Building custom camper jack legs

[headingwest]

Hello all,

I'm building a custom camper for my truck and I'm looking to build legs from structural aluminium. I'll get an engineer to verify the load and buckle capacity.

My question is how to wind up the leg? How much weight can a threaded rod lift? Are there other methods to extend a telescopic leg?

Thanks for any ideas or suggestions.

Jim.

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[4x4JeepCamper]

I'm not sure this suggestion applies, as I don't know exactly what you are trying to do. Why not use standard camper jacks?

 

[headingwest]

The standard jacks don't mount where I want them and are also very heavy. I'd prefer to build them if possible.

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[4x4JeepCamper]

The standard jacks don't mount where I want them and are also very heavy. I'd prefer to build them if possible.

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Your "very heavy" comment implies you intend to leave them on the camper all the time. I take mine off after loading the camper. I suppose you might want them with you, so you can remove the camper once you arrive at a destination.

 

[headingwest]

I'll take them off when travelling but if I choose to take them then that's 50 liters of water in weight that I can't pack. Also have a bad back and wrestling them into place isn't fun.

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[CampStewart]

Some methods of actuation that come to mind are hydraulic, pneumatic, and mechanical. The strength of a threaded rod would depend on the length of it, the diameter, and how it is supported. How about a drawing and dimensions of what you want to accomplish? I am not sure how anyone can give reasonable advice with the vague information given

 

[headingwest]

Here's a working proof of concept, final version would be welded to avoid the sideways bolts.

It has a 12mm (1/2 inch) threaded steel rod pushing the lower plate. Threaded rod extends from 100mm to 500mm to push out the lower leg by 400mm (about 15 inches)

This is cheap, thin aluminium. Final version would be double thickness, double tensile grade aluminium with an engineers report for buckle strength.

But beyond the wall strength how difficult will it be to turn that bolt to lift it with 700kg / 1500 pounds resting on it. That's fully loaded front legs lifting unevenly.

How do I even test it?

Thanks again for your ideas and comments.

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[headingwest]

This shot also shows the push plate that moves the lower leg. It has a 12mm steel rivnut

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[shade]

The threads on that rod aren't designed for what you want to do, and trying to use it in a lifting device will be a very tedious process. I doubt they'd last long, even on a larger diameter rod.

You'll want to use Acme threaded rod, or something similar. I think you're going to find it difficult to create a DIY solution that fits your parameters, but it's worth a shot.

 

[headingwest]

That's a great help thanks shade. As soon as I searched acme a whole lot of options came up that look robust.

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[tanuki.himself]

i'm thinking of doing something similar with pultruded fibreglass profiles . I've been speaking with a UK jack maker about supplying just the screws to lift upto 400KG over 900mm travel and they supply a 24mm threaded rod that they say should be sufficient - for me the issue is more buckling rather than shear given how much travel i want

 

[shade]

You may be able to adapt something like this to your project.

 

[The Artisan]

I am using 1" acme thread for mine. tensile is 60k psi and yield is 40k psi. I think I am good to go
Kevin

 

[headingwest]

Hi Kevin,

That dimension rod would hold a lot of weight. Have you done any testing to see how hard it is to turn the screw and lift under weight load?

Jim.

 

[The Artisan]

The threaded rod works with a worm gear crank and bearings. It can also be driven with a 20v impact. I have tested some but not with my 1200 lb pod
Kevin