Planning how to use the styrofoam cutter

Of course i didnt build the styrofoam cutter just for fun. we want to put styrofoam under our pool as isolation. But our pool is round. I could now go outside and lay out the platters and draw on them where to cut them, or i could use modern technology for this. Of course I used the latter :P

First i opened GIMP and created a new picture measuring 400x400 pixels (pool is 3.66m in diameter and we want a bit of overhang). I then drew a circle spanning the full width of the picture and placed rectangles to cover it. My styrofoam sheets are 0.5m x 1m in size so i used rectangles measuring 50x100 pixels. The result is this:

With this pattern i can propably save 4 or 5 of my 32 styrofoam sheets. Now i have to layout this onto my sheets. And here is the layout:

On the left the white stuff are leftovers. As you see i can save 2 sheets. But i managed to put one piece twice in a sheet, so i save a third one on the other half (wohoo 5 sheets saved!). The whole thing is symmetrical so i have to cut out each piece twice. Thats what im going to do the next days :D

little update: today i cut all the styrofoam sheets and of course i fucked it up and did not save the 5th sheet -.-. But otherwise it worked like a charm :D

MacGyvered styrofoam cutter

Welp its time for my first blogpost.

We are getting a new pool because the old one broke and we wanted to enhance everything (one of those with the one air filled thing on top that floats and hold itself up).

Our old pool cooled down every night to 16°C or maybe less(20°C during day), and only kept temperature during the hottest days in summer, so we decided to put some styrofoam under it. Sadly styrofoam does not come in 4m big circles, so i have to do it myself. There were two options: Cut it with a knife and get it everywhere, or build my own styrofoam cutter.

I always love to tinker with dangerous things, so of course i wanted to build my own cutter. a quick and dirty method would be to weld a knife into a piece of metal so it sticks through, and then heat it from the underside with a gasflame, but first, i suck at welding, and second we dont have a gas outlet (i would have to do that by myself too and thats where my parents would kill me). so i have to find another way.

I like electricity so i tried to follow the example of other styrofoam cutters and wanted to use a heated wire. I have a cheapo lab PSU that i wanted to use first, but it couldnt get the wire hot enough. So i wondered how could i get more power but still be able to control it?

Good thing i always keep all the things because i will need them 10 years later. I have an old 12V motor that can also act as a generator, as it has permanent magnets. So i wanted to use this as a Generator to supply the wire with enough power. Now i have to drive it with something. I salvaged a 230V universal motor from our old broken washing machine (circuit board went up in smoke for some reason, also salvaged the solenoid valves and the little waterpump that were in there). To drive this motor i also got myself a noice 1000W variac. I also mounted it on a piece of wood so i can clamp it to a table because that motor can cause some karnage.

So now i have to connect both motors. First i thought about a beltdrive, because i also kept the belt from the washing machine, but the other motor doesnt has any grooves on its rotor, so the belt would slip of or i had to position both motors in a specific way. And again i could use something that i got a few years back.

For the old pool we purchased a longer hose for the pump because i wanted to use a car cooler to heat the water with a fire, but we didnt want to position this close to the pool. So i cut up a 20cm long piece of it. The hose fits over the rotors of both motors with a gap. To make it fit tighter i cut up an old bike tire tube and pulled some over the rotors until the hose fit tightly. I then secured it on both rotors with hose clamps.

So i also mounted the smaller motor on a piece of wood so i could secure it too (yes i did this after i connected both motors because im stupid and lazy). I clamped both motors to the table and hooked the big one up to my variac. I then put my piece of wire in a hacksaw and connected both sides to cables that lead to the 12V generator.

AAAANNNND We're done. I then let the motor run at about 115V. As the generator was under load it ofc didnt spin that fast, and the hose also did its part to slow things down (its a pretty rigid one). But the wire got hot enough to cut through styrofoam like butter :D.

Now i only have to layout the styrofoam sheets so they cover a circle and then start cutting :D

pics:

The variac with attached outlet:

Big motor with its wiring:

Small motor attached to big motor with hose:

Hacksaw with wire and cables:

Motors and variac in one pic: