Making adjustments to grind setting while motor is running

Grinders are one of the keys to exceptional espresso. Discuss them here.
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Shenrei

#1: Post by Shenrei »

This might be a beaten topic, but there's some questions I have regarding the practice.

The rule is, while making any grind size adjustments, have the motor/grinder running while adjusting finer. With going coarser, this isn't an issue but many do it anyway.

Aside from the possibility of the motor being jammed, what else can happen if you adjust finer without the grinder running? I'm asking because something like this can be a very easy to do with a home burr grinder sitting in the kitchen with plenty of family members. Can the grinder lose calibration/alignment? Will it result in permanent or temporary inconsistent grind? If so, is this damage reversible?

Also, with commercial grinders, does this rule apply as well? (with Bunns / Mahlkonigs, etc)
- Tim

lain2097
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#2: Post by lain2097 »

Actually before coffee forums I tended to adjust the grind whilst stopped. Never heard of adjusting while running until I got into alt.coffee. :| Though honestly I doubt going one click in either direction is a big deal. Now I have a Versalab so the burrs are always empty when done so I can adjust without reservation.

I think yes the rational is to indeed prevent a stall and to minimise crushed grinds getting all over. Stalling makes sense as the highest amount of torque is on start up to twist against the half-crewed beans so to speak. So when in park, there's no swinging vanes to throw the grinds out hence getting crushed. Usually when cleaning a grinder most of the muck is super fines sticking near the burr group.

Still I feel if it's espresso adjustments like small amounts it will probably be fine but massively finer might be an issue.

Nate42

#3: Post by Nate42 »

On something like a baratza that has plastic burr carriers, in extreme cases you could actually break the burr carrier. My wife actually did this on an old maestro we had many moons ago. Also, when making large adjustments like from press to espresso, you want to make sure there's no trapped coffee putting stress on the carrier if you want to get repeatable adjustments.

With a commercial grinder you're probably not going to break it, but you could lock up the motor, and in extreme cases I suppose the motor could overheat if you tried to run it too long in a locked condition.

Personally, I don't worry about it when making small adjustments, but I either run the grinder or make sure its empty when making large adjustments.

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Shenrei

#4: Post by Shenrei »

Yeah, just curious if this applies to something like a Bunn G1 or a EK. Most videos of people using them I've seen don't run the grinder while adjusting the grind size, ditto with something like the Kalita Nice Cut as well.
- Tim

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boar_d_laze

#5: Post by boar_d_laze » replying to Shenrei »

Auger fed, bulk grinders like the G1 and EK have near-zero retention if the hopper is run completely out (which it is every time in normal grinding), so not an issue.

With typical grinders a few bean fragments caught between the burrs when the gap is tightened is a BIG issue. The most common problem resulting from tightening grind with detritus in the burrs, is forcing the burrs out of alignment.

Unless you've permanently damaged something -- plastic Baratza burr carriers, e.g. -- alignment problems can usually be fixed by taking the burrs out, putting them back in and recalibrating.

I don't know the Kalita very well, don't know if it's auger fed, but guess that if the hopper and grind chamber are completely run-out adjusting the space between the burrs without running the grinder at the time is very likely safe. I mean if there's nothing in there, there's nothing in there.

Hope this helps,
Rich
Drop a nickel in the pot Joe. Takin' it slow. Waiter, waiter, percolator

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Shenrei

#6: Post by Shenrei »

Yup, that makes a lot of sense now! Thanks!
- Tim

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bostonbuzz

#7: Post by bostonbuzz »

Theoretically, if you tighten it significantly and there is a bean stuck on one side of some flat burrs and there aren't any beans jammed in the other, you could bend the shaft. The amount of mechanical advantage on a 4 inch wide 1.5mm pitch thread (mazzer) is enormous. That being said, I doubt beans stand a chance. I exclusively single dose, but if I didn't I would make any adjustment over one notch in difference while the grinder is running simply to avoid jamming or taxing the motor.
LMWDP #353

Mike_

#8: Post by Mike_ »

Personally with my Super Jolly I make small adjustments in both directions while the motor is off. However the SJ has a lot of power so there just isn't much chance of the grinder getting hung up with a small adjustment even in the fine direction. This isn't the case with non-commercial grinders.

The whole point is to keep the grinder from hanging up which if left in that condition with the motor on could cause bad things to happen. If the grinder isn't hanging up, you don't have much to worry about.

TheJavaCup77

#9: Post by TheJavaCup77 »

Honestly to the OP, this is a very risky proposition....

One, the burrs are being re-positioned while spinning....

This can be bad for your grinders motor and especially the burrs....

Why do you want to do so?

To increase workflow speed?

Assuming no barista has done so....

The outcome is un-predictable

Only proceed at own risk!
It could be as complex or as simple as you want. It's the choice of the barista.

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dsc

#10: Post by dsc »

bostonbuzz wrote:Theoretically, if you tighten it significantly and there is a bean stuck on one side of some flat burrs and there aren't any beans jammed in the other, you could bend the shaft. The amount of mechanical advantage on a 4 inch wide 1.5mm pitch thread (mazzer) is enormous. That being said, I doubt beans stand a chance. I exclusively single dose, but if I didn't I would make any adjustment over one notch in difference while the grinder is running simply to avoid jamming or taxing the motor.
In my opinion a whole bean doesn't stand a chance, flex might happen, but it wouldn't be enough to damage a mechanical part like a shaft. I'd say the biggest worry here is small particles / bean fragments stuck between burrs further down the line of bean breakage, closer to the edge. These can be indeed hard fragments and tightening the grind with a full burr of small fragments could lead to binding the thing and blowing the fuse on the motor / triggering other over-current protection or simply burning the motor if there's no protection / or it fails.

Regards,
T.