I have a TI84+CE(-T) calculator (but my question is also related to other TI calculators).
Do I have to worry about using my calculator keys too often?
I use my calculator very often and so the keypad is used very often.
Some keys are pressed more often than others (for example [2nd]).
Especially when I`m programming large programs on-calc or I`m playing a game,
I am constantly pressing the keys.
(Just imagine playing Calcuzap)
I don`t fear that my keys will fall out, but do they not soon wear out to a hardly usable state?
(the keypresses feel weird and not comfortable anymore or you can`t use them in the same velocity as before or unreadable key labels).
Does someone have long-term experiences with using calculator keypads?
I've never had that happen so I wouldn't be too worried about this. Unless you drop some soda on it or something like that...
But not from normal use.
EDIT: If you do drop soda on your calc, you should immediately open it and clean it out.
Oh, I hope that I`ll never drop soda on my calculator.
I trust you that the keypad won't break from normal use,
I think you have a lot of experience.
It is also a good thing not to use the calculator with sweaty or oily hands.
This can cause dirt to build up behind or besides the keys.
After about 2 years (while writing many ICE programs) I had the problem that the arrow keys no longer came up, so it was like touch, but it still worked...
I had the D-pad on my TI-92+ go bad. There was no printing to wear off, so I have no idea if it would have lasted longer mechanically than visually. It turned out to be because the up arrow had punched a hole in the rubber sheet, & when I went to replace it, I also had to replace the D-pad itself because the up arrow part had a little piece of extra plastic that seems likely to have caused the hole. So it seems like it would have lasted a lot longer had it not been for that manufacturing defect. On the other hand, the D-pad had also gotten very mushy-feeling, which made it hard to press individual directions without accidentally also pressing one of the adjacent directions, so complete failure is not the only possible problem.
Before my old TI-89 Titanium broke, its arrow keys & Enter key had started double-pressing rather often, which can be a problem if you are trying to press Enter exactly once. Again, there are more problems than just not pressing at all. In this case, there was printing on the keys, & I think none of it had worn off of those keys by the time they started misbehaving. But my new TI-89 Titanium occasionally has keys double-press despite having seen a lot less use, so maybe it is just a problem with TI-89 Titaniums specifically.
I have never had keys go bad on any Z80-based TI calculators, & I played lots of Tetris on my TI-86 in the past, so their keypads may be made somewhat differently than the 68000-based TI calculators. Or it might just be random manufacturing variations...I do not have enough calculators to have anywhere near a representative sample of anything.
On the other hand, I have had printing partially wear off of various keys, & I think none of those keys failed. So it seems there is no obvious correlation between mechanical problems & worn printing (even though lots of usage causes both). This might be because both are unlikely, so that the conjunction is less likely still; or it might be because different styles of pressing cause different types of damage (e.g., sliding one's finger across keys probably causes more wear on the printing than mechanical wear, while pushing hard without sliding probably causes more mechanical wear).
To add on to what zeroko said, I have also had the printing on the keys wear off partially but the keys remained functional. My CSE got pretty gross because I carried it around in my backpack and pencil case for a while but I just opened it up and cleaned it properly (there were crumbs in the screen, pencil lead residue on the case and some keys were a little gummy) and now a few years later, its still working fine It doesn't hold a charge very well but that's to be expected of li-ion batteries after a few years, in fact, the first thing that will start to fail on the CE once they get a littler older will definitely be the batteries.
I'm actually thinking about storing the batteries separately from the calculators for the units that have li-ion batteries in my collection. I might have to start making something like
this but for li-ion batteries once they get a little older. My TI-Nspire CX prototypes are from 2010 which is a bit of a stretch for the batteries.