Telescoping Climber Tube Sizing

Our team is prototyping a telescoping climber similar to 2910s climber design for future years. We are wondering about the best gap between each section. If you have any help it would be greatly appreciated.

Have you checked their CAD model? Presumably the gap in the CAD model is pretty optimal.

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And… now you can also check out the AndyMark Climber in a Box. Looks like they use 1-, 1.5-, and 2-inch tubes on their 2-stage option.

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It really comes down to what size tubes you can procure. Square extrusions in 1/4" or 1/2" increments are easy to find from a variety of metal sources. Metal Supermarkets sells a decent selection of square aluminum tube.

The tricky bit is leaving enough room to install the linear springs, and to have room for the fasteners that hold the top and bottom bearing blocks in place. Designing with the 1/4" increment tubes (1.00, 1.25, 1.50, 1.75, 2.00) will make these other details very important. Using the 1/2" increments (1.00, 1.50, 2.00, 2.50, 3.00) leaves you with more room for those other things but will also end up with a much heavier design for the same number of stages.

My recommendation (especially for a prototype) would be to use the 1/2" increment tubes. Once you learn and refine the end caps, guides, and springs, if you feel like you can deal with all the tight clearances, then you could design a final product using the 1/4" increment tubes.

The wall thickness you chose for those tubes probably does not need to be that thick lateral loading should be relatively low and would be limited by other aspects of the design other than the tube wall thickness anyway. For the 1/4" increment tubes you will need thin wall tubes. Remember that the inside dimension is the outer dimension minus 2 x the wall thickness. So, a 2.00" square tube with 0.065" wall will have a inner dimension of 1.87". Inserting a 1.75" square tube into that 2.00" tube will leave 0.060" gap between the tubes on all sides. If you need thicker walls than that, I would stick with the 1/2" increment tubes.

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Thanks this is really good information.

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If you need suppliers, I’ve heard good about https://alcobrametals.com/telescopic-tubing/aluminum-telescoping-square-tube/ in terms of tolerancing and choices avaliable.

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