Introduction: 3D-Printed Electric Slide Switch (Using Only a Paperclip)
I've dabbled in wiring together my own little electrical projects over the years, mostly in the form of paperclips, aluminum foil, and cardboard cobbled together with hot glue. I recently bought a 3D printer (the Creality Ender 3) and went looking for a printable model that would let me create more reliable electrical components using the same common household metal. Most recently I needed an on-off switch that I could wire into a standard 2-pin computer fan being powered by an AC wall adapter.
To my dismay, I could find only one printable model that didn't require ordering special metal parts for electronics (Hackaday), and the last update to that project revealed that it stopped working after some light use in 2016. But I thought the core function of their design looked promising, so I decided to take a shot at creating a similar simple electrical switch.
After a couple days in Sketchup and several iterations, I've designed a (so far) reliable electrical switch that, besides the printable plastic housing, only requires about half of a large office paperclip for the conductive components.
- 3D printer
- Wire snips
- Large office paperclip (or equivalent 1mm dia. [18 AWG] conductive wire)
- 6-7g 3D printer filament. I use a cheap PLA
The printable model consists of 3 parts:
- Superglue or your preferred equivalent
- Metal file or sandpaper
Step 1: Print the Case
I 3D printed this reliably on a stock (except for a glass bed) Ender 3 at 0.2mm layer height with a 0.4mm nozzle. Sliced using Cura with the following notable settings:
- 0.2mm layer height
- 3 walls (shells)
- 20% cubic infill
- Supports: Touching Buildplate (only needed for the Slide piece)
- Support Density: 50%
- Build Plate Adhesion: Raft
Everything else was left at the default "Standard Quality" settings. Should print in about an hour depending on your setup. The parts themselves take up about 5g of filament, with raft and supports adding a little extra.
When it's done printing you'll have 3 separate parts: Body, Slide and Top.
Step 2: Paperclip Info and Tips
This was model was designed specifically for 1mm dia. (18 AWG) uncoated paperclips because that's what I happened to have on hand when making this. Anything larger or smaller either won't fit or will be too loose and result in unreliable behavior. However, feel free to modify my Sketchup file to meet different needs! Also, you might be able to just scale the model to make it accommodate larger or smaller paperclip diameters, but I haven't tried that.
I'm not sure if there's a standard paperclip measuring system, but I'll update this with that information if I ever run across it. I have no idea what exact kind of paperclip I used because I threw away the box years ago.
Straightening Paperclips (See images)
Slight bends in the paperclip metal may prevent the Top of the case from fitting correctly (1st pic). To effectively straighten the residual bends after hand-straightening it, use pliers to grip the paperclip at a straight segment right before a bend (2nd pic). Apply pressure to the paperclip after the bend until the bend is perfectly in line with the straight segment (3rd pic). Then move the pliers to the next bend (4th pic). Repeat until all the small bends are straightened (remaining pics).
It's ok if there's a slight curve to the "straightened" paperclip; it's the short and sudden ones that will cause problems later.
Step 3: Shape the Static (Right-side) Paperclip
Place the straightened end of a paperclip into the horizontal channel on the right side of the Body. Push it though until it contacts the triangular point on the left (1st pic).
Bend the paperclip to about 90° (2nd pic).
- Leaving it at a slightly >90° angle will help keep it in place via tension forces later.
- Make sure the original 3 contact points (1st pic) are maintained after the bend. Adjust as needed (3rd pic).
Snip off the internal end so that it extends out of the horizontal channel a little less than halfway to the triangular corner that it originally touched (4th pic). Also snip off the external end to the desired lead length (5th pic).
Step 4: Shape the Pivoting (Left-side) Paperclip
Place the plastic Body part on a flat surface and insert the straightened end of the paperclip into the through-hole (1st pic). Use it to bend the paperclip 90° (2nd pic). This will give you close to the right length at the end of the bend. You will probably have to use pliers to get a full 90° bend that doesn't spring back to a wider angle.
Place the paperclip in the channel along the left side, bent end up (3rd pic). Hold the bent end in place and bend the long end around the pivot corner (4th pic). Tweak the pivot angle until the bent end point is about in line with the top ledge (but not quite touching it, 5th pic) when the vertical section is flush with the edges. The ideal length is when the paperclip can rotate on the pivot corner and just barely touch the right edge next to the through-hole (6th and 7th pics).
- Err on the side of being further away from the top ledge; if it's too close it won't be able to bend downward to make contact with the other static paperclip.
