How to build a stir plate for less than ten quid

[strange-steve]

I've just replaced the fan on my DIY stirplate but now I've got the whole "centering an odd shaped magnet" issue. Any tips on how to center a hard drive magnet (like a flat kidney bean) so the fan doesn't vibrate so much?

I haven't used a harddrive magnet so I can't help I'm afraid. Plenty have though, so maybe they'll be able to help.

 

[Dutto]

Move it towards the centre so that it hangs over both sides?

Waiting for a month for the magnets in the photo to arrive was worth it ...



... but I still have to have the right length of Stirrer in order to spin at full revs without it being thrown off!

 

[-Bezza-]

Move it towards the centre so that it hangs over both sides?

Waiting for a month for the magnets in the photo to arrive was worth it ...

View attachment 12904

... but I still have to have the right length of Stirrer in order to spin at full revs without it being thrown off!

Has everything in your house got some sort of hand-written reminder on it!? :laugh2:

 

[Dutto]

Has everything in your house got some sort of hand-written reminder on it!? :laugh2:

Just about! The batch of reminders on the Stir Plate was made after I had thrown the Stirrer into the FV for the THIRD time!

I put it down to beer and old age. :wave:

On the plus side, without a reminder, I still remember to undo my flies before going for a pee! :thumb:

 

[BeerCat]

Has anyone ever used a heat mat with their stirrer? I have a 5l flask on its way so thinking about some doing some small experimental batches to propagate some yeast at the same time.
Maybe a simple pilsner wort with a hop shot for bittering and a hop tea. There is something very rewarding about watching a flask make yeast.

 

[svenito]

Move it towards the centre so that it hangs over both sides?

The magnet doesn't extend over the edge I'm afraid. I've got it as centered as possible, but there's always that annoying hum of a clearly off center mass. Maybe I just have to build a soundproof box around it

 

[Drunkula]

centered as possible

With the hard drive magnets I found the problem to solve was aligning the magnetic centre. Find the lengthways centre by measuring it and draw a line across it - imagine cutting a rainbow in half. Now drop your stir bar onto the magnet and it'll line up across the length of it. I drew around the bar and then made a cross in the middle of that with the first line.

Then I used sticky pads on the fan, put that on as best as I could then started spinning the fan and moved it until the cross was in the middle. As it was spinning I touched it with a pencil, slightly off-centre, until it would leave a circle centred around the cross.

On another plate I used two hard drive magnets and had to use a lolly stick in the middle to keep them apart. The stick lying flat so they are nearly a cm apart. You have to work out the north and south side of the magnets doing that and put one of each upward. I find it a better solution even though there's more weight on the fan.

 

[Dutto]

Has anyone ever used a heat mat with their stirrer? I have a 5l flask on its way so thinking about some doing some small experimental batches to propagate some yeast at the same time.
Maybe a simple pilsner wort with a hop shot for bittering and a hop tea. There is something very rewarding about watching a flask make yeast.

Never used a Heat Pad but I agree that watching a Yeast Starter do its stuff is one of life's greater pleasures; especially thinking "I did that!" :wave:

Using the "Two Day" approach means that I'm in the garage on Day One and the Brew Fridge in empty. Before doing the "Milling and Mashing" steps I get the Yeast Starter underway and stick it in the Brew Fridge overnight at 19*C.

It's usually 18-24 hours before pitching so although 19*C is a bit cool for a Starter the yeast has plenty of time to get going.

As 19*C is the temperature at which I want to start most brews, it gets the fridge at the right temperature and minimises the shock to the yeast when it's pitched into the wort; hopefully without the Spinner! :thumb:

 

[foxbat]

Anyone having issues with the stir bar being thrown should seriously consider these. They don't get thrown, period, not with rare earth magnets on the fan as well. Delivery is a bit steep but could be offset by a group buy.

 

[BeerCat]

@Dutto For some reason it never crossed my mind to use a fridge. Always trying nto over complicate things. Definitely an option but i would also like to ferment hot(35c) for the kveik. and the bonus is extra beer.

@foxbat Definitly I am up for that. I have noticed that not all stir bars use the same strength magnets! I replaced the standard one with a round 25mm bar and i can get this up to 88 on my voltage controller. I bought another the same and this flips off around 75. Massive difference and reduced yeast production. If i could get it to spin flat out i would be very happy.

