Suggestions for a good variable 12VDC motor?

[Electrobes]

Hey everyone, I am looking for a quality 30 rpm 12VDC motor. I plan to use it like the following, using an Arduino board and a motor shield:

- Half spin at 30RPM and the other half at about 4RPM (Would like torque to be anywhere between (20 lb-in = 2.2597 Nm to 40 lb-in = 4.5194 Nm)

Does anyone have any good recommendations for a motor that can handle this well?

Thanks!

 

[Electrobes]

I am pretty unfamiliar with electric motors in general, and what they are capable of, I am curious to know if something like this would work for my application?

http://www.ebay.com/itm/1Pcs-DC-12V...899?pt=LH_DefaultDomain_0&hash=item20db1618bb

 

[Amoque]

It is difficult to say, Christian. The picture shows a 24V rating and you ask about 12V... Of course, if you intend on controlling RPM (presumably with PWM) most any RPM output higher than your need should work. Perhaps if you explained what you intend to drive, it would be more clear what motor would be suitable.

Some things that may help to determine your success...

*Do you need to reverse the motor or are you running in only 1 direction?
Will you run the motor continuously or what percentage of the time will it be on?
*Do you need to "track" the motor position (you mention "Half spin at 30RPM and the other half at about 4RPM" - is this 1/2 of each rotation at the RPM you list, or are you planning on more than 1 motor)?
* You didn't mention a gearhead in your post, but the motor linked has one - optional?

I would google "robot motor" or "drill motor"; also, maybe look at specs on commercial units that do a similar task to what you intend. Arduinos are incredibly popular, but I'm a PIC guy and unfamiliar with the motor shield, so not terribly competent help on the control side, but you should look and see just how many amps you can deliver and what your control range is.

 

[Electrobes]

Ack, I did screw up the Voltage (I meant 24V) and I should have been way more specific:

- It does not have to run in reverse.. one direction is fine.
- It will run continuously.
- I know which motor you're talking about (The type that is) but I was planning on using Hall Effect sensors in conjunction with an Arduino Board to control speeds in position. I only require one motor.
- I only think a gearhead would serve best for my application, based on general information about types of motors, so I could be very well wrong in thinking gearhead motors are best suited for me.

I did find an appropriate H-Bridge for most motors (It's way about the amperage I need). The only info I usually lack is the amount of noise it makes, but at this rate it's something I'll just have to deal with.

Thanks!

 

[Electrobes]

And welcome to reef central, btw!

 

[Electrobes]

So after a while searching I found this motor, and am thinking it will do the trick nice. What do the DIY people think?

http://www.ebay.com/itm/1Pcs-DC-24V...761?pt=LH_DefaultDomain_0&hash=item20db67ca41

 

[zachts]

If I may, what are you making? That's a lot of money for a motor for anything DIY in our hobby. If you are considering spending hundreds contact a motor company like Pittman-Ametek or any of a dozen others and give them your specs and needs. They can get you the exact motor you need with warranty.

Still need to know what your making, but know that gear drive motors are noisy but efficient and provide a ton of torque compared to direct drive motors. If you need silence that will be more costly and much harder to find.

Low RPM a gear drive is probably going to be best but you should consult a reputable company to help find the best motor/gear combo for your needs.

 

[Electrobes]

Zachts: Thank you for the suggestion, I will contact that company. Do you have others that you would recommend?

I wasn't going to say what I am trying to create, but honestly, I might as well. I am creating a water moving device that mimics the the slower waves in shallow reefs. I find the current items like the Waveboxes/wavemakers to be far too quick than found in nature. I understand it's the bounce back of water in a container, that keeps the water motion bouncing to and fro too quickly (There is much more, but that draws attention away from the intention of this post).

My device is pretty simple in design, but only works for particular tanks... ones that have a fairly flat back (including overflow.. unless separate units are used.). Anyway, I basically use a fin (For my 48" half cylinder, I plan on using a 36" fin that is about 1/4" or less thick and about 3" deep... out of acrylic.), and it's connected to a motor that forces the brackets of this fin to go up and down (I am using an Arduino and a H-Bridge to control the motor.. the Apex can't do what I need it to).

The fin is angled about 20 degrees.. with the downed end facing the back of the tank and the higher end facing the front of the tank.

The programming of the motor basically has it do the following:

- During half of the cycle that pushes the fin down (From the top of the aquarium to the floor) the motor ups it's RPM (I am estimating to about 45 RPM) to make an appropriate wave. I will have the programming randomize the speeds (Within a set parameter) of the wave... making all the waves a bit different in strength.. like the actual ocean.

- During half of the cycle that lifts the Fin back up towards the top of the aquarium, the motor is slowed (Enough to have about 6-7 "waves" per minute).

As crazy as it sounds, my goal is for this to be the only form of water movement (Minus the return pump spraying the back of the fins, vertically, to help move freshly filtered water forward).

Anyway, that's what I need the motor for. I basically need a strong motor that can deal with the constant change in workload. It being quiet would be a bonus. I unfortunately do not know what kind of torque I need to accomplish this task. I am trying to play it safe and say I need about 60+ lbs-in (about 6.78+ Nm). More would be better.

Thanks again!