Solderless Unibody Switch

I started playing around with this idea for a solderless switch, and also decided to try a unibody approach just for fun. It turned out better than I expected. Would appreciate your thoughts. Pictures, notes and STL as follows:


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STL Print settings:
Solderless UniBody V1.0.stl (49.4 KB)

  • Material = PLA (PETG should work too, haven’t tested yet though)
  • Layer height = 0.20 mm
  • Shells = 3
  • Infill = 100%
  • Orientation = Edge side down (this is important to ensure layers are aligned with the curve)

Assembly Instructions: Solderless Switch Assembly Instructions.pdf (599.1 KB)

Comments:
The main purpose of this design exercise was to test to see if crimps would be able to make a reliable switch connection without the use of a Crimp Tool, or heat gun (I.e no specialized tooling)

Here are my comments:

Crimping approach

  • Used the same switch and mono cable as the Light Touch & Raindrop

  • The crimps used were about $0.16 each.

  • https://www.amazon.ca/gp/product/B01LNMO7DY/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

  • Using the Plier nose on the crimping tool allowed for a narrow crush length and I believe this helped. Will need to test with other common tools (pliers, etc.)

  • I suspect standard version crimps (without marine heat shrink) would work as well. The price difference is negligible. The plastic crimp covers may prove to be in the way a bit though, so would need to account for that in the base design if using this same switch.

  • I found assembling each of the crimps onto the wire first much easier to manage compared to starting with them on the switch.

  • It will be important to ensure the crimps are supported and contained within the body of the switch to ensure the longest service life possible.

  • Bonus, the crimps provide a very solid element to use a tie strap with, so also gives a pertty solid, and clean looking wire retention method.

Unibody switch design approach

  • Wanted to play with this…because why not

  • I haven’t taken assembly pictures yet, will do this on the next one.

  • This demonstrates that the base plates for both the Light Touch & Raindrop can be easily modified for use with this crimped approach.

  • Removes the pain point of needing to find a hinge, or print small hinge parts

  • Remains fairly low force, and design can be tweaked to reduce baseline forces from the body if needed

  • I added super glue between the switch component and the 3D Printed body as an added control / retainment.

  • The legs on the opposite side of the switch are also mechanically retained under a small lip at the front of the base plate for additional control / retainment.

  • Limited stroke length, and low strain on the body. Will need to test to confirm repeat activation robustness.

@loretodalt @KenHackbarth @MMC_Tyler @MMC_Stephen @imtiaz @ConnorM @lyonsm

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Amazing! I’m ordering some of the connectors today and test will it out. Maybe use the design during our PD day in October if that’s OK? Printing in PLA is good or does it need a different material?

I’ll give it a try. I’m just excited to see someone thinking outside-the-soldering-iron :upside_down_face:

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Yes, I used PLA and it works pretty well. PETG would also work I suspect, but I haven’t tried it yet. Let me make another one today and I’ll also take assembly pictures this time so I can share my build process so far too.

Happy you’re interested to give it a go…and yes, use it at will as far as I’m concerned and any feedback / remixes welcome. Just wanted to get a few more people involved to provide some testing and feedback before putting it into the library.

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@MMC_Justin this was a great idea. This no-solder design will open up the creation of this type of device to a lot more people I would assume. We will have to give it a shot at the workshop here soon. I’ll happily provide some feedback if we do.

I wonder if adding a curl upwards on the top end portion of the 3-D printed switch body would allow foR easier more reliable pressure to be applied to the switch inside. with the downward angle of the top portion of the 3-D printed body it looks Like an individual with limited strength might have their finger just slide off the end of it without enough pressure pushing downward. what have you found through your test with activating it? Pretty easy and consistent?

Connor

I agree and do think some other end styles would be worth a try. We can probably spin up a few ideas pretty quick to try out. I was also wanting to try out a spoon style end that helps direct a users finger into the middle.

For what it is, it works pretty well and feels quite solid. It certainly needs to be fixed in some way as it’s so light that even just cord twist will topple it over. Comparable to the Light Touch and Raindrop switches in that way though.

Printed one with PETG now too, seems to be just fine.

