I'm building a roller for a "pool" cover I got at home. The cover weighs 10kg (8kg but I'm considering some weigh added by the water present on it). I have a bosch profile structure where I will support it.

Now I need to choose a pipe. I don't know which pipe to choose. Will a steel 35mm diameter with 1.5mm thickness pipe does the job without deflection? Should I increase the thickness or the diameter? The tube lenght will be 4m.

Thank you

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  • $\begingroup$ What does "work" mean in this context? Do you have any specific failure criteria? $\endgroup$
    – JMac
    Jul 18 '18 at 10:50
  • $\begingroup$ Welcome to Engineering! This looks like a "homework question" (even though it isn't homework). In order for such questions to be answered in this site, we need you to add details describing the precise problem you're having. What have you tried to solve this yourself? Please edit your question to include this information. $\endgroup$
    – Wasabi
    Jul 18 '18 at 10:57
  • $\begingroup$ @JMac I want to know If I'll get deflection on the pipe. $\endgroup$
    – metRo_
    Jul 18 '18 at 16:56
  • $\begingroup$ @metro_ You will. The question you should be asking yourself is "how much deflection is too much?" But we still wouldn't really be a good resource for solving that. $\endgroup$
    – JMac
    Jul 18 '18 at 18:30
  • $\begingroup$ The question lacks specific information such as applied load profiles, intended use case, or a sketch of the engineering problem. Without improvement, unfortunately, it will probably be closed. $\endgroup$ Jul 31 '18 at 18:50

10kg of cover on roughly 10kg worth of pipe? Never mind moist environment where rust will be a serious problem... never mind if you intend it to roll by crank (like in the PDF attached), in the beginning you'll be rolling about 10cm of the cover per revolution.

Go with a much larger diameter PVC pipe - 10cm or more. Rust-free, can be easily worked with lightweight tools - no need for welding or similar hard metalworking; a set of drills and good epoxy glue will suffice; pre-made plastic parts (like end-caps) should be easy enough to attach to the axles, it will suffice to hold the weight of the cover and roll it in/out in far fewer turns of the crank, and it won't be as dangerous as pool-side device (leg against pipe breaks pipe, not leg.)

  • $\begingroup$ and slide on some spacers to the axle to reduce the bending $\endgroup$
    – Solar Mike
    Jul 18 '18 at 12:38
  • $\begingroup$ For some reason I thought galvanized steel is rust-free. "never mind if you intend it to roll by crank" what do you mean? I haven't think of PVC because I thought it couldn't hold the weight. $\endgroup$
    – metRo_
    Jul 18 '18 at 16:58
  • $\begingroup$ @SolarMike can you show me an example? $\endgroup$
    – metRo_
    Jul 18 '18 at 17:00
  • $\begingroup$ @metRo_ take two end caps - remove the « edges » or lips that stops it sliding in the tube and voila : spacers... $\endgroup$
    – Solar Mike
    Jul 18 '18 at 17:15
  • $\begingroup$ @metRo_: 1. Galvanized steel has rust-proof coating which will be indubitably damaged as you adapt it. 2. How do you intend to turn that pipe in order to roll the cover onto it? A crank at the end is an obvious solution. 3. You thought of thin pipes, closer to bars. Think closer to a gutter drain pipe or just a bit thinner. These are quite rigid, and the extra circumference means more cover foil rolled onto the pipe in one turn. $\endgroup$
    – SF.
    Jul 18 '18 at 18:00

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