When I had it already fully restored, I found it to be much more pingy than anticipated, so I desperately needed to reduce that level of noise to be able to use it at the office as intended (without being killed by my coworkers).
I tried the usual trick, the dental floss mod. It worked, but I always end discarding it for a couple of reasons:
- It suppresses the pingy noise but it somehow it also modifies slightly the tactility. It is specially evident in the upstroke movement that becomes scratchy. Its not the end of the world but I don't want to trade smoothness for silence.
- I am worried that the floss will disintegrate over time because it is subjected to mechanical stress when the spring buckles. I expect a model M/F not to require any maintenance once it is restored for many many years.
To test this mod you need the following tools:
- 3mm thick foam. I used EVA foam but I think anything with the right thickness will do the job.
- 3mm diameter leather punch
- Keycap puller
- Some tools needed in case you can to remove and reattach springs, like chopsticks and ballpoint pen assembly
For convenience I'll show this using a Model F switch tester by orihalcon, but will work the same for a real keyboard.
First, punch some foam plugs with the leather punch
Remove the key
Compress slightly the foam plug rolling it between your fingers
Then take the plug with the tweezers to insert it into the spring. Just insert, don't push it yet.
Change the tweezers to your left hand and using the right hand hold the spring with your index finger nail like this.
Now while still holding the spring push VERY CAREFULLY the plug into the spring, so that you leave its top approx. 1mm inside the spring. This is the most delicate part, if it's not deep enough it will affect the key action over the spring. If you press too much it will interfere with the buckling action, and this is worse because if it's too deep it is impossible to remove the plug without removing the spring. If it's not so deep you can remove the plug easily pulling it off with a needle.
So this mod is only recommended if you are comfortable removing and reattaching springs, because it's the only way to remove a plug inserted too deep. In case you need, search for the "Sandy's chopstick o' death method". Of course a floss mod is more convenient in the sense that it is easier to remove, but I think the foam plug is more durable and gives a more uniform keyfeel.
Example reattaching the spring inside the tester
And that's it, just install your key again and test that it still works fine.
With this mod I cannot detect any difference in tactility with my F122, and the metallic ping is completely gone. Here are a couple of sound clips with and without mod for comparison. Sorry for the poor quality as I have only very basic sound recording hardware.
I've also tried this mod with other keyboards:
- A model F XT, this keyboard is in great condition and it's not pingy at all, so I thing it makes no difference to use the mod with it
- Some different model M's, but I don't quite like it, I can't say why but I don't feel any of my M's need to be less pingy.
So at this moment I can only recommend this for a model F122 or anything else that's really pingy. But that's in my case, maybe this is useful for you in other situations, or maybe other foam materials will do a better job for a model M.