Magnetic Torque Transfer Vortech Pump

[sushi chef]

Introduction:
Sorry for the crude drawing, I used illustrator instead of photoshop because PS vectors are a real pain.

I saw the Ecotech Marine Vortech Pumps a few days ago on the RC forums and was really impressed by the design concept, but really can't swallow the price tag. Here's the link to it for anyone who hasn't seen it: link.

I figure you can make one for well less than what EcoTech is trying to charge for it, but seeing as I haven't actually seen a Vortech in person, and don't know much about motors, I was hoping I could get some feedback on the design and components.

Design Explanation:
The design is pretty simple. On the propeller side, there’s a thin, solid, circular acrylic plate that has been routed to hold a circular thrust bearings. NdFeB magnets are attached to the edges of the fixed plate. The purpose of the fixed plate is to keep the magnets from rubbing on the glass, as well as to hold the thrust bearings that will support the smaller spinning plate. A carbon fiber or stainless steel rod will be imbedded in the center of the fixed plate to guide the rotating plate, airline tubing and propeller (much like the Maxi-Mod prop). The rotating plate will have four neodymium magnets on the edges spaced at 0, 90, 180, and 260 degrees. The rigid airline tubing is glued to the center of the rotating plate, and the propeller is attached to the tubing. An end cap (not drawn) is slipped onto the rod to keep the propeller and rotating disc assembly seated firmly against the bearings.

On the motor side, an identical rotating plate is attached to the motor assembly. The motor is mounted on the casing. The casing has neodymium magnets on the edges and will hold the fixed plate on the opposite side of the glass in place. When lined up, the motor side rotating plate turns, which in turn causes the rotating plate on the water side to spin in sync, which turns the propeller and hopefully spews out 1000000 GPH flow

That’s all I have so far. Obviously there is no micro controller, or battery back up system on this DIY model, since I have no idea how to make one. Like I said, I have never actually held a Vortech pump and don't know if this is how it works; it could use electro magnets for all I know, but I think this should produce similar results.

Does anyone have any comments or suggestions?

Here are a few questions I had:
1. Do neodymium magnets break down in water? If so, does anyone know what kind of magnet those MagFloat algae scrappers use, and how they are enclosed?
2. What kind of motor should be used? Since it would be funny (and useful) to build a wavecontroller for 2 or 3 of these before the Vortech one is released, are there any silent DC motors out there that would suit this purpose?
3. Are the thrust bearings necessary, or am I over thinking things?

Total cost of this could vary depending on how much a silent DC motor costs, but should be well less than 100 US Dollars.

[chadfarmer]

same design as kalk reactor with a stir bar


suggest using stong magnets

[smells like fish]

PM liveforphysics on Reeffrontiers. He built one already.

This is his post from from RF.

Anyways, it turns out that makeing your own Vortch DIY copys is as easy as doing the maxi-jet to tunez conversion.

Thick acrilic disk with a Ti rod pokeing straight out of it, then a close fitting carbon fiber tube with an RC boat propeller slipped on the top of the tube. At the bottom of the tube you have a little 2" acrilic disk with 2 cutout for CD player lens magnets, or harddrive magnets, or really any little neodimium magnets positioned across from eachother on the outsides edges. Then stick a cover made from a plumbing bell reducer over the assembly just like what the pic you posted uses.

The next part is even easier, take a 2.5" PVC pipe section about 2.5" long. Stick a cheap RC car toy motor mounted in the center of the little 2.5" PVC tube. Stick the 2" disk with equally spaced neodemium magnets flush mounted into opposite sides to mirror the one you made for the propeller assembly.

If you didnt use super powerful magnets for the torque coupleing, then you might need to glue a couple of permanate magnets in approprate places on both halfs to ensure a solid sticking, but with the magnets I use, falling off seemed pretty much impossible, kinda like one of the very strong algea magnet scrapers. Put a thin little bead of silicone around the surfaces that touch the tank anywhere. Let that dry throughly to act like a vibration dampener and ensure silent operation. Now, the alignment is crucial to long happy and silent operation, so spend some time and get it dead nuts.

