But my portafilter uses a basket for which I use a 57 or 58 mm tamper, so I think that's a different portafilter.

That is a 58 mm portafilter The standard Elektra group on the larger machines is a 58mm. Sorry, I did not mean 53 mm (looked at too many pictures trying to find the right one).

Indeed, James, I have one of those new 58mm standard Elektra portafilters, which I got from Stefano for my T1. I also have some "vintage" 1999 T1 portafilters, and their portafilter lugs/ears are much more slanted (though still not as steeply as Joep's). I doubt that the portafilter is the problem; it doesn't show any particular signs of wear, and whether it's flat or not, it's still just 2 pieces of metal smashing the basket against the gasket. Doesn't need to be flat to do that, as long as it's thick enough to press hard enough.

And it seems to be doing so--Joep notes that it seals fine for part of his shots, indicating something slowly coming out of place. Since the portafilter isn't moving, it's clearly not that, so I suspect a problem with the gasket, either inferior quality, improper seating, or just some gunk in it screwing it up. Both of these guesses seem consistent with an issue which is solved by gasket replacement, at least temporarily. I don't think that a diagnosis of "you have the wrong portafilter" is consistent with the observation that it actually works fine with a fresh gasket replacement.

Thanks Nicholas, I know you and quite a few others have much more experience with Elektra products than I do. My thought was that the steeply ramped wings may allow the portafilter to loosen up after the pressure builds in the basket because there would not be as much contact area between the PF and the thread if they do not have the same profile. New gaskets could initially solve the problem until they become fully seated. I only suggested he may have the wrong portafilter, I did not mean to insist that is the case.

Thanks, James

shadowfax wrote:I doubt that the portafilter is the problem; it doesn't show any particular signs of wear, and whether it's flat or not, it's still just 2 pieces of metal smashing the basket against the gasket. Doesn't need to be flat to do that, as long as it's thick enough to press hard enough.

I believe this is not true Nicholas. You could smash flat against a perfectly good gasket and form an initial seal, but if there's too much clearance behind the tabs OR if the groove has a wallowed-out spot....this could allow the portafilter to "rock" and thus lose the seal and allow the hot contents to spew.

shadowfax wrote:Since the portafilter isn't moving, it's clearly not that

But the OP says that the portafilter DOES move!

The fact that the portafilter physically MOVES after the pressure starts to build is very telling I think. And it makes me believe the problem is almost certainly not related to the gasket. The gasket apparently seals fine, allowing the pressure to build (plus, I believe the OP said the gasket is new).

Joep wrote:By the way, also when it doesn't 'explode', the portafilter handle comes up a bit in the first couple of seconds after initiating the brew process when pressure builds up, and comes down again when I stop it.

If I understand correctly, Joep is talking about up and down movement. I experience this every day on my Elektra, although it's very subtle unless you hold the portafilter handle during brewing or watch it very closely. One thing that puzzles me is that Joep describes exactly the opposite of what I see: When the pump engages, it slowly pushes the portafilter down, I assume it's the flex in the system as pressure is applied, the water forcing the gasket against the portafilter and then against the group bell channels for the ears. When brewing ends and the 3-way valve opens, it jumps up in my hand slightly as the pressure is relieved. I assume Joep just switched his words around--can you clarify, Joep?

If your portafilter is moving laterally, i.e. the the pump is forcing it to back itself out of the group, this is a huge problem. I think, however, that it's MUCH less related to how the ears mount in the channel and more with how lubricated the gasket is with coffee oil. To whit, try this: get some food grade grease, the type used for lubricating steam wand assemblies (Dow Corning 111 is good), and lube up your gasket on the portafilter side. Now lock with a blind filter, hit the brew switch, and watch it slide out. This won't happen on every machine, but it definitely does on my old Elektra. This can happen naturally from coffee oil as well, depending on how often you use detergent to backflush, and how much coffee ends up in contact with the gasket. If you want to get rid of it again, simply do a good portafilter wiggle with detergent in the backflush disk till your gasket locks nice and tight. A really clean one will lock it quite tightly. Anyway, this doesn't even sound like what Joep is describing...

