Hello again /diy/,
For those of you who don't know, I'm the anon who was initially looking for some type of rigid chain to extend straight out when unrolled. Further research and some experiments with tape measure blades now lead me towards using 1095 spring steel. In the 60's, NASA researched and developed prototype sand working models of basically the same thing I'm trying to design. The principal is that a bi-stable material (can maintain two rigid structures) can be rolled into a spool, and upon exiting the spool it rolls into a stronger cylindrical shape.
So does this mean that my work comes to an end? Hell no. There is no design that can effectively extend 5-8m in all directions. Also, few designs can transport more than 30 pounds fully extended. And last but not least the pull strength is almost never accounted for except in a few NASA prototypes/Working models, (but no gravity lol).
The picture is a mockup design and will most likely not be the final product. What makes this design different from the rest is the addition of a children's toy, a slinky. The slinky is a low torque tension spring that will be anchored to the barrel as well as the hook end of the device. As the spring steel is unwound and bent into a cylindrical shape, it will pass through the barrel where it is already preset to be in a cylinder. It will also be preset into the retracted tension spring and a cylindrical end cap as it's fed out. As the steel cylinder gets longer, the spring will automatically stretch and fill in the gaps creating reinforcement bands around the tube. When a tube or pipe bents, the width becomes wider at the failure point. If you give the cylindrical tape no room to unravel, bend or kink, it has no choice but to maintain it's shape and rigidity. The slinky can also be tightened around the tube by twisting the anchor end.
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![ai_aa_stem[1].jpg](https://i.imgur.com/9rwQiCH.jpg "ai_aa_stem[1].jpg")
>>1005677
So I bought some spring steel and slinkies of various sizes. I got the steel today and I think it's going to be too thick to form in a tube. I want the tube to be 1 inch in diameter, so I bought some .018 inch thick steel at 4 inches wide so I get a nice curl. The problem is that shit is tough! I think I need .010, but I don't know shit about spring steel. That leads me to why I'm here, I have run into a few other problems as well.
Questions:
1. What thickness of 1095 blue tempered steel would work? It needs to curl into the tube stated above.
2. Are there any flaws with the theory regarding the spring as being a support for said tube?
3. With the spring steel feeding in this direction, will it jam? How can I prevent that from happening?
Other devices like this:
https://books.google.com/books?id=A8iIK5oUb-UC&pg=PA7&lpg=PA7&dq=bistem&source=bl&ots=v6qhIsKV0g&sig=Pqj2btUQ8rhb7doBl2FQSoRwNq0&hl=en&sa=X&ved=0ahUKEwiawLa-lZnNAhXH0h4KHSPeAyQQ6AEITTAK#v=onepage&q=bistem&f=false
Pic is a dual tape/stem approach.
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>>1005688
You first:
What does the spring do? Support the blue projectile or propel it? Or both?
What is the blue thing connected to the gears? What kind of purpose are we talking about here?
>>1005698
read my post, it goes into the mechanics of it in great detail. The spring supports the tape so that it can't bow out and kink.
The blue thing connected to the gears is the spool of spring steel connected to a shaft that is connected to the gears. Again it's not the final design.
Purpose: So many I can't count, here's a few for example; lighter and stronger telescoping poles, control arms, assembly belts, lifts grappling hook to name a few.
>>1005706
O.K. how do you plan to have your steel strip bend into a tube while also being able to retract onto a tight reel? Tape measures dont bend into cylinders they have a U shape
![AAP_EX-30AP460[1].jpg](https://i.imgur.com/njZL9t4.jpg "AAP_EX-30AP460[1].jpg")
>>1005711
that is why spring steel was the selected choice for this. It is a "Bistable" material, it can roll up while also rolling back into the cylindrical form because of the mesh like structure and the tensile stress of the steel. This take place between the spool and collet of the pictured design, although I will have to modify it so that there is something in between like a cone shape wedge. The bowing stress between the collet and spring coil next to the gearing will cease at the coil roll itself as it won't be able to continue forming into a cylinder whilst also being on a spool. When deployed out of the collet it will instantly go inside the tension spring (slinky) so that it cannot unfurl out of it's cylindrical shape.
