Trusters for my first ROV project

Anything to do with Propulsion.
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crazyrobin
Posts: 3
Joined: Dec 6th, 2013, 12:50 pm
Location: Veghel the Netherlands

Trusters for my first ROV project

Post by crazyrobin »

Hello everyone here!

After severall years of silence since i wrote something at the new baby's column, i'm finally starting a ROV build for myself. After a long period of thinking i have dicided to go for bigger build then i had in mind first.
It's going to be about 3 foot long and 2 foot wide and high and will be based on the oceanering type of rov's, such as used for wreck exploratin, just a little smaller.
I have found and bought ten second hand 24 volt brushed, 100 watt, DC motors, which should run about 1400 rpm at max.. I've also found a very useable type propellor from plastic about 6,5 inch diameter from minn kota, type MKP 1. It's a propellor normally used for small super silent elektric fishermen boats.
Also quitte affordable.... just 28 euro's..
After a quick test i soon found out the the propellor runs perfectly under water at just 6 Volts! With no more power consumption as 300 milli app's. Even at 6 volts i have quitte a nice among of trust, so i'm
Actually very pleased with it.. Now the motor and propellor have past the test, i'm going to make a aluminium closed and bio oil filled housing for the first motor. After that i will run some tests again.
For the propulsion of my Rov i'm thinking of using 5 or 6 motors. Two in front, two in the rear, all in a certain angle, for fast and accurate turning, and one or two for vertical trust.
In front i hope to install some sort of gripper (s) for picking up objects....
Because of the bigger motors i need bigger batteries as well, so i think i'm gonna use onboard sealed lead gel batteries.. Don't know yet how to, but i will find a solution for possible risk of gasses and explosion during batterie charging. Not sure of using relais or some sort of electronic motor controlling yet, but first i'm going to focus at the propulsion.

I will post the progress here, greets Robin

Comments are very welcome offcourse
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SSN626B
Posts: 194
Joined: Nov 16th, 2013, 2:11 pm
Location: Ft. Lauderdale FL

Re: Trusters for my first ROV project

Post by SSN626B »

@crazyrobin,
How do you plan to seal the dc motors against water intrusion?
Regards,
SSN626B/TCIII
rossrov
Posts: 383
Joined: Feb 28th, 2013, 5:01 pm
Location: Australia

Re: Trusters for my first ROV project

Post by rossrov »

Hi crazyrobin.

I think pressure compensation is a good and simple way to waterproof BRUSHLESS motors. Just a suggestion for the motors you have, do some testing before making the housing, to check that the oil or fluid does not affect the brushes.

Ross
crazyrobin
Posts: 3
Joined: Dec 6th, 2013, 12:50 pm
Location: Veghel the Netherlands

Re: Trusters for my first ROV project

Post by crazyrobin »

In the next few weeks / months i want to build the housing from aluminium like i said before.
Basically from alu tube, about 2,5 to 3 inches wide and approximately 3 millimeters thick.
I'm blessed to have a nice workshop, not at home, but at the company were i work.
Lucky me, my boss doesn't give a ###t if i use it in my spare time. So ( TIG ) welding and grinding is no problem.
Since a couple of weeks i also have a turning lathe / turning cutter bench, if that's the correct word for it, were i can cut or mould aluminium pipe or STAF material if i need to.
I need to make the motor assy / shaft longer, with a extender / adapter probably from brass.
That extander will have a extra bearing and two rubber seals, ( like used in cars and all kind of engines ) to prevent oil leaking out and water leaking in.
The assy will be eight millimeters in diameter and the seals and bearing a 32 millim. type.
In futute i would really blame myself in case of a oil leakage into the water, so there for i will use mineral oil, maybe sunflower oil or something like that is useable. Somebody overhere ever tried?? There will be an outside tube or something for pressure compensation, ( the forum here is very usefull for information like this ) . Don't know exactly how to seal the motor housing after installing everything in it, there are different ways to make it work i think..

Thanks for the advice about testing the motor in oil Ross. :idea:
You could be very wright about brush problems by using wrong oil. :o
Luckyly i can take the motors apart in about half a minute, so if there are problems during the test i can check my brushes very easily. :) I will put one in a oil filled container or something an leave it there for a few weaks. Ofcourse with some testing and connecting to a battery now and than.

Soon i will order some materials and start building the first motorhousing.... lot's of problems to overcome i suppose... :?

Can't wait to get started :D Greets Robin
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