Option 1 is the ThinkPad X1 Carbon Gen 10 that I started with.
I need to respin my adapter PCB in a bit of an L shape, and I’ll likely have two more PCBs for structure: one which mates with the leftmost pair of pogo pins but has no electrical function, and then a center section which mates with the group of three “touchpad” pogo pins and just fakes out the sense resistor to pretend there is a touchpad connected. Maybe I need a little MCU there as well. I’ll 3d-print a little 6mm filler for the left side of the keyboard, buy an extra “touchpad” spacer for the right bottom side, then just need to make a little custom piece to fill in the remainder of the touchpad space. It’s a bit wide to 3d print on most printers, but maybe it can be printed as two halves. (It would be nice if framework would sell the touchpad module without the actual touchpad installed, to trim costs a bit.)
By my measurements, you’ll need to shim up the screen hinges by about 2mm, but that should give plenty of space. I guess there can be a 2mm screen rest on the part I make to fill the touchpad gap as well.
Disadvantages: there’s a little metal can used for the track point controller to the left of the track point buttons which is a little awkward. The X1 Carbon Keyboard also comes by default with 3 metal standoffs on the bottom that have to be manually clipped away, and there’s no plastic cover between the keys (although that could presumably be printed as well). The FPC cable is short and the connector is unusual, although possible to source from JLCPCB in a single orientation only.
Option 2 is the X280 keyboard, which is nice and compact, fits the space pretty well, and has an integrated plastic cover between the keys:
It’s main drawback is that it rather inexplicably has two long screws that protrude further than they need to beneath the track point:
These hold up the entire keyboard and keep it from sitting flush.
They could probably be filed down and/or replaced with shorter screws, and/or perhaps a spot can be found where a trackpoint-sized hole could be cut in the midplate. The space underneath this area is pretty tightly packed with heatsink, but it’s possible careful alignment could make this work out. If the trackpoint could be made to sit flush this would be a pretty good option: the fpc cables are both fairly standard and long enough to accommodate a connector underneath the more-spacious trackpad area. It might also need some tabs made for the top to get it to seat properly underneath the ventilation ledge, as it tends to pop up there. The mouse buttons even pop up a bit so you could put a thin PCB below them to interface with the touchpad pogo pins without increasing overall thickness. If you can find space to recess the trackpoint bottom plate, you probably would only need a 1mm shim, maybe not even that.
Taking off the midplate and sliding the keyboard around, there’s a place about 6mm down and flush left that has enough space to let the trackpoint slip down. By that point the keyboard is low enough that the arrow keys overlap 2 of the 1.75mm pegs which serve to align the input modules. But if you’re cutting holes in the midplate might as well shave down 2 unused alignment pins as well?
I wonder how much a replacement midplate is, if I wanted to experiment? (Answer:
$99 – it would be nice if Framework would sell just the midplate, not the whole “kit” to trim the price a bit.)
Option 3/4 are the E14 Gen1 and E480, which are almost identical. Their main drawback is width: they are wider than the stock framework keyboard (by a couple of mm!), so you’d need to omit one of the side input modules, and then you’d have a lot of space to fill. They are also tall enough to overlap with the input module locator pins on the arrow key side. They could be made to work, but the other options are probably preferable.
Lastly, a brief word about hinge shims. The hinges are easy to get to, just underneath the ventilation plate, and I’ve measured the dimensions for a 3d printable shim that will sit underneath them. They are held in place by T5 M2.5x3mm screws; you’d need to get slightly longer screws once you fit a shim. The only catch is that the (purely cosmetic) top of the expansion module sits pretty close to the top of the hinge, so you’ll need to find a way to open it up to let the hinge sit 2mm or so higher. I’ve got some ideas about that which I’ll 3d print and prototype.
