4 Roll Malt Mill Adjustment

[I.D. Rinks]

Can anyone help with the theory behind adjusting the top or bottom rollers for a finer grind and why.

Thanks

J

[dick murton]

In broad brush terms, you use the top rollers to crack the husk and separate the husk from the endosperm, and use the bottom set to grind the husk only.

The closer together you set the top pair of rollers, the more complet the separatio of the husk from the endosperm, but the more fractured the husk. Unless you are running a mash filter, you want the husk as complete as possible, but with minimal endosperm attached

The bottom set you set closer to produce as much fine and medium grits as possible, with as little flour as possible (mash filters excepted) as with a mash tun or lauter tun, the more flour, the greater the risk of having set beds, or badly channelled (sp ??) beds, with loads of fine material being carried through and poor extracts

Ideally you should be able to get samples separately from the discharge of the top and bottom rollers. If you can't, open out the bottom set, and adjust the top set until you crack open the husk, with largely intact husks. Then trim in the bottom rolls to finish off the separation and produce the grits, without too much flour.

If you are having slow runoffs with lots of set beds and / or deep raking, then you need to open the gaps, probably the bottom pair first to reduce the flour and secondary damage to the husks.

Don't forget that if you have separate mash mixers and transfer pumps, these can completely destroy a good grist - a high speed centrifugal pump for mash transfer used to completely finish off a pretty dreadful grind in one brewery I was doing a bit of consultancy in. So it may be necessary to consider the whole of your milling & mashing system, not just the mill

Hope this helps

[soundbrew]

4 Roll mills

Dick's comments are well taken. I'd like to point out that a PROPER 4 roll BREWERY mill will have shaker screens that separate the husks from the endosperm after the grain passes through the first set. The husks and fines drop straight through and only the coarse grits go through the second set of rolls.

In this case, "proper 4 roll brewery mill" means (for the most part) one from Europe (usually Germany), or at least **Not** a glorified feed mill consisting of two sets of stacked rolls without any separator screens. If you have one of those, you have to be very careful about settings. If you don't like cement in your lauter tun, start with the bottom rolls wide open and set the top set for runoff, not extract. Then very gradually close the bottom set down till you optimize extract vs. runoff.

And, yeah, I've been there and done that with grist and mash destroyed by improper equipment. No fun.

[I.D. Rinks]

A double stack feed mill would be a good bet....