shadowfax wrote:Why?

On several occasions I've seen people get coffee grounds up in the tube, and that having put the screw back in turn on the group and shoot the grounds into the dispersion screw preventing water leaving the group.

This is a better case scenario because at least the screw can be removed and cleaned out. It could get clogged more permanently quite easily.

shadowfax wrote:Have you been reading James Hoffman's blog?

Yes Nick, James did start me off on this kick, so I thought I would find out what the others here may have to say.

One other thing I though I would ask...

I tend to not leave my PF locked into the head when I am done cleaning and shut the machine down. I have this suspicion that having the gasket compressed like that over time would accelerate the need to replace it. On the other hand with the limited time and number of shots we pull in a day a once a year gasket change may more than make up for this.

-Cecil

CRCasey wrote:I tend to not leave my PF locked into the head when I am done cleaning and shut the machine down. I have this suspicion that having the gasket compressed like that over time would accelerate the need to replace it. On the other hand with the limited time and number of shots we pull in a day a once a year gasket change may more than make up for this.

Best advice: lock in the portafilter softly. Don't torque it down at all, just turn it till it just touches the gasket. That way the portafilter stays hot in the group, but you don't compress the gasket. You're right that leaving the portafilter locked tight in a hot machine will over time compress the gasket/deform it so that you have to lock it in further over. This isn't really a bad thing--you're mostly just adding wear to an entirely disposable part. Technically locking it in like this also wears down the metal on the portafilter lugs/group 'rails,' but I would categorize that as negligible wear at best, especially compared to even a moderately busy shop. But you might as well do the soft lock--no reason not to.

When running and hot I do use the light lock method, and since I do not use the basket spring I do not lock in tight to keep the top of the PF from cutting into the gasket as well.

What I was commenting on was more to do with end of day operations and not leaving the PF in the head tight then.

-Cecil

King Seven wrote:On several occasions I've seen people get coffee grounds up in the tube, and that having put the screw back in turn on the group and shoot the grounds into the dispersion screw preventing water leaving the group.

This is a better case scenario because at least the screw can be removed and cleaned out. It could get clogged more permanently quite easily.

James, would I be going out on a limb if I guessed that the people you've witnessed getting grinds up the feed tube when backflushing sans dispersion disk were maybe following a regimen where they simply pulled the screen for a soak and started backflushing without de-gunking the dispersion block (or whatever they call that disk behind the screen on an LM-style machine)? I have no idea if that's a bad idea or not, but I don't see the harm in backflushing screenless and screwless if you've cleared all the big grinds via, for example, a good brushing and flushing with a blind filter loose in the group (wriggling side to side). Indeed, it's been pointed out to me by a forum member that the GS3 Operating Manual recommends removing the screen and dispersion screw when backflushing:

GS3 Manual wrote:Cleaning (Daily)

1. Cleaning the Diffuser Screen.
   During the discharge operation (subsequent to coffee brewing), small amounts of coffee grounds may slowly build-up on and obstruct, even partially, the diffuser screen. Remove the diffuser screen by unscrewing the diffuser screw. Place 2 or 3 teaspoons of detergent powder for coffee machines in about 1/2 a litre of hot water. Place the diffuser screen and diffuser screw in the solution and leave them fully submerged for about 30 minutes. Rinse thoroughly with clean water. Install and run hot water through the group head several times with the screen installed.
   
   
   
   
2. Cleaning the Brewing System.
   Remove the diffuser screen as described in the previous step. Install the blind filter into one of the supplied portafilter handles. Place a tablespoon of detergent powder for coffee machines into the blind filter and install the portafilter into the espresso machine.
   
   Cycle the espresso machine on and off using the continuous button. Cycle approximately 10-20 times. The cycling of the espresso machine allows the detergent powder to flow through the brew system cleaning the components. Remove the portafilter from the espresso machine.
   
   After cleaning, rinse the group head by activating the continuous button or approximately 10 seconds. Using a damp cloth wipe clean the area where the portafilter engages into the group head. Then replace the diffuser screen.

