Olympia Cremina 2002: The evolution of design - Page 3

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srobinson (original poster)
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#21: Post by srobinson (original poster) »

texican wrote:Since you brought up the :wink: steam arm, have you thought of replacing the steam tip with something other than an Olympia tip (unless Olympia offers optional tips... hmmm.)
Steve, Now the question becomes....can you do that? On the 67 the tip in completely integrated into the steam arm. Now have they changed that? You will notice that I like the cliffhangers to keep you coming back. I'll hit this on a steaming post.
Steve Robinson

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srobinson (original poster)
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#22: Post by srobinson (original poster) »

lino wrote:Hey Steve, can you still buy piston shafts and pistons for your machine? Are they expensive? I have an idea...
Lino, yes you can...only money. I need to see what you are up to and what you need to drill ...you and Jim have me thinking about doing some research on the variable pressure of a lever pull. I think that Jim is onto something with his hypothesis that the pressure goes through three stages on a manual pull. I can feel it, but I want to measure it. Dan and I are about to rig something up and I wanted to see if I could get your data on the work you did on Elektra spring strengths.

Hope things are well for you.
Steve Robinson

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RCMann

#23: Post by RCMann »

Couple of shots of the pressure gauge.

Not brewhead pressure, but I'm sure with a bit of work that can be accomplished also.

We can equip these with more gauges than an F-18...RC


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lino

#24: Post by lino »

srobinson wrote:Lino, yes you can...only money. I need to see what you are up to and what you need to drill ...you and Jim have me thinking about doing some research on the variable pressure of a lever pull. I think that Jim is onto something with his hypothesis that the pressure goes through three stages on a manual pull. I can feel it, but I want to measure it. Dan and I are about to rig something up and I wanted to see if I could get your data on the work you did on Elektra spring strengths.

Hope things are well for you.
Hey Steve,

The more I think about it, the more I think it would just be easier/cheaper to duplicate the piston and rod. Perhaps at some point you could take yours out and I could measure them for an hour or so... Maybe once the holidays are behind us...

My thought is to put the pressure gauge roughly where the nut is on the top of the shaft. Run a pressure tap down thru the shaft, and thru the piston (which will now need to be sealed to the shaft). The big hurdle is how to deal with the lever pin that goes thru the shaft too...

The challenge with the Pavoni, Elektra, and Olympia design is that there isn't anywhere to mount a gauge that sees brew pressure all the time. And that's even before the, understandable, reluctance of drilling into the shiny group head. Y'all shoulda got a LaPeppina :wink:


Anyway, I'll look around and see if I can find the notes I took on the Elektra spring, and the LaPeppina spring too.
Actually, I don't recall that I measured the new Elektra spring... Hmm... I'll look.


ciao

lino

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srobinson (original poster)
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#25: Post by srobinson (original poster) »

RC, I think you win my Mad Maxx award for that beast...what a bare metal hot rod. Looks like you have an early 70s machine. Now I don't know if you plan to run full time with the case off, but please be very careful with that boiler. Those machines spook me.
Steve Robinson

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#26: Post by srobinson (original poster) »

Thanks Lino...would love to chat with you on ideas in the new year. I can always convince Dan to loan you the Elektra if you need to take some new readings. I am sure we can get it back together :lol:
Steve Robinson

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#27: Post by srobinson (original poster) »

As I dig deeper into the mechanical aspects of this machine, I begin to better understand and appreciate what Olympia's design point is for the Cremina and I am able to better appreciate the subtle aspects of its construction. Basically, this is a well crafted machine whose purpose is not to deliver a couple years of useful service, but with proper maintenance, multiple decades of solid consistent performance. I have a lot of pictures tonight but even so, I have had to limit my shots to those pics that either show the uniqueness of the Cremina's design, or the novelty of their solution to common problems.

To drop the piston on this machine you first need to remove the top nut and retaining nut at the top of the piston shaft. I was thinking of Lino's interest in tapping the pistons shaft since there is a lathe mark at the end where they machined this piece:

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Now as I mentioned in the reply to Teme, there is no play in the handle. They have threaded bolts running through the fork which allow for no sideways play. Now the question in my mind was whether these would stay tight over many years of use and it looks like that was on the mind of the Olympia engineers as they back tapped the rear fork and used a threaded retaining nut to ensure that will not happen....I like this touch.

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This design also allow you to simply remove the front bolt on the fork and the arm will now swing back giving you full access to the piston shaft. So with a couple short taps with a plastic hammer and the screen pops free. You will notice that they have moved away from the clip-on style that they had with my older machine and have adopted the style of most levers where the dispersion screen is held on with a major gasket:

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Now you can easily remove the piston. The piston is the heart of this machine. If you have followed my posts, you have seen plastic ones in Pavonis, you have seen the spring loaded ones on the Elektra, you have seen the mysterious 4 holes on my classic Cremina, but you have never seen anything like this. So let me start to show you why this is so special.

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There she is as you pull her out of the machine. Solid chunk of metal, novel use of color on the gaskets, and you see three instead of the normal two gaskets. So let's start at the bottom and see what they have done:

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First you will notice that the piston bolts onto the shaft. Most of the other machines simply have the piston head itself screw onto the piston shaft. Seems like a process that works OK, but if you use a machine consistently over time you will notice that one of the bad traits that they have is that they slowly unscrew themselves and block the water inlet. One of the most common complaints that I get on the Lever Machine Forum are from Pavoni owners who can't get water into the grouphead. That will not happen here.

