Greetings-

I inherited this rub with the purchase of my Pavoni:

It's left-side only, as there's about 1/64" of space on the right side.

Not sure why the lever wants to sit this way, and what to do about it.

Any help greatly appreciated!

Charles

Quick questions:
How do the pins look? Are they evenly worn?
How about the lever pin holes?

Perhaps the former owner did not realise that there exists a substance commonly called "grease"! Failure to lubricate metal to metal contacts not only can, but will, cause serious wear. By the way, I think the clips holding the pins on this lever are not the type originally supplied by La Pavoni. (I can not check mine, because I discarded the pins on mine LONG ago!)

You should first remove the pins and check to see if they be worn. Then you should check the holes in the handle. They should be round and not elliptical. You should also check the slot in which the roller holding the back pin fits. Failure to lubricate this can result in serious wear.

The original pins and handle arrangement have a lot of "play." This thread has a discussion of problems with them:

La Pavoni Europiccola Lever Insert & C-Clip problem

With a piece of 6mm piece of round brass stock and four "acorn" nuts one can use a M6 tap and a hacksaw to replace the rods with ones threaded on each end. As mentioned in one of the posts in the above thread, the length of the metal stock is fairly critical. Done properly, this will force the handle to move as a precision device!

Do not fail to lubricate these moving parts when you reassemble no matter what you do!

[EDIT: SInce posting this, I've had a chance to digest the C-clip thread, and a few others related to lever forks.]

Thanks Dan and Robert for your interest.

I think the pins, holes and bushings are not badly worn:



The wear to the pins appears to be oxidation (?) where the chrome plating has been worn away. The metal doesn't feel grooved or uneven.

I realize that I should have photographed the lever holes as well, but they seem in good shape.

The one thing that mystifies me is the shape of the lever fork. The fork is brake-formed and not cast. It is wider at its mouth than farther in its jaw, as diagrammed in this exaggerated drawing:


So there's an inbuilt tendency to rub, because the clearance for the grouphead around the frontmost pin is only about 1/64-1/32" in total for both sides.

Finally, I switched the pins around, and I believe it's (mysteriously) increased the play in the lever, but I won't really know if that's an improvement until I pull an espresso a little later today.

Best, Charles

So while I welcome any comments on my post, it seems that this topic has been explored previously, and my best course of action is to make some shims for the lever.

I've got some 1/32" thick Teflon gasket material, but I'm not convinced I could fit two pieces in the gaps where the lever fork meets the grouphead at the piston shaft.

Would the Teflon compress? Do I somehow widen the lever fork by bending it? Do I need a new lever?

Thanks! Charles

I just went out to my shop and got a micrometer. (It was cold out there!) I have two of these machines. I measured both of their handles. On both of them the "tines" of the handle actually are narrower at the tip by about 0.5mm, rather than wider as yours is. The handles do not tightly hold the roller, but the "play" back and forth a the end of the handle is only about six millimetres on both machines. Both handles move very very smoothly and do not ever bind against either side. They pretty much move like they should on a precision machine.

I suspect because yours has so much play it does not stay absolutely even when you are pulling a shot with it. It is very easy to replace the pins with threaded rods, as mentioned earlier. If you have a chrome machine you can put stainless "acorn" nuts on rods that you need to thread with an M6 die. You do need to cut the rods to fair precision. It will look better than stock. (You could, of course, put chrome acorn nuts on a brass machine, but it looks better with brass ones.)

Since we don't have a picture of the fork itself I'll assume you don't need a replacement. They generally last for quite a while, and even when they get loose and wobbly you'll see people pulling really hard on them in youtube videos.

Good news is the group looks to be in great shape other than the rubbing. The pins look a little worn and slightly pitted, and in my opinion you could use them if you don't want to follow rpavlis' advice on cutting your own - although new pins might help. When I replaced the pins on my Pavoni, much more worn than yours, it made a big difference in the pull and alignment.

You can oil or grease all those parts quite easily even with cooking oil, but it's messy. I like the Dow 111 silicone grease that I also use for lubricating the piston and seals; it's sticky and doesn't run all over the place like most other greases and oils. You can get Dow 111 in quantity quite cheap - I purchased a 2oz tub on Amazon for $10.

Teflon/PTFE can be purchased in thin sheets that would form a U bend if you want that, or you could even cut 2 pieces that fit the sides of the lever perfectly with holes punched for the pins. That would ensure your group would no longer rub on the lever. Even a teflon washer would probably do the job you want.

The original design of the Pavoni levers must have been that the tines be parallel to the rod, and symmetrical about the axis. You could draw the tines inward if the pins were threaded on their ends (per rpavlis' instructions), and make them closer to parallel. I think that in the long run this would be the best solution.

rpavlis wrote:On both of them the "tines" of the handle actually are narrower at the tip by about 0.5mm, rather than wider as yours is. The handles do not tightly hold the roller, but the "play" back and forth a the end of the handle is only about six millimetres on both machines.

Mine is exactly the opposite: at the tip the tines are ~1mm wider than where the handle attaches to the fork.

DanoM wrote:I like the Dow 111 silicone grease... Teflon/PTFE can be purchased in thin sheets that would form a U bend if you want that, or you could even cut 2 pieces that fit the sides of the lever perfectly with holes punched for the pins.

Yes, I used some of what was left from Orphans' gasket kit to lubricate the grouphead, but given what's been said here, I could do a more extensive job. I have a bunch of Teflon gasket material, but the issue I'm wrestling with is that there's about 1/32" spacing on either side of the pins that attach to the grouphead, but barely any clearance at the pins that attach to the piston shaft.

hankbates wrote:You could draw the tines inward if the pins were threaded on their ends, and make them closer to parallel. I think that in the long run this would be the best solution.

Agreed, but I wonder what kind of pressure will be created at the piston, as there is now very little space, and it will be compressed more by this solution.

It seems that the only way to find out will be through experimentation.

I assume that for a short term, I could used millimeter bolts instead of machining some custom pins? That way, I could prove the solution before committing to a bunch of machining.

Also, I pulled my afternoon espresso, and as I had suspected, my switch of the pins' locations/orientations have greatly improved the alignment. Things are now equal on both sides (as opposed to pushed right) and the lever operates much more smoothly. But I haven't the faintest idea what's going on: why the switch produced an alignment change. More investigation to come.

Thanks all of you for your help! Charles

vze26m98 wrote:I assume that for a short term, I could used millimeter bolts instead of machining some custom pins? That way, I could prove the solution before committing to a bunch of machining.

I think that might have problems with causing extra wear if you use it for more than a few pulls, so if its just for getting the sizing right you would probably be okay. I just wouldn't want run a machine with threads on the interior of those pins.