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The spring is the thing
I'm curious, since it seems that the 'magic' of a spring lever shot is how the spring works in the lever, does that mean that there are different spring designs? Do machine makers personalize their creations with their own spring design? To shape the pressure profile in the shot?
Thanx for indulging my curiosity.
Thanx for indulging my curiosity.
Comments
Linear or progressive.
If you have the money any spring could be made, there are companies that make springs; look at automobile suspensions.
I do not know for sure but I think every manufacturer of springs might have trick formulas for metals/alloys.
Good luck getting the necessary info out of the Italian manufacturer of the L-I Groups. There has been much published and also written in the coffee forums about spring ratings in Bar of pressure in the puck but that tells you not so much about the springs themselves.
:-)
I guess I'm making the spring equivalent to the 'secret sauce' when maybe there is a different part of a given machine that makes it special. For example, the L II & III's way of keeping temp stable through smarter plumbing. Sorry if I'm over simplifying all the work that went into the design!
There's a brilliance in simplicity of designing the boiler and thermosiphon pipes in such a way that over time the temperature remains stable, when the group is used intensively or just a few times a day. Some manufacturers have a more direct bolt-on connection of a similar group to their boiler, which can have detrimental effects.
There are variants with double spring, but on the L1 they would not be an improvement, I understand. The single spring delivers plenty of push and when the brew chamber is filled at a (slightly) higher pressure on the L1, the power exerted by the spring is stronger already. That way the user can safely play with the variables without losing a consistent fine extraction.
He made the offer to sell a double spring to the last person who wanted one but when the price was divulged the OP though it to expensive. Ha, money is the ruling factor and if more single springs groups sell then why not only sell single springs?
Quick Mill Achille was, or perhaps is, a double spring group and the reports are that it is a real handful to pull, ie very hard in comparison to the single spring.
Maybe you could get Reiss to put a double spring on one of the groups on a multiple group machine, like the L-II or L-III, but I am sure it would cost more. Perhaps Reiss might correct me since I certainly cannot speak for him.
Okay, that's good info. Also thank you Frans.
Stephen- Are you saying there's a thread here with that discussion? Can you point me to it (even if it's not here). I'll take a PM if you have a bunch. If you're saying that from memory of threads long gone then don't sweat it, I can dig them up. I only ask because researching seems to be a lot of hay and very few needles so any help is appreciated.
So there are/were at least two ways to go and Reiss chose the single spring. I do remember reading somewhere else here mention of the double spring. I don't think I found the thread you mentioned, but I did see it mentioned in another one.
That's a good point about the pulling the lever on the QM Achille. The spring will affect the pull of the lever as well as the profile of the shot!
Just to clarify- I'm not interested in changing springs in my machine, I'm simply curious as to what the options are for the manufacturers like Reiss. Now I see there are at least two options, I thought there might even be more.
Thanks again for the info, springs are new to me so I'm keen to get any good info I can on them.
I believe you could look on any of the Coffee Forums and search and find Lever Machines and then wade through all the crap to come to the thought that, yes, there are 2 spring groups and some people like them and some don't.
Trying to figure out spring rates is a fruitless endeavor IMHO and when you change the diameter of the Lever Group you will change springs and baskets and every little thing about the shot.
Take day or two and read until your eyes bleed through HomeBarista, CoffeeGeek, CoffeeSnobs, UK Forum, etc. and you might come to a conclusion that worrying about it is pointless if your taste buds tell you what is good.
The answer to my question is that a lot of machine manufacturers are customizing their own springs. I believe.
I find that "studying" subjects like this on one of the big forums is also made harder because the threads are sprinkled with comments by guys who pose as experts. If I read a complicated contribution by a guy using very formal language, casually juggling formulas and techno-jargon, also mentioning how utterly remarkable his own results are, I suspect it's a clown posing as expert, but unless I can go over there and taste the guy's coffee, I have no way to know.
Also, some people who *really* know this stuff are way too busy to chat about it online.
Proves how little I know! ;-)
I finally gave up and found a relatively local 3 Group Lever to try. I tasted the shots first and then asked to pull a shot, which I was allowed to do. Once I had done that I asked the question whether it was a single spring or a double spring group. It was a single spring in all 3 Groups.
That machine was made by Bosco but uses the same Group as the L-I, L-II and the L-III. Bosco now adds an extra piston seal but I have found no reason to need one . Bosco also has a different boiler architecture that is a bit more complex but in all honesty I thought the L-I shots were as good or maybe better! Maybe it was the coffee being ground or the shot prep but the Londinium machines really do work, and do so with one spring.
But the special bit, and the bit that really expensive pump machines try to emulate (without success) is that after the spring has taken control of the piston... following pre-infusion, a gently declining pressure is applied to the water that is sitting on the puck... Beginning with at least 9 bars... and eventually of course ending at 0 bars.
I am no "espresso expert", I rarely drink it, but I understand that some aficionados like 6ish bars best, which of course an L1 gently passes through along with loads of other 'bars' on its way to the best shot that money can buy.
You pay about the same amount of dosh for a pump machine that doesn't do any of the above, or you can pay a helluva lot more for a boutique model that plays at diminishing pressure profiling, without ever getting near achieving it.
