Tight Arse Stir Plate

[Trough Lolly]

As a result of stuffing around with the voltage all day, I now have all the DC power packs around the house in my possession - and boy, don't we have a decent collection of them?! Every bloody phone charger, answering machine unit, camcorder charger etc - I've got a slew of them on my workbench!!
TL

 

[Ross]

As a result of stuffing around with the voltage all day, I now have all the DC power packs around the house in my possession - and boy, don't we have a decent collection of them?! Every bloody phone charger, answering machine unit, camcorder charger etc - I've got a slew of them on my workbench!!
TL

[post="129535"][/post]​

I know the feeling TL - i bought one for my stir plate & then realised when I got home, that we have over a dozen redundant transformers i could have used <_<

cheers Ross

 

[Trough Lolly]

Yup....and when you're trying to measure the gap between the end of the rare earth elliptical magnet and the outer edge of the fan with a ruler - don't use the METAL tape measure! Grab a timber ruler from the kids and you've got a lot less 2 part epoxy to clean up...!!
I think I'll call it quits, grab a beer and watch the footy - and do the centering of the magnet in the morning!!
Cheers,
TL

 

[Trough Lolly]

TL
Has anyone thought about a Train Controller....Would it work...???? if so
Tell the Kiddies Daddy wants to play with it....
Cheers
PJ

[post="129528"][/post]​

//Totally unqualified wildassed guess follows//
I suppose it would - it depends on the output voltage and current. My old CB Radio transformer is a regulated 13.8V supply that can push a couple of amps under load - which is way above what the 12VDC 200mA fan needs...

Cheers,
TL

 

[sosman]

I'm also getting cavitation from the fan - which I didn't think was a problem

Hmmm, the fan is not supposed to be inside the wort.

 

[vlbaby]

I'm also getting cavitation from the fan - which I didn't think was a problem

Hmmm, the fan is not supposed to be inside the wort.

[post="129691"][/post]​

I think TL means vibration not cavitation.


vl.

 

[Trough Lolly]

Quite so - apologies for the Red October freudian slip!!

I think my problem may be with the distance between the magnet on the fan, it's centering on the fan and the distance between the magnet in the case and the stir bar - I bought a large case, big enough to comfortably sit a 2L flask and thus, its deeper than the smaller models - I have added some nuts to the bolts holding the fan in place so I can adjust it's height in the case, and thus bring the whole assembly with magnet closer to the underside if the top of the case.
If this cunning plan fails, I'll ditch the elliptical magnets and buy a couple of cheap bar magnets from Jaycar...
Cheers,
TL (who's off to Adelaide for a couple of days tomorrow - will be lurking in the vicinity of the Stamford Plaza bar!!)

 

[Damon]

Not sure what the Motorola motor driver circuit costs but as an option you could use either the top or bottom circuit of the attached to drive a fan up to 3A (3A might be a bit of overkill...). It uses a 555 timer to adjust the PWM applied to the fan and hence the speed for those that are electronically minded. This circuit can adjust from 0% to 100% drive.

Cheers,

Damon

View attachment stirrer.PDF

 

[goatherder]

I finally made it to dick smith to pick up the pot. I ended up grabbing the 500 ohm 3W wire wound job, I figured it would be pretty hard to burn that fella out. It's just wired up in series with the fan, easy as that. It works a treat.

Here's a pic, thanks to everyone who posted for your ideas and methods.

 

[Jye]

Nice one goatherder Did you have any problems with the magnet?

 

[goatherder]

Thanks Jye, your photos were a great help.

At first I couldn't work out why the fan wouldn't turn the magnet. The fan would start to spin but would just sit there and quiver. I think the magnet was interfering with the motor, so I stuck a 3/8" washer under it which made it go. I guess my fan didn't have a metal bit under the centre like some pics i've seen.

I was a bit lucky when I glued it all in, I must have got it almost centered. If I keep the speed low enough, the stirrer doesn't develop any precessional movement. I reckon if I want higher speed i'll have to raise the fan up a bit inside the case with some spacers. I should be OK without it though.

I ran it non-stop overnight in the 2l flask and it was still running happily this morning, with no signs of overheating. Now I just need to wait for the wyeast order to come in.

