DIY stir plate problem

[Kmcogar]

Well, the DIY stir plate looked sooo simple. It actually was pretty easy. I am just really good at messing things up. Anyhow, I finally got it working. Its not throwing my magnet anymore! No loose wires! Nothing.

I'm just not getting the vortex. It puts movement in the water so I'm probably fine but I was wondering If anyone had some suggestions. How could I get it to vortex. I just want that "oh cool vortex!" factor.

Bigger stirrer? More power? Better fan?

I dunno you tell me. I made a quick YouTube video so you could see what was happening.



Thanks.

 

[matthewstn]

It looks like the magnet on the fan could be off balance. If you get the poles of the magnet to be perfectly centered on the fan the vortex will be dead center in the water because the stir bar's rotational path will be centered around one point rather than a larger area in the middle of the plate.

 

[TheDudeLebowski]

Does your stir bar have a ring in its center to lift it off the bottom of the flask? If not you can use a diptube rubber gasket from a corny keg and roll it onto the center of the stir bar. Gives a better stir to your starter by having space under the bar. Also, there's no hole cut out in the cigar box. Maybe the the strength of the magnets on the fan isn't strong enough. Try an experiment and take the fan out of the box and have nothing between it and the flask.

The magnets do look a little off center tho as previous post mentioned.

 

[krazydave]

That looks like you have the magnets wrong. Like you have them with their poles identical on both ends. So the stirbar is pushing away from one and sticking to other. It should be spinning dead center when it's correct.

If you're using two magnets. Try flipping one over and see if that helps.
The best way I found to get everything position was to epoxy a washer to the top of my fan. Get the epoxy on there and stick the washer on, then turn it on, adjusting the washer to get it balanced and centered. You have to do that step fast though if you're using fast setting epoxy.
Once that's done, you can just stick your magnets to the washer and move them around until you find the orientation that works.

I'm not sure what type of magnets you used, but the hard drive magnets NEVER worked for me. I'm an IT guy too, so I tried all different sizes and shapes of magnets. I could never get them to work very well though. Ace hardware sells these "Super Magnets" that are the rare earth variety and around 1/2" round. One of those on each side of my washer was all I needed.

 

[mdgagne]

I found that to get maximum vortex I had to tune the strength of my magnets. There are a couple ways of doing this:

1. Adjust the distance of the fan to the bottom of the box or
2. I used small button-sized neodymium magnets, one of each side of the fan's center section. I epoxied two down with their polarities opposite and just added/removed magnets until I achieved optimum vortex.

 

[stonebrewer]

I'm no expert but this looks to me like it is spinning a lot slower than mine does. I have a variable amplitude AC-DC power adapter that I use and this looks like what I see on very low amperage (amperage = speed in this case). How many amps DC is your adapter putting out?

I also had a similar issue when I used the small rare earth magnets from a more recent hard drive. I dug up one from 10 years ago and the magnet was much larger and more powerful. That made all the difference in the world. YMMV...

 

[william_shakes_beer]

That dimple is plenty big enough to act as a stir plate. However, if for whatever reason you prefer to suck the chrome off a trailer hitch with this thing, I found that the RE magnets interfere with the operation of the motor unless you install a spacer between the fan body and the magnets. A 1/2" wood gets disk epoxied to the fan and you epoxy the first RE magnet to the disk, then let the second magnet jump onto the first. Be sure when you mount the first magnet that you align the center of the stir bar magnetic field and the center of the RE magnet magnetic field with the geometric center of the fan. Just stick the stir bar on the first magnet, then move the magnet so the middle of the stir bar is in the center of the wood disk and glue down. Once the epoxy has dried, epoxy the other side of the wood disk to the center of the fan.

 

[Kmcogar]

Well, I took the fan out of the box. It did work a little better. It's almost there, but it just isnt right. I might cut a hole in the top to see if that helps. The stir bar does have the ring in the center. FYI. I had it do it definitely was balanced well but still not strong enough. The power source is 12V. the magnets are directly on the fan..... I didn't put anything in between the fan and the magnets. That could be it. The problem is I glued the magnets to the fan and they are stuck there pretty good. Ugh..... I'm gonna see if the hole thing works for now. I need it for a starter tonight. Then when I get time I will try to rip the magnets off the fan