Boba U4

Hmmm. I’m gonna try this tomorrow.

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I’m a fan of long-pole stems (like the Kailh Pros) in Boba housings - they’ve spoiled me when it comes to sound.


have you then tried then a U4T stem into a Boba top with Zealios Bottom? After my first tests it feels better than Zykos.

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I did try some pro purples in a U4. It was okay, but I wouldn’t go out of my way to make a board with these switches. I did try something I found interesting (although again, I probably wouldn’t go through the trouble of making a board of these):

U4 housing with a Kailh Pro Light Green (clicky) switch. Surprisingly nice improvement on sound and feel from the Kailh switch. And I already thought the Kailh clicky sounded and felt much better than Cherry. Dare I say, but it almost has an Alps clicky feel to it.


I’ve mostly resisted trying Zykos because I don’t like the sound that Zeal bottoms produce on bottom-out, but I suppose I should at least give it a try with U4 parts and Boba tops to help me observe the differences between the two and what trade-offs there are with that choice.

For my taste, the Boba bottoms are just a huge step up from Panda bottoms in seemingly every way that matters to me so it’ll be useful to see how the leaves stack up against Zeal’s.


I think we can all agree that the Boba bottom is second to none. But if there wasn’t friction on the leaf (I don’t lube the legs and leafs most of the time).

With the Zeal bottom it feels extremely smooth, you have to like the sound or not.


Can I ask what lube and springs did you use?
Do they return fine?

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I’m using 55g sprit springs, the springs are lubed with krytox 105 and the stems are lubed (including the tactile legs) very lightly with krytox 205. they may have some issues returning for the first couple strokes, if you have lubed them more heavily, but if you spam them a bit it should fix itself. I’ve been running these switches for a few months now and I’ve had no issues since I assembled them.


yep you understood correctly, I’ve never used trybosis, but I’ve heard its a little thinner, so I would think it would be better for lubing them yes.

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I’ve been using Boba U4t stock and it doesn’t feel as heavy as Boba U4 (stock or lubed with Krytox 203g0). Not sure why. Are there any less tactile switch but tactile bump starts at the top? Is Durock T1 less tactile?

Durock T1 is similar in tactility, isn’t it? It’s also top-mounted. Some people have said that U4 Boba feels like a silenced T1, although that’s inexact.

A less tactile switch in which tactility is at the top is BOX Brown, Kailh Pro Purple and Speed Copper. There’s also BOX Silent Brown, but it’s also pretty tactile.


If you have the parts or are willing to spend extra, you can tone down Silent Box Browns by swapping the bottom with a regular one.

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I’ve tried BOX brown and BOX silent browns. Both feel linear when pressed quickly. The tactile bump is at the top though.

After months of using Boba U4ts, I realised something. The actuation point is slightly over the bump, is that so? I’ve been missing some keystrokes and I thought it was my ID80 V1 PCB or switch issue. I’m a relatively light typist and therefore dislike bottoming out if possible. Are there still alternatives to Boba U4t where:

  • decent tactile bump at the top where it doesn’t disappear when typing quickly
  • actuation point is during or right after the tactile bump


What do you mean by top-mounted switch?
T1 feels slightly sharper tactile bump with more dampened sound compared to boba u4t. Boba U4t bottoming and topping has a higher-pitched sound.

I’ve tried TTC Bluish White switches too. Tactile bump is rounder (which made it feel less tactile than boba u4t which I prefer), bottoming is dampened by design, but topping sounds high-pitched but not as full-bodied as boba u4t.

I bought a larger pack of TTC Bluish White for mounting on a board. I’ll see if I like those instead.

Unfortunately it’s my understanding that the former is a matter of physics with the MX internal design; actuation can only happen when the stem gets out of the way of the leaf:

Animation of the internals of an MX Brown switch. The leaf begins in a displaced state and, after the stem's bump gets out of its way, settles into a state where contact can be made to actuate the switch

Therefore (if my understanding is correct?), a tactile cannot physically actuate during the tactile bump using standard MX internal designs. (Clickjacket clickies achieve synchronous tactility and actuation because of their two-piece structure, which circumvents this entirely)

For the latter, something like the NK Blueberry should actuate pretty quickly after the bump due to the sharper post-bump dropoff, but this also seems to make for a higher spring force requirement for returning back from that steeper dropoff and a stronger return bump, which may or may not be desirable.

