Portafilter trying to unscrew itself...why?

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JakiChan
Posts: 58
Joined: 11 years ago

#1: Post by JakiChan »

This weekend a new behavior in my machine has developed - the portafilter starts unscrewing during the shot. It hasn't happened every time, and so far I've caught it when it does, but this is weird. Too many things have changed in my setup, so let me lay them all out and maybe someone can guess what I'm doing wrong.

The machine is a Quick Mill Anita HX machine. Been running great for 3 years. Back in November I replaced the gasket with the Cafelat gasket, I replaced the screen with an E61 Precision Screen, and I started using the Cafelat portafilter with a VST 18g basket. All was well. The only issue that I would note is that the Cafelat portafilter doesn't "screw in" as far as the stock portafilter. If the stock portafilter has it's handle sticking out at 6pm (so directly away from the machine) then the Cafelat portafilter is at 7 or so. Cafelat, when I contacted them, suggested I should use the smaller gasket but I disagreed given that a) the size I used is what Chris Coffee/Quick Mill says to use and b) the stock portafilter still fits the same.

Cue to this weekend, where three things happened. One: I changed my grinder from a Baratza Vario to Mazzer Mini E. Two: I took the bottom of the portafilter off so I could watch the extractions. Third: I cleaned the machine using Full Circle wash, backflushing per instructions. After the cleaning is when this "unscrewing" began. It may be a matter of my just having failed to lock the portafilter in enough, but this seems strange enough that I'd see if it's a symptom of something that I didn't know about. I appreciate any insight.

zimberto
Posts: 98
Joined: 13 years ago

#2: Post by zimberto »

The reason this is happening has to be due to pressure from the brew water pump and/or lack of adhesion between the rim of the basket and group gasket. One possibility is that you are grinding too fine with the new grinder and that has increased the pressure in the portafilter. In addition, the cleaning with full circle may have reduced the grip of the gasket, either on the basket or in its housing. It also sounds that the new gasket either isn't fitted correctly, or it really isn't the right one. There are different thicknesses of gasket and it sounds like you could do with a slightly thinner one. Last I heard, Chris Coffee was not covered under papal infallibility. Lastly, I assume your brew pressure is not vastly exceeding 9 bar?

JakiChan (original poster)
Posts: 58
Joined: 11 years ago

#3: Post by JakiChan (original poster) replying to zimberto »

I'm pretty sure they're on about the proper thickness of the gasket. And, as I stated, the original portafilter that came with the machine fits as it always has. (I use the single PF that came with the machine to backflush, and that hasn't changed in it's fitment.) Unfortunately I didn't try using the new PF with the old gasket, but others have stated in their reviews of the Cafelat PF that they saw similar fitment issues.

I'll make sure to check the brew pressure when I pull my shot tomorrow morning.

Mad Wally
Posts: 6
Joined: 8 years ago

#4: Post by Mad Wally »

Isn't it more likely that the basket is rotating in the portafilter as metal-metal usually has less friction than metal-rubber?

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Paul_Pratt
Posts: 1467
Joined: 19 years ago

#5: Post by Paul_Pratt »

I had to go back and check the emails. You should change the gasket for the smaller 8mm one. It is a set, that is how it was designed. Although there are only 2 or 3 manufacturers of the E61 replica groups there are differences in the machining tolerances. Supplying 2 gaskets with the E61 is designed to cover the bases of the manufacturing tolerences of the group.

Aside from the gasket, if the coffee dose in the basket is too high it will touch the screen preventing the pf from engaging properly. But in this case using the thinner gasket is the key.

DaveC
Posts: 1743
Joined: 17 years ago

#6: Post by DaveC »

Paul_Pratt wrote:I had to go back and check the emails. You should change the gasket for the smaller 8mm one. It is a set, that is how it was designed. Although there are only 2 or 3 manufacturers of the E61 replica groups there are differences in the machining tolerances. Supplying 2 gaskets with the E61 is designed to cover the bases of the manufacturing tolerences of the group.

Agreed, gasket is too thick, the engagement lugs on the portafilter are sloped and the downward force winds open and incompletely locked portafilter e.g. one where it's not locked as far as the flats of the lugs. Seen this problem many times.

nuketopia
Posts: 1305
Joined: 8 years ago

#7: Post by nuketopia »

I owned an Anita for a number of years. Whenever this started to happen, it was a sure sign of it needing a new brew gasket. The 8mm is the standard size.

I had a naked PF sourced also from Chris' Coffee that worked, but would not lock in the straight out position, where as the standard Quickmill PF's would. All the various e61 vendors kind of do their own thing. Also found that teflon gaskets for servicing the e61 itself also varied in size from different vendors.

Paolo
Posts: 551
Joined: 17 years ago

#8: Post by Paolo »

I have had this problem just after I have lubed the piston seals on my Brugnetti Aurora. Some excess Dow 111 had worked its way to the portafilter gasket.
I had to give it a thorough clean but it came good.

Is there any chance some lubricant was used near the portafilter gasket during your cleaning process?

mauijer
Posts: 317
Joined: 10 years ago

#9: Post by mauijer »

JakiChan wrote:, I replaced the screen with an E61 Precision Screen, .
Sorry to be off topic, but did you notice an improvement with the precision screen? I've been debating buying one.

JakiChan (original poster)
Posts: 58
Joined: 11 years ago

#10: Post by JakiChan (original poster) »

Paul_Pratt wrote:I had to go back and check the emails. You should change the gasket for the smaller 8mm one. It is a set, that is how it was designed. Although there are only 2 or 3 manufacturers of the E61 replica groups there are differences in the machining tolerances. Supplying 2 gaskets with the E61 is designed to cover the bases of the manufacturing tolerences of the group.
nuketopia wrote:I owned an Anita for a number of years. Whenever this started to happen, it was a sure sign of it needing a new brew gasket. The 8mm is the standard size.
So, to be clear:

1. Chris Coffee, from whom I bought the machine says that the machine takes an 8.5mm gasket:

https://www.chriscoffee.com/Group-Gaske ... asketg.htm
http://wysrt.cnwfk.servertrust.com/v/vs ... Manual.pdf

Can someone provide a link to something that says otherwise? And this Cafelat gasket is about 4 months old. That seems like an awfully short lifespan for a gasket.

2. The portafilter that came with the machine still fits the same.

I'm really having a hard time understanding why the issue would be with the gasket and not the portafilter. (And if you search on the Cafelat portafilter you'll see other people saw the same thing without changing their gasket.)
Paolo wrote:Is there any chance some lubricant was used near the portafilter gasket during your cleaning process?
No - the only cleaning I did was backwashing with Full Circle wash.
mauijer wrote:Sorry to be off topic, but did you notice an improvement with the precision screen? I've been debating buying one.
Really hard to say. I also got a VST basket at the same time.

This morning it did NOT happen, btw. Brew pressure was maybe 9.5 on the dial.

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