kailh low-profile switches with Signature Plastic's LP Family 13 keycaps

At the Atlanta keyboard meetup, someone had brought a PMK grab-bag for rummaging. In this bag was several LP Family 13 keycaps. Much to my surprise, the blank keycaps work on Kailh low-profile switches!

off-centered stems, consistent with Cherry ML
fits on the switch
looks close
Success! Kind of...

I had floated this idea to PMK and Novelkeys before, but the off-center stems were a concern. To investigate, I ordered a varied array of Family 13 (and some defunct Family 11) keycaps. While PMK's website does not advertise these, PMK's parent company Signature Plastics keeps an inventory for commercial customers who use Cherry G84-series keyboards (thanks again, Melissa).

What I found is that with blank Family 13 keycaps, there is a small amount of contact between the switch and keycaps. See the pictures below:

Static

Depressed beyond point of actuation (90%-ish)

Front of the keycap depresses further when forced
So on a heavy bottom-out, the front of the keycap actually travels further down than the rear, as the rear of the keycap contacts the switch housing. However, the travel is within the range of motion for the switch stem, meaning that the keycap stays seated on the switch. There isn't any rubbing, it just feels like there is more give after the rear of the keycap hits the switch housing. This is kinda similar to the interference seen on GMK keycaps on upside-down cherry/clone switches; some notice it, others do not, and for some it's a deal breaker. To investigate it further, I have decided to make a keyboard using these keycaps and will report back.

On the downside, double-shot PMK Family 13 keycaps exhibit detrimental rubbing against the switch housing, and in my mind are incompatible. The fact that PMK utilizes thinner ABS than cherry for their blank ML replacement keys was the key factor for kailh low-profile compatability.

So to sum it up, the only keycaps that work with kailh low-profile switches are:
1) standard kailh keycaps (17.5mm x 18.5mm spacing)
2) PLUM keycaps (standard 19.05mm)
3) Signature Plastic Family 13 - blanks only (18mm) <=== slight rubbing

I'm assuming that the pad-printed Family 13 keycaps would work as well, but I don't have any to verify this. Double-shot ABS is a no go, unfortunately...

More to come...
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