did up a quick model making it as small as practical. Overall Dia of 40mm, Hull Hole size of 34.5mm. Top of T100 would be 14mm off the face of the hull. All the parts are min 2mm thick
Picked up the first complete mount today from 3D Hubs. Mounts are more solid than I hoped. I did do a 5mm thick slice of all the parts printed first to check the tolerances. From that, I made a couple of minor adjustments. The complete unit fits well and the tubes are a nice fit together. I will get the second unit during the week, some of the parts take 11hrs to print! Next weekend I will fit it into the boat ant take some photos and underwater video. I was a little concerned I made it all too wide (diameter) but it all looks good and the extra size will mean that it will handle a lot more torque than what the thrusters can produce.
Spally,
Cool. I’m looking forward to seeing some pictures of the parts!
I imagine that you could make bosses for the screws but thin the walls everywhere else to reduce the cost. 5mm is super thick for the wall sections. It will be very strong!
-Rusty
Awesome work Spally!
I’ve just finished moving into the new house, so no chance yet to add my addition. Essentially if I had to I could get away with an extension of the servo mounting platform.
Looking forward to seeing how the prototypes perform!
Cheers,
Mike
Made a few modifications for the gear motor to Spally’s servo-oriented design, to make a continuous rotation capable version. Note the addition of a side mount for the assembly that will be used to hold the overhead mount for the speaker-jack slip-ring that’s still being designed. The gearmotor platform is simple, and provides space for a Adafruit 5V “Trinket” micro-controller. One could use gears, or alternatively a timing gear/belt combination with simple roller tensioner for ease of construction…
Spally,
That looks awesome! I’m very excited to see how it works. It looks really strong.
-Rusty
Well here you go. Mounted to some board to confirm it all works before drilling 2 holes in my boat. Yes one is white and the other is black. The 3d print guy ran out of black. I could have waited another week for black or have it now in white. Since this is a test system, the colour doesn’t matter. I will fit it to my boat tomorrow.
Well done! That video looks excellent!
Is there much resistance in the rotation? The servos sound like they might be under stress even when they are not moving.
I’m really excited to see how this works in the water. Keep up the good work!
-Rusty
Rusty,
Virtually no resistance. These digital servos from hitec always seem to “sing”, don’t know why… The one in my monster truck does the same thing.
Spally,
Ah. I’ve had similar experiences with their digital servos. It never actually seemed to be a problem but they sound like they are stressed out all the time. How do you like their waterproof servos so far? Have you tested them in water yet? I know the specs say 6-7.4V are you using them in this range or at 5V?
Rusty
Bring on the sea-trials Spally!
Do you still plan on conducting a “thrust-off” between the old and new thrusters?
Trying to find spare time to progress on the full azimuth derivative. Intention is take the modifications you’ve seen to the standard model and apply them to the ultra compact derivative, developing further from there.
Well guys, I finally got them installed. Yay! I ran into some issues with the angle of the hull causing the trusters to hit the inside of the sponson. My bad… My production hull will be flat across the mount area so this won’t be an issue. (It will also be shorter, wider and taller with a newer designed top). Anyway, to fix it, I got some wedge rings printed to allow the mounts to be vertical rather than perpendicular to the hull. I had also installed the 10kg Transducer to the bottom of the hull.
Here is a video of the mounts before I put it in the water. The fan noise is from the electronics box.
Video: Dropbox - IMG_2954.MOV - Simplify your life
This video shows just putting around at 1/4 throttle.
Video: Dropbox - IMG_2955.MOV - Simplify your life
This shows full throttle, full lock.
Video: Dropbox - IMG_2956.MOV - Simplify your life
This shows the thruster from the underside just after pulling it out of the pool.
Video: Dropbox - IMG_2958.MOV - Simplify your life
Thoughts.
Very happy with the turning circle. I think I will dial in some steering exponential as this boat turn aggressively at speed.
No water came through the mounts note through the mounting holes. I used a little silicon sealant on the mount tube before screwing it to the hull.
Mounts turn freely and even leaving it for several hours to dry, they still feel good.
Overall, very happy with the results. Next week I will do some long hours trials.
Looking forward to dropping a pair of T200’s underneath!
That looks like a racing catamaran hull, you’re modifying it to produce a USV for underwater surveying right, or could it be the RC fisher from hell? Lipo or lead acid batteries for power?
Spally,
That looks excellent! I’m very impressed with the turning radius.
Thanks for sharing the videos. That’s a pretty big boat for that pool 
-Rusty
Yep, it is a racing cat but my survey boat is more than 300mm shorter and is 100mm wider, plus a centre hull added to mount the transducer internally.
Batteries are 2 19.6Ah LiFe batteries from K2 Energy. They weigh less than a 7Ah SLA! I also use a “Booma RC” twin battery cable to manage the power from both and provide system cutoff.
Deckie & Rusty,
just an update on the thruster mounts.
The mounts are working really well. Friction when under full load doesn’t appear to be an issue. They have had over 20hrs use in fresh and salt water and have not bound up at all. The 2 T100s can push at close to 1.8m/s at full throttle and maintain around 1.4m/s at 3/4 throttle. Not bad for pushing 18kg! With my battery config, I am getting around 3.5-4hrs runtime out of a pair of batteries. The Blue ESC will help as I will not require a fan in the electronics to try to keep the ESCs cool.
Issues. I was originally connecting both ESCs to the receiver and had 2 Hitec 6456 WP servos running off the power they were getting via the ESC. That all appeared to go well with my initial tests however, when I ran the boat down at my local harbour, I ran into some issues. I noticed that when running from 3/4 throttle or higher, the servos would respond and turn but would not straighten. As soon as I backed off, because the boat was doing circles, the servos would straighten. It appears that when the truster is up there in throttle for more than 30secs, the BEC in the ESC can’t continue to supply enough amps to the servos. As soon as you back off, this fixes itself up. I solved this by supplying the Servos with their own power supply (currently set at 6.8V). Since doing this, I have had no more issues.
on the plus side, I get a production hull this week!
Spally,
Good to hear that things are going well. That’s a pretty impressive speed for such a heavy boat. Looking forward to hearing about the production hull!
The Basic ESC has a really weak BEC (0.5 A). I’m not surprised it couldn’t handle the servos. The ESC is actually intended for multicopters which don’t need to power anything through the BEC. Glad you got it fixed.
-Rusty
The modified mounts are now being printed by the same Hub used by Spally. I did have a (now cancelled) order with a Hub here in Perth, however moisture issues prevented them from producing quality parts.
Slip-rings remain a problem… can’t find anything yet that will fit, that doesn’t cost twice the price of the mounts and T200’s together.
On an amusing side-note i’ve been quoting various CNC machining companies just to see what they’d want to do the job, and the lowest price i’ve seen so far is $3600 for two mounts. That price applied for both ABS and Aluminium…
Have had a breakthrough with the slip-rings. The MW-1630 model is fit for purpose…