Is this a commonly reported issue? I don’t think this has happened with any of mine 
What I’ve heard is that it happens more often and more severely when swapping a different stem into retooled Cherry housings. @ChrisSwires shared measurements a while back that showed that the rectangular part of retooled Cherry stems is thicker in the Y axis (if viewing from above looking at the stem cross) which would be consistent with my findings; a stem that is thinner in the Y axis would allow the keycap stem to move closer towards this edge and be more likely to bind or scratch against it.
I’ve even seen reports though of minor binding even with unmodified retooled black switches.
Yep, can confirm, I’ve had the issue swapping a number of stems into retooled, the tolerances are super fine across certain batches in regards to the stem and housing interplay, adding in a third party stem with looser tolerances can create issues for sure. I haven’t had issues with any of my retooled out of the box as you mentioned but given the tightness, yeah seems plausible as the moulds age certainly.
Especially true when attempting to make Holy Chickies. Been thinking of making a batch and was able to reproduce the biding problem with GMK keycaps, but not ePBT. The key cap will stick or even stop at the top of the depression if you press from the bottom of the key.
Here’s a Reddit thread on the same issue with a tedious fix.
Here is a better picture of why the retooled tops can bind with GMK caps, especially if you use a different stem.
The keycap stem can snag against the curved part in the middle, which used to be flat.
This can happen even with stock Cherry switches and GMK caps, though it is much less likely because the Cherry stems are thicker which spaces the keycap stem away from this curved area. See comparison:
https://imgur.com/a/xznLkSj
So I was thinking of trying this U-shaped chisel to shave material off retooled top housings. What you guys think, 2mm? https://www.amazon.com/Flexcut-Micro-Carbon-Cutting-MT20/dp/B016DBI61E/ref=pd_sbs_4?pd_rd_w=dxOM6&pf_rd_p=2419a049-62bf-452e-b0d0-ca5b7e35a7b4&pf_rd_r=YQV0YSCPH1SN3MJXMVRK&pd_rd_r=ee289701-fa0a-46c4-affb-fdc5d274c0c2&pd_rd_wg=2Of9c&pd_rd_i=B016DBI61E&psc=1
Amazon.com
If anyone is curious about Hyperglides, I got some in and they have the same curve on the top housing and do in fact interfere with GMK caps on non Cherry stems. I tested with Halo stems.
I was gonna say - I saw some folks talking about that on reddit just a couple days ago. One was like “am I nuts or are my GMK caps hanging on these switches” - wish I’d known about this post to point them to, just so the one guy knows he’s not crazy!
I believe this was also a discussion around the use of a U4T stem in a Cherry Black housing. @kelvin0113 noticed this phenomenon when mounting GMK caps. I tried epbt and that didn’t cause issues on my limited sample but supposedly GMK would bind, which is a bummer because the sound was great and I preferred the reduced tactility of the cherry housing
I haven’t experienced this with GMK myself but I did have issue with CRP keyset on North-facing retooled black. Which makes me wonder why there aren’t more people complaining because, if retooled blacks have this issue when South-facing, clearance is worse when North-facing.
Reporting back; I tried a 1.5mm flat micro chisel and that’s a big negatory on shaving away material. The curve area is ultra thin, so it basically disappears if you try to chisel it flat, and you end up with and opening exposing the front of the stem. Also I stabbed my thumb and it didn’t bleed unless I squeezed it. Mhmmm
We all appreciate your blood sacrifice so we don’t have to cut ourselves trying the same thing!
maybe a touch from a skinny dremmel sanding bit on low speed?
More great news on this topic. Upon dismantling my older MX Clears for their top housings, I had the genius idea of using the retooled Blue tops on the Clears! Surely Cherry tops with Cherry stems should have the tolerances to accept god damn GMK keycaps. Nope. You can force the cap’s stem to scrape/catch the top, and there is significant friction on the inside going all the way down. Soo… who speaks German and wants to write a scathing letter to Cherry?
“Oh come on Lake, it can’t be that bad. At least we have Hyperglides with their new tooling. Maybe if you don’t swap third party stems they can be good.”
Well here are some Hyperglides with GMK Hydro. That sharpie line was transferred to the keycap from the top housing. Everytime I check something with these curvy top housings I am disappointed. You can’t even using GMK on new Hyperglide switches, are you messing with us Cherry?
Yikes
Has anyone tried using a soldering gun, heated to temperature hot enough to soften nylon but not enough to melt, to straighten the line like it was before retooling?
If the bottom edge is not binding but just rubbing against the stem, polishing and/or lubing the stem side may work.
Not a bad idea actually! I wouldn’t do it with a good iron cause you’re bound to get some melted plastic on it even though the ideal is not to completely melt the plastic. That melted plastic really messes with tips & is hard to clean off IME. Definitely worth a shot with some of the crappier switches out of a batch & cheapo iron I think!
Yeah. Getting melted plastic on solder tip is not a happy moment. I’d wrap the tip with aluminum foil and also use only side of the solder tip, raising temperature a degree at a time.
It’ work better if there was something to push back on the other side. Maybe a wooden cloth pin? 