Recalibrate grind?

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jmcphail
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Recalibrate grind?

Post by jmcphail » Thu Jul 08, 2010 12:40 pm

It's been a while since I've posted here!

I have a 2-1/2 yo S1VII with no mods, supplied with plumbed-in softened filtered water. I've had no problems of any sort until a few weeks ago. I changed the group gasket about a year ago, the replacement seems fine and hasn't hardened.

The problem is that when pulling a shot the three flashing amber ( or green, depending on shot button ) "no flow" lights come on during the shot. The resulting shot is okay, but since the metering requires a working flowmeter I have to manually stop the shot. The lights don't come on when using the shot buttons to run water through the group, only when actually pulling a shot. So the flowmeter works fine with an empty basket.

The problem happens to both me and my wife. Neither of us have changed our dosing and packing procedure, but there are probably sight variations from day to day.

I am going to try recalibrating my grinder ( a CMH ) with a stopwatch and measured shot glass to make sure I haven't drifted somehow. Doing this should take into account any change that might have happened with my coffee of choice ( PT's LBV ).

I also wonder if humidity could play a role, or what else could cause this problem? Does anyone else have any suggestions or ideas?

Thanks,

-John

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Endo
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Re: Recalibrate grind?

Post by Endo » Thu Jul 08, 2010 3:48 pm

I'd first give Chris Coffee a call to make sure there is no other reason for this fault but......

Sounds like a flowmeter problem to me.

I'd open it up and check for a bad connection first. Next I'd remove the flowmeter and look for some debris inside. Once out, if it's not totally sealed, I'd check if the bearing has gone, or maybe just some scale build-up over time.

Not sure what the MTBF is for these meters, but whatever the cause, you may need to swap meters to see if it solves the problem. Are you near enough to a tech who might let you borrow one?
Endo

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"It's the coffee, stupid."

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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Thu Jul 08, 2010 4:07 pm

Thanks Endo, I'll give Chris's a call.

It seems odd that the flowmeter correctly measures a blank shot, and has the problem only when actually making coffee.

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Endo
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Re: Recalibrate grind?

Post by Endo » Thu Jul 08, 2010 4:43 pm

jmcphail wrote:It seems odd that the flowmeter correctly measures a blank shot, and has the problem only when actually making coffee.
Might just be because a blank shot has a higher flow rate and therefore has more ooomph to spin the sticky meter (just a guess).
Endo

LaSpaziale Mini Vivaldi w/progressive p/i
HG-one, B.Vario, Quest M3

"It's the coffee, stupid."

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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Thu Jul 08, 2010 4:55 pm

It seems possible.

I'm going to recalibrate my grind and report back to Tim at Chris's tomorrow.

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Re: Recalibrate grind?

Post by jmcphail » Thu Jul 08, 2010 8:29 pm

Thought I'd follow up, I've loosened my grind a tad and the flowmeter problem is not occurring. I'm going to play with it a bit and try to find the tipping point for this, but it's progress.

FWIW, on my grinder, a La Cimbali Max Hybrid, the difference was changing from 3-1/4 to 3-1/2 on the dial. I'm just trying to say that it took very little coarsening to make the difference.

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Endo
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Re: Recalibrate grind?

Post by Endo » Thu Jul 08, 2010 9:03 pm

Are you doing some super-tight ristrettos?

What is your dose, shot time and volume?
Endo

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HG-one, B.Vario, Quest M3

"It's the coffee, stupid."

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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Thu Jul 08, 2010 9:33 pm

Yes, tight double ristrettos.

It's more zen than actual measurement, but it's probably 3/4 oz. of grinds for a tallish double ristretto in about 30 seconds. I basically overfill a double basket, level it, tap it, pack and pull. My pack has been consistent for a couple of years. My guess at this point is actually the humidity or *possibly* some change with the roast. Whatever the change is, affected both my wife and I - we do things differently but consistently.

I have a triple-basket coming and a modified PF shipping back to me now and I'll need to get everything set up again, but I'll be pleased when I can make larger drinks.

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Endo
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Re: Recalibrate grind?

Post by Endo » Thu Jul 08, 2010 10:35 pm

I think a unsettled and levelled basket averages around 15.5g and not 21g (3/4 oz).

A tall double ristretto is 1.5 oz and is usually pulled for 30 seconds. I usually go even a little tighter and do an average ristretto at 1.25 oz in 30 sec. So you should not be having any issues.

If it was just too fine a grind or humidity, your shots would take longer.
Endo

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"It's the coffee, stupid."

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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Thu Jul 08, 2010 10:52 pm

Like I said, I brew to taste and not using exact measurements. Perhaps at a looser grind it's only 15 grams unsettled, but after taring the basket itself and then weighing 1/2 oz. into it the basket was around 2/3 full at my original grind.

The shots were definitely taking longer - slow enough that the flowmeter wouldn't register. Which was the problem.

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Re: Recalibrate grind?

Post by roknee » Fri Jul 09, 2010 1:16 am

heya
im also finding that 3 amber flashing lights are popping on during a tight shot (just as when backflushing). i presume this is not prob at all. usually once the flow rate increases during the shot, the lights stop flashing.
not to be rude but why is it a prob for you practically? or are you concerned that it may be some fault?
cheers
aaron

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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Fri Jul 09, 2010 4:14 am

During the time that the lights are flashing the pull isn't metered, so the shot goes "long", past when it should stop. Too much blonding, too tall, etc.

I was concerned that I had mechanical problem with the flowmeter itself. But since the flowmeter measured correctly during a clear water shot and the problem started up after working right for a long time I was confused.
roknee wrote:heya
once the flow rate increases during the shot, the lights stop flashing.
not to be rude but why is it a prob for you practically? or are you concerned that it may be some fault?

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Endo
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Re: Recalibrate grind?

Post by Endo » Fri Jul 09, 2010 7:47 am

It's interesting. It does make me wonder what is the minimum flow rate required. Does this min rate increase over time, possibly as the meter ages? Does this limit some people in terms of making shots like ristrettos?

Unfortunately, I can't say much since I own a Mini (and the "no flow" fault lights never come on, even when backflushing), so I can't be much help. You'll have to rely on other regular S1 users for help.
Endo

LaSpaziale Mini Vivaldi w/progressive p/i
HG-one, B.Vario, Quest M3

"It's the coffee, stupid."

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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Fri Jul 09, 2010 8:35 am

It *is* interesting; my guess is probably, and probably not.

My main concern with metering is having it work consistently for my better half, who isn't willing to do the things a lot of us are willing to do for a go(o)d shot :D Programmed buttons aren't really a concern for me all by myself, but the WAF is important in my situation. I have enough gray hair... but at least there's still hair.

I really appreciate the help you've offered!
Endo wrote:It's interesting. It does make me wonder what is the minimum flow rate required. Does this min rate increase over time, possibly as the meter ages? Does this limit some people in terms of making shots like ristrettos?

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JohnB
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Re: Recalibrate grind?

Post by JohnB » Fri Jul 09, 2010 9:40 pm

Most of my favorite shots with the Vivaldi started off with those lights flashing but since I always cut the shot manually I never considered it a problem.
Speedster/Bosco Sorrento/ K10WBC/K30/Bunnzilla
KvdW/Pullman/RB Tampers
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jmcphail
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Re: Recalibrate grind?

Post by jmcphail » Mon Jul 12, 2010 5:23 pm

Hi JohnB, long time!

I hadn't had the problem unless I gorilla tamped :D So I haven't, for a long time.

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