My Boba housings are in my mailbox! Definitely gonna make a few of the linears I was talking about above in the thread tonight to see how they do. Will report back here once I’ve done it.
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So I finally got around to messing around with some different stem combos in my boba housings & unfortunately they are not too hot for modding. GazzeW has such tight tolerances on the tops (& bottoms to a lesser extent) more stems bind in them than actually fit. JWK/Durock stems too big, Gateron stems too big, modern Cherry stems too big, Zealio V2 & V1 stems too big, etc. The best fit’s I found were Cherry vint black stems, Halo stems, Invyr PE stems (the ones that were in spec), & OG Sky stems. For linears they really don’t seem to be anything special, even with the softer nylon they use it still feels & sounds like an above average vint or retooled black. Tactiles shine a good bit more in them, but require fairly high spring weights as the leaf is very, very stiff.
On the other hand the couple U4 samples he sent with my housings order are easily the best silent MX tactile switch I have tried to date. I would highly recommend them already without even using them in a board TBH (which probably will never happen for me as I am not a fan of silent switches). I’m not gonna totally give up on the project though, I have to hit good old hbheroinbob up to see what linear stems he has on hand. I still think if you have a non silenced linear stem made with the tolerances to properly fit the top housings (those being ultra tight are the real problem & 99% of other top housing are not compatible with the boba bottoms) they will make for a killer linear.
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That is great to hear, I can’t wait to try them in a board as I’m a big fan of tactile+silent.
Off topic question… Do you feel a break in period for switches makes a lot of difference before lubing? I’m thinking how I can get the most smooth+no wobble + silent + low/medium tactile switches out there 
(compared to bke domes I prefer ultralight after using lights for a while, but weighting also has a thing to say in this as I really liked a buddies 45g Zilents V2
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Honestly no I do not think breaking in switches before lubing is worth it in anyway TBH. To me the switches feel the worst when brand new & they will break in just the same with or without lube IME. So why torture yourself using unlubed switches for no good reason is how I’ve always looked at breaking in before lubing.
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I’m sorry to hear about your modding experience. If I hear about any cool mods or experience any myself, I’ll be sure to let you know.
I am thinking of using them stock in a build. My Leopold took to Zilents very well, and I’m thinking it might be the same for U4s. I’ll have to figure out the right spring weight, and some people say 62 gr is too light for the U4 stem. 63.5 and 65 gr have been working for me, so I’ll try that if 62 gr is no-go.
EDIT: Also, Halo and original Sky [including Silent Sky] stems were my main candidates for modding these switches anyway, so I’m glad to hear that they will fit.
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Due to the multiple post services / countries involved, my switches didn’t arrive last week like they were supposed to. But they’re on the last-mile carrier now and close by, so I think they are coming very soon. I’ll put the 45 gr springs in the Boba housings and see what happens.
I wonder if Everglide stems would squeeze in there - they seemed on the smooth-but-wobbly side IIRC.
I’m still waiting on my Bobas - any day now!
My wallet is so thankful for hotswap… shelves of switches is a little more doable than shelves of keyboards… for now. 
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Don’t tempt me. I found that the Jades were fun in the T1 housing. But all my Jades are going towards an actual build, I don’t want to buy more!
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Just got some Boba U4 switches in the mail today. Excited to try them out!
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I finally put the Boba switches in a build and I have to say that I am very impressed.
I didn’t really “get” the point of the switch when trying them out in the hand. They have a very sharp and brief tactile event. I think most of us are used to long, rounded tactility. They were quiet, but it is a silent switch so that is to be expected.
Once I put them into a build my view changed completely. Most silent tactile switches are over damped and feel very boring. The sharp and brief tactility makes this a very, very snappy and fun switch with very distinct moments of action.
Unlike Aliaz or Zelios or silent Gateron/Cherry this switch is not boring.
It is still a very quiet switch, but it retains some of the fun of typing on a tactile switch. Someone earlier in the thread compared these to Holy Pandas, and I think this is why, because the force curves really aren’t similar.
I put these on expecting to not like them (I have never used silent switches for very long because they are boring), but I have decided to keep them on my build and use them.
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Here are some first impressions based upon putting a couple of them together, but not installing them in a keyboard yet.
First, these are the components for the switch that I received in the mail:
-U4 Silent Tactile Stem
-“Pearl White” switch top [no slot / no LED]
-“Pearl White” switch base [linear / tactile leaf]
-62 gr Korean spring
-PTFE Lube Blend for springs
We have to remember that the Boba is envisioned as a modular switch.
