What Adam has said I support. Key in a bit… turn, wait for flow to stop (I just leave and go away for hour or so) key in a bit further… turn wait for honey to stop, key in further… turn. I have no spillage into the hive. The Flow is made to do the extraction on the hive not elsewhere.
When my outside frames are over 90% (the only ones I usually physically check and replace) and the middles capped as much as I can see I go ahead and do the lot in situe.
The first year I took every frame out, checking all the time and only when I physically saw all capped I extracted. In subsequent years I have found this to be a waste of time and effort . This year I only looked at the outside frame without the window and relied on vision from the windows and this was was fine with ripe honey under 17% when I extracted. I do check water content with a refractometer .
My future extractions will be based only on the assessment of capping through the windows. I am confident now I can see enough to decide if there is sufficient capping without pulling frames out.
As I do now, I check ripeness twice during extraction and would keep separate any frame not ripe (have not had to do this yet).
I do the key turn 3-4 times, going further into the frame each time to minimise any spill and I have not had since the first extraction and that was only minor.
What I do will draw a lot of criticism I’m sure but it works for me.
AuBeez my advice maybe contrary to others but if the frames look full and look capped at the back window and the outside frames are 90+% capped… extract. If you wish, or unsure check the ripeness of each frame with a refractometer (they are cheap and easy to use…just make sure you get one for honey)
And its not all doom and gloom if you get a frame which is say 21% water. I extract all the honey in the Flowsuper in early April and take the Flowsuper off for Winter. The honey is generally unripe but I pasteurise it ( do a search for how) and use it just fine. I don’t give it away or sell it though.
This is the time you can inspect every frame with out bees or honey for any problems…