hi mike
the whole blunt end thing dosnt come into play unless you incubate the eggs verticlely such as in a system like this one
**broken link removed** or this one **broken link removed** the main reason this kind of method is used is so you can have a greater number of eggs per X amount of space in an incubator, i normaly choose this method myself particuarly for comercial hatching, HOWEVER there is are disadvantages to it and its a completely unnatural way for a egg to develop, hence why you dont see hens trying to stand eggs up
but to answer the actual question......... you incubate eggs blunt side up if you want to put it thay way because the air space in a egg is that way and you dont want the embryo to develop accross the top membrane and impede air defusion.
humidity is complex and important, the actual level depends on the normal humidity but as a general rule it should be slightly higher for the last three days, however the correct way is too candle the eggs and judge the air gap you are looking to loes 15% moisture over 18 days, now before anyone acreams at me i am aware the normal figure quoted is 13% but its incorrect the actual figure is pretty close to 14.3% but again its nonsense to get that bogged down in it, aim for around 15% over 18 days (not 19 as is normaly quoted) and you wont go far wrong, to give you a ball park figure for a sensor normaly 43%-55% RH will get you around 12%-17%ish fluid loss over 18days, keep in mind that its alot better to have a slightly too low level than it is to have a slightly too high level. you will know straightaway at the hatch time if your way off with too high humidity because you will get drowned chicks as they just start to hatch! its realy upsetting to see cracks in the eggs and beaks starting to poke through but then nothing seems to happen untill eventualy you crack the egg open after a day or so and find alot of fluid and a dead chick. for the last 3 days up the humidity to around 63%RH - 66%RH this helps soften the inner membrane(s) and makes life easier for the chicks, it also mimicks better what happens in nature as hens sit for longer in the last 3 days and the humidity under them increases. before i go into how i actualy adjust it my own method of incubateing with humidity sensors is.... i keep the eggs to be incubated at around 12C for 24 hours before i put them in the incubator then i incubate at 40% RH for 2 days then here in devon uk i normaly aim for around 46%RH for 16 days then i place eggs in hatcher with RH around 66%.
i gave up using light bulba a long time ago for heating, they are a real pain in the long run for all kinds of reason's, i found the cheapest and easiest way was too goto a charity shop and buy hair tongs (woith the flat ceramic heat plates) for about £3 each this will give you 2 plates normaly around 120-150W each i use theese as heaters
trust me they work great and blow like bloody bulbs and arnt as easy to break! to adjust humidity i use a simple vent with a fan and servo when the humidity gets too high servo opens vent and fans turns on medium speed for a few seconds untill humidity lowers, i do it in stages tho so the temp dosnt drop, say open vent medium speed fan for 5 seconds then fan off leave vent open wait 10 seconds and fan back on for 5 seconds, dosnt normaly take many cycles here to get it back down to the set level. if its a very humid summer say or for whatever reason i have realy high levels of RH that are hard to controll by venting then its a case of placeing eigther a little table salt or a few sillica gel packs on a saucer and changeing every few days, but its very rare i have to do that.
to up the humidity i have a small container with waterand a lid with a slot i, sticking out slightley from this slot about 1 inch to start with is a cotton strip (like old sheet) approx 6 inch long and 2-3 inch wide. the end outside is connected to a servo so i can lift a strip upto 3 inch or so out the slot there is a fan pointing at this strip whoes other end is inside container dipped in the water. so when you need to up the humidity it lifts up through the slot and a fan blows small amount of air at the exposed strip and thus increases the humidity once correct level is reached fan shuts off and servo lowers most the cotton back down into the slot
simples lol but there are many ways to do it
anyway hope that helps a little. any questions please ask
regards Jason