Stir plate/stir bar problem

I made my own stir plate which is awesome, but I use a growler to make my starters and the stir bar won't stay on the bottom because it is slightly concave so every time I start the stir plate it falls off, anyone have any suggestions other than buying an Erlemeyer flask? Will a different stir bar work, the one I picked up at the LhbS is smooth and about 1 inch, don't know if a larger one will work or one that is octagon. Thanks.

No stir bar will work if it is supposed to be sitting on top of a dome of glass. You'll have to get a growler/bottle with a flat bottom or a flask. There has been some discussion on here about people using glass apple cider jugs with some success. I guess they must have fairly flat bottoms.

Check out this link, scroll halfway down to find some dumbbell shaped stir bars - those might work well in a growler like you describe.

My erlenmeyer flask has a slightly concave bottom and would throw off a standard stir bar. I switched to a barbell shaped stir bar and haven't had any more problems.

stratslinger said:

Check out this link, scroll halfway down to find some dumbbell shaped stir bars - those might work well in a growler like you describe.

Click to expand...

I tried this. They do not work at all. It's almost impossible to get them to stay in the middle of the growler while you set it down on the stir plate because they can roll. Then if you do manage to get it, it gets thrown just as easy as a regular stir bar. Save your money for sure.

Try 2 keg dip tube O rings. Space them out evenly from the center of stir bar, Hopefuly you can find a sweet spot that works.

Upgrade to a 1 gallon glass jug. It has a flat bottom. They are less then $5 at my homebrew store.

You could just go to Wally World and pick up a 1 gallon glass jar... I think they run like $7.

stratslinger said:

Check out this link, scroll halfway down to find some dumbbell shaped stir bars - those might work well in a growler like you describe.

Click to expand...

might as well buy a flask for that kind of money

Tinga said:

might as well buy a flask for that kind of money

Click to expand...

Fair enough point - I wasn't really paying attention to the price, to be honest - that was the first thing google gave me. I'm pretty sure there are cheaper suppliers out there though.

If your magnets are strong enough it will hold the straight 1" bar. I use a flask but I also have a growler, a 1 gal carboy, and a 1 gal. glass pickle jar all with concave surfaces and I can spin a straight bar in all 3 containers and pull a 2" vortex with the containers half full. I use (4) ceramic 3/8" magnets all touching each other in a straight line and they are right up to the bottom of the flask when I'm stirring. My stir plate has a 2.75" hole in the center which allows me to see the magnets and make total use of the pull force of the magnets by not having to pull through whatever your box/ plate is made of. I raised the magnets up almost touching the glass by stacking up layers of double sided tape and sticking the magnet to that. I originally was using only 2 magnets and couldn't get them to hold. I almost pulled the trigger by buying (2) 3/8" X 3/8" neodymium magnets but then decided to use 4 magnets instead and it works beautiful.
So if I was you and didn't want to buy a flask, I would mess around with the magnets because your idea of using a straight bar in a growler can work.

I just changed my configuration on my stir plate to work with a 1inch smooth round stir bar and the 1 gallon cider jugs, which have a very concave bottom.

The key is instead of having two opposing magnets, stack the two (harddrive in my case) and get it close to the bottom of your stirbar so it holds it tight. It does not work with my octagonal bar!!!! but it works great with the smooth one.

Also I upgraded to a true 12v power supply instead of the cell phone chargers. My first configuration worked like crap mostly because I had two opposite magnets on a washer attempting to catch my bar in the middle??!?!?! just use one or two stacked to do your stirring and it will work much better.