Measured Topre Switch Weight of Leopold FC660C?

[Hypersphere]

The stated actuation pressure of the Topre switches in the Leopold FC660C is 45 grams (or 45 cN, but commonly given in grams). However, I measured several of the keys using the number of US 5-cent pieces ("nickels") required to keep the key bottromed out on the keyboard. I did this by adding a stack of nickels to bottom out the key and then removing nickels until the key would pop up again. A US 5-cent piece weighs almost exactly 5 grams.

Using this technique, I found that most of the keys on my keyboard were 30 to 35 grams rather than 45 grams. The spacebar was a noticeable exception because of its auxiliary spring, which brought it up to 55 grams.

I would be interested in knowing what other owners of the FC660C are finding when they measure the weight of the keys.

These results have some bearing on making decisions about which Topre switch weight to choose in other keyboards, although it should also be borne in mind that there may be inconsistencies in weight designations of Topre switches across different makes of keyboards. Such discrepancies would help account for perceived differences in switch weights when comparing 45-gram Topres in a HHKB Pro 2, Leopold FC660C, or Realforce 87u.

Before doing this experiment, I had thought that if I were to buy a RF 87u I should opt for the 55-gram version, because I found the presumed 45-gram switches in the FC660C a bit too light. However, if the switches in the RF 87u are truly 55 grams, I might find them too heavy, and a 45-gram or even a variable-weight board might serve me better.

Just another reason for needing to try things out in order to determine if you will like them or not!

[Daniel Beardsmore]

1 cN = 1.01971621298 gf (gram force). I use them interchangeably, but they're not the same, just very close.

[webwit]

You're doing it wrong. 47g. More variation than Cherry though.

http://webwit.nl/input/witometer/

[002]

Yeah definitely something wrong there. 30-35 seems way too light. When I measured the 104U (with a force gauge) that's currently on tour, I noticed that nearly every key was slightly over what it was supposed to be. The spreadsheet is in the original Realforce tour thread if you're interested.

[Hypersphere]

Yes, even while I was doing my crude measurements, I thought I ought to be using a vial and filling it with something like Pb shot to trip the key and then weighing the vial on a balance. Thanks for the pics of that method. And yes, I am aware that "gram" is a unit of mass, not force; we are assuming F = ma, where a = acceleration due to earth's gravity at sea level = 9.8 m/sec^2.