Thanks for all the kind comments! I'm happy to see other people are just as enthused about this project as I am.
Let me address some of the questions you all have posted:
On stem design:
orihalcon wrote: ↑23 Jul 2021, 22:19
Also, how are you holding the beam spring to the stem at the bottom? Small screw perhaps? I get the preservation of the "square" cutout on the beam, but I almost think a more narrow rectangle that runs parallel to the beam is all that would be needed for alignment purposes and wouldn't have as much of a weak spot for the beam to break in the middle as it wouldn't have as thin of metal around the square.
0x00 wrote: ↑24 Jul 2021, 22:26
I always figured the slider would be the hardest part; how do you intend to embed the beam spring in it?
In the original switch, the beam spring is insert molded onto the key column. Meaning, the spring is placed in the mold, and the molten resin flows through the square cutout and forms a sort of "cap" holding the spring onto the column. There's no denying that the large cutout produces some structural weakness in the spring, but I imagine the large cutout is necessary to ensure a strong flow of material through the spring to form the cap. It can be very difficult to get molten resin to properly flow in small gaps.
I really like the idea of using a small screw! Due to the logistics and tooling needed for the insert molding, the key column and beam spring assembly will likely end up being the most expensive part. However, using a screw and possibly a small washer would eliminate the need for such tooling. Using standard parts such as M3 screws could also reduce costs as you wouldn't need to produce your own screws. You could also reduce the size of the gap in the middle of the beam spring and increase its integrity as previously suggested. A side benefit would be the ability to replace the beam spring if damage occurred to it as well. The only initial downside I can imagine would be that this wouldn't be a
true reproduction if I went that route, but I think the pros far outweigh the cons in this instance. I will immediately start exploring using a screw to fasten the beam spring to the column.
On MX style mounts:
orihalcon wrote: ↑23 Jul 2021, 22:19
Only other thing I could think of that may be worth doing is having a stem version that accommodates MX mount caps.
I would certainly be interested in making a key stem that supports MX caps! In terms of design I imagine it would be fairly simple, but there will likely be some pain in manufacturing. Since the current stem is simple and flat, it can be cut from a single sheet of material. The MX mount on the other hand would be 3D and couldn't be cut from a single sheet. It would likely have to be casted into a metal mold, which can be very expensive to set up the tooling for. That being said, once it's all set up it shouldn't cost much more to produce than the original stems. I'll spend some time this week 3D printing some prototype MX stems to seem how it would all go together.
On switch height:
inozenz wrote: ↑24 Jul 2021, 19:15
Would it be possible to lower the height of these switches?
Theoretically I don't see any issue in reducing the height. You would need to spend a lot of time trying to get the right balance of feedback when shortening the height if you wanted a drastic reduction, though. There is some dead space in the key column and key module that could be removed for maybe a ~15mm reduction in height without needing to modify the components responsible for feedback. This is just an estimate based on first glance, though. There are likely some other issues I haven't considered.
The real issue in reducing height is how you're going to use the reduced switch. I'm not aware of many custom beam spring PCBs and cases where you could use such a switch. To my knowledge, you're currently really limited to using the original IBM beam spring units, where the height is necessary due to the case design. That being said, imagining a world where you could use a traditional beam spring without the complimentary carpal tunnel is certainly tantalizing. I wouldn't be opposed to exploring this idea down the line, but I'd like to get the original design down first (if anything, for the sake of familiarizing myself further with the switch).
On future plans:
dcopellino wrote: ↑23 Jul 2021, 22:01
Wow, my congrats with you for the awesome project that seems paving the way to
www.modelbkeyboards.com for a full beamspring keyboard replica market place.
orihalcon wrote: ↑23 Jul 2021, 22:19
I would imagine that designing a custom Beamspring PCB/custom barrel plate would be child's play compared to switch design? I've had some ideas for custom layouts using original (or these reproduction) switches.
I'd be lying if I hadn't considered something along this train of thought. I figured the switches would be the most difficult part in a reproduction effort, and that if the reproduction switches were solid then the rest would follow. I do have some electrical engineer friends of mine looking over the original PCB and controller exploring the possibility of a modern version. I'm not too well versed in PCB design though, so I can't speak too much to this. However, from what I hear from them it wouldn't be too much effort. It will 100% be where my attention goes once the switches hit a point I'm comfortable with.
The rest of the assembly (barrel plate, case, etc.) would be very simple in design. The issue with these parts is the cost of prototype and production. As you can imagine, doing a test one shot metal casting of 11 pounds of solid steel isn't the cheapest thing in the world. The tooling cost for an injection molded barrel plate would also be pretty high considering the large size. For reference, the tooling for the small key module was just under $2,000. I would absolutely love to design and make these parts though, despite the cost. However, these steps would have to come later as I'm doing this all out of pocket at the moment and I don't want to bankrupt myself for a metal shell with nothing to put in it.
On cost:
Kabong30 wrote: ↑24 Jul 2021, 03:42
Any idea what the final product might cost?
I can't accurately speak to the parts that haven't been quoted for manufacturing yet, but I can try to paint a clearer picture. If I had to hazard an estimate based on the low quantity orders I've made so far, I'd say: $12 / switch. There's a lot of speculation in this price, though. It's also based off the precedent that one were to have manufactured only the exact number of switches needed for a single keyboard. Bulk orders would certainly drop this price; to what degree, I can't say. I can imagine it would be significant for the plastic parts, though.
On community feedback:
Weezer wrote: ↑23 Jul 2021, 22:10
I'd love to try one of these out. Are you open to mailing me one?
I wouldn't be opposed to sending out samples to the community to test and validate my designs. I don't have a huge quantity on hand, though. The bigger issue is that the only parts that I could send out currently are the compression springs and key modules. If people still want to sample these then feel free to PM me or something, but you won't get quite the full picture doing things piecewise.
I hope that's answered most of your questions! If I've missed something or people come up with something else please let me know. Thanks again! - superfoil
