Why 2500lbs - seems excessive to me! I'm following Hoss's lead here as he managed some big / heavily loaded cuts using a drawbar tension of 600 - 800lbs on his X2 based machine (which mine is)

And you only need to move the bar enough to break the taper - in theory 0.01" should do it - my aim of 0.125 is probably overkill. 3/8" wouldn't achieve any more!

So my calc works out thus.......700lbs / 3.14 = 222psi (2" dia slave)
0.75" bore Master so Master - Slave ratio is about 5.33?
222 / 5.33 = 41.65lbs - not much !
To lift clutch slave 1/8" then the master has to move 1/8 x 5.5 (to keep it easy) = 0.6875"
As I was planning a pedal having a 6:1 leverage ratio then the pedal tip is only having to move 4.125" - no worse than your daily driver!

Anyway - back to the washers - McMaster Carr won't even post outside the USA citing US Export restrictions...... what BS! How hard is it to tape 8 or 12 washers to a piece of card, put it in an envelope, add some stamps and drop it into a mail box? Hardly a toxic or dangerous load is it? So if anyone wants to earn some drinking vouchers by getting them internally and posting them on - get in touch via PM and i'll forward some currency!