[IC] Individual buckling spring switches

[dj027x]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. I suspect the height may have to be increased by no more than 3mm but if there is enough interest in the idea, I'll investigate further. Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$. Casting and using resin would be a much cheaper, much slower option though. Basically just cost of materials at that point. If there is enough interest to sell them for any profit whatsoever (I just don't want to lose money on this), I think I would be willing to risk the investment. I'd like to aim for around 50 cents/switch.

[Melvang]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. I suspect the height may have to be increased by no more than 3mm but if there is enough interest in the idea, I'll investigate further. Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$. Casting and using resin would be a much cheaper, much slower option though. Basically just cost of materials at that point. If there is enough interest to sell them for any profit whatsoever (I just don't want to lose money on this), I think I would be willing to risk the investment. I'd like to aim for around 50 cents/switch.

The biggest problem in this idea is buckling springs are not a traditional momentary switch like Alps or Cherry are.  Granted yes M style in a way function that way but they actuate more like a rubber dome switch with the contacts being between multiple membrane sheets.  And F style work with a capacitve change between a pair of pads on the PCB.  This is VERY sensitive to changes in the frame and surrounding structure.

I don't mean to rain on your parade, just trying to inform you of some of the largest challenges of making this work.

[dj027x]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. I suspect the height may have to be increased by no more than 3mm but if there is enough interest in the idea, I'll investigate further. Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$. Casting and using resin would be a much cheaper, much slower option though. Basically just cost of materials at that point. If there is enough interest to sell them for any profit whatsoever (I just don't want to lose money on this), I think I would be willing to risk the investment. I'd like to aim for around 50 cents/switch.

The biggest problem in this idea is buckling springs are not a traditional momentary switch like Alps or Cherry are.  Granted yes M style in a way function that way but they actuate more like a rubber dome switch with the contacts being between multiple membrane sheets.  And F style work with a capacitve change between a pair of pads on the PCB.  This is VERY sensitive to changes in the frame and surrounding structure.

I don't mean to rain on your parade, just trying to inform you of some of the largest challenges of making this work.

Understandable. The design I have in mind would be far from the traditional design. I was thinking simething along the lines of having a stem that is cherry like on the top, however inside the body would be an angled nub that the spring would sit on to give it some sheer, so it buckles when pressed. The metal rocker at the base of the switch, when activated will fall between 2 contact points angled like a V so as to reduce bounce. Another thought I had was to simply have one pin connected to the spring, and the 2nd pin connected to a plate that sits against the wall the spring buckles to. The spring buckles against the wall to complete the connection. I imagine that would lend itslef to bouncing and an unsteady connection though.

[intelli78]

I think you'll have the most success if you can make them fully interchangeable with MX switches. Easier said than done, I'm sure.

[CPTBadAss]

Very interested in a proof of concept.

[FrostyToast]

If you can prove that this works, I would be fine with a dollar per switch.
Definitely interested. Although every thread that tries to make BS switches dies very quickly.

[Melvang]

If you can prove that this works, I would be fine with a dollar per switch.
Definitely interested. Although every thread that tries to make BS switches dies very quickly.

I think a lot of this is due to how tight the tolerances are for this type of switch actuation.  I don't feel that 3d printing has the tolerances required for this sort of thing short of they 3d printers that Boeing uses.  This pretty much necessitates the use of injection molding.  The molds for this will run multiple thousand dollars before anything physical is even made or tested outside of a digital environment.

[dj027x]

So, I actually may be able to use my college's injection molding machinery for only cost of materials. I should be able to use it for prototypes, and if I end up with something functional, I'll look into buying a machine myself. As Melvang mentioned, molds are going to be the difficult part. I'm looking around for an ME on campus that would be able to make some, or teach me how to make some out of aluminum. I can design one easy enough, but damned if I know how to use an industrial cnc machine. Plus I'm sure there a lot of peculiar behaviours different materials exhibit in the manufacturing process like distortion due to heat and such, that I am unfamiliar with. In any case, I can do some prototype prototypes via 3d printer, then put several designs in a single mold, and see if it yields a good result. I may be jumping the gun here, but my hopes are to be able to produce completely clear switches, or a spot for 5mm leds for backlighting purposes, have cherry mx and alps compatability (in different models of course), and match as close as possible the force curve of traditional buckling springs. Trying to match the sound would probably be a wasted effort. I'll definitely start with functionality though haha
Sidenote: If this seems feasable, I'm totally producing alps keycaps too, cuz they just don't exist anymore, and theres no telling when matias is going to start producing them.

