It is cheaper to just buy a replacement. The machining and chrome plating cost is greater than the replacement cost. You would have thought the owner would have noticed a little slop in the mechanism.

OldNuc wrote:Phosphor bronze works well as either will require grease. I like the color.

Surprisingly I like the brass on chrome as well. Makes my Cremina so much easier to maintain. I am starting my Pavoni pins tomorrow .

Could one use pfte as the roller in the back ?

On the lever note, I have a cast lever I am pondering rechroming off a 62. The pressed, I would just replace.

PTFE is probably too soft for the back roller. Brass would probably work, though as well as the roller bearings of that size.

I now wonder if every time you changed the seals on your piston also changing the pins and rollers could keep group roller slots and levers from wearing much? Keeping those parts more round is likely to keep them moving more smoothly wouldn't you think? I've never really considered it before, but I notice that The Espresso Shop from the UK now has a group service package set that includes the pins and roller with it:
http://www.theespressoshop.co.uk/en/La- ... -2792.aspx

I've ordered a set from them for future service of my machine, but I've never before seen a seal set include those parts and the dispersion screen too. Seems like it could be a nice way to combat wear on the lever movement.

Grease and ball bearing roller solves the wear issue. The roller is a high pressure part and a pair of ball bearings pressed into a steel tube is the easy way to do it but instrument bearings have inner and outer races of the same thickness so a shim on the outside of both inner races is required so it all can be clamped tightly in the clevis. The piston rod pin does not rotate in the clevis if you use nuts and the wear points are the low cost piston rod and pin if there is any wear.

Thanks to Mike (forbeskm), my 1964 Europiccola and 1987 Cremina now have neat new pins and no more kludgy circlips. Thanks, Mike!



Here's a (blurry) photo of a pin assembled and with the cap off.



The brass complements other elements of both machines. The 1964 Europiccola has the brass showing through on the steam wand and OPV drain tube. I've left those alone to indicate it's a vintage machine.



The Cremina now shows brass at the lever fork that contrasts with the chrome.



But this complements the badge that I sanded down in the restoration to get rid of scratches in the raised portion. That exposed silver metal and left a gold background. Apologies for the blurry iPhone photo.



Another set that will be installed on a La Pavoni soon.

Want. Mike, are you able to supply more of these to HBers who wish to purchase them?

I don't mean to be a contrarian, but I'm not so sure the brass pins are the way to go. I can appreciate the logic of wanting to use a softer material for the replaceable part. You may find it interesting that when soft plastic bushings are used, they have the LEAST wear when hard chrome shafts are used. It also might be instructive too read up on the lapping process, where typically a soft copper plate (the tool) is used to wear down a much harder work piece. The abrasive gets imbedded in the soft material and grinds away the harder material. I don't think you will get this lapping action with hardened and polished pins. They won't contribute any abrasive particles to the joint, and the particles from the mating piece will tend to roll rather than imbed. Just another way to look at it. I don't want to see an entire herd of people emulate this, and have them find out in a few years that it had the opposite effect as they intended.

Lubed non rotating bronze pins do just fine with the soft steel, thin chrome plate on brass, or raw brass. With quality grease it is easy to spot film failure when doing periodic group maintenance.

You are correct the steel wear particles will end up embedded in the brass and turn into a machining tool wearing away on the steel.

Good points. I know for sure that a steel pin wore a distorted hole into the piston shaft on one of my La Pavonis, so that piston shaft needed to be replaced. Was it that it wasn't sufficiently polished or lubed? Maybe.