This is the incubator I recently completed. The major design and construction was finished weeks ago, but since then I’ve continually tweaked the set up. The eggs that will be incubating in here are not just mine, my partner, Doug Horwich has a sizable stake in the young that hatch out as well. For that reason the final design had to be nearly perfect. Right now, the incubator will hold four shoebox sized tubs. Hopefully, by next season I will either find better fitting, smaller tubs or find a way to add more tubs.
I think I’ve hit it. The initial design had many problems. For starters the outside two tubs were achieving temperatures that were 6-8 degrees less than the middle two tubs. On top of that my thermostat needed to be set to nearly 96 degrees F to achieve the proper temp in the middle two tubs. Gradually, I was able to tweak the design and bring the variance in temperature between the outside and inside tubs down to 3-4 degrees and dial down my thermostat to 91 F. In this final design (which is detailed here) the variance between all four tubs is less than 0.5 degrees F. On top of that my thermostat is actually set to a degree LESS than my desired temps. Over the past week the temperature inside the incubator has never fluctuated more than 0.4 degrees and it takes less than 2 hours for the temps to recover (and this is after I’ve opened the incubator for as long as 2 hours at a time).
The reason I’m writing such a long introduction is simple. I know this design is working within the tolerances I set for this project and I would assume that if you follow these directions you should be able to achieve the same results. I can’t guarantee what the effects would be if you were to use a different design or materials. Change the design and materials at your own risk. Either way, I cannot guarantee your results.
My price goal was to spend no more than $300 in materials. I found many of these materials around the house and the rest came in way below my $300 budget.
Supplies Used:
(1) – Igloo 120 quart cooler
(1)– Herpstat Digital Proportional Thermostat
(1) – 11 x 29 in. Ultratherm Brand Heat Pad
(1) – Digital Dual Probe Temperature/Humidity Guage
(2) – “Sheets” of Eggcrate
(2) – Shelving brackets
(8) – 1” PVC End Caps
(16) – 20 ounce water or soda bottles, washed and refilled with water
(2) – 4 inch PC Case fans
(1) – 12 volt AC Adaptor
- Wire Twist Ties (like those found in electronic and toy packaging… buy a kid a toy and you’ll both have what you want)
- Extra Wire for Case Fans / AC Adaptor
- Electrical tape
- Solder
- Self Drilling Screws
- Aluminum Foil Tape
- Clear Duct Tape
- Washers, Nuts, Spacers (any would be fine… you’ll see)
- Small piece of sponge (about 2-3 inches in diameter)
- Velcro
Tools:
Various Pliers and Screwdrivers
Scissors
Soldering Iron
At least one extra set of hands
Something to cut and shape the Egg Crate (any tool that will snip or pinch should work)
First start by opening the cooler and removing the drain plug. This can be done with a pair of pliers and a little elbow grease. You will be running your wires out through this hole and will need to use a sharp knife to slightly enlarge the hole so the plug from the heat mat will fit through.
Next cut your egg crate to sit on the bottom of the cooler. You will be making two “shelves” both can be cut to size now and set off to the side. Cut the egg crate to fit as perfectly as possible – too tight will be a pain to remove as you tweak your set up and too small can cause problems later (especially with the top shelf).
Lay your heat mat in the bottom of the cooler and center it as best you can.
Apply the foil tape around the edges of the heat mat. This tape will serve two functions: 1) it will hold the heat mat in place 2) it will also serve to seal out and prevent moisture from getting underneath the heat mat.
In the above pic you can see where I applied an extra piece of tape behind the cord connection. This is added security against humidity finding it’s way under the mat. I figured that most of the water that landed ON the mat would soon evaporate, whereas any water below it could cause future problems.
Next the egg crate is placed in the bottom. Be sure to cut a notch in the egg crate for the plug to fit through. The reason for this layer of egg crate is that you will be placing your water bottles on this layer. The water bottles will act as additional mass to help the incubator retain it’s heat and recover quicker when you need to open the lid. Remember, heat mats, just like Flexwatt need an airspace to work properly. Placing the water bottles directly on the heat mat may cause the mat to overheat, hence the reason for the egg crate.
Take note of the layout I used with the water bottles. This may seem like a minor detail, but it was one of the factors that greatly influenced my final results. I tried many variations before this one. You will notice how the heat mat seems to be composed of two separate heating elements encased in the plastic sheathing. This layout maximizes the amount of water that is directly over the heating elements.
This just another view of water bottle layout. The layout is repeated on the other side of the incubator as well.
Even with the water bottles in this configuration they will roll around a bit. I used eight of these 1” PVC end caps to secure the bottles in place.
No glue required… simply wedge the end cap between the bottle and the outside wall of the cooler.
Here you see the tape running along the outside wall that is holding the heat mat cord out of the way and directing it out of the tub. The red arrow represents the height of the PC case fans. Simply take your case fans and set them on top of the water bottle and flush with the side of the cooler. Then set your shelving bracket on top of the fans. This is the minimum height the brackets will need to be for the fans to fit properly. Look to the next pictures to see how I attached the brackets.
The blue arrow is where your second egg crate shelf will sit.