Snip off the desired lead length at the exterior end of the paperclip (8th pic). Also snip off the internal end bend so that it's flush with (or shorter than) the depth of the Body (9th and 10th pics).
Step 5: Assembly
Insert the Slide into the Body's top groove (1st pic). Make sure it can slide back and forth without getting stuck (2nd pic). Snap the Top piece in place to get a feel for how it connects to the Body, and make sure the Slide still moves back and forth without getting stuck. Remove the Top piece and move the Slide to the left (off) position.
- If the Slide is too thick to fit in the top groove, use sand paper or a metal file to thin down the arms slightly. The bottom of the Slide arms (where it touches the print supports) can sag slightly or develop small burs, both of which can prevent a smooth fit.
Insert both paperclip pieces into their positions as previously described, keeping their vertical sections as flush as possible (3rd pic).
If you have difficultly keeping them in the correct position while putting the Top on, apply a small amount of glue or adhesive to hold them in place. Don't apply glue to anywhere on the paperclips other than the vertical parts. Be aware that excess hardened glue may prevent the Top from fitting into place correctly.
- If you're ready to permanently enclose the switch, this is the point where you can apply superglue (or your preferred adhesive) along the bottom edge, and the lower half of the right and left edges. The bottom left and right corners are the spots where the Top tends to pop off most easily, so focus on those. However, I highly recommend testing it before gluing it together.
Snap on the Top part (4th pic). I find the best way to do this is to touch the top-left groove corner to the Slide, then snap the bottom-left corner into place (5th pic). Then apply pressure to the bottom-right corner until it snaps in place (6th pic). Make sure to lightly pull the paperclips towards the center (so they're flush) as you do so. The bottom-right corner may require a fair amount of pressure to snap in since it's intentionally a tight friction fit.
Step 6: Success! ...Or Troubleshooting!
Now that the switch is fully assembled you can test it! I use the Continuity mode of a multimeter to make sure it's working correctly. Or you can hook it up to a known-good circuit of your own design if you don't have a multimeter handy.
Below are some problems you might run into and how to fix them:
Top won't snap in place
- Make sure the vertical sections of paperclip are straight and flush against the bottom and side edges.
- Make sure the pivot (left) paperclip's internal bent end (near the through-hole) was snipped so it doesn't extend higher than the rest of the Body.
- If your paperclip is larger than 1mm dia. (18 AWG) then you won't be able to get the Top to snap in. Try scaling up the model, or use sandpaper or a metal file to carve wider channels into the Top to accommodate the thicker metal.
- If you applied glue or adhesive that dried in place it may take up space that prevents the top from fitting in place. Remove the dried glue or re-print the Body.
Slide is stuck
- Sand or file down the parts of the Slide that slot into the grooves until it fits better.
Paperclips are loose or wiggly
- Most likely you paperclips are too thin. You can try printing a scaled-down model. If you do and it works, I'd love to hear about it. Alternatively, maybe the top isn't fully snapped in place, or your printer isn't well calibrated and it made the internal groves too big.
Circuit doesn't complete when switch is "on"
- Make sure the right (static) paperclip extends further left than the bent end of the left (pivot) paperclip, and the bent end of the pivot paperclip extends at least as high as the static paperclip. When the pivot paperclip is pushed down (away from the Slide) it should make contact with the static paperclip (4th pic).
- Make sure the pivot paperclip doesn't extend too close to the top ledge or it won't be able to pivot downward when the switch is pushed- instead it'll get stuck between the Slide and the wall (see 2nd pic for good spacing example).
Circuit is complete when switch is "off"
- The pivot (left) paperclip is probably bent at too small an angle and touching the static (right) paperclip when relaxed. Slightly increase the angle of the bend at the pivot corner so there's a bit of space between the two. Alternatively, slightly angling to bend end away from the static (right) paperclip may help, but increases the risk of that end getting caught on the Slide (see next problem).
Switch won't move all the way to the "on" position
Switch tends to pop out of the "on" position on its own
- The end of the pivot (left) paperclip is probably getting caught between the Slide and the top ledge. Adjust the bent end so that it's angled very slightly downward, away from the Slide and towards the static (right) paperclip.
Step 7: Final Thoughts
I'm by no means an electric engineer, but I assume that as long as you only use this with currents and voltages that are safe for you to touch then this won't have any safety issues. If you discover otherwise please let me know.
I'm licensing all this under the Creative Commons Attribution-ShareAlike license. I want people to be free use this design for anything they want, and hope that others can use or improve this design to create other open-source 3D printable electrical components that use common household conductive materials.
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