Forgive me for doubting you guys, but considering this is a home machine and the pictures I have seen so far of the portafilter, I highly, highly doubt this is from wear and tear on metal (such as wallowed out spots or a worn down channel. I'm a lot more prone to suspect something along the lines of a moving gasket, having seen that type of crap on Elektras. That's one thing I will say about Elektras--their group gaskets are absolutely pathetic compared to LM, Synesso, and Faema gaskets (and other flat ones). Joep actually has a flat-faced one, which seems nicer than the round ones for my T1. My gasket is finicky about leaking if it's even slightly dirty, though it starts to leak immediately.

Whew, what a responses, thanks!

I made some pics of the group head:




The gasket is indeed practically new.

And indeed, my portafilter moves only up and down, not sideways. I really think my handle moves up when I start, but I would have to check tomorrow.

I do see by the way that the slot for the wings is much less steep than the taper of the portafilter wings...

shadowfax wrote:My gasket is finicky about leaking if it's even slightly dirty, though it starts to leak immediately.

Interesting. I can see how a round-section o-ring might not be as robust a seal as the flat gaskets seen in many other machines, but if the leaking in caused by upward tilting instead of rotation then there is almost certainly a geometry problem of some kind.

It was my understanding that Joep was seeing his portafilter shift upwards markedly, not gradually or slightly. He also seems to have indicated that the gasket leaked even when cleaned

Joep wrote:Well, I had cleaned everything when I installed it....
<snip>
What do you think about the fact that my portafilter lifts up when I engage the pump? Is that normal for the Elektra?

Joep wrote:I do see by the way that the slot for the wings is much less steep than the taper of the portafilter wings...

WOW! Talk about real-time response!

I'm not sure if this is meaningful but I do notice that the pictures make it seem as though the front part of the right side groove is worn to expose the brass, but the tail end is still chromed. Perhaps it's just the action of the flash...

Joep wrote:And indeed, my portafilter moves only up and down, not sideways. I really think my handle moves up when I start, but I would have to check tomorrow.

I'll be interested in this too....

Do you have another portafilter to try? I wish you were closer, I would send you one of my LaMarzocco portafilters to see if it fits tight enough to hold the brewing pressure

No, I don't have another portafilter. Buying another one is not what I want, although I wouldn't have to buy one complete with handle, just the cast part.
But since I'm more or less also looking for a machine with easier temperature control and a pressure gauge, I wouldn't want to spend much on this machine if you get what I mean..

Jon--I don't disagree with you in principle, I am just trying to say it seems very unlikely to me. I could be wrong, though, and I'm glad Joep is getting help from plenty of people with different ideas.



Joep, I was wondering about the 2 areas I highlighted. Is it just a trick of the flash or the angle, or is there some unevenness to how the gasket is seated? it looks like it is raised (lowered?) out from the body of the group bell on the left, hence the shadow. On the right side, it appears that it's flush or even sunk in, with an angled bevel cut into the metal just to the right.

How does the gasket feel on your finger along the perimeter of it? does it have some give in certain parts?

Edit: Also, do you see water flowing predominantly from one part when the seal breaks, or is it pretty much all over the place?

To me, if the handle shifts up during the extraction, it means it is pivoting on something... the only pivot point that makes sense for that direction of movement [to me] is the wings of the portafilter. The more extreme angle on the portafilter wings seems like it would encourage such a pivot. Think of it like this, when it locks in the more extreme angle on the wings [as opposed to the slot in the group head] would leave a gap between the front of the wing while the back of the wing makes contact. When pressure is applied, the portafiter rotates down until the entire wing (i.e. the front which was not in contact shifts down) make solid contact which would leave a gap between the edge of the portafiter closest to the machine and the gasket... hence the grounds not hitting the user but spraying over the machine. From my perspective, reading the previous posts, this seems to be the simplest answer that explains the specific problems he is describing. Just my guess though...

karl_a_hall wrote:To me, if the handle shifts up during the extraction, it means it is pivoting on something... the only pivot point that makes sense for that direction of movement [to me] is the wings of the portafilter. The more extreme angle on the portafilter wings seems like it would encourage such a pivot. Think of it like this, when it locks in the more extreme angle on the wings [as opposed to the slot in the group head] would leave a gap between the front of the wing while the back of the wing makes contact. When pressure is applied, the portafiter rotates down until the entire wing (i.e. the front which was not in contact shifts down) make solid contact which would leave a gap between the edge of the portafiter closest to the machine and the gasket... hence the grounds not hitting the user but spraying over the machine. From my perspective, reading the previous posts, this seems to be the simplest answer that explains the specific problems he is describing. Just my guess though...

