stir bar jumping

[DeepSea]

I am making a stir plate and am having trouble getting the 2.5 inch stirbar to stay put. It jumps off at the lowest speed. The flask is virtually sitting on the hard drive magnet. I am using a 5000ML flask. Do need to buy a larger magnet? Thanks for the help

DeepSea

 

[wyzazz]

Try slowing the speed down and bring it up off the magnet a bit. If that doesn't work then you'll probably need a stronger magnet. A 2.5" stirbar is pretty hefty and needs a strong magnet.

 

[passedpawn]

I am making a stir plate and am having trouble getting the 2.5 inch stirbar to stay put. It jumps off at the lowest speed. The flask is virtually sitting on the hard drive magnet. I am using a 5000ML flask. Do need to buy a larger magnet? Thanks for the help

DeepSea

I've been down this road, pal.

to get a long bar to spin (I use a 2"), you need to either use a long magnet or space two "oppositely-polarized" magnets apart about 1.5". I did the latter with stacks of those round magnets. I posted some pics at the end of the epic stir plate thread.

Alternatively, I bet you could spin a 1/2" bar no problem. It will pull nice vortex down a 4L Erlenmeyer flask (I've built a few of these).

 

[DeepSea]

I've been down this road, pal.

to get a long bar to spin (I use a 2"), you need to either use a long magnet or space two "oppositely-polarized" magnets apart about 1.5". I did the latter with stacks of those round magnets. I posted some pics at the end of the epic stir plate thread.

Alternatively, I bet you could spin a 1/2" bar no problem. It will pull nice vortex down a 4L Erlenmeyer flask (I've built a few of these).

I already have (2) two inch stir bars I would like to use. Can you suggest where I find a large magnet? Does HD or lowes have anything that would hold a 2.5 inch bar? I have seen regtangle shaped ones? Would that work?

Thanks

 

[diatonic]

Rare earth magnets from Harbor Freight?