Just tested my discs for warping and took some pictures of how I did it.
Id be interested if there is other ways of doing it as I was happy that mine aren't warped just scored badly from cheap goldfren pads (6000 miles only on them never to be used again)
I used an axle paddock stand and ran some cable ties from the stand to the discs and watched for the movement.
Is it my computer or are those pictures way too big, I'll try and make them smaller.
Try this
You really need a dial test indicator and then do the same test, this will give you the exact warp dimension, you need an engineer mate and ask him, or nip down to your local engineering shop and beg a favour.
Alan
The cable tie would tell you if they were really warped but so would the brake lever.
As Alan said You need to use a DTI. You can get all kinds of clamps for them and they aren't that expensive these days.
http://www.ebay.co.uk/itm/Dial-test-indicator-DTI-gauge-magnetic-base-stand-clock-gauge-TDC-TE107TE108-/120985547302#vi-content (http://www.ebay.co.uk/itm/Dial-test-indicator-DTI-gauge-magnetic-base-stand-clock-gauge-TDC-TE107TE108-/120985547302#vi-content)