Added a draft of some assembly instructions here: Solderless Switch Assembly Instructions.pdf (599.1 KB)

This looks really cool.
I am placing an order for the parts and we’ll see what it is like to build.
Thanks for tagging me on this post :smile:

At first look I had a couple thoughts:

  1. Does is slide from under you finger when you push the button? What if you push it from the front edge?
  2. Does the twist tie wrapping under the switch destabilize it and allow it to rock side to side?
  3. Would putting a loop in the cable where you twist tie it help with reducing the strain on the crimp? if the cord is pulled or twisted with daily use.
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Woot! Thanks for the great instructions @MMC_Justin. I managed to build one after playing around with various pliers. I had the most success with shorter needle-nose pliers. I was struggling with the crimper end of my wire cutter and getting a little frustrated. I do have a heat gun but was testing out the hair drier option since getting multiple heat guns and plugs may not be feasible during larger builds. Alas my drier was not hot enough but the lighter did a great job.

I agree that it would be a great idea to play around with the tops. A design that cradles the finger would be great and I’m also thinking perhaps a larger circular surface area to perhaps use it for head input a la spec or jelly bean switch? This would make it a faster and easier build than the interact. If it works…

3 Likes

Solderless Switch Body V2.1

I’ve updated the design files for this one based on all the great feedback. Here’s the new STL file and print settings, along with a couple pics. I like where we’ve gotten this to. Please give it a go, and send feedback. @loretodalt @imtiaz @ConnorM @KenHackbarth @MMC_Jake @MMC_Tyler @MMC_Stephen @MMC_Chad

unibody switch v2.1 - 0.3 layer height.stl (302.2 KB)

Key changes include:

  • Contoured finger placement area
  • Bottom channel for velcro / to keep tie strap above surface
  • Slightly wider & adjusted dimensions for print settings

Print Settings:

  • Layer Height = 0.3 mm
  • Layer Width = 0.4 mm
  • Material = PLA
  • Shells = 3
  • Infill = 100%
  • Orientation = Edge side down

3 Likes

There’s still opportunity to speed up print time, but it came in at about 40 minutes for me as is.

@janellesingh would also be great to hear your input on this too.

1 Like

Nice fast print here - 26 minutes on the Prusa Mk3S.

The finger ‘groove’ feels really nice and the activation force is pretty reasonable (98-100 gf).

It’s good practice to add a small chamfer around the edge in contact with the print bed (0.3 mm) to reduce any elephant foot (though most slicers will compensate for this now).

Not sure what to do with the sharp corners on the front edge. Could be cut or sanded after the print is complete, or a chamfer could be added to help break the edge.

I think there’s likely an opportunity to reduce the height of the front edge so a user doesn’t have to lift their finger as far.

Unibody approach is cool. Could also consider a two part option to separate out the activation surface (more print orientation options, different colors, etc).

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What tool are you using to model it? Those front corners could be chamfered - or even filleted.

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Hi,

Wow these are really neat. I like both versions because it gives people options on where they can use the switch and playing around with the tops would be fantastic.

Some of my single finger switch users have very minimal strength in their fingers. I like that these have similar activation force to the raindrop and light touch switch. The ability to rest on this switch is a nice feature for someone with limited mobility in their hand.

Having size options for the width might be nice? We usually mount multiple switches at multiple fingers if possible for the patient. For pediatric clients a smaller size might be beneficial as well?

We have a patient diagnosed with ALS who only has limited flexion in a few fingers on both hands and no other movement in their hands. We mounted switches at the end of his wheelchair armrest where his fingers hung over the end and he could press a few switches. These would have been really nice to test out with him. I have another patient with MS using a pinky extension to activate a switch.

Love the no solder approach. I’ll have to try to build both styles once my 3D printer is fixed. Can’t wait to try it out. Really cool creation. Thanks for tagging me!

2 Likes

This is looking great. We will definitely give it a test in the workshop. I like the idea of size options and filleted corners suggested above.

Updated STL for some finer finishing points, and I think we’re actually at a point we can start prepping to publish this one now. Would be good to get a couple other test prints on this too, so please let me know your feedback. I figure we get this version up and posted, and then we can start working additional variations (i.e. low profile) after that. Appreciate all the input here everyone, great work!

unibody switch V2.4.stl (147.3 KB)

Print Settings

  • Material = PLA (PETG also works)
  • Layer Height = 0.3 mm
  • 1st Layer Width = 0.5 mm (new spec)
  • Layer Width = 0.4 mm
  • Shells = 3
  • Infill = 100%
  • Orientation = Chamfered Edge Down
2 Likes