Stir Plate Using Hard Drive Spindle Motor

Hi,

First off, let me just say that, although I’ve done some wiring and soldering and the like, I’m not an electrician by any stretch of the imagination. With that in mind . . . . .

I’m trying to convert an old hard drive into a magnetic stir plate basically using the directions found at http://tutorialtub.com/info/build-a-...n-old-computer. I’ve got an old Seagate barracuda model# ST118273LW that I was hoping to use. One reason I was thinking about using a hard drive spindle motor instead of the pc cooling fan was so I could have something strong enough to use to aerate an entire 5-6 gallon batch if I wanted to. I’d probably order a 4” long rare earth magnet for the bass and another 4” rare earth magnet for the stir bar. Any suggestions?

Anyway, I plugged a power supply from another computer into the hard drive and it started up fine. Then I popped the top off and removed the arm and magnets leaving only the spindle motor & platters inside. When I plugged it back in and powered up nothing happens. What’s going on? Is it possible that in removing the arm I took out some circuitry necessary for a start up diagnostic or something? If so can this be bypassed? Do I need to do something with the jumpers maybe? If I remove the spindle motor (3 posts) is there a way to wire it up without using a controller or anything and just be able to control the speed with a dial of some sort?

Thanks,
evenstill

I need to know... why are you stirring 5 gallons? Sounds like a cool project though. Can you isolate th motor and remove everything else? It is possible that one of the leads to the motor ran through the arm or another component now removed.

Good luck, and if you do spin up a 5 gallon batch I want pictures!!! :rockin:

A drive motor spins far to fast to use in a stirplate. Also, the magnetic coupling between the stir plate and the bar limit how much power will be available to spin the bar, not the motor itself.

evenstill said:

Hi,

First off, let me just say that, although I’ve done some wiring and soldering and the like, I’m not an electrician by any stretch of the imagination. With that in mind . . . . .

I’m trying to convert an old hard drive into a magnetic stir plate basically using the directions found at http://tutorialtub.com/info/build-a-...n-old-computer. I’ve got an old Seagate barracuda model# ST118273LW that I was hoping to use. One reason I was thinking about using a hard drive spindle motor instead of the pc cooling fan was so I could have something strong enough to use to aerate an entire 5-6 gallon batch if I wanted to. I’d probably order a 4” long rare earth magnet for the bass and another 4” rare earth magnet for the stir bar. Any suggestions?

Anyway, I plugged a power supply from another computer into the hard drive and it started up fine. Then I popped the top off and removed the arm and magnets leaving only the spindle motor & platters inside. When I plugged it back in and powered up nothing happens. What’s going on? Is it possible that in removing the arm I took out some circuitry necessary for a start up diagnostic or something? If so can this be bypassed? Do I need to do something with the jumpers maybe? If I remove the spindle motor (3 posts) is there a way to wire it up without using a controller or anything and just be able to control the speed with a dial of some sort?

Thanks,
evenstill

Click to expand...

Couple thoughts -

Do you have a reason to believe that the hard drive motor is more powerful than a fan motor? Spec sheet from the manufacture? Once the hard drive spins up it takes little power to make it continue spinning, just enough to overcome whatever friction is in the system. A fan, on the other hand, has a substantially greater amount of resistance to overcome due to it constantly pushing air. Without having spec sheets in front of me I'd guess that the fan motor is more powerful than the HD spindle motor.

To spin a 4 inch stir bar at any rate of speed it will have to be manufactured to pretty high tolerance to be balanced and not get thrown. The longest stir bar I see on Cynmar's site is 2"

Your stir bar must be food safe, you can't just drop a 4" rare earth magnet in there, some of the material might dissolve in your wort. Rare earth magnets also tend to be fragile, simply having one spinning around in contact with the bottom of the container could lead to bits coming off. Many a child has suffered a perforated bowel from swallowing magnets from their toys and having them "find" each other from different places in the small intestine. We want you to remain healthy and enjoying your homebrew for many years!