[dj027x]

I'm headed to florida for a week, but when i return, Ill be taking a tour of my schools industrial engineering machine facility, and see if they have the right tools for the job.

[sethk_]

This would be nice to have on a keychain, or to try out buckling spring, I would be in for 1 as long as it is a reasonable price.

[CPTBadAss]

I'm headed to florida for a week, but when i return, Ill be taking a tour of my schools industrial engineering machine facility, and see if they have the right tools for the job.

I think what you're going to want to check out is the machine shop in the ME building. When I was there, it was called Gleason. Not sure if it changed names or not.

[dj027x]

I think what you're going to want to check out is the machine shop in the ME building. When I was there, it was called Gleason. Not sure if it changed names or not.

Oh wow, are you alumni? Yea its still Gleason.

[Vizir]

I'm very interested in this!

[Computer-Lab in Basement]

good luck

[dj027x]

Iv'e gotten into contact with an industrial mech professor, and we are considering the different options we have for creating and casting the switches. My per-key rgb backlit keyboard project is taking precedence at the moment, so that, combined with school work, and yet OTHER projects, it might take some time before i have a prototype :/ I however will not let this thread die (said the last reply ever to be posted here lol)

[jacobolus]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. [...] Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$.

How are you arriving at a $3000 price? I’m guessing you’re off by at least an order of magnitude, if you want to produce these at any kind of scale, with with consistent high quality.

Sounds like an awesome project though, if you can get something working. Good luck!

[Melvang]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. [...] Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$.

How are you arriving at a $3000 price? I’m guessing you’re off by at least an order of magnitude, if you want to produce these at any kind of scale, with with consistent high quality.

Sounds like an awesome project though, if you can get something working. Good luck!

This is actually probably on the cheap side of things when you factor in the cost of producing a mold at the required tolerances.

[dj027x]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. [...] Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$.

How are you arriving at a $3000 price? I’m guessing you’re off by at least an order of magnitude, if you want to produce these at any kind of scale, with with consistent high quality.

Sounds like an awesome project though, if you can get something working. Good luck!

I was going to grab a desk-sized injection molder http://www.injectionmolder.net/ We've got a few machine shops on campus, so getting an aluminum mold wouldn't be too difficult. And the scale would be very small. I imagine i could fit roughly 5 to 10 units in a single mold, so id be producing them at a rate of about 1 switch per minute, considering the fact that each switch will need to be cut from the mold and have internals installed. So I could have 120 done within 2 hrs, and sell them for roughly 20 cents per switch. I of course am pulling every one of these numbers out of my ass, but it works for a very rough estimate. I'm sorry if you thought the scale of this would be anything impressive :/ But there doesnt seem to be enough interest in the idea to facilitate large scale production.

[Touch_It]

Interested for sure, if this turns out to be feasible.

[panrc]

I would definitely be interested in some of these switches. I hope you go through with this.

[Dihedral]

So I'm considering creating buckling spring units with mx compatible stems. Basically the idea is to create a switch similar in dimensions to the mx switches, but with buckling spring internals. I suspect the height may have to be increased by no more than 3mm but if there is enough interest in the idea, I'll investigate further. Actually creating them would require the purchase of a plastic injection system and molds and springs and raw plastic, adding up to roughly 3000$. Casting and using resin would be a much cheaper, much slower option though. Basically just cost of materials at that point. If there is enough interest to sell them for any profit whatsoever (I just don't want to lose money on this), I think I would be willing to risk the investment. I'd like to aim for around 50 cents/switch.

If you can make it fit in a 14mm by 14mm plate cutout that would be awesome, always thought that bs would need a bit more space though. awesome idea, postingforinterest

[0100010]

I had a similar idea a while back ( http://deskthority.net/keyboards-f2/buckling-spring-switch-for-diy-keyboard-t5892.html ).  Now with the XTant, this seems a better route to go for custom layout buckling spring boards.

