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How do you run your rakes?

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  • dick murton
    replied
    Try only running the rakes during mashing in and perhaps for a minute or so after all the malt is in. If you grist is right, you should then see the mash rise a few inches in the following couple of minutes, which is correct for traditional mash tun operation - it indicates trapped air in coarse grist, and a nice porous bed. If you the get the run off and sparge flow rates right, you should never need to run the rakes again during wort runoff. You should then also see your extract efficiency increase dramatically as you no longer have compacted/impervious areas in the grain bed - you should be looking at 90% at least.

    If the runoff is still poor and the bed doesn't float (rise) on completion of mashing, coarsen the grist a little.

    You probably have far too few rakes, and control od rake speed and height to get any real benefit from them - virtually every small tun I have seen gets no benefit from the rakes - so you could almost certainly throw them out altogether.

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  • colinthehippie
    replied
    Originally posted by BrewinLou View Post
    Can you control how fast the rakes spin? We have a potentiometer on the rakes so we can run them slower or faster. Without this I would not recommend running the rakes after mash in.
    Do you underlet 30 gal? Our underlet is critical to float the bed thru the lauder. With a grant you should be able to run without collapsing the bed. Each size batch will be slightly different run off speeds.
    How far are your rakes from the false bottom?

    We run our rakes in cut as slow as they can run. We also chase the bed down after the sparge by lowering the rakes slowly as the level falls. Cheers. Joel
    Resurrecting this to try to understand what you mean by "underlet," I'm reading that as leaving behind wort in the MLT purposefully to keep the grain bed afloat. Am I interpreting that right?

    We're running a fixed rake on a 10 BBL MLT and I've toyed with the speeds through mash-in and through the first 2/3 of the mash (40 min.) and my mashes don't float the way I want them to, I'm guessing the rakes are messing up the mash be structure. My efficiencies are consistently lower than anticipated (about 75% of the time) and I'm having a hard time pinpointing why. I think I'll coarsen up my grind (presently ~ 69.5% on a #14 sieve) and stop the rakes after mash-in and see what happens.

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  • BrewinLou
    replied
    Rakes

    Can you control how fast the rakes spin? We have a potentiometer on the rakes so we can run them slower or faster. Without this I would not recommend running the rakes after mash in.
    Do you underlet 30 gal? Our underlet is critical to float the bed thru the lauder. With a grant you should be able to run without collapsing the bed. Each size batch will be slightly different run off speeds.
    How far are your rakes from the false bottom?

    We run our rakes in cut as slow as they can run. We also chase the bed down after the sparge by lowering the rakes slowly as the level falls. Cheers. Joel

    Leave a comment:


  • jwalts
    replied
    I agree with Dick. I brewed for a couple years on a 15-bbl mash/lauter tun with rakes, and the rakes were too bulky for effective cutting/lifting. They also made cleaning more difficult, so I took them out. Due to the shaft down the middle of the vessel, I couldn't use a paddle very effectively for mixing - so I started with the grain-out paddle near the false bottom (but not touching it) and gradually lifted it up throughout mash-in so it was slightly below the top of the mash as much as possible. It wasn't perfect, but my wort clarity and brewhouse efficiency were better than lautering with the rakes on at any speed.

    I'd also bypass the grant. Unless you have no other way of avoiding excessive suction, it's simply a wort oxidizer.

    Joe

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  • horseblanket
    replied
    We sieve our crush and by all standards it is extremely course, 80% of the malt is caught in #14 and all kernels are cracked. We have a 15bbl ABE system the rakes do not have variable height adjustment, just mix and cut. We have a bbl of space under the bottom, we mash at 1.25qt per lb and have a grant. We typically lauter 200 gal or so. Most of our mashes have a large portion of adjuncts and we hull every batch. We typically lauter in 90 minutes.

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  • BrewinLou
    replied
    First a couple questions. Do your rakes move up and down? Do the rakes turn from mix to cut? How much water volume do you underlet, and total volume of your lauder? Keeping the bed from collapsing/compacting requires different adjustments for malt bills large and small than the designed volume of your lauder tun. Cheers

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  • dick murton
    replied
    Unless you have a separate mash mixing vessel and transfer to your wort separation system - throw them out and get the grind right

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  • horseblanket
    started a topic How do you run your rakes?

    How do you run your rakes?

    We've tried running our rakes several different ways and I am curious how others do it. We are having some efficiency and lauter issues and running our rakes might be the reason for it. Our rakes typically run at 25hz, a little under half speed. We thought it might be beating up the grain bed too much so we tried running them at 9 and had even more issues with compacting and separation. Anyone care to share their SOP for running rakes in a mash/lauter?
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