Sordna, the o-rings from WASD are not actually 1.6mm they are a -009 o-ring which is 1.53mm +-.08. They can be anywhere from 1.45mm to 1.61mm. This is a normal thing for rubber o-rings.
I have updated the post, but you need to look over the sizing a bit more. 008 and 009 are the same cs material size based on the ASE standard 1.53+-.08 while the ID is different. 4.73+-.13 for 009 vs 4.47+-.13 for 008.
The size of the WASD o-rings are 009 as I sent off one of my o-rings the to company in order to work out the order. They are the ones that correctly sized the o-rings based off of a sample o-ring from my previous order from WASD.
The sizing they had listed in the initial quote based on the o-ring I sent them is 5mm x 1.5mm. I have begun the paperwork of finalizing the order based on the 40a o-ring from WASD I provided. The final sizing will be as follows, 4.5mm +- 0.13 x 1.5mm +- 0.08.
This is based on the measurements they took from a sample o-ring I provided. This might not be the official size reported of the WASD o-rings, but they are identical to what I have from them currently and enjoy.
I just wanted to jump in here and comment about your sizes a bit more. The -009 size you mentioned is wrong, it has a ID of 7/32”, which converts to roughly 5.56mm, much too large for a keycap stem. Based on some charts, it has a actual diameter of 5.28mm, still too large for a keycap stem. The stem has a diameter of about 5.10mm, so the O-ring’s ID needs to be smaller than that. You said the ID of a -009 is 4.73mm, which is just a wrong measurement. Both O-rings sold on WASDkeyboard are not -009, they are -008. As far as the thickness, -009 and -008 are the same though, but the ID makes a huge difference in the fit of these.
Second, I think you’re trying to force the two different measuring systems too much. US standards in inches and metric system are different, although you can do conversions. Sordna posted a pic of all the different O-rings I ordered, and you can see a visible difference in diameters and thickness of a 5mm x 1.50mm metric size Oring vs a -008 (3/16” x 1/16”). So you can’t already claim these O-rings will be identical to the ones on WASD without getting a sample from the company first. The -008 O-rings that I have are already tight enough with a converted size of 4.76mm ID, so if you’re ordering 4.50mm with a tolerance of +-0.13mm, then there is a chance they could even be 4.37mm ID, which
might be too tight for these to fit on the stems.
If I were personally running this GB, I would just stay with the tried and true 5mm x 1mm or -008 size. The -009 you mentioned was just a wrong measurement, and 4.5mm ID might be too tight. Although since 40A is pretty soft rubber, it can stretch, but for the ease of installations, I would stick with 5mm ID size.
