On your thumb. Attached is a picture of my thumb after pushing the power button.
I measured it as 157 ounces or about 1/3 of a pound direct force. I do have a peak hold on the spring scale I used, but not sure if I got a good reading of the force, but the “thumb knows”.
The depression surrounding the power button is smaller than a thumb. The diameter of that depression is 10.68 mm. My thumb is like 18 mm diameter. You would think the smart engineers would have at least allowed for the thumb.
On a good note, the toothbrush turns off when you place it on the charger. The button is molded into the product case – no extra pieces.
Other than that, it's not a bad brush. In my opinion, it's not suited for someone with arthritis of the hands.
Welcome to the disposable generation. It seems like more and more things are being designed so older folks can't work them -- or is that just the effect of getting older.
It could be worse, though. The button could have been on the left side so lefties couldn't use it at all. While that may not affect you, it would affect me. I have a portable power saw that has the safety interlock built like that. It no longer has that interlock.
I'm a Lefty converted to a Righty when I was a kid. Mom would always change the hand I used to pick up stuff. In reality, you just have to practice with the other hand. I can write with my left, right normal and mirror image. Now, I just use whatever hand is convenient or necessary. e.g. Right-handed scissors.
Sitting next to a lefty at a restaurant, I become a lefty to avoid hitting elbows.
How come there is a difference between US gallons and Imperial gallons?
I was under the impression that it was something to do with (fluid) ounces.
My own opinion is that the Metric (SI) system has much to commend it.
Getting back on topic, I have a similar (previous model?) electric toothbrush which is a couple of years old now.
The on/off switch is firm but nothing like as stiff as the one which KISS is trying to use.
This awful set (mobile phone/radio) for Nextel service built by Motorola is probably the worst of the so many I ever had. Needing to push to talk, you quickly realize how bad is the design of the buttons and how much force you need to apply.
And then the remote PTT of my 260 Vertex Standard VHF handy. While it saves you carrying it in your hand, pushing the buttons, after 6 to 10 hours of continuous operation, it is painful. Thanks God, I issue short instructions so mostly no dialog.
I think that age has little or nothing to do with this. Simply imagine keyboards built with switches equivalent to this. They would be thrown overboard in minutes.
I re-did the measurements using a much better system and got around 4 lbs of force. The spring scale was AWS PK-110 which has peak/hold and a resolution of 0.05 lbs in the 44 lb range.
I took a light (weight wise) and cut it into about a 3" x 8" piece. I made two cuts in the end centered about 1/2" apart and 3/4" deep. Placed some soft wire you get at the hardware store and made a hanging flat piece of wood. I placed a machine nut on the board and centered the power button on it and pushed until the toothbrush turned on. Got around 4 lbs using multiple trials.
So, it;s currently about 4 lbs of force to push the power button.
It feels less than the initial presses and the thumb indentation seems less.