I'm jumping in!

[olegodo]

I have looked in to those, and they could be used. But they need to be protected from the sea water in some way or the other.
My reason for wanting to take my approach is that after modifying the brushless motros, it can all just run straight in the water without any hassle.
Also I want to see if it is doable. I pretty much want to do as much as possible using my 3d printer. I often hear people saying "oh, 3d printers? those are not useful for anything other then making small figures and other useless stuff" Guess I just want to prove them wrong

The whole worm gear idea is scrapped now btw. New and I believe better idea to use rotating nut/threaded rod to convert the rotation of the motor to linear motion. I have thought of that some time a go, but then I got distracted and wanted to use servos. Servo idea got scrapped also So with the threaded rod idea and a few mechanical linkages I hope I can get this figured out.

[sthone]

I played with the threaded rod idea over the years and it works pretty good. Here's a few test pieces and unfinished examples

http://www.homebuiltrovs.com/stingermanipulator.html
http://www.homebuiltrovs.com/manipulator.html

I'm working on a 3d printed design one now but haven't gotten far enough with it yet to show off.

edit: there some planetary gear boxes that can be printed on thingiverse (such as https://www.thingiverse.com/thing:169755) that would probably work to slow down a brushless motor. (not sure if that one wound have the right ratio but it's an example of a way to go.

-Steve

[olegodo]

Great stuff sthone. Same principle that I am thinking about.
First gear the brushless motor down a bit, say 20:1 or something similar. Then use that gear to drive the threaded rod.
I think have it all figured out in my head, how to implement it all in my ROV just need to get the time to model it. Maybe next week. If only there were more hours in a day!

I have looked in to the printable planetary gearboxes, should be doable, but I fear many potential problems with so many moving parts. Also the cylindrical nature of them is not the most fitting in my ROV plans.

[zimmerm]

My students love the 3D printing you are doing for your ROV. They have been using their MOST delta printer to make parts for their ROV, and have released two designs on thingiverse.
http://www.thingiverse.com/thing:338127

The real reason they asked me to write was to check on how your tether was coming along. They were wondering the brand of the braided line you used and if the diameter was .6mm not the 6mm as listed.

Did your braiding tool work? Would you be willing to release an STL of the design if it did?

Thanks

[olegodo]

Hi zimmerm.

I'm glad your students like it. The funny thing is that it was from your design I got my initial idea from when I saw it in thingiverse.

As for the tether I haven't done any progress yet. I have been concentrating on making linear actuators for the most part. Plus my printer is waiting for spare parts after it broke down.
The rope I have is 6mm in diameter. It might be enough with a 4mm rope also, but I will have to test that to see if my 24awg wire will float or sink. It is made locally I think. It's called "danline". But similar rope should be available anywhere in the world I guess.

If it works out I will share the files for sure. I am quite busy with some home improvements at the time so I don't really know when I will get to make any progress though.

[olegodo]

So not much done here in a while. But printed the first two parts for my next prototype today.
Who can guess what this hopefully will be when it's done?

[a_shorething]

I give up. I think you said you were working on some kind of gripper or grabber. Is this the arm for that?

[olegodo]

Yes. Using the same design ideas as with the thrusters. That is, running the motor and everything else flooded with water (With protective measures taken ofc)
For this first prototype, the motor will drive a 1:10 gearing, with built in clutch. this will then rotate a threaded rod inside the tubes. The piston, the smallest diameter tube in the picture, will have a nut in it. transforming it from rotational motion to linear motion.
The idea is that the clutch will start slipping when the piston is at the ends of its travel or when the load is to high. The clutch will also be adjustable.

I will try using the same motor as the thrusters, but I might need to move over to one with a bigger diameter to get more torque. we will see!

[a_shorething]

Ah, what do I win?

Ha ha.

I know we spoke about the possibility of using stepper motors for different things. Maybe this is the right application for that. Low speed, precise operation, high torque (and low cost). The NEMA 17 is a good choice I would think. The only issue would be: Can you do the same kind of protective measures on a stepper that you can on a brushless motor?

[olegodo]

The size, weight and need for an enclosure kind of turned me off using nema17 steppers. I have them so if this method doesn't work I can still try that approach.
I really don't think the accuracy of the steppers are needed for this application. After all the gear reduction I will be using with the brush less motors I believe it will be plenty accurate.
We will see in a few weeks after the holidays and new years happenings are over