Bat House Project

[reality_boy]

5-19-2019

First Data! I need to clean up my logging code a bit, and work out a better way to visualize the temperature differentials, but we have data!

Looking it over it seems that the outer chamber is heating up a bit over ambient. I think that is because this material is not completely opaque but instead lets a small amount of light through. Painting the outside of the chamber would help, as would using a darker material like black.

Also for some reason I expected the upper segment of the chamber to be cooler, even though heat rises. Of course the ceiling is always hotter than the floor in your house, when the sun is out so I was just thinking incorrectly. I need to see if building a taller box makes a difference on the temperatures, it may have an impact.

[reality_boy]

Question for later, does the pole absorb heat from the bat house via conduction. Figure out how to mount a temperature probe to the pole to see if it is cooling below ambient. This would only happen if the ground was absorbing energy.

[curious aardvark]

Okay - first, I take it you haven't done much research in to bats ?
The reason they usually rest in caves, roof spaces, tree holes etc is that those are shaded places that retain heat in winter and stay cool in summer.
A solid chunk of plastic in the open arizona sun - will not attract any bats.

Secondly, most bats are very very small - their bodies are smaller than most mice. They tend to go for very small spaces and can crawl through cracks smaller than you would believe.

Your house would be better, both smaller and made to attach to buildings below the eaves, or on tree trunks in shaded areas. Places nearer where they would naturally roost.

A big cylinder on a pole in the open in arizona (of all places :-) will not attract bats, as it's clear it will be too hot during the day.

So that's my first suggestion, do some research on bats, then redesign the box to suit the bats.

You don't need the pole.

Secondly - why on earth does it weigh -2-3 kg ? That's a lot of money in filament. To get it that heavy it must have a lot of solid shells and really dense infill.
Thinner shells and a lower density infill mesh will not only make it cheaper and lighter (able to be mounted more places) but the larger mesh will increase the insulation properties of the box.

Bats like small tight spaces that daytime predators can't easily access.

Thirdly (lol) bats crap during the day, so the box should be fitted with a way making it easy to clear it out. a hinged trap door type base would be favourite.

Different bats will like different box types - so make small ones for small bats and larger ones for larger bats - though there are a lot less of those generally.

Pipistrelles are the most common bats in the uk - and a cigarette box sized house with a 5mm entranceway could easily house a half dozen bats.

Also a small, building mounted box, could have a micro camera built in, so the kids could see whether or not it was occupied.

I applaud your project - but you probably need to start with the bats and then design a house. Than work on the principle: 'If I Build It - They Will Come' :-)

Oh yeah, like most small mammals bats have claws and can climb what looks like smooth walls to people. Print the b at houses at a fairly large layer height and fast and the natural grooves will be sufficient for most bats to easily hang on to.
The majority of bats don't sleep hanging upside down from the ceiling.

Something like this:

with a trapdoor base would be quick ad simple print and easily attached to buildings, trees and shaded areas.

[reality_boy]

Thank you for taking the time to look over my project. You raise good questions, hopefully I can try to answer some of them to the best of my ability.

First the house you are showing is considered a poor design by current standards. Both because it is too small to house a nursing colony, and because it lacks enough variance to allow the bats to find there ideal temperature in any weather condition. The current recommendations call for at least a 24 foot square house with 2-4 chambers, that is a substantial thing!

An alternate design is called a rocket box, it is basically the above house wrapped around a pole. This is nice because it is simpler to mount away from a building and it tends to be simpler to construct as well. Rocket boxes tend to keep the same internal volume as traditional houses, they just build up rather than out. My larger bat house design mirrors one common rocket box design in size and livable volume.

How rough to make the sides of the house is a big unknown. Right now I'm using horizontal groves to increase the roughness, but there are probably more efficient textures that would both use less materials and be faster to print. My design requires the walls to be around 4 mm thick, rather overkill otherwise.

As for material, I'm using as little material as I possibly can without compromising the integrity. I am fairly new to 3D design, so I'm sure someone else could optimize the design even better, but I have tried many variations in an effort to reduce the material count. The truth is that this is a really large print. However I am aware that getting this shrunk down so it only takes one spool of filament would go a long way towards making others interested in printing it.

I'm experimenting now with ways to improve the insulation on the house. I think what I have now is actually holding up fairly well. At least if my thermos test from above is to be believed. The house is nearly as good at keeping the bats cool as the thermos is in direct sunlight. At night the thermos seems to have the advantage, but in my defense I left the lid on it, so it was not open to the night air. I suspect paint is going to matter more than anything, but I do need to build a wooden bat house for comparison to see if I'm in the right ball park or not.

Finally, my hope is to find some bats to validate this all with, and redesign as needed if it does not hold up. My goal is the bats, not the house. If it is not helping bats then there is little point in publishing the design. That is why I am being cautious and holding off on releasing the stl files. I don't want to release a bad design into the wild.

[reality_boy]

I managed to clean up the images above, the way I was hosting them before I could see everything but no one else could. Hopefully that clears up some confusion.

I ran two temp tests overnight. First I placed all my temp probes in a sealed thermos in a closed room. You can see from the plot below that the sensors are all reading a bit off from each other. This is a plot of the difference between the first probe and the others, basically a measure of there relative error. They should be accurate to within a degree but they are fluctuating by 2 degrees instead. Considering we are seeing only 4-8 degrees of temp differential in the house that is not nearly sensitive enough.



Next I filled the bottom of the thermos up with ice, while keeping the probes dry, and let it sit for a while. Here is a plot of the difference in readings from the first probe to all the others. You can see that there is no consistent pattern to the temp offset, we can't just subtract or add a degree to bring them into allignment.



I don't think I can really move forward with these probes. So I'm looking into some i2c temp probes that have a 0.3 C accuracy and a finer resolution. Hopefully they are close enough. On top of that I'm considering building a wooden rocket box to compare the temperatures against.

In the meantime while I'm waiting on parts I will make a test print at various thicknesses, and look into alternate ways to texture the inside of the house.