Building a stir plate, check out this USB adjustable computer fan

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Just finished getting my 2 stir plates together and tested with water. I threw in some pepper so I could see how well it would suspend the yeast AND looks like it will work wonderfully! Just curious how to be sure not to drop the stir bar into the fermenter? I almost lost it down the drain when pouring out my pepper-water...




Well that answers that.... Pretty Slick!

Grab an extra magnet and stick it to the bottom of the flask before pouring...the stir bar wont move :D
 
drewmedic23 said:
Grab an extra magnet and stick it to the bottom of the flask before pouring...the stir bar wont move :D

That'll work but it can be awkward.

As we all know, stir plates are commercially manufactured and used in all sorts of actual laboratories. So obviously, there should also be a solution for this issue that's manufactured and used in actual laboratories. There is, and they're called retrievers:

b_l_stir_retriever.jpg


They're basically just long sticks with a magnet at the end. The magnets are coated with an inert substance, usually Teflon, which allows it to remain food-grade. It doesn't take a genius to see that you can make one by using an extra stir bar for the magnetic tip, using something like small-diameter stainless steel pipe for the shaft. Or you can save yourself the trouble and just buy one... they're not that expensive. You just stick it in the flask and pull it out with the stir bar. It's easier than trying to hold the stir bar in place with a magnet on the outside while simultaneously pouring it out... it's the standard for a reason.

That being said... I don't have any problem at all keeping the stir bar in the flask while completely pouring it out. The only time it will end up in the fermentor is if I forget the bar is in there, in which case no magnet or retriever would be of any help anyways.
 
A little thread necro to recommend a different type of product. That lab-grade retriever sure is cool, but probably pricy. Automotive shops have been using telescoping poles with magnets on them for years.

Here's one for $5 at Harbor Freight before coupons. I think I'll be picking one up soon.
 
A little thread necro to recommend a different type of product. That lab-grade retriever sure is cool, but probably pricy. Automotive shops have been using telescoping poles with magnets on them for years.

Here's one for $5 at Harbor Freight before coupons. I think I'll be picking one up soon.

You didn't actually include a link, but that could be a good thing as I doubt an automotive retrieve has a food-grade coating, and magnets themselves are not considered food-grade.
 
Yup. Not food grade. Stay away from it if you're the type that can't trust a cooler mash tun because it contains plastic. :eek:

If you're that worried about piece of non-food-grade steel that touches your beer for at most 5 seconds, consider this: touching a wrench, door knob, or car key, then making hand-to-mouth contact (eating a sandwich, biting a fingernail) without washing your hands first will give you a larger dose of nastier chemicals and we do it constantly.

Unless you're auto-immune compromised, it's not going to harm you. And really, if you're going to go all-out, you'd probably be better off having your stir bar tested for residual lead from the Chinese factory that made it.
 
Don't want to start up and old thread, but I may have some useful information. I have been looking into getting a magnetic stirrer and in most of my searches all I could find were stirrers from ~$90 to $200...not gonna happen. In one of my searches I came across: the Bell Brewery stirrer. I was going to go with the DIY stirrer. I really like the design, but then I added up the cost. For $40, the Bell Brewery stirrer isn't much more than building your own. Granted you don't get the satisfaction of a DIY project and I don't know what, if any, shipping costs are, but it is another option.
 
I figured one way to show my appreciation for all the great reads here is to post something that might encourage someone else to take a shot at building one of these.

I used the 120mm fan from Amazon, but I might use the 80mm for my next one.

This couldn't have been easier--all told this cost me around $30 but I had to acquire everything from scratch. Made my first starter for a batch of saison over the weekend. If you're on the fence just do it.

A couple of photos:
2r7oqo4.jpg

2ns5onr.jpg
 
Intense vortex. I'm amazed it has that much power as the 120mm fans are typically lower speed and torque, but I've seen it suck vortexes in 5L flasks filled to the 5.5L mark to the point that air bubbles hit the stir bar.
 
Just ordered the 80mm fan and some stir bars. Excited to finally build a stir plate. I harvested magents from a laptop almost two years ago now.

At this rate, I might have this project done by 2020.
 
pbnj-
i'm attempting a DIY with a gallon glass wine jug like i see in your picture. With the bottom of the jug beveled, I was hoping you could tell me how you are keeping the stir bar centered. once i get it there, it is flying off. different type of stir bar?
 
Thanks to this thread I ordered the 80 mm fan. I was not sure what to use for a case, so I used the Amazon box it shipped in. I still have to dial in the height of the fan, but looks like it will get me by until I get a more suitable enclosure.
 
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