Starting at minute 3, you can see the rubber buttons with LED backlights:
Is there a service or how can I create the rubber top and the carbon layer for a prototype myself?
I was looking into this, you can buy those standard square grid buttons anywhere, china sites have tons of them , and you can also get services to custom mold and print them, but for non commercial or small runs
I think you can use silicone ink and silkscreen them, i have not pursued any further, but it is my understanding that silicone ink will cure bond to silicone, I think it is heat cured, same thing they do with those silicone bracelets.
Frank,
Is this a personal project or commercial? If commercial, there are providers of this service.
Making a proper rubber button with a carbon puck that has the "snap" or tactile feedback is not something that can be done without a mold. Those molds take precision machining in order to work properly. Then there's the matter of making and curing the rubber. It's all doable, but is not really practical on a DIY basis.
For DIY, cut out rubber buttons from another device and put them on top of microswitches. There are also snap domes that can be used directly on the PCB, but I see not advantages over a cheap low profile microwitch for a prototype.
I was looking into this, you can buy those standard square grid buttons anywhere, china sites have tons of them , and you can also get services to custom mold and print them, but for non commercial or small runs
I think you can use silicone ink and silkscreen them, i have not pursued any further, but it is my understanding that silicone ink will cure bond to silicone, I think it is heat cured, same thing they do with those silicone bracelets.
Thanks, if I can get the buttons somewhere would be best and sufficient for prototypes. Maybe I used the wrong search terms, do you have some links? Searching for "square buttons" results in lots of HTML tutorials and in fashion accessories on Aliexpress
I would like to have RGB LED as background light.
Is this a personal project or commercial? If commercial, there are providers of this service.
This is currently only a personal project. Thanks for the idea with the microswitches, I might try it. Maybe I can place some RGB LEDs at the sides, too.
Sparkfun used to sell nice 4x4 button pads like that which could also be back lit, but they don't seem to stock them any more.
Charles from Pax Instruments (a member here) has had custom silicone buttons made up for his temperature datalogger - custom size and icon printing.
He may be able to give you more info on where he got them and if there are off the shelf ones suitable for you.
http://paxinstruments.com/products/sku927/
I was just gonna say , yeah adafruit sells these
https://www.adafruit.com/product/1611I just found them on alibaba, but last time i was looking i found alot more, even 8x8 grids not just 4x4.
silicone elastomer conductive rubber buttons pcb led etc.
Making a proper rubber button with a carbon puck that has the "snap" or tactile feedback is not something that can be done without a mold. Those molds take precision machining in order to work properly. Then there's the matter of making and curing the rubber. It's all doable, but is not really practical on a DIY basis.
There speaks somebody with no mould making experience.
If you've some mould making experience it's almost trivial to make these on a DIY basis. The only tricky thing would be finding a sheet of suitable carbon loaded rubber to punch some 'pucks' out of.
The simplistic summary goes:
- Find a working button you want to copy.
- Assemble a prototype out of those buttons and make up the missing bits with some dental impression wax, plasticine or other suitable modelling material.
- Make a (2 part) mould from that using RTV silicone moulding compound adding ports, sprues etc as you go, with a fibreglass (or even plaster) backing.
- Cast new buttons in that mould using two part urethane rubber or RTV silicone rubber.
People do this stuff all the time to produce props for gaming, LARP, steampunk and even honest old fashioned sculpture. It's not hard and pretty much anybody can learn to do it if the arts and crafts types I've known over the years are anything to judge by.
There speaks somebody with no mould making experience.
Making props for cosplay and making functional snapping buttons are two totally different things. And I've never seen anyone successfully make anything like that at home. I'd be glad to be proven wrong here though.
I'm also interested in people experience with making custom professional rubber buttons.
I was wrong - SparkFun do still sell them - https://www.sparkfun.com/products/7835
Thanks, they are perfect, I just ordered one 4x4 pad and some (diffuse) RGB LEDs for it. I guess they can be cut, e.g. in 1x4 rows? The Adafruit listing says it can be cut.
Making a proper rubber button with a carbon puck that has the "snap" or tactile feedback is not something that can be done without a mold. Those molds take precision machining in order to work properly. Then there's the matter of making and curing the rubber. It's all doable, but is not really practical on a DIY basis.
There speaks somebody with no mould making experience.
If you've some mould making experience it's almost trivial to make these on a DIY basis. The only tricky thing would be finding a sheet of suitable carbon loaded rubber to punch some 'pucks' out of.
The simplistic summary goes:
- Find a working button you want to copy.
- Assemble a prototype out of those buttons and make up the missing bits with some dental impression wax, plasticine or other suitable modelling material.
- Make a (2 part) mould from that using RTV silicone moulding compound adding ports, sprues etc as you go, with a fibreglass (or even plaster) backing.
- Cast new buttons in that mould using two part urethane rubber or RTV silicone rubber.
People do this stuff all the time to produce props for gaming, LARP, steampunk and even honest old fashioned sculpture. It's not hard and pretty much anybody can learn to do it if the arts and crafts types I've known over the years are anything to judge by.
Wow. You are a real piece of work.