I have to admit I am rather surprised, and indeed I actually find their instructions a bit lacking when it comes to order (wait until after backflushing to wipe the gasket?) and thoroughness of rinsing (just a 10 second flush?). Anyway, I thought it was an interesting point. I'm tempted to think the screen thing is more "no big deal" than a wisdom issue, but that's just my opinion as someone not well-versed in big commercial LMs. I understand LM installed 0.6 mm gicleurs right behind the dispersion screw on some Lineas and FB70s (and maybe others?), which strikes me as the perfect recipe for getting your group clogged up if you're not careful. The devil may be in details of that nature.

adding the 0.6 gicleur to any LM is a very standard modification in the commercial world.
but i've seen people pull this sort of "clog the plumbing" move on non LM machines as well (an Astra and a Faema). in one case, of course, it wasn't exactly due to backflushing without the screen but due to forgetting to put the screen back in after backflushing and then pulling a shot.

If you've de-gunked the dispersion block properly then it is extremely unlikely. However I would much rather the chance of something bad was zero, rather than just very small. The pulling of a shot without screens in is pretty much worse case scenario.

As for gaskets - I suspect this is where the commercial world differs from the domestic. I tend to just leave handles locked in as normal. I have a big stock of gaskets, and while I don't believe in being wasteful I do probably change mine a little more often than normal because my machine is both a training machine and a showcase machine and everything ought to be perfect. Similarly I drain my boilers way more often than most people (but then again I rarely use steam boiler water for anything so should err on the side of caution).

I have yet to replace a group gasket. I pull plenty of shots and would consider my machines use to be a bit heavy for home but very light for commercial use. I lock the portafilter in light when it is not in use, barely hanging actually. When I lock in to pull a shot, again I lock the portafilter in lightly. I find that most people wrench in their portafilter way harder than necessary. You just need enough pressure to create a seal between the gasket and basket lip. As long as the gasket is clean, it does not take much. Use two fingers, not a hammer.

But, gaskets are cheap and easy to replace. I keep a couple in the parts drawer along with a vacuum breaker and a few other little bits.

Everyone has a different routine, some are a bit on the light side others appear to be on the heavy side. You just have to find what works best for you with your consumption level. Contrary to logical thought, a light use machine would need to be cleaned more often than a heavy use machine. A heavy use machine will get oiled up, but the oils will always be fresh since shot two will remove the oils from shot one, shot three will remove the oils from shot two, etc... Oil will dissolve oil, water does nothing to it. So a light use machine that gets a shot a day could have rancid oils on/in the group while a machine that gets 5 shots a day will still be fresher the next morning. Just use the machine, clean it after x days and see if you notice a difference, find the maintenance window that fits your use and go with it.

shadowfax wrote:Indeed, it's been pointed out to me by a forum member that the GS3 Operating Manual recommends removing the screen and dispersion screw when backflushing

I should also point out that the manual excerpt posted by Nicholas recommends using a tablespoon of detergent for backflushing. I'm nearly certain that's a typo, possibly a repeat of the tablespoon reasonably recommended for soaking the screen, screw, PF, baskets. I'm no expert, but from what I've read and heard, a tablespoon of detergent for backflushing might be dangerous to the health of the machine. I use a Pallo scoop of detergent, which comes to less than 1/2 teaspoon. I think that's pretty standard.

Peppersass wrote:I should also point out that the manual excerpt posted by Nicholas recommends using a tablespoon of detergent for backflushing. I'm nearly certain that's a typo, possibly a repeat of the tablespoon reasonably recommended for soaking the screen, screw, PF, baskets.

I doubt that very many people in Firenze know what a tablespoon is, as this is an English measure one would never use Italy. Unless the manual was written in Seattle, the writer presumably had no intrinsic gut level feeling for what constitutes a tablespoon. The only English measure I ever hear used in conversation in France is "mile," although I doubt that most people who I've heard use it could tell you what a "mile" is in a coherent explanation. Rather, a lot of airlines, world wide, have "mileage" programs, and I'm not aware of any of them using km. instead of miles as the measured distance. When I tell French people that I got a free airplane ticket with "miles," they know what I mean, but that is as far as it goes, unless they have visited the UK, where miles are still used.

ken