The new lever group thoughts - Page 2

A haven dedicated to manual espresso machine aficionados.
User avatar
nickw

Postby nickw » Jun 02, 2016, 4:13 pm

I feel it's good, but there's room for improvement:

Looks:
- I like the aesthetics of the internal bearings.
- The overall aesthetics are nice (best commercial lever out there imho), but it could be tweaked for a more pleasing look/balance imho (top vs bottom half of the group). It taper. etc.
- Or one could go modern make it clean lined (like a Pavoni, Samba/PV)

Quality:
- Many of the units have defects in the brass which are chromed over. This shouldn't happen.
- Some have more drastic problems, such as scratches in the sleeve.

Servicing:
- Access to the group head screws could be better. In fact the whole way of attaching the top of group could be improved.
- Could be made to use an 8mm gasket - ironic we're asking the lever to now conform to the e61 :)
- Group seals: Could be tighter tolerance between sleeve and piston. And/or use silicon. It goes through seals much faster than the Strega ever did, and skips more often. Would hopefully extend service interval.

In use:
- Using a LM style portafilter with centered ears would be nice.

Overall: it's good and workable group, but they seem content with their market lead and stopped improving it.

Thats about all that comes to mind right now.

User avatar
JohnB.

Postby JohnB. » Jun 02, 2016, 4:43 pm

nickw wrote:
Quality:
- Many of the units have defects in the brass which are chromed over. This shouldn't happen.
- Some have more drastic problems scratches in the sleeve etc.

Servicing:
- Access to the group head screws could be better. In fact the whole way of attaching the top of group could be improved.
- Could be made to use an 8mm gasket - ironic we're asking the lever to now conform to the e61 :)
- Group seals: Could be tighter tolerance between sleeve and piston. And/or use silicon. It goes through seals much faster than the Strega ever did, and skips more often. Would hopefully extend service interval.

In use:
- Using a LM style portafilter with centered ears would be nice.

Overall: it's good and workable group, but they seem content with their market lead and stopped improving it.



First off they have been improving it since it first came out. Robert Bosco tells me that they have asked for & gotten a number of improvements as issues arose in commercial use. Bosco has incorporated their own improvements including the 4 seal piston & silicone seals plus they have made a number of tweaks to the groups they install on their machines which they don't pass on to the mfg'r or the general public. Kees incorporated his own improvements for his machines. It's sold as a basic group which some companies chose to just bolt on as is while others with a bit more (lots more in some cases) lever building knowledge make modifications.

As far as going through seals regularly I haven't had that problem. Installed the 4 seal piston in my 2011 Sorrento with the silicone seal set lubed with Dow Molykote 111 in Jan. 2015. It's been used daily since that time & still is quiet & works smoothly so I haven't touched it. Never had a slipping/skipping issue.

No defects in the chrome nor any scratches in the liner.
LMWDP 267

User avatar
nickw

Postby nickw » replying to JohnB. » Jun 02, 2016, 5:12 pm

Re upgrades:
It's nice that Bosco keeps requesting the changes and improvements. I wonder how many changes the mfr has made on their own accord? I suppose no way of know.

Re seals:
I know Bosco had made some improvements here. It's curious that the mfr doesn't also make similar upgrades?
I wonder if Bosco makes their piston with a slightly larger diameter, in addition to it having extra seal, and using silicone seals? Either way, the seals would be my primary complaint with the group. Nice that Bosco has gone above and beyond here. So beyond it just working for a year (seems to be the average on the stock group) that the bosco went much longer.

Re cosmetic issues:
I also wonder if Bosco gets nicer looking groups? Many of the stock groups (use by various manufactures) on other machines seems to have them. Not all the groups have cosmetic blemishes, but it's not uncommon.

Overall it just seems like the manufacture is okay with letting things slide rather than continuing to improve things.

Cheers,
Nick.

User avatar
JohnB.

Postby JohnB. » Jun 02, 2016, 5:28 pm

The Bosco 4 seal piston is the same 3 seal piston everyone else uses with the top machined for the 4th seal. No other differences. No idea why Londinium owners seem to be experiencing the skipping issues, spring noise issues, ect. I'm sure that Reiss could install a silicone seal set if he chose. I'm in touch with Bosco owners & Londinium owners. The Bosco owners don't seem to be seeing these issues.
LMWDP 267

Ellejaycafe

Postby Ellejaycafe » Jun 02, 2016, 5:50 pm

I just bought a vintage 2 group Astoria fiore that has one of each (the old style CMA group and a new one) It will be interesting to see what the difference between the two will be. I have to wait a mont to receive it. But I'll be coming back to give my thoughts, it will be my first lever machine. 8)

Image

I'll remember to come back to this thread (or make another one) and share my thoughts between the two.
LMWDP #544

User avatar
IMAWriter

Postby IMAWriter » Jun 02, 2016, 6:05 pm

William!What a swell machine. Is that going into your Coffee shop space or (you lucky stiff) HOME?
Rob
LMWDP #187
www.robertjason.com

Ellejaycafe

Postby Ellejaycafe » replying to IMAWriter » Jun 02, 2016, 6:15 pm

We are building a catering/mobile cart. It's the next step for our business I hope. Simple menu, highlighting the coffee. All propane ran and deep cell batteries for the rest (machine has the option of 110v as well) We could make espresso in the jungle if we want too! :lol:

A good thing is that there isn't a single lever machine in a Nashville shop. Hoping to be the first! I think the lever will work well with our comfort food espresso blend; a blast from the past if you will.

We should be ready by August and will be testing it out at a wedding venue my wife works at. So it will be at my home a lot of the time to learn the machine and experiment. 8)

Guess that's the best of both worlds?

I'll keep you updated on our progress! We are working the hype machine now and hopefully can open up at farmers markets, food truck venues, anywhere people want us

We will still have the shop in the office building.
LMWDP #544

User avatar
IMAWriter

Postby IMAWriter » Jun 02, 2016, 6:43 pm

Interesting question from you, Paul. Almost feels like the teacher asking advice from the students. :lol:
I heard tell that the group on John's Bosco is NOT the same exactly as the sort of generic group of which Paul speaks. I would trust his judgement, considering how many vintage machines he has rebuilt, how many groups with which he has dealt.

I will say, not including taste...as the Strega is not your traditional lever...It's mechanism seems very smooth, not in the least jerky. As to it's mechanical QUALITY, I'm not nearly expert enough, nor experienced enough to ascertain this. I BELIEVE the group Bezzera uses it's own proprietary group based on an Astoria?

Paul is it the performance or quality of construction you question? Both? Even as a 3 year Spring lever "newbie" I'd be interested in your comparisons to this group you're dealing with, and perhaps your favorite from one of a thousand or so ( :D ) vintage machines you restored.
Rob
LMWDP #187
www.robertjason.com

thebookfreak58

Postby thebookfreak58 » Jun 02, 2016, 6:48 pm

Would you consider making silicone seals for this group Paul? Would that help alleviate some of the issues?

User avatar
Paul_Pratt

Postby Paul_Pratt » Jun 03, 2016, 12:13 am

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.


Image

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.

Image

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...

Image

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.

Image

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.

Image

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.

Image

Anyway so I replaced all the seals and the screens..old ones top and new silicone set bottom.

Image


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 :D 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.

Paul