Now once you remove the screw, you see that the piston is not solid, but a multi-piece unit:

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Now only you leverheads that have struggled with putting new gaskets onto a machine can understand the frustration of trying to get new V gaskets on a solid piston. You heat, they flip, you scratch them, you pry them....guess what....on this machine you simply drop them on and you are good to go. No fuss, no muss. That is almost worth the price of admission there. But while we have it apart, let's take the time to look hard at these gaskets. Now on the Elektra, there are two unique gaskets, but on the Olympia, there are really two vastly unique gaskets.

As you look at the green one, you first notice that they are not normal rubber based gaskets but the external portion are made of a much denser vinyl composite. As Teme noticed in an early post, the 4 holes are gone that you see on my older machine which was a very elegant solution to allow the rubber gaskets a tighter fit against the grouphead walls. So with a firmer material and not water holes, how will you get both the smooth operation and an extremely tight fit. This you won't believe:

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This is the top gasket. Embedded into the gasket is a spring which allow the gasket to flex both on the upstroke and the downstroke.

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This is the bottom gasket that is filled with a porous spongy material that I think can still utilize water to help with its action on the upstroke and the downstroke. Some serious engineer work went into this solution. With the harder material you have gaskets that not only perform better, but I would assume have a much longer life than the older design. This combined with the piston design allows for less frequent maintenance but when needed, much simpler replacement.

Now how about the middle gasket...How the hell do you replace it. Again you will see that Olympia went with a hard material and simply precut the gasket. Snaps right on...brilliant.

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Now to the step that you dread when replacing the piston. New pistons = tight seal and the biggest headache with most designs is how to get the lip of the top gasket into the grouphead. Now with other machines I have used a scribe to help with the rubber washer but with this harder material I was a bit concerned whether it would flex enough to keep me from marring the gasket or the grouphead.

And then it dawns on you. With a multi-piece piston, you can simply insert the piston shaft, insert the first gasket and then add the rest of the piston and tighten the piston IN the grouphead.

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My hat's off to Markus and the Olympia engineers for that trick.

So with this simple tour of the grouphead and piston you start to see how well these machines are thought out and how their design has been planned. I often get asked whether I can make as good a cup in another lever machine as an Olympia and the answer may be yes on day one, but if you tested that one year down the road, 5 years down the road or even 20 years down the road, my opinion is that it becomes obvious that the long term test will go to the Cremina.
Steve Robinson

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Teme

#28: Post by Teme »

Truly fascinating stuff. I start to realise why these machines do cost (significantly) more than e.g. the Pavonis. Hmm...
srobinson wrote:I'll do some compares on the baskets later in the reviews. I am getting very good performance from both on the older machine.
I see that you have already pulled some very nice looking shots indeed and I look forward to your further evaluations on the various baskets, including the Elektra double basket if it fits.
srobinson wrote:1) New one will take a clip
Does the portafilter / basket really take a clip? This would be a first I've seen in a lever machine and while I'm not sure I'd want to use a clip, it is interesting nonetheless.

Br,
Teme

RCMann

#29: Post by RCMann »

"RC, I think you win my Mad Maxx award for that beast"

Steve-It's only sans bodywork until I strip it, clean it, and replace the gaskets/seals which will be over New Year's weekend. Meanwhile, it's making great espresso even with old rubber.

It's a 1974 Zabar's special.

Regarding asbestos, it's only an airborne hazard, and even then only for chronic exposure, so unless you've gone into business sanding old Cremina tanks without a respirator, there shouldn't be a problem. Even if a bit flaked off into the cup, ingestion isn't an issue with asbestos.

One could always paint the tank with some hi-temp engine paint to seal it if it was a concern.

BTW, will the new piston fit into the old head? The Oly site lists the 2002 'piston assembly, complete' for ~$382 which seems high, I wonder if that's the whole brewhead? If the piston is reasonably priced and fits, maybe a nice upgrade!

Rod
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srobinson (original poster)
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#30: Post by srobinson (original poster) »

Teme, yes, the Olympia and the Elektra come with a clip. With my process I don't use them though. I always grind into a separate cup and dose from that to try and keep the wife tolerant of the hobby. Trying to dose in these small diameter baskets are quite the challenge. I also keep multiple baskets at hand and am usually preparing 2-3 at a time. Thus, I can just do a pull, flip the basket in the sink, add another one and get all my pulls in before the machine gets too hot. We are debating adding a coffee bar to our kitchen redo, so may go with a knockbox there and I would use the clip more.

Rod, I hear you. I have a friend in construction who makes his living removing asbestos and some of his stories just give me the creeps around it. I have seen some machines where the cement they use deteriorates over time. As long as it is stable....

It is hard to tell from their site what that price covers. I think if you were considering this upgrade, I would drop them a note to be certain. I added up just the shaft parts and it was in the $170 range. Another option for you with your older machine would be to simply upgrade to the piston and gaskets from the 67. I really like the action of performance of that on my older machine. I think for 300+ bucks I would be upgrading my grinder.
Steve Robinson

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