I ordered the “no slot” top, as it is said to most greatly reduce wobble. It precludes the use of LEDs in that location, but that’s not the priority here.
My first thought upon putting one together is that these switches have relatively tight tolerances. Which is expected, since I’m using the “tight tops.” The parts fit together great, but there’s not as much “give” as some other switches. It’s not “loosey goosey.”
I had to push firmly to ensure that the top and bottom housings were properly mated. I experienced the same thing with the older Sky tactile housings.
Switch-Feel:
I can see why it is described as a “D” shaped profile. If the Silent Forest is represented by a “P” shape, it which there is a definite but perfunctory ‘bump’ at the top of the keypress, followed by almost linear travel, the U4 is better described as a “D” shape.
There is almost no pre-travel at all, probably less than Aqua Zilents, although I’d have to check. The stem does not protrude above the housing as some silenced MX tactiles do. Maybe ever-so-slightly, but it is almost imperceptible. A hair’s width.
So when you do press down, you are met immediately by tactile resistance. The resistance immediately ramps up, and does not taper down until the very bottom of the key-press. So it is a “D” shape, and the non-tactile portion of the keypress is almost non-existent.
The level of tactility reminds me of a T1. It’s not the same tactility, but the intensity is similar. It’s not wildly different from pressing down on the stock 65G T1s on my hotswap board. Definitely a greater intensity than most of the Ergo Clears I have tested. But I think Zilents are more tactile, sharper, and offer greater resistance. This could be a good or bad thing, depending on your preferences.
Whomever said that 62G springs were not enough for the U4 stem, I don’t know what they were talking about. The stem rebounds forcefully, and energetically. The springs remind me of 62 gr Spirits, maybe the Spirits are a little stiffer. It’s MX Blue-like. The fact that these springs rebound so heartily gives me confidence that the 55 gr Spirits I have might work. I’ll test the 45 gr as well.
Anyway, this is a lot of text to describe only assembling two switches. I will assemble more and try to use them. I will try 55 and 45 gr weights. Then, I would like to test the Halo stems, Silent Forest stems, and regular OUTEMU Sky stems. Maybe I’ll pull some stems out of MX Clears as well.
Other notes:
There is indeed a ‘Tao’ symbol on the housing underside, as described in reviews. The OUTEMU label is clearly etched into the bottom [the top housing reads “GAZZEW”]
The housings themselves are semi-translucent. When I press downwards, it is possible to see the white stem bottoming-out.
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OK, I tried 55 gr Spirit springs with the stock Boba parts, and it worked out really well.
[I would have ordered the U4s with 55 gr springs, but that option wasn’t available to me as an international customer.]
What can I say? I’ve finally found a use for my 55 gr Spirit springs.
At first, it looked as if they weren’t going to be powerful enough to drive the stem. When I was assembling the 2 switches, the stem ‘hung’ or ‘caught’ in the housing while I was pressing it down.
But once I assembled the switch, the upstroke was fine. Almost as poppy as MX Brown (in which the upstroke is fairly strong for such a light switch.)
Using them side-by-side with the 62 G Bobas, I found that the contours of the tactility was more pronounced in the 55 gr version. Just as the lighter Zilents are said to be more tactile than the heavier ones, the 55 gr at the very least doesn’t lose any tactility.
I could feel the full tactile profile, which was more clearly ‘D’ shaped in the 55 than in the 62 G. And you will be able to trace out that stem shape when you release slowly, just as in Zilents. Slowly releasing the 55 G Boba reminded me closely of the same on the 62 gr Zilents.
There is a possibility of upstroke ‘catch’ with the 55 G that doesn’t exist with the 62 G. I actually managed to stop one for a moment by lifting my finger too slowly. This was a brand new, unlubed switch though. They don’t do that during normal typing. Kind of like you might experience with 55 G Ergo Clears in the same weight.
Anyway, both of these weights feel fairly bouncy and rubbery during normal typing, probably like they’re supposed to.
Their sound is a muffled ‘thunk.’ It’s lower pitched than the Golden Skies that I built with Silent Forest stems. Sounds kind of like a rubber-dome, like a cheap silent Topre clone. A better board than my hotswap would make it quieter. I’m pleased to report that it wasn’t difficult to silence the springs. Ping seems reduced compared with other switches. It’s harder to quiet the springs on my “Golden Skies.”