I wanted the brackets to sit a little ways away from the side of cooler. This way more of the shelf’s weight will be distributed along the bracket and the risk that the egg crate shelf falling or sliding will be minimized. Also, if you did happen to cut your egg crate a little too small this setup will be more forgiving of that mistake.
The spacer used can be anything you can find that has a hole in it and will be of uniform size. Nuts or washers will work just fine. For mine I used leftover spacers I had from an under-cabinet kitchen CD Player. Whatever you decide upon you will need four of them.
This is also where an extra set of hands comes is nice to have (get the kids involved – they love to help). You will simply have one person hold the fans in place while the other rests the bracket on them with your spacer of choice against the outside wall of the cooler. Using a screw driver you will have to press and twist the screw through the wall to affix the bracket. Do this on both sides. I don’t recommend using a drill to bore out your holes ahead of time. You may drill too deep or wide and then it will be difficult to get the bracket to stay in place. Hand tight with a screw driver should be sufficient.
Here’s a pic showing how the egg crate shelf will sit upon the bracket you just installed.
Create a notch in the egg crate just above the drain hole in the cooler. Then run your various probes in through the drain hole from the outside. Don’t worry about placement at this point, just be sure to pull enough of the cords through the drain hole to allow for plenty of slack for you to work with later. When you complete more of the incubator you can secure the wires along the walls of the cooler so they stay out of the way.
This is a overhead view of what you’ve done so far. The red arrows point to the brackets. The purple circles are the PVC end caps that hold the water bottles in place. The orange arrow points to the temperature and humidity probes that will go inside of the egg tubs. The green arrow is your thermostat probe. Take note that all of the various probe wires are secured along the side of the cooler – this will keep them out of the way and prevent them from getting snagged and possibly creating problems later on. The last 6-8 inches of all of the probe wires are not secured. This will allow you to place them in the proper place later.
If you want you can wait to secure the wires to the sides of the cooler until after you have completed more of the incubator. This way you will be able to place them more accurately.
This is just a pic of the AC adaptor I ended up using. Most people have an AC adaptor they no longer use somewhere. Just be sure you are using a 12 volt adaptor with 12 volt PC case fans. If you are not sure of your electrician skills you should be able to have an electrician wire up the fans for you.
Simply remove the part of the adaptor that plugged into whichever device you stole it from. Strip and solder the case fans wires to the appropriate wires on the adaptor. The black wire will go to the solid black wire on the adaptor. The red fan wire will go to the adaptor wire that is marked with either a stripe or a dash. If your fan has a blue wire this can be ignored as long as the end is properly sealed.
Be sure you have enough wire to reach all the way across the cooler. You will be attaching the fans to the underside of the top egg crate shelf.
This pic shows the egg crate shelf upside down and with the fans attached. Each fan will be kiddie-corner from one another. Use wire twist ties to attach the fans and the wires to the underside of the egg crate.
The red arrows show the direction of the airflow. You are looking to have the air circulate throughout the incubator. This is very important to achieving and maintaining stable temperatures. Since the fans are below the tubs and never blow directly on them they will not provide any type of cooling effect. Hot air will always rise, the fans ensure that the air is mixed and the temperature of the rising air is consistent throughout.
Here the thermostat probe is placed in the middle of the shelf and taped into place. You may want to place your egg tubs on the shelf first to be sure that the probe is not in the way.
This is a final overhead view of the everything. Notice that the digital temperature and humidity probes are now placed in one of the tubs. I’ve since attached these probes to the side of the egg tub (on the inside) to keep them clean and dry. Either way has yielded comparable results with the temperatures and humidity readouts I’ve taken.
Now plug the drain hole with a piece of sponge. This will keep excess heat from leaking out of the incubator. Just be sure to cut your sponge to a size larger than the hole – this way when you wedge it in it will be tight enough to fill the hole.
I attached the thermostat and the digital thermometer/hygrometer to the outside using Velcro. You can use whatever works for you.
For my egg tubs I prefer the no-substrate method. There is more than enough information about this to be found on the forum using a simple search.
These tubs are nice because the lid is attached to box and I don’t have to “pry” them open. They snap shut easily and open with enough ease that I don’t have to worry about disrupting the eggs. These are Sterilite 6-quart shoebox tubs that I found at Wal-Mart for about two dollars each.
I used colored electrical tape along the edges both for easy identification and to help seal the lid a little more. They still open and close easily, but now there is a little less chance of too much humidity escaping.
That’s it. I took quite a while to get the temperatures within the tolerances that I was looking for, but the extra work was worth it. I am still waiting on the first clutch of the season, but am glad that it hasn’t come yet. It gave me the extra time I needed to perfect the incubator,
I know that some of this may seem over explained to some of you, but I’ve noticed that some “How-to’s” are not nearly explanatory enough. I don’t know everyone’s ability to engineer such a project and so I felt it best to lay this out in as much detail as possible.
I hope this helps someone and I will be working on getting more capacity out of this incubator. It would be nice to be able to fit up to eight clutches in this setup. As soon as this year’s clutches hatch out I will begin working on that and will post any positive results I achieve.
These pictures and instructions may be copied for personal use. However, please refrain from selling or posting them on commercial websites.
Thanks,
Brandon Sander (working with)
Doug Horwich of Meridian Reptiles