Also, the bearings in the cheap motor can also be noisey depending on what you got. Some small motors are really quiet with nice ball bearings and you cant hear them at all. Others sound like annoying whiring sounds, but I would say still more quiet that most closed loop pumps. Anyways, then you just supply it with power from whatever source you want, old computer powersupplys work great as a controler with the addition of a little pot interfaced with the voltage regulation circut for speed control. That way your powersupply can stay under $5. There are a zillion other ways to power them, or make your own controler and wavemaker or whatever, but its 3:52am and im tired of typing.

But yeah, thats how to DIY vortechs for about $35, depending on the quality of components you wana use.

[mech]

that is really cool

[dhnguyen]

Even easier might be to use a large PC cooling fan for the DC motor then you would be have killed 2 bird for one stone so to speak Turning the propeller as well as keeping the whole thing cool

Just a thought.


D.

[sushi chef]

chadfarmer: Will definitly take a look at DIY kalk reactors, but yeah, this is basically a small magnetic stir rod device with a prop attachment.

smells like fish: Will try to contact liveforphysics. It seems like he built his alot like mine, but without the bearings; makes me wonder again if I need them. I'd be interested to see if his acrylic is getting worn down though.

dhnguyen: I wonder how strong those fan motors are. I really have no clue as to what kind of DC motor would be best for this thing; the fact that I don't even know how much power I'd be needing to turn the prop at a good rate just makes it worse.

Does anyone know anything about neodymium magnets? I only thought of using them because I remember my chemistry instructor playing with two of them. It turns out they have iron and boron mixed in with the neodymium as an alloy along with "a few transition metals." Not sure if it would be reef safe, but do those magfloat scrappers use neodymium magnets? I know those things have really strong pull.

[EricM]

I was wondering about the type of magents myself. I had looked at ceramic ones, but I'm not sure that they will have enough power, or that they would be truly reef safe. I was thinking of making the "disc" that hold the magents a little thicker, so that the magent could be completely epoxy encased within the disc.

I was also figuring on using 1/8" nylon rod to connect the disc with the prop to avoid the need for any metal and change of size using the tubing.

And while it might be more complicated (and $$), I'm planning on a brushless motor to avoid maintenance and reduce noise. But it does make the controller more difficult to deal with.

[BeanAnimal]

The magnets MUST be uncased...

The drive plate must float on the motor shaft, or at least the magnets must be able to float against the thrust plate if the drive plat is rigidly attached to the motor. Most motors you will find do not have thrust bearings and will wear out if the shaft is "pulled" towards the glass.

Bean

[EricM]

Excellent point that the motor will not be able to withstand the "pull" on the shaft. That had not occured to me.

Not sure what the magents couldn't be encased.... take for example the magent cleaners... they are encased. The trick would be make sure the magent is strong enough to account for the additional thinkness. Am I missing something?

[BeanAnimal]

Nope... you cna encase them by drilling a flat bottom hole (forestner bit for example) and filling with epoxy... or using a half and half type of arrangment with a sealed perimeter.

The better mag scrappers use epoxy I think. The cheapies just have a glued on "lid"

Bean

[ghever]

maxijet to tunze conversion?? anyone care to point me in the right direction to read about this? sorry for threadjack..also interested in this vortech DIY

nevermind, found it... free bump

G

[dvanacker]

Cool DIY....but I find it funny how people are saying this is so easy yet I have not seen a picture or heard of one working model.

Has anyone actually built one yet. I know liveforphyics talked about it but I havent heard or seen pics of a working model.

[EricM]

Maybe by the end of next weekend I'll have a prototype.....
It's spring out, you know... to many things to do.

[sushi chef]

Alright, so the magnets must be encased, not too huge a deal I suppose; there are small neodymium magnets rated for 40 pounds of pull, should easily work through any epoxy or acrylic.

The drive plate must float on the motor shaft, or at least the magnets must be able to float against the thrust plate if the drive plat is rigidly attached to the motor. Most motors you will find do not have thrust bearings and will wear out if the shaft is "pulled" towards the glass.

As far as the motor goes, I think I understand what you are saying about the drive plate pulling on the motor's rod, BeanAnimal, but I'm not quite sure how the problem should be solved. If the plate is allowed to float then how will the motor be able to grip and spin the plate?

