Dental Vibrator and clumping

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

#1: Post by Bertie Doe »

I recently upgraded my Nemox Lux to a Pasquini K2 despite the good write-up in 'Titan' but we both work from home and the Nemox is just too noisy. The doserless Pasquini still produces clumps, but it's so much quieter!

I ordered the 220v version of the vibe from eBay for $42 + posting. The first victim was a dark roasted oily MM, at 2/3 power for 20 secs, there were just a few tiny clumps at 2mm across. I use dsc's 'wine cork and needles' tool to help distribute, as I vibrate. Weight 5 lbs, table dia is 4".

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Next I used a lighter roasted Dattera and there were no signs of clumping at all. It's early days and I've only done 9 doubles and thus far, no signs of channeling, which suggests grain distribution is pretty good. I'd like to try with different roasts and I'll be doing a batch of Barahona and Sidamo this afternoon.

For me, the extra 20 seconds onto my normal routine dosn't present cooling issues, as I use the Zaff's spare p/f, which is kept warm on the cup tray. I spotted another seller of 110/220v volt machines among http://search.ebay.com/vibrator-dental so I guess in an ebay auction, you could get away with a sub $40 bargain. Probably not a 'must have' accessory for the doserlessly impaired, but I thought I'd share.

Bertie

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mogogear

#2: Post by mogogear »

What a name Bertie- Cumberpatch. Quite proper :wink: Something about reading "Dental Vibrator" just makes me smile.................................................... :lol: :lol: A lot!
greg moore

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Bertie Doe

#3: Post by Bertie Doe »

mogogear wrote: :wink: Something about reading "Dental Vibrator" just makes me smile.................................................... :lol: :lol: A lot!
Strange, the word 'dental' has the opposite effect on most folk. I can confirm there is no feeling of pain, provided you don't cough while crossing your legs.

Edit : Just got a PM to say that the dental vibe has been covered before in HB, my fault, should have searched. Dental vibrator for espresso grounds?
I'm glad I didn't see this post, as I may well have been disuaded from buying. For me, there are 2 compelling reasons why the vibrator works with a doserless grinder.

By disolving clumps, it reduces chaneling and extends the pour, before blonding. Early adopters of the doserless Nemox, found that mid tamping How to make a beautiful "naked" triple espresso and careful distribution, helped offset the clumping problems. Now I no longer need to mid tamp.

Bertie

Bertie Doe

#4: Post by Bertie Doe »

Here's a quick update after 2 months use and a fair amount of tweaking. At first I alternated between my regular distribution method (dsc's wine cork and needles) and the vibe. Issues raised in an earlier HB thread about fines migration, soon became apparent. The vibe shots were 10 seconds longer and had an under/overextracted taste. This was 15g of MM taken into R2, with lots of oiling.

One method I tried, to reverse the fines' direction, was to grind into a whiskey glass and place the glass on the vibe for 10 secs. There was an improvement, but you still need to transfer back to the p/f and re-vibe for 5 secs - a lot of time and hassle.

The answer came when I was looking at an unrelated thread on the use of the tamper to prevent popcorning. So why not grind into the p/f, distribute, rest tamper on grinds, place finger on top of tamper, to steady. Switch on vibe at 25% power and watch the tamper descend 4mm, under it's own weight. Total vibe time 5 secs, giving a nice level pack, longer pour before blonding and a smoother espresso.

I'm only guessing, but I think the tamper's presence has a containing stabilising effect on the grounds and yet allows some sideways movement on the grounds, to fill any voids and distribute any dense spots. For anyone interested, there are a couple of sellers on ebay.usa (Dental Section) selling both 110v and 220v models. Expect to pay about $40, weight is 1kg, so add on shipping.Image

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HB
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#5: Post by HB »

Thanks for the update. Your usage of dental vibrator is certainly unusual and indirectly confirms assumptions about the effect of agitation on fines migration.
Bertie Doe wrote:Issues raised in an earlier HB thread about fines migration, soon became apparent. The vibe shots were 10 seconds longer and had an under/overextracted taste. This was 15g of MM taken into R2, with lots of oiling.
Indeed, I've observed the same effect for aggressively stirred grounds, i.e., dark "front loaded" extractions.
Bertie Doe wrote:Switch on vibe at 25% power and watch the tamper descend 4mm, under it's own weight. Total vibe time 5 secs, giving a nice level pack, longer pour before blonding and a smoother espresso.
Not sure what the ubiquitous "smoother" descriptor means, but the longer extraction indicates the puck retains its integrity longer.

Oddly enough, I'm reminded of Lino's talk about asphalt compaction techniques. A layperson like myself assumes roadwork is fairly straightforward: Create a solid bed, spread around some asphalt, roll over it with heavy equipment, done. Not at all, there's a lot of science behind creating an integral surface that equalizes and distributes the load. Think espresso extraction... is it just me, or does this sound like a similar problem and solution?

While I have no way of proving it, my gut feel is that most of the advantage high-end espresso grinders hold over their smaller siblings lies in the consistency with which they render the particles distribution. Like the WDT, your approach sounds like it's compensating for a grinder deficiency.
Dan Kehn

Bertie Doe

#6: Post by Bertie Doe »

HB wrote:Not sure what the ubiquitous "smoother" descriptor means, but the longer extraction indicates the puck retains its integrity longer.
Perhaps I should use 'repeatable, consistent' rather than smoother
HB wrote:Oddly enough, I'm reminded of Lino's talk about asphalt compaction techniques. A layperson like myself assumes roadwork is fairly straightforward: Create a solid bed, spread around some asphalt, roll over it with heavy equipment, done. Not at all, there's a lot of science behind creating an integral surface that equalizes and distributes the load. Think espresso extraction... is it just me, or does this sound like a similar problem and solution?
Ha! 2 months ago, my nabe who repairs the potholes in the service road R/O our properties, thought he'd found a solution, when he snagged a trench/tamping power-rammer on eBay. Unfortunately, the plugs of tarmac and asphalt, are starting to break up again.
HB wrote:While I have no way of proving it, my gut feel is that most of the advantage high-end espresso grinders hold over their smaller siblings lies in the consistency with which they render the particles distribution. Like the WDT, your approach sounds like it's compensating for a grinder deficiency.
Agreed, I think the small burrs on the Nemox and the Pasquini, do contribute toward clumping. If the Cimbali Jnr had the same sizes footprint as the above, I may well have gone the doser route. I do find however, that the vibrator using just the tamper weight, does give a repeatable shot. Perhaps 'longer pour' is a bit of an exaggeration and the words 'eliminates occasional early-blonding shots' may be more apt i.e. 'consistency'.
Bertie