I did this professionally for years, thank you very much. Read what I wrote. It wasn't in reference to casting a simple button.
Rubber switches using carbon pucks are typically molded in a matrix of switches and the portion of the matrix which gives the proper switch action is extremely thin and requires very precise alignment of the A&B halves of the tool. A couple thousandths of an inch in misalignment is the difference between a great switch and one that does not work at all.
Urethane and RTV are not used for key switches.
All (good) switch matrices are cured with the tool under heat and tons of pressure in a hydraulic press.
And lastly, speaking of tools, are you available to make switches for Frank?
There speaks somebody with no mould making experience.
Making props for cosplay and making functional snapping buttons are two totally different things. And I've never seen anyone successfully make anything like that at home. I'd be glad to be proven wrong here though.
I'm also interested in people experience with making custom professional rubber buttons.
The 'cosplayers' point is that if a bunch of cosplayers and art students can do it, it ought to be a walk in the park for an engineer.
You can make almost anything you like to minute precision with modern off the shelf moulding materials as long as you've got something to crib from. Silicone RTV mould making rubber is fantastic stuff, it'll accurately reproduce features at the 10s of microns level and has negligible shrinkable for the size of parts and accuracy requirements we're talking about here.
I've quite regularly made replacement mechanically functional plastics parts by simply making a mould from an existing part.
Last year I repaired the geared track of a damaged ophthalmic trial frame by making a mould from a non-broken one. I cut the broken section out of the damaged one and cast a repair in place by clamping a mould made with silicone RTV rubber onto the remains and packing it with carbon fibre and epoxy resin. The result was as good as the original and actually stronger than the rather brittle cast aluminium that the original was made from.
Read what LabSpokane says. Making actual functioning buttons and just copies of things are two very different things.
You are sounding like that dude with t-shirt silkscreens claiming that he can do better PCBs than anyone else.
Making a proper rubber button with a carbon puck that has the "snap" or tactile feedback is not something that can be done without a mold. Those molds take precision machining in order to work properly. Then there's the matter of making and curing the rubber. It's all doable, but is not really practical on a DIY basis.
There speaks somebody with no mould making experience.
If you've some mould making experience it's almost trivial to make these on a DIY basis. The only tricky thing would be finding a sheet of suitable carbon loaded rubber to punch some 'pucks' out of.
The simplistic summary goes:
- Find a working button you want to copy.
- Assemble a prototype out of those buttons and make up the missing bits with some dental impression wax, plasticine or other suitable modelling material.
- Make a (2 part) mould from that using RTV silicone moulding compound adding ports, sprues etc as you go, with a fibreglass (or even plaster) backing.
- Cast new buttons in that mould using two part urethane rubber or RTV silicone rubber.
People do this stuff all the time to produce props for gaming, LARP, steampunk and even honest old fashioned sculpture. It's not hard and pretty much anybody can learn to do it if the arts and crafts types I've known over the years are anything to judge by.
Wow. You are a real piece of work.
I did this professionally for years, thank you very much. Read what I wrote. It wasn't in reference to casting a simple button.
Rubber switches using carbon pucks are typically molded in a matrix of switches and the portion of the matrix which gives the proper switch action is extremely thin and requires very precise alignment of the A&B halves of the tool. A couple thousandths of an inch in misalignment is the difference between a great switch and one that does not work at all.
Urethane and RTV are not used for key switches.
All (good) switch matrices are cured with the tool under heat and tons of pressure in a hydraulic press.
And lastly, speaking of tools, are you available to make switches for Frank?
If I've upset you, sorry. Perhaps I should have qualified that as "small scale mould making". If you claim so, then I'm sure you do have years of experience at doing this on an industrial scale, but perhaps that leaves you blind to what can be done on a small scale.
It is relatively easy to make this kind of thing at prototype scale, that's what Frank is after, not the sort of scale that involves milling a mould out of tool steel. At Frank's scale the material options are all going to be catalytic - it's that or nothing. Yes, a heat cured product would be ideal, but that ain't going to happen at this scale. But, as I said, one is going to need a working button to crib from (unless one happens to have the mech. eng and materials science chops to design the critical hinge/snap bits) and I'm sure that the change in material properties would affect the switch feel. But some attempt at making it is better than saying 'It can't be done'.
If Frank was down the road, rather than over in Germany, I actually would get off my arse and give him a hand at trying it.
And lastly, speaking of tools, which one did you use to write that final sentence, a crayon?
Read what LabSpokane says. Making actual functioning buttons and just copies of things are two very different things.
You are sounding like that dude with t-shirt silkscreens claiming that he can do better PCBs than anyone else.
I give up. You're right. It would never work and it was foolish to suggest that some ingenuity and trial and error would ever produce anything that worked for a few prototypes. Only major corporations with expensive engineering resources have ever made anything worth having. Nobody working at home has ever improvised something that even works, let alone begins to rival what can only be done by full-time professionals.
[Sarcasm mode off]
But I do give up. There's better things to do with my time than try to explain to you how it's possible to at least have a crack at this when it's clear that doesn't actually interest you.
