Telescoping Tube Help

Burnette12

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Joined
May 18, 2023
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6
Hi everyone,

I am building a small prototype for a product I’m developing and could use some help. I’m using Evergreen’s Square Polystyrene tubing to create a telescopic assembly. My issue I’m running into is how to keep the assembly together without pulling the sections apart. I’ve been trying to figure out a way to flare the top and bottom of each section or add some type of flange but I’ve not found a good way to do this.

For reference a small metal radio antenna that expands and collapses is a good example of what I’m looking for. Force is applied to extend it and force is applied to contract it. When pulled the sections move one at a time until they catch a groove which keeps it from moving any further and then the next section comes through until you reach the end. There are multiple sections of tube with various diameters but they all work together as one mechanism.

If anyone has any advice or experience with something like this I would love some help. Thank you all so much!
 
Hi everyone,

I am building a small prototype for a product I’m developing and could use some help. I’m using Evergreen’s Square Polystyrene tubing to create a telescopic assembly. My issue I’m running into is how to keep the assembly together without pulling the sections apart. I’ve been trying to figure out a way to flare the top and bottom of each section or add some type of flange but I’ve not found a good way to do this.

For reference a small metal radio antenna that expands and collapses is a good example of what I’m looking for. Force is applied to extend it and force is applied to contract it. When pulled the sections move one at a time until they catch a groove which keeps it from moving any further and then the next section comes through until you reach the end. There are multiple sections of tube with various diameters but they all work together as one mechanism.

If anyone has any advice or experience with something like this I would love some help. Thank you all so much!
Hi and welcome. Maybe some photos would help us.
Pantherman
 
So something kind of like this, but it will be attached to a base plate. So the bottom, widest tube would be fixed to a flat surface and there would be nothing above it. So what I need it to do is go from a collapsed state to an extended state without pulling apart. If I had like a small lip at the top and bottom of each piece where the bottom of the inner section would catch on the top of the outer section then when you pull up on them they wouldn’t come apart. My problem is I don’t know how to add something like that to this material.
 

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How do you extend it ?
Dig a booger out of your nose and stick it to the end of the center section and pull ?

What is in the base ? nothing ?
It's just a flat board or something ?

What is this thing anyways ?
How is this telescoping assembly finished ? ( paint , cladding etc )
Loads ?
Extended or retracted .
compression , tension , moment ...

There's different avenues to achieve what you want but I need more info .


Here ,
Look over these drawings ,
maybe you'll have an epiphany :
https://www.google.com/search?q=tel...BAJIBAJgBAKoBC2d3cy13aXotaW1nsAEK&sclient=img
 
I’m adding a link to a video of how to make a telescoping assembly in Solidworks. I’m trying to make something that functions like this. The tubes would be turned upside down and nested into each other to be assembled. The outermost piece would then be fixed to a solid flat base that will hold the outermost section in place when upward force is applied. At the top I’ll have a flat cap piece that keeps the innermost rod from sliding all the way down into the mechanism. You would pull up on the top to extend it and you would apply downward force to collapse it. So the outermost piece will never move as it’s fixed to a permanent base and the inner tubes need to slide and stop at a point, section by section until the innermost piece is fully extended. So I just need something that slides through one another freely, but doesn’t pull apart. One side will be free moving and won’t be fixed to anything else so my challenge is how to add a flange or small cleat like you mentioned to get it to stay together.

Imagine a spyglass, a collapsible fishing Rod, or a small radio antenna. The difference is it will move upward from a flat solid base. The finish and all isn’t a problem right now because it’s just a prototype for something I’m trying to build. This won’t be a finished product right now but just to test a mechanism.

 

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The design is right. I guess what I’m asking is if there are any techniques that I could use to make it actually work out of styrene tubing? At this small scale I wasn’t sure how to add material to the tube. Just get wider tubes and cut a strip of material and glue it flush to the inside and outside of each tube? Say if my innermost was 1” diameter and each tube outside of that was .5” larger then that would be fairly easy. But working at such small scale I’m having difficulty getting material that is thin enough to not completely block the tube.
 
Like engineering wise I know how the assembly works. My difficulty is executing it at a small scale without 3D printing it. I considered trying to heat the material to manipulate it so it’s flared at both ends. I also considered adding material to the tubes on the inside and outside part to create a flange. I’m just having difficulty in the execution of making the model itself. I’m not used to working with polystyrene. If it were metal I would just crimp it, but I need it to be a plastic assembly and I’m not used to working with the medium and definitely not at this small of a scale.
 
" I guess what I'm asking is if there are any techniques that I could use to make it actually work out of styrene tubing? "
Huh ?
That's what we're talking about .
What issue exists doing this out of styrene , round or square , or triangle tube stock ?

Yes , you need to build up the sections like my second drawing OR you need to machine material down .
The former is 1000 times easier .

If the fit is too tight between the tubes you can always sand away a tiny amount of material around the outside of the tube to free it up .
 
Why are you using stock that is too small for your abilities ?
If this thing is just for show and scale is irrelevant why not stick to the larger , easier to handle sizes ?
 
The scale is important as it’s a mechanism I’m trying to make for a product. Ideally I need the entire assembly under .5” diameter in square stock tube. This is just a first version so I was trying to prove it worked before we try to determine manufacturing costs.
 

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