If anyone is interested I've knocked up a quick android app that calculates cut time from floc point. Simply set multiplier, press button when rennet added, press again when floc point is reached, and it will alarm at cut time. Also chimes once per minute, and has a simple timer for other activities. If anyone wants a copy (no guarantees, no warranty etc. etc.), send me a PM, and I'll send you the apk file.