All-in-all, this seems to be a competent take on a Zilent / Tacit type switch, with a somewhat different tactile profile. That profile becomes more apparent, IMHO, with the lighter spring weights. But I’ve only tried 2 weights so far.
Personally, I think that these highly-tactile silenced switches offer more tactile feedback than I actually need in order to type, but for those who appreciate the higher tactility, this seems to be a higher-tactility silent switch that can be assembled in a variety of weights.
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I’ve got some coming next week. Sounds like a fun switch.
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45 G Boba U4
Ok, I have finally tried it with 45 G springs. An interesting experience for me.
I have never used springs this light. And I knew that there would be issues, given how borderline the 55 G unlubed U4s were.
I am inexperienced with lubing, but I used the included brush to lube the slide rails on the stem, and the internal rail cutouts in the housing, with the included #6 blend. I very carefully lubed each end of the 45 G spring with the brush.
While assembling, I could see that the stem did not want to leave the housing bottom, at least not at first. As I eased the top housing onto the bottom, the stem elevated itself, and I was able to mate the housings. I experienced more difficulty doing this than with the other spring weights.
The first few times I pushed the stem down, it hung a bit, just staying there. But as the lube spread more evenly, the stem popped up consistently.
In the board, with GMK keycaps, there was some hanging at first. But then the switches functioned regularly.
It’s a strange feel. It reminded me of those light but tactile rubber domes you might pick up from any store back in the 90s or early 2000s. The beige rubber domes.
The closest comparison is to the 55 gr (unlubed) U4. The unlubed U4 was also barely functioning at first, but then got into its groove. In terms of tactility, the 55 G has what I experience as a richer, broader tactility. It almost feels like a 45G Niz dome on the ABKO K935P. Not as rich or soft or as long a stroke as the ABKO, but the tactile intensity and weight of the 55gr U4 seems to be within the same ballpark.
With the 45 G U4, you can really feel that contour, the shape of the tactile legs as it plays out. You can feel it more in the 55 gr than the 62 gr, and moreso still in the 45 gr. I find that there is less ‘noise’ and general tactile ‘richness’ in the lubed 45 compared to the unlubed 55 gr, and the 45 gr is mostly about the shape of the tactile legs. Which is very pronounced. It’s not sharp, there isn’t enough weight or speed, it’s more rounded.
I think if you are going the 45 G route, you are going to want to lube very carefully. I don’t know how it will perform with heavier modifier keys, I haven’t tried it. It seems to work on the alpha keys, but it can be very sluggish on the upstroke. That’s why I say you will need careful lubing.
I got away with not lubing the 55 G on the alphas, but I doubt that is ideal. I think the next step for me is to try lubed 55 G. Because I am liking the 55 G U4, it is my favourite 55 G yet. [The only 55 G I like.]
It is also worth noting that the keycaps on the 45 and 55 G Bobas seem to be a little lower than their nearby brethren, which are HPs and T1s and other tactiles.
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I was able to answer your question just now, in this post:
Some Other Notes
Some follow-up on other weights and stems, in which I use the OUTEMU Silent Sky stems.
In addition to testing the 45 G U4 Boba, I had earlier put some Silent Sky stems into the Boba housing. I used 2 weights, 55 gr Spirit, and 60 gr TX. I did not use lube (except the springs).
The 55 gr Spirit seems to be enough to comfortably return the stem, even without lube. It feels less weak and a little more robust than the same stems and springs in MX and TTC Gold Brown V2 housings.
Like the 55 gr U4 switches, these 55 gr Silent Sky Bobas are the best implementation of 55 gr switches I have experienced. The Silent Sky Bobas are light and cheerful, and seem to have good travel. They are very quiet. These are maybe the best Silent Skies I have used so far.
I also made 60 gr Silent Sky Bobas. They remind me in feel of the Golden Skies I described in the Frankenswitch thread. But they are easier to quiet spring noise than was the case with the TTC Gold Brown V2 housings. with the Golden Skies, I felt as though I had to use 60 gr TX, as 55 gr Spirits just felt too weak. But both weights are credible with the Boba housings.
I don’t know if the 55 and 60 gr Silent Sky Bobas need lube beyond the springs. Maybe someone can try and find out?
I also made some unlubed U4 Bobas with 63.5 gr Spirit springs. But I did not like those. It felt like it provided more spring weight than was necessary. The 62 gr stock springs are already more than is needed.
