Hi all, tks for the dialogue. OK so sort of relieved to hear that some companies make adjustments on the machines they sell. I was just a bit surprised that is all that something so pure and simple has been tampered with. I like the top section, it looks beautiful and I can understand Kees VDW liking the bearing arrangement. So just so we know these are the 2 variations of the groups. The older style on the left and the updated on the right.
As I manufacture portafilters I have on hand each group and/or machine so I can do final fitting of the portafilters we sell. So I have had the older style for many years and have even used it on a Gaggia machine for testing. Recently I made my own lever machine for fun, and for the first few months I used the old group, the black cover did not suit it at all. So I purchased several of the new groups for my machine and for testing portafilters.
After bolting on the new group I noticed the shots were pretty ordinary compared with the older one. I let it go thinking I must play with the grind, dose etc....Still no luck. Then I wondered if my machine had a design flaw. It's a twin boiler lever with a 0.5L boiler bolted directly onto the back of the group and therefore the boiler is pressurised all the time, same as Marzocco. Maybe the boiler pressure is messing with the pre-infusion. No a Scace device showed the pre-infusion pressure was 1.5 bar, same as my line pressure.
Then I noticed I was getting 12-14 bars pressure at the basket from the double spring! Thats a lot when you figure a traditional lever machine is 6-8bars at the basket. I also noticed that on my internal pressure gauge inside the machine (so I can set the lever boiler expansion valve) during extraction was going over 16 bars.....OK so something is wrong.
Yesterday I took the group apart..as you can see the seals were not sealing, the pressure was going back into the boiler. These seals have done less than 40 shots.
Apart from that you can see an extraordinary amount of grease on the seals, yuck. OK so the seals failed, hardly surprising with a 14 bar spring, but why on earth did the one way valve (ball bearing) not stop the pressure going back further? Time to take out the one way valve...
On the left is how it came out of the group, the right from a new group. So a mistake during assembly, someone had not seated the teflon seal properly. You had one job assembler. OK an easy fix, put in the new one way valve and I installed my silicone V rings which are softer and should make a better seal. I also cleaned away all the goop and used new dow 111.
After that I wanted to remove the 2nd (inside) spring. The pressure is outrageous, if I wanted that much pressure I would buy a pump machine. Anyway seems they used loctite on the piston rod so that will have to wait for another day.
So apart from the poor seals and the ridiculous spring another thing that annoys me is the E61 style shower screen. It is wrong and not suitable for this group. A traditional lever uses a pop on/off screen, they have worked for 60 years why change now? Using the E61 screen results in much less headspace and means you have to be very careful with the dose in the basket. Below are the old group using the normal screen, new group using the E61 screen.
In the photo above you can clearly see the headspace issue, the E61 screen sits so much lower. I understand IMS and others have done a great job of making new and improved screens, but I can't see the point here, you lose so much headspace and dosing becomes very finicky. The old one works, has done for decades. If it aint broke......besides the E61 shower does not fit with the gasket. The gasket in these machines is very thin, no add the screen into the mix which sits behind the gasket it is like wearing shoes 2 sizes too small. To compensate they reduced the group gasket to 5.4mm from 6mm to help the E61 shower fit.
Another drawback of the E61 shower sitting so low is that it is now a magnet for coffee grounds. It makes the group screen and the bayonet lugs of the group very dirty. The beauty of a lever group is that it is so clean, no backpressure at the end of a shot. As such the screen is clean, as is the gasket and the group. Not once in 8 years since I made the cafelat group brush have I used it on a lever machine. Come to think of it I may have only wiped the screen a few times in my life. Here is the screen from the group, after only 3 or 4 dozen coffees.
Anyway so I replaced all the seals and the screens..old ones top and new silicone set bottom.
Now the performance is much better. Whatever benefit a more uniform dispersal pattern from an E61 show gives, is certainly cancelled out by a lack of headspace, finicky dosing, and a very dirty group.
So a long story short...
The seals don't work
The spring pressure is far too high
The E61 shower screen is not suited to this group
Aside from that the group is great to look at, although as with others that have mentioned it, all mine have serious cosmetic dings and dents.
My own love affair with levers arises from their simplicity. You pull, get a nice gentle pre-infusion from a column of water and then a nice gentle declining profile. Dose and tamping are considerations not necessities
The groups are maintenance free and require no cleaning whatsoever with seals that last years. The modern lever now requires a very precise dose and tamp thanks to the low screen and lack of headspace. You then get a regular pre-infusion but then WHAM that massive double spring producing 12bars+ of pressure is more like a pump machine than a lever experience. The group requires a lot of cleaning.
After making the changes I am much happier with the group, I will be even happier once I remove that 2nd spring and get a gentler pressure. Of course some people may like the group just the way it is, but I just wanted to put it out there that this is not a typical lever experience. Levers are as hassle and maintenance free as can be.