The reason a tape measure isn't like this is because it needs to be read and it's also not inside of this cylindrical spiral that i wish to implement. There is a predefined U shape to a tape measure yes, and it is held stiff by a tab at the end of the tape and the "U" form where the tape lock is. Basically the same concept only with an "O" shape.
If you have a scrap tape measure, cut the end of it off and slide a squeeze a bunch of washers on it. It won't bend (from one direction). Take them off and the tape may be a little deformed, but sure enough it will flatten out and return to the spool.
Another example would be a sheet metal cylindrical air duct for a dryer. It is formed as one piece of sheet metal with one joint running down the center to form a cylinder. Cut it and you'll be able to flatten it and roll it any direction you please.
Pic related.
The slinky isn't going to do anything. When the steel tape wants to bend and break, the slinky is just going to spread apart and give way because it's a slinky.
https://www.youtube.com/watch?v=wbp-EtVSBEs
![large.5654972bdc8d2_TypesOfSprings.jpg.cf77df617d4218ba71dee59cc33fdb6f[1].jpg](https://i.imgur.com/K97hfCp.jpg "large.5654972bdc8d2_TypesOfSprings.jpg.cf77df617d4218ba71dee59cc33fdb6f[1].jpg")
>>1005807
I'm going to try and explain why I think the slinky will do something structurally to the steel tape, please continue to try and to disprove me I need constructive criticism.
The slinky by itself offers little stability in terms of compressing/tensile strength. I'm not concerned with that, that would hinder the devices performance in terms of extending and retracting because that is what the steel tape is for. However it can maintain it's circular shape pretty well, meaning that it it has a lot of torsion strength.(I think).
Now the steel tape will roll onto a spool in it's flattened form. It will exit the device from enough distance as to not stress the steel tape and will be assisted by some sort of die such as a conical funnel or series of bearings. This will curl (and stress) the steel tape into a cylindrical tube shape and it will exit the device as such. There will be a slight overlap (1 inch ideally) of the tape inside the now formed tube to both strengthen its shape. This process however will put too much stress and it will inevitably uncurl and break upon extension.
That's where the slinky comes in. It will prevent this process from happening. The properties of the slinky will also allow it to be tightened and wound so that it can grip the spring steel pole tight. Eventually yes the tape will become so stressed in the middle that it will break in between one of the Slinky's wires, but perhaps I could later customize one that would expand with more rings deploying towards the middle of the steel tape.
I hope I don't sound too crazy.
>>1005822
>cancer.jpg
>>1005677
The gears and everything will help it retract right? will it also help it shoot out?
>>1005837
Yes the gears are connected to the spool which the steel strip is anchored to. It acts much like a linear actuator, the compression strength of the tube being formed allows it to unwind and exit the device as it spins. Friction will be a foreseeable issue, but that's not my concern.
>>1005822
I didn't get a bingo, bummer. Checked
I've been designing a product for the last year and I was stuck because I needed exactly this part. Do you have an email OP?
>>1005869
[email protected]
I would like to hear about your product. Tell me what part you're referring to.
>>1005878
An extendable/retractable but rigid metal pole essentially. I need it to be portable, and your idea seems to potentially be able to do that. I'll email you once uni is over for the summer, because I don't have time to work on it just now. When do you plan to assemble/test this?
>>1005885
This weekend I will start building a basic housing and finding a 4 inch spool/shaft. I will also assemble the hook end and collet that will support the line. Right now I'm not focusing on gearing, I'm focusing on the concept of the rigid line. Later designs will probably incorporate a gearbox of some sort and I'll probably be using a drill for the motor. Provided my slinkies arrive in time I will also start testing the line concept with stacked and rubber cemented paper sheets. The next gauge of steel I'm going to order is .006 or .004, much easier to work with and should be strong enough.
What are you studying at your uni?
>>1005900
Okay, I'll drop you an email over the weekend to see what's up. I'm studying architecture. What do you think the overall size would be roughly?
>>1005902
My current goal is 25 feet.
>>1005910
I need around twice that, but that's an okay starting point.
If you can find some 5160 steel to your specs it'd probably last a good bit longer. 1095 is good stuff when spring tempered, no doubt, but 5160 is a significantly tougher spring steel.
bumping for interest
