Non-Flat Erlenmeyer Flask Solution?

I have searched and found people talking about that some of the cheaper Erlenmeyer flasks can have concave bottoms instead of flat and such, but I haven't been able to find if anyone has a solution.(By the way, mine was $30 from the LHBS for a 2L, so I wasn't really trying to go cheapo)

I am wanting to use this with my stirplate, but it keeps throwing the bar. I know it isn't an issue with my magnets not being lined up because I can put the stirbar into a flat bottomed bowl or even on a notebook on top of my stirplate and it spins like crazy with no signs of being thrown.

I am just wondering if anyone out there has come up with a solution for this at all? Otherwise I might try to take it back, although I bought it about 3 months ago, so likely they won't take it back even though there is no sign of usage.

Does your stir bar have a pivot ring? If not that might help. I use gallon glass jugs and they have a somewhat domed bootom and I don't have any trouble with thrown stir bars. All my stir bars have pivot rings though. I can't think of any other solution.

BBL_Brewer said:

Does your stir bar have a pivot ring? If not that might help. I use gallon glass jugs and they have a somewhat domed bootom and I don't have any trouble with thrown stir bars. All my stir bars have pivot rings though. I can't think of any other solution.

Click to expand...

+1 on the pivot ring. One of my flasks had the same issue and frequently threw the bar. I went with a slightly longer bar with a pivot ring and this fixed the issue for me. I'm not sure if it was just the pivot ring or the longer length that helped it hook up better to my magnets...or maybe a combination of the two, but I'd try the pivot ring approach.

Now for the pivot ring, could I just use say an o-ring for the pivot point or no? It absolutely shouldn't be an issue of the bar being too small, it's a 2" bar in a 2L flask.

Actually, barbell-shaped stirbars are far better when working with a flask like that. And just by looking at them, it's easy to see why.

For example: http://www.brewmasterswarehouse.com/product/0102250/magnetic-barbell-stir-bar-1-inch

absoluthamm said:

Now for the pivot ring, could I just use say an o-ring for the pivot point or no? It absolutely shouldn't be an issue of the bar being too small, it's a 2" bar in a 2L flask.

Click to expand...

If you have a small o-ring lying around that fits really tight, give it a try with some water in the flask and see if it works. You'll have to get it centered perfect and the o-ring might drift after a while. If it deosn't work, try buying a better stir bar. The ones emjay posted look pretty cool. If I didn't already have a working set up, I might try those myself.

So I went and got some o-rings to try to no avail. One being in the middle, it still gets thrown, I think mostly because it is still on the concave surface and needs to be balanced absolutely perfect. I tried an o-ring on both ends and can't even get it to do 2 rotations before it gets thrown. I think it's because the o-rings are rubber and they don't have the low friction surface like the Teflon does, so it "sticks" and gets out of polarity and throws.

I have been trying to see if I can get Brewmaster's Warehouse to swap my current stirbar, which I ordered from them last week, to the barbell, but I don't really agree with what they're trying to do with the situation, so we'll see if I'll be going through them.

They should be available from lots of places. I just used a BMW link because it was the first thing to show up in my Google search.

However, I don't know of any HB stores that will completely eat the cost of an "error" on the customer's part, so hopefully it's not something you'll boycott them over.

It's more just that it is something so small. I have had to return many things online before and haven't had a problem exchanging anything. If you're returning something and not getting something else instead I understand when places charge restocking fees since you're not making another purchase.

Really, it just comes down to the shipping not that they wouldn't take a return. I'm not going to pay $7 to ship something that is 1 1/2" long when it can be placed in a folded envelope and shipped for $0.90, ya know?

Shipping is a PITA.

absoluthamm said:

Really, it just comes down to the shipping not that they wouldn't take a return. I'm not going to pay $7 to ship something that is 1 1/2" long when it can be placed in a folded envelope and shipped for $0.90, ya know?

Click to expand...

its not worth 90 cents to them to take the time out and do it. $7 is to pay the person who has to put it in the envelope, print the lable, get postage, and ship it. if they only deal with UPS or FEDEX and not USPS, then there is not an easy way to simply 'drop it in an envelope' for 90 cents. they have to go out of their way.

you are asking them to do you a favor. dont get mad at them if they refuse.

I had the same problem with my stirbar and I refused to come off the money for a real flask so I use the glass jar from my french press coffee maker for a flask. Flat bottom but the volume is a bit low, it works great for my purposes and if I need more yeast I just make two starters

The other option is to try and adjust the magnets on your stirplate if it's one of the ones built from a fan. It sounds like the magnetic coupling isn't enough to hold it in place.

A proper (like lab equipment type) stirplate won't throw a bar just because of a concave bottom. On mine (a surplus lab unit) I can actually pick up the flask and move it around (and thus move the stirbar) to knock stuff loose around the edges.