 

[andreic]

Hi all,

just went to Jaycar today to get those "oblique-spheroid hematite magnets". They are on special this month - $6 instead of $15.

Since the thread is titled "tight arse" I thought some others might be interested in a $9 saving...

cheers,

Andrei

 

[goatherder]

dammit, i only got mine two weeks ago

 

[laurent]

Thanks Jye, your photos were a great help.

At first I couldn't work out why the fan wouldn't turn the magnet. The fan would start to spin but would just sit there and quiver. I think the magnet was interfering with the motor, so I stuck a 3/8" washer under it which made it go. I guess my fan didn't have a metal bit under the centre like some pics i've seen.

I was a bit lucky when I glued it all in, I must have got it almost centered. If I keep the speed low enough, the stirrer doesn't develop any precessional movement. I reckon if I want higher speed i'll have to raise the fan up a bit inside the case with some spacers. I should be OK without it though.

I ran it non-stop overnight in the 2l flask and it was still running happily this morning, with no signs of overheating. Now I just need to wait for the wyeast order to come in.

Hi,

I did almost the same thing. Only, I glued the magnet to the fan using Blue Tac. Very strong and I can still move the magnet around to reduce vibration. Did you get the vortex up to the bottom of the jar? Sometimes when the speed is too high my stirrer jumps around and might break the jar. I suspect it might be too heavy. I'll try to find some real stirrers. Anybody has one spare for sale?

Cheers,
Laurent

 

[crozdog]

I pulled a few old hard disks apart over the weekend. Each one had 4 rare earth magnets for driving the arm to move heads over the platter. :beerbang:

I dunno if they were glued or spot welded onto the mounts, but a few minutes with a grinder (bench or angle) would cut the mounting plate back to the magnet.

I also reckon they were a good shape to mount on the top of the fans & as they are only a couple of mm thick, spacers might not be required between the fan body & the case.

Here's to tight arse brewing & creative recycling. :beer:

Crozdog

 

[goatherder]

Hi,

I did almost the same thing. Only, I glued the magnet to the fan using Blue Tac. Very strong and I can still move the magnet around to reduce vibration. Did you get the vortex up to the bottom of the jar? Sometimes when the speed is too high my stirrer jumps around and might break the jar. I suspect it might be too heavy. I'll try to find some real stirrers. Anybody has one spare for sale?

Cheers,
Laurent

Same thing happens with me when the speed gets too fast. I couldn't get the vortex going to the bottom without the stirrer getting shaky and threatening to break my shiny new flask. From what i've read it doesn't matter, keeping the yeast in suspension is the goal. A slow speed will be enough for that.

 

[Trough Lolly]

Same thing happens with me when the speed gets too fast. I couldn't get the vortex going to the bottom without the stirrer getting shaky and threatening to break my shiny new flask. From what i've read it doesn't matter, keeping the yeast in suspension is the goal. A slow speed will be enough for that.

Same here...and this is my problem - I keep blaming the magnet but perhaps it's something else? I find that the fan can only get down to a certain speed and then if I try to slow dow the fan any further, the whole lot comes to complete stop. The stir bar jumps around like I've put some voltage through it and I can't get a vortex. Oh and if you want to trash your 2L flask, let the missus DROP a hermatite oblique magnet into it, when the flask's empty... :angry:

Perhaps I need to solder in a couple of resistors in series between the power and the 500ohm trimpot?

TL the electrical numpty...

 

[Ross]

I get a vortex going using these magnets with quite a slow spin, I think being able to control the speed correctly is the most important part. The faster spin showers liquid everywhere, long before becoming unstable.



Cheers Ross

 

[bindi]

I have aquired the gear to make a stir plate now to build it

soon I will have enough yeast to take over the world :blink: .

 

[laurent]

Hi Ross,

how much liquid did you have in this flask? Sorry, cannot see very well from the picture B)

Thanks,
Laurent

I get a vortex going using these magnets with quite a slow spin, I think being able to control the speed correctly is the most important part. The faster spin showers liquid everywhere, long before becoming unstable.

View attachment 7606

Cheers Ross