Making an incubator

15 10 2013

I’ve so thoroughly reworked the incubator, I’ve decided to make a completely new post about it….

Our ducklings hatched last week.  All five of them, which from two clutches of some thirty six eggs was frankly disappointing.  I don’t know if it’s a case of bad mothering on the part of our hens, bad fertilisation from the drakesducklings (yes, we have two drakes, you’d think between them they’d get the job done…), but whilst Christmas Dinner is now secure, five ducks (even every five weeks) is hardly going to keep us in sustainable meat production.

So I hopped on youtube, the fount of wisdom for almost anything you may need to survive life, from how to fix your rideon mower, to building a chicken plucker (my next project – because plucking ducks is not a job I enjoy) to yes, building an egg incubator from scratch.  Mind you, you have to screen the idiots from those who know what they are doing, there’s some ning nongs out there with video cameras, let me tell you….!

Incubator turned on

Incubator turned on

I already had an old Broccolli polystyrene box with lid lying around, so I started by cutting a rectangular hole in the top so that I can see inside it.  The hole was covered with a spare piece of glass I’ve kept in case our old windows ever need fixing.  Electrical tape did an excellent job at holding it in place.

Next, I went to Bunnings to spend some of that money a couple of you have donated via this blog (much appreciated, thanks to all concerned – and NO this isn’t me begging for more…) and purchased a reading lamp holder with a dimmer and a 25W incandescent light bulb.  I never thought I’d ever buy one of those again, but they make good heaters, which is why no-one uses them anymore, they are even outnumbered ten to one on shop shelves by CFLs and LEDs, making them hard to fi

To incubate eggs you also need to know what the humidity in the box is, so I also

25W bulb with hi-tech humidifier

25W bulb with hi-tech humidifier

purchased a combined digital thermometer and hygrometer online for the princely sum of twelve bucks.  A word on digital thermometers though, I have three of them now, this one, the one I use to make cheese, and the one incorporated in my energy monitor, and you wouldn’t believe it, their readings inside the box were all different…..  So, which one to believe?  In the end I decided to stick with the one I bought for the job, and suck it and see…….  proper scientific observations and record keeping (not something I’m particularly good at!) will have to be followed.  Apparently Muscovy eggs have to be incubated at 37.5°C, and if you go over 40°C you kill the embryo, and if you go under the eggs take longer than the prescribed 35 days to hatch….  so we will see what we will see.



I had the unit on for several days using two different dimmers trying to stabilise the temperature, but they’ve turned out to be next to useless.  It may well be a combination of the fact dimmers are not very accurate for good control of the light output, and that the digital thermometer is so slow to react to temperature changes, the two devices were actually working against each other!  In the end, I decided to get another one of those digital control units I use on my two fridges, especially as I have discovered the price of these things has almost halved (I paid $69 for the last one, and this new one, exactly the same, only cost $36 + postage on eBay).   While looking for a link for you who may want to get one of these too, I have just discovered a site in China that sells them for only $14.98!  Grrrrrrrr!!!

My concern about the heat vaporising the polystyrene has vaporised itself, after many days of heating the smell has disappeared.



A new hole was cut in the box for the controller, and the old one where the dimmer was plugged up with some spare polystyrene.  If you don’t know what you’re doing with 240V


New Controller

electricity, DO NOT WIRE THIS UP YOURSELF…!  The instructions are somewhat confusing, and every time I have to do this, I need to sit down and remember how I did it last time.  The instructions can mislead you into putting wires in the wrong place, and at best it won’t work.  At worst you could blow it up, and in the very worst situation, you could start a fire.  Consider yourself WARNED…  On Glenda’s suggestion, I may yet draw up my own instruction on how to do this, if I can find the time, and the software to make a wiring diagram.


Action Stations!

When I switched it on, it quickly became apparent that the box heats up much faster than the thermometer was telling me, which is why I was getting far too hot a result with the dimmer when left overnight.  It also cools down much faster than I anticipated.  It’s a relatively cool 20ºC in the house this morning, and it takes just one minute for the eggs to cool down 0.3ºC.  The light bulb cycles one minute off, three minutes on at this ambient temperature.  I wonder how long the bulb will last cycling like this?  The only other improvement I’ve made is replacing the bowl of water with a 3L milk bottle.  This would add some thermal mass to the system, and reduce the number of cycles.

I just timed the cycling with the 3L water bottle…….  it was ‘on’ for 2:10 minutes, and ‘off’ for 1:10 minutes, so it has improved.  I may give Serge’s suggestion of laying the whole bottom of the box with water bottles….

If/when the eggs hatch in 35 days, you will find out…..  fingers crossed!




8 responses

16 10 2013

The eggs have to be turn over every day for success.

16 10 2013

I actually turn them four times a day….

16 10 2013

I would cover the entire floor of the box with 2 lt bottle filled with warm water and cover the “window” with polystyrene when not looking in. Also you should have the eggs horizontal in an egg carton.

16 10 2013

May be I should make one as well. I just had the worse hen sitting ever.
2 hens sitting on 12 eggs each, after 2 weeks eggs in the first batch started to blow (rotten), after a few blews, the hen abandonned the nest. I shifted the rest under the other hen (she started sitting only a couple of days after the first one),
but eggs kept on blowing and the second hen left the nest as well this morning, she’s back on it tonight, but I am not holding my breath.

16 10 2013

Maybe you should hold your breath…… it must stink!

18 11 2013
Darren (Green Change)

I’ve just repaired my old Hovabator incubator with a digital controller pretty similar to the one you used (in fact, it’s probably the same controller board with a different faceplate!).

The old wafer thermostat never seemed to work very well, and was fiddly and frustrating to get set just right. It finally died, spurring me to actually do the replacement I’d been putting off for 3 or 4 years.

Having a digital controller now makes it dead easy – just set the temperature and forget it!

18 11 2013

Cool…… I have one of those fridgemates as you call it to run our freedge

The advantage of the newer model is that it reads to 0.1 degree accuracy, I suppose not that important if you’re going to operate it over a range of a degree or more…

Our first batch of four duck eggs are due to hatch today or tomorrow, and I’m waiting for that to make the new improved version that will hopefully use less energy to run. Watch this space…!!

18 11 2013
Darren (Green Change)

More accurate sounds ideal for an incubator! 1 degree accuracy is OK for a fridge, but 0.1 degree would perfect for eggs. Apparently they’re supposed to be kept at exactly 37.7 C for optimum results.

I’ve already got two Fridgemates, but maybe I can think of an excuse to get one like yours as well :-).

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