 

[BeerCat]

Never used a Heat Pad but I agree that watching a Yeast Starter do its stuff is one of life's greater pleasures; especially thinking "I did that!" :wave:

Using the "Two Day" approach means that I'm in the garage on Day One and the Brew Fridge in empty. Before doing the "Milling and Mashing" steps I get the Yeast Starter underway and stick it in the Brew Fridge overnight at 19*C.

It's usually 18-24 hours before pitching so although 19*C is a bit cool for a Starter the yeast has plenty of time to get going.

As 19*C is the temperature at which I want to start most brews, it gets the fridge at the right temperature and minimises the shock to the yeast when it's pitched into the wort; hopefully without the Spinner! :thumb:

Tape some magnets near the top of the flask to remind yourself to keep the stir bar. :)

 

[Dutto]

Tape some magnets near the top of the flask to remind yourself to keep the stir bar. :)

Ooooh! I like that idea! :hat:

So simple and so easy it makes me feel so stupid! :headbang:

Anyone having issues with the stir bar being thrown should seriously consider these. They don't get thrown, period, not with rare earth magnets on the fan as well. Delivery is a bit steep but could be offset by a group buy.

I bought a lot of different sizes as per this link ...

https://www.amazon.co.uk/gp/product/B01CTJZ3YW/?tag=skimlinks_replacement-20

It took some time (doh!) before I realised that only one of them wouldn't get thrown off at full speed; however, another two of them will pull a full vortex at lower speeds without getting thrown off. :thumb:

BTW, when fixing the magnets to the fan, my biggest problem was stopping the two magnets from migrating towards each other or towards the magnets in the fan motor.

What a fiddly job that was!

By the time the magnets were secured in place buying one was almost (but not quite) becoming a favoured option! :Cheers:

 

[BeerCat]

The ones with the ridge as in the link above wont spin as fast as a smooth one and make loads of excess noise and if you think about it are also further away from the magnets.

 

[Dutto]

The ones with the ridge as in the link above wont spin as fast as a smooth one and make loads of excess noise and if you think about it are also further away from the magnets.

Agreed; which is another good reason for doing my Yeast Starter in a Brew Fridge in a garage separate from the house! :thumb::thumb:

 

[BarnBrian]

Ooooh! I like that idea! :hat:

So simple and so easy it makes me feel so stupid! :headbang:



I bought a lot of different sizes as per this link ...

https://www.amazon.co.uk/gp/product/B01CTJZ3YW/?tag=skimlinks_replacement-20

It took some time (doh!) before I realised that only one of them wouldn't get thrown off at full speed; however, another two of them will pull a full vortex at lower speeds without getting thrown off. :thumb:

BTW, when fixing the magnets to the fan, my biggest problem was stopping the two magnets from migrating towards each other or towards the magnets in the fan motor.

What a fiddly job that was!

By the time the magnets were secured in place buying one was almost (but not quite) becoming a favoured option! :Cheers:

My plan is to make a disc out of thin ply the same size as the centre of the fan, then drill two holes in it to accept the magnets. Glue the disc on first and then glue the magnets in the holes.

Brian

 

[BeerCat]

These stir bars are expensive but never seen them before.

 

[Old_P]

I've just replaced the fan on my DIY stirplate but now I've got the whole "centering an odd shaped magnet" issue. Any tips on how to center a hard drive magnet (like a flat kidney bean) so the fan doesn't vibrate so much?

Take your HD magnet and place it on a piece of paper, draw around the outside. Cut around the outline so you have a perfect paper cutout of you magnet. Then fold it in half and then fall again. Then unfold it and you should have a nice cross where the centre is.
It worked for me, hope it helps.

 

[Saisonator]

I ran my fan and carefully lowered a marker pen onto the fan where I wanted to stick my magnets, then turned off fan and stuck magnets where marks were.

 

[svenito]

Take your HD magnet and place it on a piece of paper, draw around the outside. Cut around the outline so you have a perfect paper cutout of you magnet. Then fold it in half and then fall again. Then unfold it and you should have a nice cross where the centre is.
It worked for me, hope it helps.

Will give this a try. Certainly sounds like the tip I needed to center the bloody thing. Of course, I didn't manage to come up with the paper idea, which is so nice and simple.

 

[svenito]

Take your HD magnet and place it on a piece of paper, draw around the outside. Cut around the outline so you have a perfect paper cutout of you magnet. Then fold it in half and then fall again. Then unfold it and you should have a nice cross where the centre is.
It worked for me, hope it helps.

This has worked really well. I found the middle, spun the fan, held a Sharpie to it to find its center and stuck the paper on. Then stuck the magnet in the paper.

Thanks for a great tip