Homebuilt ROVs Forum

I finally collect all the parts for three thrusters and I almost finish the magnetic couplings.Now I am ready to assemble them and test them

That's one good looking thruster.

Wow, those are beautiful!

Major works of art Dimitris. Really like the face seal.

Ross

Thrusters Update:
So when the first thruster was assembled last night it was time to check the efficiency of magnetic couplings.
And here are the results:
DISASTER! After 10 seconds the motor stopped running smoothly and the propeller stopped.I disassembled the housing and after testing each part individually I realized what was wrong.It stopped working because of the Eddy Current effect created by the magnets and the aluminium.
Lesson learned the hard way .
So I redesigned the housing and all the parts where the magnetic couplings are nested and made them from acetal today. I tested it and everything went well.
Now it's time to test it underwater and start measuring the thrust, the battery consumption and the force needed to separate magnetic couplings if propeller gets stuck!

And a few more pics:

I tried an aluminium pressure bulkhead too and was suprised by how much power loss the eddy currents caused. I replaced it with a piece of (blank!) 1.6mm FR4 circuit board, FR4 being strong for a given thickness. The magnetic field will be densest through the bulkhead so maybe you can keep the tailcone metal. Wondered what you were using as a bulkhead in the earlier pics but could not see.

rossrov wrote:I tried an aluminium pressure bulkhead too and was suprised by how much power loss the eddy currents caused. I replaced it with a piece of (blank!) 1.6mm FR4 circuit board, FR4 being strong for a given thickness. The magnetic field will be densest through the bulkhead so maybe you can keep the tailcone metal. Wondered what you were using as a bulkhead in the earlier pics but could not see.

Hello rossrov.Yes all housing at previous pics is aluminium.I wish i could keep tailcone metal but I tested each part seperately and the braking effect was massive.Even at the tailcone.So I replace the parts with acetal.I changed the thickness of the bulkhead from 2,2 mm to 4,4 mm and everything run smoothly now.

Very nice Mr. Bubbles, you look like you're pretty handy with a lathe

Martin