My shamelessly cheap $12 DIY stir plate

[tre9er]

I've found that more magnets is always better -- you want a strong connection. But my 2" stir bar in a 2L starter is too hard for the fan to turn. A 1" stir bar in the same starter works fine.

Well that stands to reason to a point, though. Stacking magnets brings them closer to the flask, too. Mine are darn-near flush with the bottom. These are strong-ass magnets, too. Hard to even separate by hand. I think being THAT close makes it difficult for a fan motor, used to spinning just a plastic blade, to spin the weight of the washer, magnets, and now the increased resistance from the magnetic force.

 

[troyh]

Is your fan motor separated from the magnets? I found that I couldn't just glue the magnets directly to the fan, I had to put a spacer between them. I think the magnets interfered with the magnetic field in the motor.

 

[tre9er]

Is your fan motor separated from the magnets? I found that I couldn't just glue the magnets directly to the fan, I had to put a spacer between them. I think the magnets interfered with the magnetic field in the motor.

no, they didn't separate. I was saying that they're so strong it's hard to even separate them from one another (I have three stacked on top of each other on each side of the washer, which is in-turn glued to the fan). I was saying they're hard to even pry off of one another, so that's how strong they are and perhaps getting them so close to the flask/stir-bar was creating too much magnetic "friction" for the motor to handle.

 

[troyh]

I meant that they have to be farther away from the fan. Before I put a spacer between the fan and the magnets I had similar issues that you seem to have.

In one stir plate I used a half-inch piece of PVC conduit as a spacer and a real aluminum spacer in the other. The spacer is glued to the fan and the magnets are glued to the spacer.

 

[tre9er]

I meant that they have to be farther away from the fan. Before I put a spacer between the fan and the magnets I had similar issues that you seem to have.

In one stir plate I used a half-inch piece of PVC conduit as a spacer and a real aluminum spacer in the other. The spacer is glued to the fan and the magnets are glued to the spacer.

Yeah, I have a zinc washer glued to the fan and the magnets stuck to that. Never had any issues with my pickle-jar but the 1L flask does. Like I said, the pickle jar has a convex bottom so the stir-bar is further away from magnets, and it seems to work well in terms of starting up and not stopping.

 

[tre9er]

Mine is setup almost exactly like this guy's

https://www.homebrewtalk.com/f51/yadiy-stir-plate-thread-279569/

 

[troyh]

Magnets can stop the motor, I'd try separating them. But if it works in one container and not in the other, it doesn't make sense to me. I don't understand why the stir bar being further away would be better, unless the magnetic field created around the stir bar and magnets is bigger and is enough to stop the motor while a smaller field doesn't. But then again, I have very little understanding of physics.

Try lifting the flask a little above the plate with shims and see if that improves it and validates your theory. FWIW, my flasks all have slightly convex bottoms.

 

[jperry]

I failed terribly at building this one, everything went wrong. Also, I accidently pulled the wire out that controlled the speed. trying agin tomorrow with a new fan.

 

[NewBrewB]

I failed terribly at building this one, everything went wrong. Also, I accidently pulled the wire out that controlled the speed. trying agin tomorrow with a new fan.

This is one of the smallest diy projects but that also means most people are finished before they document anything. Makes it tough to overcome issues. Hang in there. You will get it!

 

[jperry]

This is one of the smallest diy projects but that also means most people are finished before they document anything. Makes it tough to overcome issues. Hang in there. You will get it!

Thanks for the encouragement... I actually re soldered the speed control wire, that broke off the circuit board. and have continued with the build, I'm almost done and everything is coming together!

 

[bfinleyui]

When I built mine last night, I soldered it all together, realized I had my toggle soldered backwards. Snipped the wires, soldered it back up, realized I screwed up and soldered it backwards again. Finally mocked it up correctly the third time, soldered, and now it spins like a dream. You can dooooo it.

 

[davekippen]

First run with my home made toy tonight! Thanks to all who contributed!

 

[bwirthlin]

Here's mine, this USB speed control fan is the dopest!

 

[Kyled93]

Well, here is mine.

Nothing like having you dad in the same hobby as you make you a stir plate. Love the use of the cigar box!

 

[DenverUSMC]

Here's mine, this USB speed control fan is the dopest!

:rockin:

 

[NWAleDad]

Here is mine. Used a $3.99 piece of Tupperware from the container store.

 

[SudsyPaul]

Haven't glued the magnets down, yet, but this about how well it should work, right?

https://www.youtube.com/watch?v=wYz7AVB67dk&feature=youtube_gdata_player

 

[DenverUSMC]

Haven't glued the magnets down, yet, but this about how well it should work, right?

https://www.youtube.com/watch?v=wYz7AVB67dk&feature=youtube_gdata_player

If you get that rattle noise, slip a piece of rubber tubbing over the stir bar.

 

[SudsyPaul]

I'll see what I can find before tomorrow. If not, it'll just make that noise for 24hrs

If I slow it down a bit, it stops making noise, but the vortex doesn't reach the stir bar.

 

[DenverUSMC]

I'll see what I can find before tomorrow. If not, it'll just make that noise for 24hrs

If I slow it down a bit, it stops making noise, but the vortex doesn't reach the stir bar.

Doesn't need to reach the bar in my opinion.

 

[Arrheinous]

I believe you've singlehandedly gotten me interested in starters.

 

[NWAleDad]

I'll see what I can find before tomorrow. If not, it'll just make that noise for 24hrs

If I slow it down a bit, it stops making noise, but the vortex doesn't reach the stir bar.

any benefit from the vortex hitting the stir bar?

Always figured that it was best to keep the yeast in suspension. I set it to the lowest setting and check for sediment when i walk by.

 

[SudsyPaul]

Gonna walk over to home depot. What kind of tubing is safe? I honestly can't picture tubing that's light/thin enough.

 

[SudsyPaul]

I saved my self some undesirable winter-walking. I put the stir bar into a 1" piece of 3/8" siphoning tubing, and BOOM, quiet as a mouse. The bar is a bit more susceptible to being tossed out if I go too fast, but it works fine when creating a vortex about 50% of the way down.

 

[DenverUSMC]

I saved my self some undesirable winter-walking. I put the stir bar into a 1" piece of 3/8" siphoning tubing, and BOOM, quiet as a mouse. The bar is a bit more susceptible to being tossed out if I go too fast, but it works fine when creating a vortex about 50% of the way down.

Sounds like you're good to go

 

[michgan241]

Hmm so i scavenged an old computer fan and wired to a USB plug that i then plugged into a phone charger and its running the fan now, but i dont think its 120mm will i still be able to use this for a stir plate you think?

looks like its 80mm fan.

worst case scenario would i be able to glue a washer to the fan then a larger washer onto that to get a wide enough rotation for the stir plate?

 

[jperry]

Hmm so i scavenged an old computer fan and wired to a USB plug that i then plugged into a phone charger and its running the fan now, but i dont think its 120mm will i still be able to use this for a stir plate you think?

looks like its 80mm fan.

worst case scenario would i be able to glue a washer to the fan then a larger washer onto that to get a wide enough rotation for the stir plate?

The 80mm fan is better, than the 120mm fan, because it operates a much higher rpm. I've read a few threads on here that mention that info.

 

[ishredthecello]

can the 80mm fan drive a 2000ml starter?

 

[NWAleDad]

can the 80mm fan drive a 2000ml starter?

yes, i use a 200ml Erlenmeyer flask and it works great.

 

[ishredthecello]

yes, i use a 200ml Erlenmeyer flask and it works great.

What size stir bar do you use? 1"?