I will probably disassemble those and turn them into lubed 55 gr Bobas, as that is the real question now.
I also made some lubed U4 Bobas using the 60 gr TX springs. The springs can return the stems almost as well as on the 62 gr stock springs. They seem more than powerful enough. It’s kind of a boring weight for the U4s, though, and I prefer it with Silent Skies. And I think it adds sharpness.
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Wow, thanks a lot for the detailed experiment ! It sounds like a nice switch that plays around nice in the >50g area. Mine are still on the way…
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Great and extensive !!
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Thanks, I’m glad it was helpful. I’m new to modding switches, but I tried to find out what I can.
My estimation of these switches is that they play pretty nice in the lower end, reliably around 55-62 gr without too much trouble. In fact, 62 seems almost overpowered. 60 has no issues.
For whatever reason, the Boba is better with 55 gr than other housings I have tried recently. Maybe the smoothness and tactility of the housing gets the most power and least lethargy with those springs.
I never contemplated a 55 gr build until now. The Boba housings handle U4 and Silent Sky well at that weight.
45 G is trickier for me. You are more of a slave of the stem shape at that weight. I will have to learn to lube better if I’m going to build 45 G Bobas.
But as you say, it plays nice in the >50 g area, and 50 g itself might be worth trying.
If I wanted to be really safe, I guess I could do a build with lubed 55 G U4 Bobas and 60 G on the modifiers. But I doubt anything other than the 2U+ stabilized keys could really want >55G.
Later on, I’ll mess around with the lubed 60G U4 Bobas [maybe on stabilized keys] and lubed 55 G as well. I’m seriously thinking of building the current Bobas as 55 G Silent Skies. I just need a quiet-able 65%+ board to put them in.
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Lubed 55 G U4 Boba
Did some more testing today. Swapped out the 45 G U4 Bobas that weren’t working too well, and put in their place some [poorly] lubed 55 G U4 Bobas.
Despite my very amateurish lubing, there were some positive differences. The lubed 55 G U4 are deeper-sounding than the unlubed, as expected.
The lubed 55 G U4 also reset more easily on the upstroke. As you recall, the unlubed 55G Bobas could hang a little on the upstroke if released too gently. But the lubed 55G are more forgiving.
However, because of my poor lubing [I only lubed the inner housing slider grooves and the contact points of the sliders], which was not exactly consistent and probably too generous, the switch did lose some tactility. The unlubed 55G U4 has a rich, grainy kinda light-Topre-like tactility, and I lost some of that after lubing. It became more ‘syrupy’ in feel, which is bad.
I would have to learn better lubing skills in order to create optimal lubed 55G U4 Bobas.
How do people feel about the unlubed 55 G U4? [I mean, except for the springs which I always lube]. It feels alright to me, plenty tactile, a little weak on the upstroke. Is this an okay switch? Or would you actually lube the switch?
45G Silent Sky / Forest Boba
Because of @AdrianMan’s question, I also created a 45 G lubed Silent Sky stem in the Boba housing. If you want 45 G Bobas, IMHO this is the way to go. It’s a very soft switch, gentle. Not much feedback, easy to bottom-out. It’s not hard, though. If you want a 45 G typing experience, maybe this is it.
Doesn’t catch at all on the upstroke! I am not sure about using this on heavy keys, though.
Preferred weights
My preferred combinations so far are 55G Spirit springs with the U4 stem / Boba housing, only the springs lubed.
and the 55G with Silent Sky stem in the Boba housing, also unlubed save for springs.
Has anyone tried the latter combination? I tried lubing the 55 G Silent Sky Bobas, but it didn’t lead to improvement.
Some other notes:
-I am enjoying Silent Sky Bobas more with GMK keycaps than taller OEM-profile. I think the Silent Sky probably wobbles more than the U4 stem, which makes it less-than-idea for taller keycaps.
U4 is probably pretty stable, though. Put MT3 or whatever on it, it can be like those Topre boards with MX sliders.
-The U4 stems are Boba white, which is helpful in differentiating them from the Silent Sky stems. Silent Sky / Silent Forest are a more transparent clear white, like fog. There could have been mix-ups on my desk if it weren’t for these colours variations.
-As I mentioned earlier, keycaps on the Boba housings sit lower than other keycaps.
-Springs seem to have a significant effect on the switch-feel of U4 Bobas.
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