09/08/2019 at 17:31 •
Finally a nice day, and some spare time so I could mount the thrusters to the boat. I used some stainless steel M6 threaded rod and some DIN rail. DIN Rails is great. It's cheap, has mounting holes and it is very stiff due to the shape.
I kept plenty of length on the M6 rods so I can adjust the depth of the thrusters later, if required.
Once all nuts are tightened the whole construction became quite rigid so it seems like this is going to work. The only thing that worries me is that the metal is sticking out quite a bit to the side and that it will definitely collect weed and algae.
08/10/2019 at 20:28 •
A remote controlled is nothing new, and a lot of the required electronics and controllers is widely available. But if you are not an Remote Controlled Vehicle (RC-)enthusiast, a lot of the words and abbreviations used on the HobbyKing RC pages are not immediately obvious.
First, I will need something to control the speed and direction of the thrusters. The motors are so-called 'brushless motors', which need special drive electronics. This is called an ESC or 'Electronic Speed Controller'. Then I found out after ordering my first pair of ESC's, not all ESC support changing the direction. Which makes sense if you use it to power a plane or helicopter. So I ordered a second (more expensive) pair 'with reverse'.
The contacts used for controlling the ESC are simply labelled 'RECEIVER'. Probably very obvious to anyone, except me. Now I think that the Red and Black wire are the BEC (5V) output, and the white wire probably carries the servo signal.
And that works. After applying power, and switching the ESC on, it generates some 'beeps' using the motot itself which scared me at first.. But the beeps are an indication that the ESC detected the neutral throttle signal (the servo output from the arduino) and the power. After that, moving the potmeter controls the motor speed and direction just fine. Only when moving the controller too fast from one side to another so the reversal of the motor is very fast, the powersupply switches off. Probably the reverse current is too much for the powersupply protection.
08/08/2019 at 19:36 •
So the thruster parts arrived way faster than I expected from Russia.
And they look great. Not sure how they did it, but they are very nicely printed and have a real smooth finish. Included in the box is a bundle of printed instructions for assembly. All of which are also available online, but it's nice to have them in print too. What is remarkable though is that though every aspect is of the mounting and modifying of the motors is described and illustrated using photos, there is no assembly drawing of the completed thruster. So up-to the moment I was actually assembling it I still did not really have a good idea of how it would work.
The first step is preparing the motors for underwater. the instructions mention using a slow-curing epoxy glue, but I actually used some 2 component epoxy moulding kit that is specifically designed for moulding sub-sea cables and connectors. It comes in a convenient package where the two components are separated by a removable seal.
So I created the moulding form around the motor using Kapton-tape as shown in the instructions, mixed the epoxy and poured it in. After mixing the epoxy a little bit too long it was already getting warm and started curing while I was pouring it in. Which made it look like it was not filling all the gaps. But after the mix has cured and removing the tape, it turned out to have worked really well. Just a few bubbles got trapped, leaving some of the copper exposed, but these were quickly filled using some epoxy glue.
It was only after I started assembling it that I noticed that the epoxy layer was actually a bit too high. Some filing was required to round off the edges, so the motor would fit the thruster housing.
After that it was just following the detailed assembly instructions on Instructables, and everything worked out great.