Small factories will do small molds and small runs for peanuts. Of course, they aren't the first results on Alibaba.
Small factories will do small molds and small runs for peanuts. Of course, they aren't the first results on Alibaba.
Any examples?
I was actually looking at generic individual buttons shown on the pictures in the listings from this thread. They would be perfect, but it does not look like they are available as a standard product, so they are still subject to the same MOQs. And sources like ebay and aliexpress do not offer anything like that.
Ultimately, use Alibaba's request for quotes when you'll have a STEP model.
To give you an example, a mold would be 250 USD, the parts a few cents each and the leadtime one and a half week to receive samples and one more week to have the mold polished and your small quantity done.
Ultimately, use Alibaba's request for quotes when you'll have a STEP model.
To give you an example, a mold would be 250 USD, the parts a few cents each and the leadtime one and a half week to receive samples and one more week to have the mold polished and your small quantity done.
Please post an example of something you have designed and had manufactured under this pricing model.
The bottom line on rubber buttons is that they are done for a few reasons, very few of which are applicable or necessary to hobbyists.
- Low cost for high volume products, both in part cost and assembly costs
- Surface/splash water resistance
- High cycle count applications (elastomers can be engineered to be amazingly durable at the cost of actuation force and tactile feedback)
- Applications such as medical that require a sealed keypad that can be cleaned and sterilized
If someone is out there trying to build an elastomeric keypad with carbon pucks for switching because, well, that's what the big kids do, my advice is: don't. Rubber keypads with carbon pucks are largely used because they are cheap, not because they are necessarily that good. Anyone that's had a TV remote where the rubber buttons became balky can attest to this. A plastic key over a metal snap dome or a low-profile microswitch will almost invariably be cheaper, easier, more reliable, easier to repair, and have better tactile feedback. In fact, my current cable remote control has gone over to this method: rubber over metallic switches.
If you're building a proper keyboard, my advice will change from the above.
An elastomeric key that functions like you're used to with your TV remote is actually a fairly sophisticated piece of engineering. The portion of the switch that flexes in order to create the snap-like tactile feedback is paper thin has a very specific profile and angle. Every, single key must have this delicate, highly-engineered, membrane surrounding the thick, rubber key pad or the key will seem stiff, mushy, lifeless, or worse, fail in the closed position. Additionally, each key needs a vent to the outside world, or you will simply have a suction cup. These vents are very shallow in order to not compromise the structure of the key. Another parameter is the durometer of the rubber. Softer durometers give better feel, but at the expense of life and reliability.
The contacts are also interesting. Everyone seems to know about the carbon pucks. What gets left out is the carbon silk screening over the top of the switch pads. This is essential for a switch that will work over the long term. Going without can work for a while, but carbon contacting carbon is the commercial solution.
Once you get past the above, then you get to worry about how the switches interact with whatever bezel, if any, covers the switch matrix. This gets interesting quickly. Despite appearances, there's a lot to the clearances and angles in order to have a key that consistently actuates when pressed and does not stick in the down position by becoming jammed on a sidewall on the return.
I see mentions of super-cheap custom key matrixes. Granted, none of this is remotely rocket science, but I can virtually guarantee that you cannot get anything decent at the prices quoted after all of the time and expenses are tallied. If these shops were any good at all, they would not be selling $250 tooling. You might get something in the shape you want, but it's just going to be a shitty key. They aren't charging enough to make anything good. There's an enormous amount of know-how and trial and error that goes into these things, and you need to be sure that you really, really want to go down this road before embarking upon such a venture.
And the reality is, that rubber matrixes aren't so attractive that I would forgo other options, particularly on low-volume devices. I would strongly suggest other alternatives such as a polycarbonate membrane switch, plastic key over a switch or snap dome. The road to Rome is far easier.
What's great about today is that some of the very low cost tactile switches coming out of China are FANTASTIC. They feel good and some of them put out close to perfect square waves. Obviously, you'll need a debounce routine, but the old cost/quality arguments against microswitches just aren't there like the bad, old days.
The rubber key matrix certainly has its legitimate place and will for a long time to come, but make no mistake, it's not a $250 slam-dunk to implement, and there are far more attractive alternatives for prototypes and low-volume. People have been trying to cost reduce key matrix tooling and production for decades. If RTV and cast urethane worked, it would have been done loooong ago. But it doesn't. What is being suggested is hugely time intensive and the results will be completely unsatisfactory, unless one just has incredibly low expectations.
Buying a pre-made matrix off-the-shelf like Frank is going to, is totally legit, and recommended if that works for you.
We are casting our own silicone buttons that go over microswitches. We do this cause we need some splash resistance in measurement devices we build.
It's really easy, I just (manually) milled a mold from aluminium and lightly polished some surfaces. Other surfaces (top of the button) are left with cut marks to provide extra grip. We are using 2k silicone with 45 ShA and mix in different colors as needed. Vacuum casting is then used to build a batch of 10 button strips in each cycle.
This process works really well for us, but we're only using minimal quantities per month.
that go over microswitches
Which means that you don't actually design bucking part, all you are doing is covers, not buttons/switches. And that's much easier, of course.