Hello sneaky:

Knock wrote: ... that's an interesting mod too.
Wonder how it will wear?

Thanks. =-)
How it will wear?
That's a good question ...
My guess is that it will probably behave as the original steel pins.
Maybe better, as there won't be anything but smooth clean SS acting on the holes.

Knock wrote: ... starting to get the wear in the grouphead slot I was talking about - that slight dip ...

Yes.
Fortunately it's just a bit.

I have been wondering about having a replacement roller made for it.
The alternatives I have been considering are a bronze roller or maybe one made from the hardest teflon I could find with the addition of a bronze insert for the pins to act on. That would mean 'zero' wear on the grouphead slot.

But it's still on the drawing board.

Cheers,

CIV

Hey CIV,

When this was discussed briefly a few years back the main consideration in using teflon or delrin or similar was the resistance to heat - has to be the right spec, especially given the pressure we then put through it when we pull on the lever.

An old cyclist's trick for getting different sized stems and handlebars to fit was to cut a shim from a coke can - if you need one in a hurry, a drinks can + a pair of strong scissors /snippers and you'd have a lining fairly quickly!
sneaky

civ wrote: 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.

Very nice!

I have some SS circlips here also. The other thing I considered (but didn't end up ordering) were some quick release SS pins (6 mm diameter). Those allow you to pull a ring and they release a ball on the tip that allows the pin to slide out.

Anyway, very nice job. I like the look of the allen head setup you have there.

Ray

civ wrote: I have been wondering about having a replacement roller made for it.
The alternatives I have been considering are a bronze roller or maybe one made from the hardest teflon I could find with the addition of a bronze insert for the pins to act on. That would mean 'zero' wear on the grouphead slot.

The company which supplied the bronze bushings to me (for the lever), also makes a bronze roller that will fit into the group head slot (on the La Pavoni). It's not a 100% perfect fit, but it's very close. In fact, I had originally ordered one, but due to the delay in sending the order out, it ended up being canceled.

Ray

Nice job on the bronze bushings. I've helping get a friend's sisters La Pavoni back into working condition and the roller pins are looking shot. Luckily the lever itself doesn't seem to have worn nearly as much as yours.

Mark

I was annoyed with the steel pins and clips in the group handle from the moment I acquired my brass Europiccola. I measured the pins and the holes in the handle and found that the holes in the handle were about 6.08mm, and that the pins were about 5.82mm. I wondered if all of these machines had this much "play" in the pins as this seemed excessive. The Young's modulus for steel is about 200 GPa, for bronzes and brasses it typically runs a bit over 100 GPa. (Al is only about 70 GPa). Either brass or bronze would still be adequate!

It was apparent to me that placing bronze or brass pins instead of the steel one would be an improvement, and I could make them more precise than the originals. Furthermore the coefficient of friction of steel against either brass or bronze is lower than steel against steel. I turned down a piece of 0.25 inch 360 brass, and then cut M6 threads on either end. I obtained four stainless steel acorn or dome nuts and four stainless steel washers and used these to hold the brass pins in place. (It is necessary to cut the threads just the right length, and to cut off the brass with some precision.) I put some of the Teflon lubricant on the brass pins before assembly. It now takes seconds to remove the group handle, and there is much less "play" in it. (I do not think aluminium would be a good idea, it is too reactive and soft.)

Thanks Tom! Yeah, it was fun meeting everyone and seeing all the different machines.

Ray

Brass is basically an alloy that contains copper and zinc. Bronze is a copper alloy with other elements, traditional bronze contains tin. There are copper alloys that contain both zinc and tin. Anyway, bearing bronze normally contains quite a bit of lead, I think typically around 10%. It is mostly due to the Pb that makes it more slippery. If I recall correctly bearing bronze is not quite as strong as most other bronzes.

Many alloys classified as brass also contain substantial amounts of Pb. The alloy commonly designated "360" is extremely easy to machine, because the Pb tends to lubricate the tools so that it cuts very cleanly.

Brass and bronze alloy rods are readily available from machine shop supply places, there are online places too. Some will sell small lots. Bearing bronze machines fairly well, probably because of its high lead content. If one have access to metal working machinery it is a simple task to make bushings and the like.

I used brass 360 for replacement pins because (1) I had some of it, (2) its coefficient of friction against steel is fairly low, though not as low as bearing bronze, and (3) it is a bit stronger than bearing bronze.

Both 360 and bearing bronze are rather high lead alloys. It would be thus a bad idea to fabricate internal parts of espresso machines with them. For external parts, however, they are ideal.

I wonder how fatal it will be to use threaded bolts. I just get so tired of those clips! Even if they are cheap. I guess they (Pavoni) don't count on a monthly group cleaning. I'll test it on an already bent lever. The steamknob should be less critical, no? Who loves getting those pins out?

(I know, it's all improvised, but long live jars of old screws!
And that chrome was damaged already!)