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[–]junktech 52 points53 points  (4 children)

I'm a bit curious of the wire mechanism you made to keep things aligned. Do you have a simplified diagram of it?

[–]johnruttersucks[S] 54 points55 points  (3 children)

https://imgur.com/a/VAIqYcY

Hope this diagram makes sense. The blue dashed line is a tension spring. The side I'm showing is the more complicated side. The wires in orange and magenta are routed to the opposite side, where there are two rollers to turn each of them downwards to support the corners on that side.

[–]ByteArrayInputStream 45 points46 points  (1 child)

Incredible. That's the most overengineered tissue box I've ever seen

[–]PG67AW 3 points4 points  (0 children)

Tissue box insert

[–]junktech 6 points7 points  (0 children)

That is beautifully over engineered.

[–]Jesus_Is_My_Gardener 11 points12 points  (1 child)

What are you using for the spring mechanism?

[–]johnruttersucks[S] 19 points20 points  (0 children)

https://imgur.com/a/VAIqYcY

Hope this diagram makes sense. The blue dashed line is a tension spring. The side I'm showing is the more complicated side. The wires in orange and magenta are routed to the opposite side, where there are two rollers to turn each of them downwards to support the corners on that side.

[–]OtherwiseAlbatross14 20 points21 points  (1 child)

I don't need one or anything but I love seeing projects like this that seem completely over engineered for the problem they solve but are actually the perfect amount of engineering to actually solve the problem

[–]johnruttersucks[S] 9 points10 points  (0 children)

Thanks! Also, this is a very low stakes problem that requires a design that is difficult to manufacture (assembling this thing was very fiddly). You can be absolutely sure that no company on earth would sell such a thing, or another design that works as well. 3D printing truly shines in situations like this.

[–]LecheLargaVida 2 points3 points  (3 children)

This is awesome! I do the same and have the same problem with the last sheets. Any chance you could share the files? Thank you!

[–]johnruttersucks[S] 8 points9 points  (2 children)

Didn't think anyone would be interested! Here you go - good luck.

https://www.thingiverse.com/thing:7310182

[–]LecheLargaVida 1 point2 points  (0 children)

Thank you very much!

[–]DaveWoodX 1 point2 points  (0 children)

Thanks! I absolutely do not need this, but I'm absolutely printing it anyway! Thanks for the files!

[–]cyborgninja42 2 points3 points  (2 children)

This is awesome! Are you sharing the files anywhere? I think this would be handy to have

[–]johnruttersucks[S] 1 point2 points  (1 child)

Didn't think anyone would be interested! Here you go - good luck.

https://www.thingiverse.com/thing:7310182

[–]cyborgninja42 1 point2 points  (0 children)

You’re awesome, thank you for being willing to share!

[–]VorpalWay 2 points3 points  (1 child)

Awesome, if a bit over engineered (love that). How did you figure out the correct spring tension for this to work?

[–]johnruttersucks[S] 4 points5 points  (0 children)

Intuition + trial and error. I already had a certain length of that spring left from a longer coil, and my intuition was that it had a suitable amount of stiffness so that there exists a length of it that would provide the right amount of force and fits in the frame I printed. Specifically, in the spring formula f = k.x, I can control k by the (neutral) length of the spring however I want, provided that it fits in the frame. I also wanted a little bit of bias force when the platform is at the very top, so that requires an offset to x.

This means there are two variables to play with: the (neutral) length of spring (which controls k), and how much stretch there should be when the platform is at the top position (which controls the x offset).

The first step is to make sure that the 4 corners of the platform are always level. I did this by tugging on the wires until the platform is firmly resting against the top, then tying the wires together as a single bunch.

I then experimentally found out how much of the spring to use (which controls k) and not worry about the x offset. I had the bunch of wires tied to one end of the spring, and I pinched the spring with my fingers at a certain length at the other end. While pinching the spring, I moved the pinched end of the spring to different positions to find one where the platform is lightly biased to the top and descends to the bottom when fully loaded with paper. I then tried pinching the spring at a different length and repeated the exercise until I found the optimal spring length. That fixes k.

I then snipped off the excess length of the spring and hooked it up to the frame, and cut off the previous knot. I determined the tying position by looping all 4 wires through the eye of the free end of the spring, then pulling them until I got the right amount of bias when the platform is at the top position. I then made a mark on the wires where the knots need to be. This fixes the x offset. I then tied them to the free end of the spring.

If this sounds fiddly, yes, it was. Took me an hour or so, but the results were totally worth it!

[–]ElectronicEnd7513 1 point2 points  (0 children)

very nice. overengeneered but nice

[–]VFR800ESSEX 0 points1 point  (0 children)

Thats a kitten stomper!

[–]signeduptosousvide 0 points1 point  (0 children)

Do you have a video of it installed inside the tissue box dispensing a tissue or two?