EDIT: I don’t know how Alps-style internals work, so I can’t speak to whether or not Alps switches (or the perennially-upcoming Zeal 3-in-1) could be the solution to your woes.

Interesting thread! I’d like to chime in with some of my experience with these silent tactiles:

  • Boba U4 68g unlubed
  • U4 stems in Outemu Ice (clear) housings 62g, donut dipped with Krytox 205g0
  • Aliaz stems in Cherry black housings 60g, lubed with Krytox 205g0
  • Zilent 62g unlubed

For both the Zilent and U4 stems, I don’t think they perform well with anything less than 62g springs. The tactility of these stems are rather strong, and without a strong enough spring to resist the tactility, they end up feeling a little too sluggish in my opinion.

In terms of housings, I tried playing around with the Boba housings but found that they aren’t too good with lighter springs as well. On the other hand, the Ice housings and especially Cherry black housings are great with lighter springs.

I’m only mentioning Aliaz right at the end because, I think they make for excellent light tactile switches. The tactile event is much softer than Zilents or U4s, and although they’re sold with heavier spring weights, I believe they’d perform relatively well with a lighter spring weight. Lubing doesn’t necessarily make it easier or more comfortable for typing in my experience. It does help to dampen/soften the sound however – my Aliaz frankenswitches are significantly more silent than the Boba U4s or Zilents

Lastly, although I don’t have experience with the switch, OP might be interested to check out Niz 35g or 45g EC switches. They seem to be really silent and easy to type on (non-fatiguing)

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I see. I could try Aliaz switches!

Unfortunately, I’ve tried Niz 45g EC and I didn’t like the spring. Is it something like linear spring or progressive spring? I don’t like how it gets heavier and noticeable.

Hmm, maybe I should try slow springs in linears…

If you’d like a tactile bump and not bottom-out, build Ergo Clears with Progressive springs.

A lubed Ergo Clear with a 68 G Progressive Spirit spring will give you a weight and bump at the top similar to Cherry MX Brown, maybe a little higher, and a softer bottom-out, or you can avoid it as the weight becomes a little heavier towards the end.

Although I suppose the bump could disappear if typing quickly. If you’re worried about that, don’t lube the stem very much or at all.

If that’s too mild, you can probably put MX Clear stems in a T1 housing. It’s too bad you just missed the Twilight group buy. It’s a Medium Tactile stem in a T1 housing. Believe me, these things give you a decent bump at the top that you won’t miss. And actuation should be Cherry-like with the Clear stems.

Yes, maybe experiment with MX Clear, Durock Medium Tactile, and Aliaz stems in a T1 housing. They should be fine at 65 G or so.


Yes, if you are trying to build a light tactile, use Ice or probably Bobagum housings instead of Boba.

I’m experimenting with MX Brown with Boba top and Blue Ice bottom. Using a 55 G Spirit spring is fine. It gives you a more stable, better-sounding and lighter MX Brown. Trick is to only very lightly coat the stem in a light lube like 3203, you don’t want gobs in this switch.

Aliaz is easy to work with - it doesn’t take to lube very well, so it’s best not to do that. The weakness of Aliaz is the stock springs. Replace them with lubed good springs, and you’re good to go. But Aliaz is like Gateron, and the actuation point is lower. So you will be hitting the tactile ‘bump’ before actuation, which could lead to missed keystrokes. I tested it as a gaming switch, where it excelled with 65 G TX 14mm.

I have Niz. The 45 G is basically like a tactile MX Red in how it feels when pressed slowly. It is a heavier overall switch [at actuation] than MX Red or Brown, though. I think 35 G would be closer to MX Brown in push actuation.


Gosh. So much knowledge! I really, really appreciate the input! I will try Durock medium tactile stem with T1 housing then!

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