Finally got a brew down using the MM2 mill set to 0.045 (factory gap). My efficiency is up to 72% - an improvement of 20%. Happy with that.. finally some progress!
It might not be down to the crush alone (although certainly appears to be the main culprit) but I have improved a lot of things since I reported a crappy 50 odd % efficiency. Either way I'm hitting the numbers now
Things I'm now doing (most I have learnt from this thread)
- Crushing grain with own mill
- Increased sparge water temp to 80deg
- Slowed the fly sparge/lauter down to 45min-ish (last brew was for 36L)
- Using a refractometer during lauter (soooo much easier)
- Boil with the lid OFF (can't believe I didn't know that)
An interesting thing I was told (by a commercial brewer) is that once the fly sparge is well under way (I think he said half way through or more) make some groove lines across the grain bed to encourage the sparge water to go through rather than channeling around the edges. So I did that too - can't report on whether it made any difference because I was doing things so shoddily before..
Anyway there you go - from 50 odd% to 70+%