Proof of concept test- Mag coupler

[a_shorething]

Hey everyone,

Well I got my proof of concept working. It still needs some work and may not even work with the bilge pump motors I was planning to use, but the idea seems to work.

In this test I didn't even secure the magnets on the inside prop so they are sliding and grinding around in there, but the idea was to see if the motor can turn a thruster on the outside of a standard 3" PVC schedule 80 pipe and that part worked. In fact the thruster blade is probably a lot heavier than it needs to be so if I can lighten that up and get it to actually generate some thrust I think I may have something here.

Check out the video and let me know what you think:


Please be kind. I'm just happy that darned thing spun.

[sthone]

Not to bad for a prototype. I was toying with a similar design with the prop spinning around the housing but I never got to the prototype phase so your way ahead of me there.

You are probably going to have a lot of resistance with the prop just dragging on the PVC though and you might want to look into using neodymium magnets (rare earth) over the ceramic type as they are much more powerful.

I can't wait to see how this progresses though.

On a side note what are you using for a 3d printer I've been seriously thinking about getting one.

-Steve

[a_shorething]

Hi Steve!

Thanks for chiming in. Yeah the friction is a major issue and I got a suggestion from Ole on here who also suggested the rare earth magnets. I really wanted it to be able to be built with readily available parts and I can't those around here, although the internet provides pretty much all things, right? I'll check into that. The holding strength is a biggie, but the lower weight will be a big plus as well I think.

There are lots of things wrong with version 1.0 but I was encouraged by the initial results.

I'm going to see about:
> Reducing the weight and possibly size of the thruster prop. It's got a lot of surface area and that means it can potentially move a lot of water if I can just get the motor to move it without burning out/up.
> Possibly adding some kind of simple gearing. Even a 1-2 gear ratio would help some. The 1100gph motor spins really fast and I think it will work better at a lower speed, again, considering the fact that the blades have such a large diameter.
> some other ways to generally make it smoother. Too much play, too much noise, too much friction, too much inertia.

RE: 3D printer: That was last summer's project. I built it myself from a kit I got from Maker Farm. It took a long time to get it tuned properly but once I did it's my favorite toy! Prototyping stuff like this coupler took about a week to get where I am now from the first design, through several (ok quite a few) iterations that didn't quite fit, to the version I'm calling 1.0 because it's the first version that all the parts were what I thought they should be.
Iterating through stuff like this is amazing. Get an idea in the morning, spend an hour or so on your favorite 3D design program, export from there, import into the 3D printer and 4-6 hours later (sometimes more for large parts) you have a solid part with the exact dimensions you wanted. Not quite right, modify, export, print. Come back in the am and test it out. I LOVE this thing.

Mine is an Prusa Mendel version 2, I think they're up to version 3 or 4 now and there are lots of different types. Check out Reprap.org for LOTS of ideas and help. They helped me get up and running.

[ERIEWRECKDIVER]

First I have to commend you on the use of a 3D printer to make parts. Second I am very impressed with your use of the mags in your design.
I am wondering however. Why? It seems that a lot of energy is lost to the design. A 1100 gmh bilge pump with a prop would have a lot of thrust. Just saying. Maybe you are doing this for a reason that I do not understand.
Could you explain?

Best Wishes,

ErieWreckDiver

[a_shorething]

Thanks for not lambasting me as a crazy person.

There are a few reasons but mostly the reason is because I want to come up with a design that will not expose the motors to the pressure and the salt water. I think most of the designs I've seen have been either a) not very powerful, b) not very reliable at depth/after being exposed to the salt water for long periods of time, ie, they leak or start consuming large amounts of power or c) very expensive for a homebuilt project.

I'd like to address all of these issues, but mostly the fact that sealed units are pretty expensive and I think there should be a cheaper option.

Another reason is because I love the challenge of coming up with a new way of doing things and if the design is good and cheap, maybe others will want to try it.

My camera design is going to be a little different from what I've seen elsewhere, the communication system is similar but unique. The interface will be a custom program I'm writing to work with wireless XBOX360 controllers and the thrusters seemed like an interesting challenge too.

Stay tuned for version 2.0 btw. I have another iteration in the works that will incorporate what I've learned here and I think it will work much better.

Imagine being able to build a completely sealed thruster unit out of a bilge pump, some printed parts and some schedule 40 PVC (rated at 280 psi if the printing on the side of it is accurate). I think the cost could be under $30 per thruster complete and it would be rated for well over 100 feet of depth.

[turtle]

hi just a quick question i was looking into making something like this before, if i mail you some drawing could you give me a price on how much to make them.
i just need the push in end cap for the bearing and a thruster part like you have made heres a quick drawing of what i was thinking

[/URL]

[a_shorething]

hi just a quick question i was looking into making something like this before, if i mail you some drawing could you give me a price on how much to make them.
i just need the push in end cap for the bearing and a thruster part like you have made heres a quick drawing of what i was thinking

[/URL]

Hi, how's it going?

I'd certainly be willing to take a look at it. If it's not already in a format I can just upload to my printer I'd have to see how much time it would take to design it, but if it's along the lines of what I've got here I'm willing to take a stab at it.

Bear in mind though that 3D printed parts will not withstand any pressure and they are only dimensionally accurate to about .1 mm (give or take). This may seem pretty good, but it's certainly a far cry from a 'machine mating' surface or anything.

If you're OK with that, send it along...

I'll PM you my e-mail address.

Mike