Lubricating (old) mechanical keyboards

By Wild_Penguin

Hero (644)

Wild_Penguin's picture

25-02-2018, 16:14

Hi all,

Has anyone here lubricated plastic parts of their old MSX keyboards (or other plastic parts, for that matter)?

Specifically, I have an AX-350II here which keyboard I'm trying to refurbish. It has two problems: 1) There seems to be some crud between the membranes and 2) some of the keys that do work, are kind of difficult to press. The plastic parts are not moving as fluently as they should / used to. So I'm looking a solution for the second problem (to ease the actuation of the keys).

As this one was practically filled with dust and sand when I got it (I've already got most / all of it out, but I will double check), I believe it will benefit from some silicone pray to the sliding / plastic parts of the keys.

However, these sprays do not come alike. I've red (and believe) that some sprays might have some residues / adjuvant components that will degrade plastic, and this is something I do not want to test! So, any recommendations for particular lubricants (a specific one!) that would be good for this job? Or, something specific I should look in the ingredients (to avoid) ? We are looking for something that has very little / no viscosity, does not evaporate over time, and (most importantly) does nothing to the kind of plastic used! Of course it should be non-toxic, as thekeyboard will be used by hand(s). There are some metal springs also in play (two per switch), but I'd presume the plastics are more sensitive.

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By Pentarou

Champion (486)

Pentarou's picture

25-02-2018, 18:15

Molykote grease or something used in model making.
I think it's better to apply a minimal quantity with a brush, only where is needed, instead of spraying some canned grease. If you use a spray you'll have areas with unwanted product that WILL attract dust/debris.
Don't use Tamiya's Ceramic grease, as I found that it leaves an oily residue that *could* cause problems on the membranes.

BTW. If the keyboard is really well cleaned there should be no need of lubrication...
However if the keyboard is REALLY a mechanical type (as per thread title), then you will have individual micro-switched buttons and you will need to open and clean each one individually.

By Wild_Penguin

Hero (644)

Wild_Penguin's picture

25-02-2018, 20:35

I have already taken pictures of the mechanisms , they are available here. This is a membrane keyboard (the title is misleading); however it's kind of a hybrid mech-membrane since there is a mechanism which houses two springs in each key. The smaller one presses against the membranes and actuates them when the key is pressed, and the larger one lifts the keycap / upper half of the mechanism.

I invested the time to separate each and every mechanism from the keyboard plate. There was still loads of hair / wood / sand / dust between the plate and the mechanisms! I've disassembled a few and they definitely have some dust inside with the springs.

So I guess what I will do is that I will clean as much as possible of the dust, and see if that will improve the keyboard.

By Pentarou

Champion (486)

Pentarou's picture

25-02-2018, 22:05

Good luck cleaning that mess! :O
But with a thorough cleaning there should be no need for lubrication.

By Wild_Penguin

Hero (644)

Wild_Penguin's picture

07-03-2018, 00:13

Ok, I've finally got the keyboard into a working state.

First, a (perhaps nice / interesting) picture:

Then, to some findings I decided to share.

First I need to clear up that the keycaps do come off on the AX-350II (as described in the SM of related models; this probably applies to many related models). It is just very very difficult to do so, as the keycaps are very thight and the mechanisms has a weak point that is easy to break, and the plastic might have become a bit brittle over time (and/or the joint between the keycap and the mechanism has become stronger). One needs to pull very straight and very hard to minimize damage to the mechanism. This means you remove the mechanism from the plate first, do not try to remove keycaps while they are attatched to it! Then use both hands to pull or some tool which can grab both sides of the mechanism (and then pull on the keycap with fingers and / or another tool); it is imperative to pull absolutely straight on the keycap!).

I actually removed some keycaps by accident while dismantling the mechanisms, and would not have found out otherwise!

Just to recap (oo, a pun!), there are five parts in each key assembly:

  1. Keycap
  2. Upper part of mechanism
  3. Bottom part of mechanism
  4. Small spring (this will actuate the membranes)
  5. Large spring (to help lift off the keycap and pressure off from the membrane)

To dismantle a keycap:

  1. Straighten 2 staples partially, or get something similar. It might actually help if they are slightly curved in step 3)
  2. Press and hold the mechanism down
  3. Insert what you got in step 1) or some other thin pin / object into one of the holes
  4. you need to force the pin/staple in between the flap in the bottom part and top part of the mechanism, forcing the "flap" to abduct.
  5. After doing this, stop holding the mechanism down. The key should stay pressed without holding (as the pin / object you use is preventing the parts from sliding). If it doesn't stay pressed, the pin is not properly forced between the parts.
  6. Do the same (steps 3-5) from the other hole.
  7. Pull *very* hard on the pieces.

The housing should separate without damage, eventually. While pulling there should be a feeling of "giving way", as the flap is sliding along the staple, over the nipple (which is supposed to keep the parts together); if you feel hard resistance, the staples might not be between the flap anymore (and the flap is stuck on the "nipple" and will break if you continue pulling).

After cleaning all of the plastic parts with water and soap, the actuation of a key was not satisfactory (at all!). The keys would frequently jam while trying to press them. I concluded that the keys were very worn and / or the sand had made some damage to the sliding surfaces; in any case they did not slide as they should / used to.

I used silicone grease for lubrication. It should not damage plastic, but I am not sure, only time will tell. But as the keyboard was in an non-usable state, I got nothing to lose!

This is the exact grease I used (and here are it's ingredients and those interested, they even have a safety report available). It is not food grade, but I concluded its non-toxic enough, as the grease is below the keycaps in any case (in case the links die, as they will eventually, it is a generic silicone grease with no additives from a local HW store chain).

I used a very small amount - about a rice grain or less per keycap - between the upper and lower part of the mechanisms where they meet / slide. A few I re-assembled before greasing, those I greased trough the holes on the bottom - and eventually, it seems, the grease would spread into the sliding surfaces.

After getting the actuation to work, there was still the problem that some of the keys would not work. I presume that the membrane is worn and/or has some fine grained sand and/or oxidization at the contact surfaces. Using Q-tips soaked in contact spray or 98% alcohol improved things so that all keys now work! Some are still not perfect and would probablty work better after another treatment to them, but as the whole process was tedious, I'm not going to open the keyboard any time soon again. And if this is caused by wear on the membranes, the "fix" might not be a long-term one.