False Bottoms

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I am making my own plastic mash tun with a false bottom.

My question is - what is the optimum size of the holes i need to drill in the bottom of it ?

Thanks in advance.
I'm not sure of the optimum, but I used 3.5mm holes.
I also put a mesh bag over the manifold also.
My manifold can be seen in The Pub forum under the Simple rectangular cooler conversion topic, or just the picture here.

I made my own "bucket-in-bucket" mash tun. I used a 3mm drill in mine and in "Homebrewing the CAMRA guide" quotes either a 2 or 3 mm holes. What you would have to take into account is the size of the grain after it's been cracked and make sure the holes are maginally smaller. I also marked out the base of the "filter bucket" and drilled at approx 15mm spacings so that looked like a spiders web when finished
Some muslin or fine cheese cloth between the buckets also aids in filtering out the debris and giving you cleaner runnings sooner.
I also used a double thickness of bubble wrap to insulate the tun

Thanks for the feedback Linz.

I am trying to decide between 1.5mm and 3mm....leaning towards 1.5mm at the moment.

Nice idea with the bubble wrap insulation though.

I am not doing a bucket in bucket Mash Tun.

It is a bucket with a cut down lid that fits approx 2 inches off the bottom. Will take a feed from the centre though.

....priced the SS fittings today...approx $60.00.

Will order the stuff tommorrow.
False Bottom,

Here is a reply i received back from Wes Smith who runs Maltcraft.
They did a talk a couple of months ago at our homebrew club meeting.

Hi Ken,

The "optimum" is a bit of a moving target depending on which style of
brewing you subscribe to. Assuming you are going to drill your own false
bottom or "lauter platten", then think about 12% open area for traditional
German lager brewing, or the compromise we find works very well at 23% open
area using a perforated stainless sheet with 1mm holes on 2mm centres. If
you are going to drill out your own plate, then calculate the required open
area and go to it. Dont forget to countersink the holes from the back. And
dont go over 1.5mm in diameter.

The material we use is available from Perforated Stainless Products (I
think) in Sydney


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