Bronze bushings for worn La Pavoni lever - DIY

A haven dedicated to manual espresso machine aficionados.
User avatar
RayJohns
Posts: 825
Joined: Fri Sep 10, 2010 5:31 pm
Real Name: Ray
Equipment: PID La Pavoni pre-millenium Europiccola & Kyocera ceramic burr hand grinder
Location: California

Postby RayJohns » Sun Feb 13, 2011 3:10 am

I had some free time tonight, so I decided I would tackle another upgrade/modification on my La Pavoni. As some of you may recall, this machine was purchased off Craigslist and I have been modifying it here and there.

Some of the previous modifications include:

A home made DIY pressure regulator --> La Pavoni Mods - DIY adjustable pressure regulator
Cut-it-yourself DIY naked portafilter --> La Pavoni DIY Naked Portafilter
Group head O-ring repair --> La Pavoni O-ring gasket question - wrong size?

On my machine, since it's around 30 years old, the rear pivot hole in the lever had started to elongate. This resulted in some slop in the handle (during extractions). In order to halt this process and perhaps provide a little enhanced longevity, I decided that maybe I would drill the hole out and install some bronze bushings. If I'm not mistaken, someone else (Doug @ EO maybe?) did this same modification. I'm not sure where I ran across it - or who did it - but I remember thinking it was a good idea when I saw it.

Anyway, so after a little searching, I was able to find some bronze bushings (on Amazon of all places), made by a company called "Bunting Bearings". The size was perfect! 6.00 mm bore (which matches the cross pins that go through the lever on my machine) with a 9.00 mm OD and - perhaps best of all - 4.00 mm in length. The 4.00 mm length perfectly matched the width of the metal on the La Pavoni handle. As such, all I needed to do was drill out the hole to slightly under 9.00 mm, heat up the handle a bit, then chill the bearings and press everything together (this would provide a nice interference fit) - and, since the bearings were already the same length as the metal in the handle was wide, there would be little, if any, fine tuning required.

The bearings took almost a month to show up. I don't know if that's because they are made to order or what. In fact, they took so long to arrive, I actually tried to cancel the entire order (I had ordered several sizes originally). As luck would have it, four of the 9.00 mm OD bronze bushings shipped the day before I canceled the rest of the order. Once the bushings arrived at my door, I was on the hook to install them :-)

As you can see from the photos below, the bushings turned out to be a perfect fit. I ended up drilling the handle out and then using a stack of nickels and quarters as a wedge. After checking everything with a digital caliper, I heated up the handle and pressed the bushing in using my old Wilton bench vise. It all worked like a charm. The only problem was that, because the bushings were in there so tight, it sort of squeezed them down a bit. This resulted in the 6.00 mm cross pins no longer fitting into the bushings. However, after a very slight amount of filing on the inside of the bushings, the pins slid right in again.

In the end, it turned out even better than I anticipated. For now, I have opted not to do the forward holes (the ones which hold the cross pin that goes into the group head piston rod), as these holes do not seem to take as much abuse and show little, if any, signs of elongation.

In any event, I thought members here might enjoy seeing the results. For anyone who wants to order the bushings, you should be able to search the part # AAM006009004 on Amazon.com. In fact, here's the link I used:

http://www.amazon.com/Bunting-Bearings-...B0040GKB4A

Each bushing (at the time of this posting) cost $4.34 with free shipping.

Ray

P.S. - The final picture shows the replacement handle I bought (after the OEM one broke). I picked it up off mcmaster.com for about $9.50 - part # 3701T27

Image
The lever, cross pins and bronze bushings prior to modification

Image
Here is a close up

Image
Here you can see how the rear hole was starting to turn into a slot

Image
Close up shot of the bushings

Image
After installation. I used some nickels and quarters to brace everything while pressing in the bushings

Image
Close up shot

Image
Another close up shot, showing the final results

Image
Here is the handle, just before reinstalling it on the La Pavoni

Image
Another shot of the finished lever

Image
All done! This shows one of the 6.00 mm cross pins in place

Image
Part # and bearing information

Image
The replacement handle from McMaster - very heavy duty; great for extra leverage while pulling shots
You do not have the required permissions to view the files attached to this post.

