CNC milling keycaps - anyone with experience?

[Sigmoid]

Hey,

While 3D printing is pretty cool, I think a printed keycap rarely competes with the touch and feel of an injection molded one. I wonder if CNC milling is a possible solution for small-scale manufacturing of high-quality caps made of high-quality materials. (I wonder if PBT can be milled well? Delrin is ridiculously expensive, but it's definitely one of the most millable materials around...)

I am a 3d printing hobbyist, and am very much interested in learning subtractive manufacturing as well... and recently I've been thinking why we don't see more CNC'd keycaps. CNC routing is getting cheaper and cheaper, especially with kits like the ShapeOKO variants...

And let's face it, even specialty keycap manufacturers are cutting corners in a big way. The only source of spherical profiles I have found, Signature Plastics, for example, with their painfully thin and warpy keycaps. Pour molding is extremely labor intensive, and seems great for Transformers-inspired artwork caps for $50 apiece, but I don't think anyone could get away with pour molding an entire keyset. Placing a big chunk of plastic in a Shapeoko, changing tools a few times, turning it over, changing tools a few times, and ending up with a few dozen keycaps in a single go sounds more feasible.

So... has anyone been planning something like this too, or is there someone with experience in milling keycaps? I'd like to kick off a discussion / brainstorming. I'm a big fan of spherical profiles, and they just aren't around anymore... also there are all the old keyboard types with unobtainium keys...

[Melvang]

I feel that the biggest issue here is cost.  First you are paying more for material, as you need to pay for a block that your entire piece will fit inside, then you have to pay for either multiple setup fees, or pay for machine time on machines that can pick and place parts between setups.  IE, in order to have sloped sides you would need to pay for the initial setup cost, milling time on 5 faces, rotate part to 6th face and mill that side.  And clamping onto a part with the for sides slope like that is difficult at best for accurate positioning.  Can it be done, yes, is it going to be cheap for a quality product, no.

[HoffmanMyster]

You can definitely mill metal keycaps, but as Melvang said it gets very expensive very quickly. As for milling plastics I'm really not sure. But as a reference point, a milled metal cap is going to be at least $60, most of which is non-material costs, meaning a plastic cap likely won't be much cheaper. So if you're thinking of doing a full set of be prepared to spend a whole lot of money.

[PointyFox]

I think you can get a cheap mill for like around $10,000.  Material will be like $1-3 per cap.

[Melvang]

You can definitely mill metal keycaps, but as Melvang said it gets very expensive very quickly. As for milling plastics I'm really not sure. But as a reference point, a milled metal cap is going to be at least $60, most of which is non-material costs, meaning a plastic cap likely won't be much cheaper. So if you're thinking of doing a full set of be prepared to spend a whole lot of money.

And even then I would be willing to bet that cost would be just cutting a legend in the top, milling the stem in the bottom and leaving the four sides of it square but bringing it down to the .715" realm from probably .75" square stock.

I think you can get a cheap mill for like around $10,000.  Material will be like $1-3 per cap.

That price would be for a full sized mill that weighs in the realm of 2000+ pounds.  Granted you can get bench top versions for much less but there is a reason they are considered "hobbiest" level machines.  They can still mill metal, but very slowly.

[Sigmoid]

Lol!

I do apologize.

Anyway. As far as I understand, the hobbyist machines usually differ from their industrial counterparts in accuracy, rigidity and ease of use (ie. lack of automatic tool change, etc.) I'd be interested in the opinion of someone who has used one (like a ShapeOKO 2), whether its capabilities would be adequate for keycaps...

As for metal keycaps, milling metal is slower and requires more expensive equipment, and they are artisan items, so I don't think their sale price is fully indicative.

I'm not very familiar with the ins and outs of milling yet, but I wonder if milling multiple keycaps at the same time, using thin "bridges" of material to keep them together while working on the part could be feasible. First you'd mill the backside, with the Cherry stems... Should be easy enough, just carving stuff out of a block of plastic... then flip the block over, and do the rest, but leave thin bridges between the caps when cutting the bottom. This way you could have a sacrificial zone on the edge of the material where you clamp onto the part. Then you can just cut the individual caps free from the finished block with an exacto knife, similar to cutting injection molded parts free.

[Giorgio]

Anybody has a suggestion for a cnc service that can make a keycap?

[Oobly]

With a decently accurate machine you can certainly make Delrin keycaps. It's a great material and highly regarded (known here at GH as POM). You have to choose your mill ends carefully for the different areas of the cap, but it should be fine for a making a few Artisan caps now and then. I wouldn't use either 3D printing or CNC for full sets. Better to make a mold with CNC and use injection molded ABS, PBT or POM for those.

It's also a thermoplastic, which means minimal waste as you can remelt the swarf / shavings, so you have almost zero loss, but it's a bit of extra work to wash and remelt.

If you're after good spherical keycaps, though, I highly recommend Signature Plastic's SA profile. They're thick, solid and feel awesome (and weigh around 2g per cap). There are a number of Group Buys ongoing for them and some just about to start (look in Interest Checks). One that springs to mind immediately is the Retro SA set being offered by Matt3o and Ctrl|Alt: https://geekhack.org/index.php?topic=71636.0

It's the first FULL sculpt SA set being made (same Row order as Cherry, DCS, OEM sets: 1-1-2-3-4-4), although the Shift keys are still Row 3 since SP still haven't made the Row 4 molds for them. There's also Jukebox, Penumbra Round 2, etc, etc... You may even be able to pick up an overstock Hack'd by Geeks.

You can also find all Row 3 sets if you want that "flat" profile a little like DSA. Like the upcoming Danger Zone set.

[Giorgio]

Recently I saw this wonderful post about the sa profile

https://geekhack.org/index.php?topic=63052.0

Maybe there was also a new article by the same author.

[Oobly]

Recently I saw this wonderful post about the sa profile

https://geekhack.org/index.php?topic=63052.0

Maybe there was also a new article by the same author.

And this was my response: https://geekhack.org/index.php?topic=63052.msg1533265#msg1533265

And a post with very interesting information from SP about the history of their profiles: https://geekhack.org/index.php?topic=63052.msg1634897#msg1634897

I love SA profile caps, both "flat" and sculptured (although I do prefer sculptured), it's my favourite keycap profile, and I've tried a lot (various OEM, Cherry, DCS, DSA, etc.).

[Sigmoid]

I wouldn't use either 3D printing or CNC for full sets. Better to make a mold with CNC and use injection molded ABS, PBT or POM for those.

Hm. From what I gather, getting a new mold sounds a lot more complex than just machining something - from the limited discussions I've had with people in manufacturing, a single mold often costs upwards of $10000. Even big players like SP have serious limitations on their offering because they just don't have the tooling, and making it wouldn't be worth it.

So my train of thought was, if injection molding is so unfeasible for small runs (like a few dozen units), wouldn't milling be the right approach...

If you're after good spherical keycaps, though, I highly recommend Signature Plastic's SA profile. They're thick, solid and feel awesome (and weigh around 2g per cap).

I'll look into that. Good to hear that it has some material in it.

I have recently gotten some DSA from them, and that is just an affront. Especially the PBT ones. I remember reading that SA doesn't even have the proper tooling fro PBT, they just do it because people keep asking for it - and I can attest that the result is ABYSMAL. I'd rather call the surface of the multi-wide keys I got from them "geographical" than "spherical".

Have you seen PBT SA's? How do those look?