I think this might very well be the case. That would also explain why my handle moves up, not down. And indeed, most grinds end up at the back plate, not to the user's side.
So I guess a new portafilter should solve this. I'll ask if I can return it if it does not solve the problem.

@Paul Pratt,
Wow, your whole portafilter blew out? Mine stays in place.

As I understand it, locking in the portafilter presses the basket against the plane of the group gasket, which in turn presses against the plane of the track it's in in the group. the diameter of the portafilter being what it is, I really don't believe that the portafilter lugs would allow the kind of pivoting Karl is talking about, even if they aren't perfectly parallel--there's not that much flex in the system. That said--if your gasket is not seated right--i.e., if it somehow doesn't form a plane to mate against the basket, or somehow deforms, this seems like a more likely cause to me, and what I would be looking for.

Still, if you can get your hands on a new portafilter body to try, I suppose it's worth a shot.

I spoke just now with the elektra tech guy to confirm a suspicion
also to him the portafilter in the picture doesn't look an elektra one
can you take a picture from the top showing the wing positioning?

Sure!
Thanks. I really appreciate all the help from here. Truly a warm welcome.
Not the usual 'hmm, there's yet another noob with a stupid question' attitude, great!

shadowfax wrote:...I really don't believe that the portafilter lugs would allow the kind of pivoting Karl is talking about, even if they aren't perfectly parallel--there's not that much flex in the system. That said--if your gasket is not seated right--i.e., if it somehow doesn't form a plane to mate against the basket, or somehow deforms, this seems like a more likely cause to me, and what I would be looking for...

Sorry - I can't help but chuckle
This is why we don't want the IT guys to design mechanical machinery


**************
For those interested in the offtopic conversation, copper and brasses generally behave VERY differently from iron products like steel and stainless steel. Compared to the steels, copper has a VERY low modulus of elasticity (YOUNG's MODULUS), and the YIELD STRENGTH is MUCH lower meaning that it will flex more easily. Together this means that copper tends to be less "springy" (the metal has much less "shape memory" - so when you flex it, it stays flexed instead of bouncing back to the original shape).
**************

As far as pressing the basket rim against the seal, in very basic terms your description is accurate BUT you have kinda skipped over the critical factor of the geometry of the arrangement as it exists now. The things I'd want to investigate are:

How much contact REALLY exists between the portafilter ears and the groove?
How much clearance is there opposite the contact faces to allow PF pivoting?

We can safely say that the seal is only going to stay sealed as long as the basket and gasket are in firm contact. It still seems to me that if the gasket was the item allowing the blow-by then the portafilter body would not need to pivot (the gasket would be the item that flexed out of contact position).


All of this certainly is an interesting debate though!

GEOMETRY:

IF the portafilter body is pinned at two small spots opposite each other on the diameter, meaning the faces of the ears DO NOT make a nice line of contact with the groove face; THEN you have an ideal setup to allow the portafilter body to pivot about the axis (line) between the two point contacts. If either the groove or the ears were worn or wallowed this could happen.

BUT - if each ear makes a line of contact with the groove then there is no tight axis for rotation because you'd have to overcome the linear spread of the supports (basically, creating a type of lever) and it would be much more difficult to pivot the portafilter body. Also, if there was no physical space for the ear to rotate downwards in the groove then the PF body would not be able to pivot far enough to break the seal.

Geez - I wish I had a whiteboard to sketch this up - I feel like visual aids would help a lot!

Hi guys,

am I the only one who thinks the gasket is not a proper group gasket? it looks more like an o-ring than a standard thick tire like gasket. Heck you can even see the metal behind it which means it's too little? it should cover the whole ridge to give a proper seal.

Exploding PFs, seriously scary stuff!

Regards,
dsc.