The tech required to fake a spring is almost ridiculous. I can't see ever recommending it to a shop, and barely 'justified' it for myself at home
Weird how the number 9 just got accepted by everyone (nearly everyone) without question. My espresso tech shared this video with me last year or so, there were a lot of good points made that got me thinking about levers, why some roasters use robusta, puck prep, tamp pressure... all kinds of stuff
Nordic Barista Cup 2011: James Hoffmann - Reinventing Espresso
Like Nordic espresso it's long, dry, and weird. Okay, that was uncalled for, I've never had the stuff. I apologize. I suspect this isn't a new video for most here, or at least the concepts aren't new.
I suspect (maybe even predict) that here in the States the trend will be mostly in the direction of super auto machines, and then a small % going for really really good lever machines. The lever group will be shops that believe in good coffee and the super autos being the group that believes in coffee flavored milk based drinks. We're already sending mixed messages to the manufacturers that they're putting a boiler per group, PID temp control, etc.
When it comes down to it- I want a temp selectable, temp stable machine that provides the best extraction of my coffee each and eery time with the least amount of steps that can keep up with demand and is low maintenance. I don't care if there are PIDs or buttons or levers or leprechauns .
Leprechauns would be fun though.
Does anyone fancy coming over to my place for a coffee?
All better now!
What is that bit between the spring and the first gasket? in the first picture it looks like cork and in the second one looks like it's brass.
The whole piston is one big lump of brass Richard. The three seals (arf arf) and the silicone guide, fit into some grooves that are profiled into the said lump. So immediately following the spring there is a sort of hollow washer that presumably stops the spring digging into the fabled lump, which begins where you indicated.
That was eighteen months of moderate family use... around ten shots per day and it was starting to leak a bit... When I removed the piston today, there was around a teaspoon of water on the wrong side.
I had this very expensive PID controlled machine at the same time for a few months and tried them both side by side for that time and I settled on the Londinium machine. Simple is better
i think everyone else has pretty much covered this off
my starting point was to ensure a continuance of lever machines, albeit niche, perhaps similar to the vinyl record revival
stage one is to bring a suite of lever machines that deliver exceptional espresso and that i can support remotely
it is important to remember that lever machines weren't abandoned because pump machines delivered a better taste in the cup
pump machines reduced the unit cost for the manufacturer (the lever machine relies on big lumps of metal to 'get the job done')
if you are a pump machine enthusiast you will say the lever is inefficient
i would agree that the lever is gloriously inefficient, relative to a pump machine, in the sense that it uses more metal and more effort from the operator, but that the reward is in the cup
almost all the headlines in coffee today are about people measuring every aspect, propelled by advertising campaigns from i think Cisco, or was it Oracle? about 'data beats intuition'
i'm far from being a luddite, but it would be helpful if some of the people in the coffee world who have adopted this mantra fro their own remembered that it comes from a corporation that sells data solutions for a living
im a long way from feeling the urge, or having the time, to sit down and build a lever espresso machine from first principles, and embark on a long, expensive, and i can almost guarantee disappointing journey and trying to second guess the distilled knowledge of the Italians that has been accumulated over at least 60 years
i think you need a certain level of arrogance to start with the assumption that you can start with a clean sheet of paper and finish with something that is superior to the group we are using, which is an evolution in itself of the highly regarded Faema group, before they went bust on warranty claims arising from their shift to stainless steel boilers, something other operators still don't seem to have learnt from
do i think it would be fun as an academic exercise? yes.
do i think there is a good chance it would end in financial ruin? yes, as sure as night follows day
do i think there is a good chance that you would finish with something that was not as good as what you can buy off the shelf? absolutely
might we investigate aspects of it from first principles in the future? sure, but only where it is propelled by a commercial imperative, for example, were we to develop our own lever group then we would embark on such an exercise as that is the window of opportunity for performing exploratory work
we could fairly easily specify a custom spring for the group, but why? its just loading the boat up with more cost and i can not for the life of me see how it would lead to us selling more machines or being able to charge more
we make solid, simple, durable machines that deliver exceptional espresso. we're not trying to do anything clever
to lift the game further it is down to sourcing better beans, better grinders, and last but not least, better barista technique
for this reason we now supply our machines with naked (bottomless) PFs - so you can easily see and learn how well you have loaded the basket based on the quality of the extraction
even with the simplicity of our machines, there are a vast number of combinations for the operator to explore for any given roast. dose, grind, basket, pre-infusion, tamping style, when to pull the cup, cup temperature, how you pull the lever, etc
anyway, i will be updating you again soon on when your machine is collected and taken to the port Richard
kind regards
reiss.
Reiss.
I stopped over thinking about extractions pressures and started paying more attention to the variables you mention. Dosing, when to pull the cup, etc ... I usually try to pull the lever gently. What effect has the way you pull the lever affect the shot?
Remembering the video's that Frans made of Stephen's TPF™, the early part of the pull over the dry cake can cause it to rise out of the position one hoped it would stay in, following a careful tamp! So care must be taken, and logically it doesn't really matter whether one speeds up after the cylinder's holes are uncovered they are so small that one is past them in a flash...
A steady controlled pull, trying not to disturb the puck, would be my rule of thumb (ROT).
Good to know, thanks.
It looks like the video is of someone pulling both levers at the same time, one with a puck and one with a Scace (?sp). The duration of the pull is pretty darn close to group with the equipment on it. So it shows what the puck is going through.
He was concerned about the temp drop during the shot, I suspected the temp drops because the pressure drops.
I was happy to see the pressure stays above 5bar until the spring has run out then it drops quickly.
There's a post with several pix of old lever machines over at HB, worth looking at -
http://www.home-barista.com/levers/couple-of-rare-levers-on-display-in-south-london-t36039.html