Something else regarding the motors: What kind of RPM and torque are we talking about here? Would a conventional DC brushless motor from a computer CD drive have the torque needed to turn the magnetic plates fast enough to create good adequate flow? If not, what kind of DC motor should be used?

[BeanAnimal]

A keyed shaft and keyed plate (a million ways to do this) would be all that is needed. The other option is to drill the holes in the plate for hte magnets and don't glue them in. Allow them to ride freely on the wear plate (in the same fashion that thrust bearings ride in a race).



Bean

[EricM]

sushi - that's my main issue right now - what size motor do I need. I'm trying to think ahead for long term reliability, ability to vary speed, and the potential to multiple "pumps" to a wavemaker type device.....

I'm pretty set on brushless for more efficiency, less noise, and no maintenace. But that makes the electronic controls more complicated.

[EricM]

Bean - hadn't thought about just letting them ride freely without being attached. I still may just use a flange thrust bearing to allow the magents to rotate just above a the glass (or thin plastic 'shield' as I'll probably use), so that the magents are not riding on a wearing surface. That gives me an easily replacable bearing should wear become an issue.

[ste6168]

I am thinking about making something like this to test out... I have a few questions though

1) How strong should the magnets be? would the 1/4"x1/8" disc magnets from this site work, or would they not be strong enough?

2) I think i read somewhere else that the MJ's rotate at 1800rpm so that would mean that an 80mm case fan that normally roates at 2700-3000rpm would work for the motor, right?

3) Should i have magnets to hold the two pieces together, or would the magnets used to spin the prob be strong enough?

4) Since the case fan is a DC motor i could just use a standard Potentiometer from radioshack per say, to adjust the rpm's of the fan, thus adjusting the flow rate?

Thanks, Mike

[Aquaduck]

Guys, I don't think a PC cooling fan motor is going to cut it. Your going to need more torque to spin the prop.

[ste6168]

Originally posted by Aquaduck
Guys, I don't think a PC cooling fan motor is going to cut it. Your going to need more torque to spin the prop.

yeah, i was kind of thinking the same thing, but looked them up and they spin 2500rpm... doesnt give torque even though it really shouldnt because it is a computer fan lol. What type of motor do you think would be best?

[ste6168]

yeah, anyway- i just opened up my computer and they do not take much of anything to stop, i really dont know if a computer fan will cut it at all.

Mike

[Trickman2]

Cool thread anymore Ideas on how to acomplish this...Parts and Pictures etc.

[ste6168]

Alright so there is my first drawings of the VORTECH style pump... I think that i am going to try and build something of this nature pretty soon. I figure that i will build the tank side very much like the MJ tunze mods only the SS rod will be held between the centerer piece and back 1/4" acrylic stationary while the rigid tubing will rotate freely on this. The magnets i will be using will be the 1/4"x 1/8" disk magnets fromthis site. The motor i will be using will be the GWS EM150 DC motor PKMOT-1006-A from this site. I will use a standard potentiometer from radio shack to control the speed of the motor. The drawing should be pretty self explanatory by the top one being the outside and the bottom being inside. Let me know if there are any other questions and i would be glad to answer them when i get the chance. Also if you have any sugestions for me, let me know.

Mike

[dvanacker]

I see magnets used to hold the two peices between the glass but doesnt there need to be magnets on the prop to make it spin??

[sushi chef]

Originally posted by BeanAnimal
A keyed shaft and keyed plate (a million ways to do this) would be all that is needed. The other option is to drill the holes in the plate for hte magnets and don't glue them in. Allow them to ride freely on the wear plate (in the same fashion that thrust bearings ride in a race).



Bean

I see. Thanks alot, I would have totally missed this

Eric:
I totally agree with you on the brushless motor thing. I'd readily sacrifice a little more money for less noise, more reliability, and more efficiency. It shouldn't be more complicated than a brushed DC motor, at least until you want to add on a controller right? I read that brushless motors need an electronic control board, where as the brushed ones can be controlled through a simple potentiometer. Other than that, if you weren't going to worry about a wave controller until later, could you just hook up the brushless like a brushed and just run it at max RPMs?