[Melvang]

I will be taking my AT off my desk temporarily tonight, I can take some measurements off the barrels.

[0100010]

The bottom part of F barrels provide spacing that is 0.75" wide, 0.8125" tall and they are 0.1635" thick.  The round part of the barrel is 0.465" diameter.  I do not recall the height of the barrel.

[dj027x]

Another point to bring up: i intend to make them metal contact switches, as opposed to membrane. Would i run into any legal issues selling them, seeing as unicomp has a patent on buckling spring switches, or would the designs be far apart enough to avoid issues?

[Melvang]

Another point to bring up: i intend to make them metal contact switches, as opposed to membrane. Would i run into any legal issues selling them, seeing as unicomp has a patent on buckling spring switches, or would the designs be far apart enough to avoid issues?

No, and on that you shouldn't have an issue with any implementation due to patents expiring decades ago.

[dj027x]

due to patents expiring decades ago.

Well this is fantastic news

[njbair]

This sounds like a fun project. Would definitely buy.

Also, have you thought about using a different size spring than a traditional Model M? I'm thinking that maybe using a smaller spring might help you knock the overall size down a bit. Of course, spring size will also affect actuation force, travel, etc.

[ThatRusty]

Sounds like a pretty cool project! It would be great to see a proof of concept.

Is there any particular reason you want to do the injection molding yourself? Once you get a working prototype done I'm sure there is a local plastic injection mold shop that could handle the heavy lifting (create the molds and production) and be able to turn out a quick minimum order.

[njbair]

Sounds like a pretty cool project! It would be great to see a proof of concept.

Is there any particular reason you want to do the injection molding yourself? Once you get a working prototype done I'm sure there is a local plastic injection mold shop that could handle the heavy lifting (create the molds and production) and be able to turn out a quick minimum order.

This is a good point. A bench-top injection molder probably won't be capable of the same quality as a more industrial setup anyway.

[Melvang]

Sounds like a pretty cool project! It would be great to see a proof of concept.

Is there any particular reason you want to do the injection molding yourself? Once you get a working prototype done I'm sure there is a local plastic injection mold shop that could handle the heavy lifting (create the molds and production) and be able to turn out a quick minimum order.

This is a good point. A bench-top injection molder probably won't be capable of the same quality as a more industrial setup anyway.

It is less a question of the injection molder than it is a question of the quality, accuracy, and tolerances of the molds.  Reducing tolerances and increasing accuracy increases the cost at an exponential rate.

[njbair]

Sounds like a pretty cool project! It would be great to see a proof of concept.

Is there any particular reason you want to do the injection molding yourself? Once you get a working prototype done I'm sure there is a local plastic injection mold shop that could handle the heavy lifting (create the molds and production) and be able to turn out a quick minimum order.

This is a good point. A bench-top injection molder probably won't be capable of the same quality as a more industrial setup anyway.

It is less a question of the injection molder than it is a question of the quality, accuracy, and tolerances of the molds.  Reducing tolerances and increasing accuracy increases the cost at an exponential rate.

That's true to a point. But industrial setups do a much better job holding alignment and this preventing flashing etc.

Really though, the only critical tolerance on a key cap is the stem.

[dj027x]

Sounds like a pretty cool project! It would be great to see a proof of concept.

Is there any particular reason you want to do the injection molding yourself? Once you get a working prototype done I'm sure there is a local plastic injection mold shop that could handle the heavy lifting (create the molds and production) and be able to turn out a quick minimum order.

Good point, but the cheapest way afaik to get prototypes would be getting my own desktop injection molder. If I have a mold and molder, might as well produce pieces until the mold wears out. If that is profitable enough,(ie, I don't lose money doing it) I'd probably let a company take over production

[dj027x]

That's true to a point. But industrial setups do a much better job holding alignment and this preventing flashing etc.

Really though, the only critical tolerance on a key cap is the stem.

I was intending only to make switches at the moment, but keycaps are foreseeable. It should be relatively easy for me to get an aluminum mold that has good alignment. Flashing shouldn't be an issue, so long as it doesn't interfere with the innards Unfortunately I have 3 other projects and college to worry about, so when I get around to this is anybodies guess. I'll most likely get serious about it at the start of next semester, or the end of this one.