User avatar
sorrentinacoffee
Posts: 649
Joined: Wed Mar 12, 2008 1:28 am
Real Name: jack
Equipment: atomic, la sorrentina, la pavoni, trimel, martian, vesuviana, caravel, bellman, bialetti, robbiati..
Location: Adelaide, South Australia, The Sothern Hemishere, Earth, Solar System, Milky Way, Universe...

Postby sorrentinacoffee » Sun Feb 13, 2011 11:36 pm

brilliant work- very neat!

what next for the Pavoni?

User avatar
RayJohns
Posts: 825
Joined: Fri Sep 10, 2010 5:31 pm
Real Name: Ray
Equipment: PID La Pavoni pre-millenium Europiccola & Kyocera ceramic burr hand grinder
Location: California

Postby RayJohns » Mon Feb 14, 2011 2:28 am

brilliant work- very neat! what next for the Pavoni?


Thank you very much!

No major modifications planned for a bit. The La Pavoni has been working so well this week, I think I'm just going to leave well enough alone and start enjoying some espresso for a change :-)

Ray

User avatar
Knock
Posts: 155
Joined: Wed Jun 14, 2006 5:25 pm
Real Name: Peter Kilpatrick
Equipment: Several Olympias, and several hundred Knock tampers & Hausgrinds
Location: Edinburgh, UK

Postby Knock » Mon Feb 14, 2011 5:53 pm

Nice job!

A sort of related question that you or someone else may be able to answer - does bronze wear faster than the surrounding brass / chrome or the steel pins? My reason for asking is that sometime ago I mooted the idea of a sacrificial roller bushing for the pin inside the grouphead (as opposed to the shaft pin) in order to save wear and tear on the grouphead in older machines where replacement groupheads are no longer an option (ie the Creminas of this world).

We didn't have the likes of Doug at OE on the forum at that point so it went cold, but still wondering if this is a practical solution to slowing down the ravages of time (and excessive leveraging!) on our old faithfuls.
sneaky
Peter Kilpatrick

User avatar
stefano65
Sponsor
Posts: 936
Joined: Sat May 19, 2007 9:27 am
Real Name: Stefano Cremonesi
Equipment: VBM DB and Super, Elektra,Macap, Baratza
Location: Elmira (Eugene), OR

Postby stefano65 » Mon Feb 14, 2011 6:12 pm

NOT to be negative here,
but as much as I appreciate improvements on ANY possible way
there root of the point is:
a lever pavoni should not be that hard to brew, to the point of breaking the lever pivot point
is so there are issues on the unit ( or coffee way way tooooo fine)
Stefano Cremonesi
Stefano's Espresso Care
Repair & sales from Oregon.

User avatar
Knock
Posts: 155
Joined: Wed Jun 14, 2006 5:25 pm
Real Name: Peter Kilpatrick
Equipment: Several Olympias, and several hundred Knock tampers & Hausgrinds
Location: Edinburgh, UK

Postby Knock » Mon Feb 14, 2011 6:30 pm

Hi Stefano,

Agree with your point after some unfortunate experiences, but the fact is that my Cremina has been making espresso for over 35 years so, even if I am a bit of a gorilla on the lever, the normal wear and tear of a more gentle soul will still have an effect, surely? The levers and yokes aren't the most expensive bits to replace but the groupheads still deserve to be saved on these older machines!
sneaky
Peter Kilpatrick

User avatar
RayJohns
Posts: 825
Joined: Fri Sep 10, 2010 5:31 pm
Real Name: Ray
Equipment: PID La Pavoni pre-millenium Europiccola & Kyocera ceramic burr hand grinder
Location: California

Postby RayJohns » Tue Feb 15, 2011 4:08 am

Knock wrote:Nice job!

A sort of related question that you or someone else may be able to answer - does bronze wear faster than the surrounding brass / chrome or the steel pins? My reason for asking is that sometime ago I mooted the idea of a sacrificial roller bushing for the pin inside the grouphead (as opposed to the shaft pin) in order to save wear and tear on the grouphead in older machines where replacement groupheads are no longer an option (ie the Creminas of this world).


The basic idea is that bronze to steel provides a lower coefficient of friction and overall better wear characteristics as compared to steel to steel contact. When you have two steel surfaces wearing against each other, they both have harder/rougher surface contact - so generally more severe wear is going to occur.

