Products With Small Strong Magnets In Them

[ausdb]

Folks, getting slightly OT here but....

There is a limit of how fast you can move yeast without causing damage to the cell walls. While you are not likely to hit this limit of 5m/s, I have not seen any difference in getting yeast growth from slowly swirling the wort or from running the wort so that it creates a vortex.

Anyone else like to comment on this?

Cheers
Pedro

I am using a really old 5 1/4" disk drive unit that is belt driven and runs the platter at 360rpm (I think) I don't get a massive vortex but it still gets the job done. Maybe we could have a bit of a youtube comparison of peoples stir plates and how well they work??

 

[randyrob]

my stir plate is still hand cranked, i've got a popeye arm from it :-(
thanks for the advice guys time to upgrade me thinks!

 

[Vlad the Pale Aler]

Has anyone thought of using a record player turntable (RR you probably never seen one) in a stirplate setup, it would be big enough to use a 5l demijon.

hijack over.

 

[TidalPete]

Folks, getting slightly OT here but....

There is a limit of how fast you can move yeast without causing damage to the cell walls. While you are not likely to hit this limit of 5m/s, I have not seen any difference in getting yeast growth from slowly swirling the wort or from running the wort so that it creates a vortex.

Anyone else like to comment on this?

Cheers
Pedro

Pedro,

Funny that you should mention this because ATM I have a 2 litre starter of 1728 Scottish on my stir plate.
I normally run each build-up (100-1000-2000) at a fast pace for the first 5 to 10 minutes then slow the stir plate down until there is a reasonable vortex happening.
After reading your post about 45 minutes ago I slowed the rate down to about 44 revs/minute (used a stop watch )
There is much now more activity going on than there was 45 minutes ago when I thought the starter was nearly finished.
I use Doc's 240v stir plate design.
I have learnt something today, thank you very much. :super:

TP :beer:

 

[kevnlis]

I use a pair of these oblique magnets from Jaycar CAT. NO. LM1650.

View attachment 16651

These magnets are self centering to each other, so work great & their size gets a vortex happening even at low speed.

Cheers Ross.

I am using those as well. I tried just gluing one ot the fan and chucking the other in the conical but that didn't seem to work. What have you done with them?

 

[Ross]

I am using those as well. I tried just gluing one ot the fan and chucking the other in the conical but that didn't seem to work. What have you done with them?

Exactly the same & works perfectly - In what way wasn't it working?

Cheers Ross

 

[kevnlis]

Exactly the same & works perfectly - In what way wasn't it working?

Cheers Ross

I think it may have something to do with the fan I am using. Maybe I need to connect a speed controller of some sort to it? The magnets just spuns too slow to vortex the water. It barely created a ripple at the top.

 

[Ross]

I think it may have something to do with the fan I am using. Maybe I need to connect a speed controller of some sort to it? The magnets just spuns too slow to vortex the water. It barely created a ripple at the top.

Absolutely, there you have your problem - a speed control is pretty well essential.

Cheers Ross

 

[tk75]

Took an old Hard Drive apart yesty and pulled out the magnets...they are very strong, I didn't know that they would have been that strong!
Anyway they are glued to a piece of cast steel(not sure exactly what type of metal?) and I'm wondering what will be the best solvent to dissolve the glue?
I have it immersed in some Turps at the moment but I'm not sure that's going to work...any suggestions?
Cheers!

 

[Screwtop]

The magnets just spuns too slow to vortex the water. It barely created a ripple at the top.

The speed control can only slow the fan from max revs, what voltage are you driving it with.

Screwy

 

[mika]

Took an old Hard Drive apart yesty and pulled out the magnets...they are very strong, I didn't know that they would have been that strong!
Anyway they are glued to a piece of cast steel(not sure exactly what type of metal?) and I'm wondering what will be the best solvent to dissolve the glue?
I have it immersed in some Turps at the moment but I'm not sure that's going to work...any suggestions?
Cheers!

I supported the piece of steel and then gave it a bit of a tap on the back. The steel mine were glued to was pretty thin and the bit of flexing from the hammer tap broke the glue bond.

 

[tk75]

I supported the piece of steel and then gave it a bit of a tap on the back. The steel mine were glued to was pretty thin and the bit of flexing from the hammer tap broke the glue bond.

I should have updated my post earlier

I thought just if I could bend the cast alloy(the casting was about 2 - 3mm thick, so not too easy to bend with just pliers) so I could get a knife blade under the magnets, then I put the casting in the vice and then bent with pliers. It gave just enough gap on the edge to get the knife under, once I slid the knife under, the magnets came off too easy!!
I'll take a pic of the magnets soon. Now I'm just looking at what size fan to use...I have a 120mm 12V fan which I think I will use instead of an 80mm fan.
I'm making an enclosed cabinet so once it's finished I'll show pics.

 

[kevnlis]

OK, I have finally built a speed controller. I have it running now with 1.5L in one of my 2L conicals. Has been going for about an hour with no problems, though it is a bit loud that is not an issue. It has a small vortex and I tested it with a few drops of food colouring which were mixed in quite quickly and evenly.

Thanks for all the help guys!

 

[kevnlis]

I spoke too soon. It just stopped, for no apparent reason

 

[Hutch]

Pedro,

Funny that you should mention this because ATM I have a 2 litre starter of 1728 Scottish on my stir plate.
I normally run each build-up (100-1000-2000) at a fast pace for the first 5 to 10 minutes then slow the stir plate down until there is a reasonable vortex happening.
After reading your post about 45 minutes ago I slowed the rate down to about 44 revs/minute (used a stop watch )
There is much now more activity going on than there was 45 minutes ago when I thought the starter was nearly finished.
I use Doc's 240v stir plate design.
I have learnt something today, thank you very much. :super:

TP :beer:

Remaining slightly OT...

IMHO, having slowed it down to a crawl, the yeast is now most likely working anaerobicly (having depleated the dissolved oxygen reserves), driving off CO2 bubbles, instead of multiplying - this is what you see as "increased activity". I usually find this as well - it looks like it's doing nothing, so you stop it, and in a short while, bubbles stort to appear as the yeast starts to settle out.
When it is whizzing around a vortex, you're continually mixing air into the wort, maintaining the yeast in an aerobic metabolic state - no CO2, but plenty of reproductive "activity" going on there.

I'm no biochemist, but this is my understanding. In my experience I usually get a huge starter when I run the stir-plate with a decent vortex.
Hutch.

 

[ozpowell]

FWIW, I use 4 of the small Jaycar Earth Magnets (2 lots of 2 stacked on top of one another) - linky. Depending on the volume of the starter, I run the 12V fan at 4.5 to 6V.

Here's the magnets I use.

Cheers,
Michael.