the tubing, you are restricting it to the cross section of the bolt. The hole will eventually elongate. As Silverbullet suggested, I put a bushing inside the inner tube so I can tighten the bolt securely. Even that is a compromise. That said, that is how trailer hitch receivers are made. Just be sure to use a thick wall tube, at least where the joint is.

 

[aliva]

The strength is the cross section of the bolt, in shear. I would suggest a shoulder bolt of the appropriate length so it can be torqued down with out distorting the tubing

 

[MikeWi]

Couldn't the inner sleeve have a bushing that penetrates both sides and is welded in? and then add a small welded bushing for lack of a better word on the outside tube to distribute the load. The bolt is still in shear, but less chance of elongating the hole.