With bronze - especially self lubricating bronze bushings - there is still going to be surface wear (this can't really be avoided), but the wear won't be as aggressive because bronze is softer (it acts almost like a cushion of sorts). True, the bronze bushing might be considered to be somewhat sacrificial in such a case, but that's okay. The overall wear will be less, even if the bronze bushing has to give up some of its surface material in an effort to wear more softly against the steel.

In the event that the bronze bushings start to wear out (elongate, etc.), they can be pressed out and replaced. In fact, I have two extra bushings, just in case they ever need to be replaced. The main idea is to remove the steel to steel contact and provide a replaceable bushing that can wear, while protecting the main steel structure of the handle itself.

Ray

User avatar
RayJohns
Posts: 825
Joined: Fri Sep 10, 2010 5:31 pm
Real Name: Ray
Equipment: PID La Pavoni pre-millenium Europiccola & Kyocera ceramic burr hand grinder
Location: California

Postby RayJohns » Tue Feb 15, 2011 4:28 am

stefano65 wrote:a lever pavoni should not be that hard to brew, to the point of breaking the lever pivot point
is so there are issues on the unit ( or coffee way way tooooo fine)


My recent experience is that, in order to produce a higher quality espresso - with a lot of crema and rich flavors, etc - some level of additional force is required. I've posted some of my experience here on this thread (around page 2 or 3):

A Lesson from Christopher Cara in Using a La Pavoni Home Lever Espresso Machine

In the case of my machine, the majority of the wear in question (on the handle) occurred before I purchased the machine. My machine is about 30 years old; I've only owned it for less than a year. I am not sure how much use it saw previously, but it was enough that the holes began to show signs of wear.

The main reason I installed the bushings was to provide a better wearing material going forward - needed or not.

At the end of the day, the lever has to provide about 8 bar of force on top of the group head piston (I think I read this is about how much force the La Pavoni provides during its extraction). But even if you are only pushing down the end of the lever a fraction of this (due to the leverage effect), there are still going to be fairly heavy loads some place in the system, in order to push the water through the puck of compacted coffee.

When I started using more force on the lever, it was to try to simulate the force produced by a 15 bar pump machine.

Ray

User avatar
civ
Posts: 284
Joined: Wed May 30, 2007 4:54 pm
Real Name: Carlos Izzo Videla
Equipment: La Pavoni 'Shirley' Older Cimbali Junior D/1 Older Cimbali Junior Max
Location: Buenos Aires, Argentina

Postby civ » Tue Feb 15, 2011 10:50 am

Hello RayJohns:

Excellent work!

RayJohns wrote:No major modifications planned for a bit ...


My Shirley, having had very little use, has not developed any deformations.
But I did not like how easily the clips could be misplaced and how the pins tarnished.

So I came up with this:

Image

Image

Image

I used SS washers, Allen head bolts (with a long unthreaded section) and retaining clips. Besides not tarnishing, this mod has the advantage of using only one set of clips and can be tailored to be the exact length, keeping the pin's play at a minimum.

Cheers,

CIV
You do not have the required permissions to view the files attached to this post.

User avatar
Knock
Posts: 155
Joined: Wed Jun 14, 2006 5:25 pm
Real Name: Peter Kilpatrick
Equipment: Several Olympias, and several hundred Knock tampers & Hausgrinds
Location: Edinburgh, UK

Postby Knock » Tue Feb 15, 2011 11:38 am

Hello again folks

CIV - that's an interesting mod too. Wonder how it will wear? looking closely at your grouphead you are starting to get the wear in the grouphead slot I was talking about - that slight dip just in front of the pin in its roller.

RayJohns wrote:With bronze - especially self lubricating bronze bushings - there is still going to be surface wear (this can't really be avoided), but the wear won't be as aggressive because bronze is softer (it acts almost like a cushion of sorts). True, the bronze bushing might be considered to be somewhat sacrificial in such a case, but that's okay. The overall wear will be less, even if the bronze bushing has to give up some of its surface material in an effort to wear more softly against the steel.


This exactly what I was suggesting the sacrificial roller for - a replaceable bronze roller bushing that we can change out every year or so might arrest a lot of wear and tear.

Doug, if you're listening, whaddyathink? I'd certainly invest in this and a couple of spares for both my manual levers.
Peter Kilpatrick