[Jon Feather]

I made my own incubator from a fridge (to form the insulated box) heated by 3 light bulbs and controlled by a digital thermometer (http://www.ebay.co.uk/itm/Digital-STC-1000-Thermostat-Temperature-Controller-All-Purpose-Aquarium-Sensor-/111540554461?hash=item19f855cadd).

It is a still air arrangement (no fan) that holds 42 eggs at a time but the hatch rate Im getting is very poor.
About 30 of the 42 eggs were showing good signs when I candled at 14 days but only 3 hatched.

I have the temperature controller set at 37.5.  The heat comes on a 37 and off at 37.8  The humidity is about 45% and raised to c60% for the last week.

I'm thinking that its a temperature problem because I'm not sure where to measure the temperature.  Should it be 37.5 at the bottom of the eggs or the top of the eggs??  Where should the temperature sensor be placed?

[chrismahon]

Think you will always struggle without a fan Jon. Still air machines are set much higher than fan assisted and it will be a case of trial and error somewhat. The figure I have for a still air machine is 41C but where that is measured I don't know. You would need to see 37.5 degrees under the eggs. The STC1000 isn't really a suitable controller as the switching range is too wide. Incubators switch within about 0.2C but they don't just switch on and off, the heat is pulsed by the energy to the heater being varied.


Obvious reasons for developing but not hatching would be too high humidity in the first 18 days, too low in the hatching stage or not turning the eggs often enough or in the correct manner (back and forth 45 degrees either way of a mark on the egg, so 90 degrees total.) It could also be too cold or too hot of course. What did the air sac develop like? Eggs shells vary in porosity so the published humidity figures are just an average. Could need anywhere between 30 -55% in the first instance. The last three days must be 75% though.

[shygirl]

not the most fertile time of year to hatch either. add a fan for sure.

[Victorian Farmer]

Even whith good incubaters it's still hard. Eggs should be done in the spring. Autumn is whith us and hens geese no this. Fertility is not good set up whith probe 31 from the top of the egg. A fan will dry the incubater up.

[Jon Feather]

Thank you for the responses.  Ill fit a fan, probably from a computer.

The STC1000 can be set to come on and off at 0.1 of a degree.  by the sound of it I think I might have had mine set too wide.

Cheers peeps.  Ill let you know how I get on with the next batch.

[Jon Feather]

Even whith good incubaters it's still hard. Eggs should be done in the spring. Autumn is whith us and hens geese no this. Fertility is not good set up whith probe 31 from the top of the egg. A fan will dry the incubater up.

What do you mean "set up with probe 31 from the top of the egg"?

[Clansman]

Fan is definitely a good idea 

You should still get a decent hatch with the range you are working in if thats what the actual egg temperature is but it may be that they are a fair bit cooler.

What sort of eggs did you set and after how many days did the three hatch out?

Chickens are usually around 21 days, if the temp is too low they will take longer and if its too high they can hatch early.

Did any of the ones that didn't hatch try to hatch or did they not pip the shell at all?

[Victorian Farmer]

37.5  temperature in the incubater top of the egg 37.  degrease minimum top of the egg

[Clansman]

31.5 temperature in the incubater top of the egg 31 degrease minimum top of the egg

Temperature is wrong VF, it should be 37.5C not 31.5

[Victorian Farmer]

I stand corrected clansman not on the ball to day still waiting for crops to be redey. Still not started havisting. Protean to high

[Jon Feather]

The 3 that hatched were at 24 days, so a little late.  The others didn't pip.  They were looking good at 14 days though.

The heater bulbs are above the eggs, by the way.  Don't know if that would make a difference??

And Im still not clear about where to place the sensor: bottom of the egg, top of the egg?

The eggs were all between 66 and 74 grams.

[Clansman]

Most incubators have their sensors just above the eggs.
if your eggs are hatching poorly at 24 days and they are chicken eggs then I'd guess your temperature is definitely too low.

It's probably sitting around the low to mid 30's at that sort of hatch rate. Were they weak chicks?

A proper medical thermometer or similar is worth having just to double check the temperature, not a cheapy digital type, a good one, go chat up a nurse

Many of the incubators on the market can actually display the wrong temperature on the readout but most of the better models can be calibrated.

A fan and a temperature check should sort out your teething problems

[Jon Feather]

Most incubators have their sensors just above the eggs.
if your eggs are hatching poorly at 24 days and they are chicken eggs then I'd guess your temperature is definitely too low.

It's probably sitting around the low to mid 30's at that sort of hatch rate. Were they weak chicks?

A proper medical thermometer or similar is worth having just to double check the temperature, not a cheapy digital type, a good one, go chat up a nurse

Many of the incubators on the market can actually display the wrong temperature on the readout but most of the better models can be calibrated.

A fan and a temperature check should sort out your teething problems

Would you put the medical thermometer on top of the eggs and calibrate the heat to maintain 37.5 at the thermometer?

[Clansman]

Yep I'd try that