Stir plates are great for continuously aerating a yeast starter. You only need to aerate your 5-6 gallon of beer once (I am assuming your not doing a 5 Gallon starter). The yeast will consume that oxygen during the reproductive phase of their life. Aerating later will lead to oxidizing you beer, which is bad. Realistically when you pour the wort through a funnel into a carboy or just pour it into a plastic bucket fermenter your aerating pretty well. If you really want to give it an extra shot of air a simple aquarium pump, filter, and diffusion stone would be a inexpensive alternative.


Anyway, good luck with your project.

Boerderij Kabouter said:

I need to know... why are you stirring 5 gallons? Sounds like a cool project though. Can you isolate th motor and remove everything else? It is possible that one of the leads to the motor ran through the arm or another component now removed.

Click to expand...

I also brew wine and wines can do better if they are super oxygenated for the first few days. I took the motor out of a couple other old hard drives but haven’t been able to get them going either. Maybe they need a controller or something. One has 3 posts and the other has 4 posts.

david_42 said:

A drive motor spins far to fast to use in a stirplate. Also, the magnetic coupling between the stir plate and the bar limit how much power will be available to spin the bar, not the motor itself.

Click to expand...

I see what your saying.

camiller said:

Couple thoughts -
Do you have a reason to believe that the hard drive motor is more powerful than a fan motor? Spec sheet from the manufacture? Once the hard drive spins up it takes little power to make it continue spinning, just enough to overcome whatever friction is in the system. A fan, on the other hand, has a substantially greater amount of resistance to overcome due to it constantly pushing air. Without having spec sheets in front of me I'd guess that the fan motor is more powerful than the HD spindle motor.

Click to expand...

Makes sense . . . I hadn’t thought of that. Well, I figured that higher rpm’s would equal more power. Maybe “power” isn’t the word I’m looking for . . . would more fluid even require greater speed or just a larger stir bar?

camiller said:

To spin a 4 inch stir bar at any rate of speed it will have to be manufactured to pretty high tolerance to be balanced and not get thrown . . . . . Your stir bar must be food safe . . . . .

Click to expand...

I was thinking about getting two of these magnets (one for the base and the other for the stir bar itself): http://www.magnet4less.com/product_info.php?cPath=1_5&products_id=78 and coating the one used for the stir bar with a food grade Teflon, vinyl or epoxy.

Also, I’ve seen a lot of posts on this topic where people have the magnets stop the fan motor from spinning . . . why not just glue a piece of sheet metal to the fan first then glue your magnet to that? Wouldn’t that shield the fan motor from the magnetic field? It would also seem to make sense to cut the blades off of the fan first to lesson the weight and resistance.

evenstill

evenstill said:

Also, I’ve seen a lot of posts on this topic where people have the magnets stop the fan motor from spinning . . . why not just glue a piece of sheet metal to the fan first then glue your magnet to that? Wouldn’t that shield the fan motor from the magnetic field? It would also seem to make sense to cut the blades off of the fan first to lesson the weight and resistance.

evenstill

Click to expand...

I wouldnt trim the blades off, it would be a PITA to balance the fan again. Also I dont believe speed is a problem with the fans.

As for using the hard drive platter motor. They are geared for high RPM, not torque. I would be surprised if you could get it to work at all. Could be worth a try though

Thought about the magnet...
http://catalog.miniscience.com/Catalog/Magnets/Cow_Magnet.html

Stainless steel is pretty food safe ;o)

conpewter said:

Thought about the magnet...
http://catalog.miniscience.com/Catalog/Magnets/Cow_Magnet.html

Stainless steel is pretty food safe ;o)

Click to expand...

The stainless steel one says:

COWMAG1462 is not recommended for science experiments and industrial applications where the magnet may be subject to pressure or vibration.

Click to expand...

The other one is not stainless steel. I don't know if the kind of use we are contemplating here would count as vibration.