SAMA Export back on the workbench

[SJM]

When last I pulled the SAMA off the table, I had just managed to get all of the new gaskets onto the piston. Now I'm hankering to get her put back together.

At this point I need to put the piston back into the group and I need your advice on whether or not the surface of the group where it will mount onto the chassis is "clean" enough, or whether it needs to be soaked or scraped more. See those bits that are still hanging on? They are worrying me.

While I'm at it, I'll post a picture of the receiving side and see whether you think I should be scraping off the old gasket or not?




Susan

[peacecup]

Are those bits of rubber gasket, or corrosion of the metal? If its rubber I would think a razor blade would remove it.

I should think you'd also need to remove the old gasket from the boiler, but I've never rebuilt one of these. Seems to me that getting that rubber off can't be too difficult with a sharp blade.

Why give give Joe at GCC a call, or try Gene at Vanelis?

The main thing is to get it back together and start pulling shots! I continue to be impressed with the espresso I get from my Export, nearly two years on.

PC

[cannonfodder]

Never put an old gasket over a new gasket. Make sure you have a clean and smooth surface for the gasket to seal against. You can use a razor blade or go to the auto parts store and ask for a gasket remover. It is basically a wide tipped screwdriver or stiff bladed putty knife. If you have a putty/spackle knife in the tool box just use it. The dangers of using a razor blade should be relatively apparent and the sharp steel could gouge the mating surface if you are not careful. I have used both.

[SJM]

Are those bits of rubber gasket

I think so; I think they correspond to that largish chunk that has come out of the original gasket.

Why not give Joe at GCC a call

Excellent idea

Never put an old gasket over a new gasket. Make sure you have a clean and smooth surface for the gasket to seal against. You can use a razor blade or go to the auto parts store and ask for a gasket remover. It is basically a wide tipped screwdriver or stiff bladed putty knife. If you have a putty/spackle knife in the tool box just use it. The dangers of using a razor blade should be relatively apparent and the sharp steel could gouge the mating surface if you are not careful. I have used both.

Well, I sort of meant was that old gasket still usable, but I see that that was a pretty dumb question. Thanks for the removal ideas. I think I already nicked the surface slightly with the corner of a screwdriver, which is one of the reasons I put everything aside and sulked for a bit before starting back up.

I remember Joe telling me that there were two kinds of gaskets and that one was really really hard to remove. Guess I should check with him about getting this particular one off.

[SJM]

So, I posed my question to Joe, and here is his response

As to removing the old gasket and bits and pieces thereof:
On the face of the boiler plate, first remove the studs. Then, with a gasket removal
tool, slip it under the gasket and try to pry it off. As it is so old, it may not come off
in one piece. But then you just have to wire brush off the remaining particles.
Don't gouge the metal, or the new gasket will not seal. Sometimes, a gasket removal
oil can be of help. The same procedure can apply to the face of the group itself.
A lot of patience and elbow grease is necessary. Tool mounted brushes of
various metals and shapes should do the job.
Regards,
Joe

So, there will be another hiatus while I find gasket removal stuff (Permatex I assume), etc., etc., etc.
Back after that.

Susan

[SJM]

Ouch. I know Timo said this was the hardest part, so I'm not altogether surprised that I'm having such a hard time with it, but here's specifically where I'm having trouble.

The next-to-the-bottom gasket on the piston flares upwards and outwards, and I am having the devil's own time getting the edges of it to tuck into the piston.

Do you know what I'm talking about?

I've got the piston partially into the bell and have started trying to clamp it in, but that edge keeps catching and bulbing out. My most recent attempt has been to try to use a tiny jewelers screwdriver to feed the edge in, but eventually I knocked into the clamp and it all came apart. (No serious pressure on the spring at that point, so no damage done...)

Any suggestions?

Susan

[espressme]

Hi Susan,
I have been told by some who have been there that a de-burred* piece of pop can wrapped tightly around the well lubed ( Dow 111 or olive oil) obstreperous gasket is the way to go. That will allow the piston to slide gently into its home!

*Deburrred means you don't get cut. A hose clamp from the hardware will hold the can coil together while with your third hand you do the deed!
Cheers
richard

[SJM]

So, Richard, does that mean taking metal snips to a soda can and making a piece that fits all the way around the diameter of the gaskets?

Susan

[peacecup]

I thought of something similar - a stout rubberband, or a wrap pf electrical tape, that would hole the gasket flush against the piston until the entire edge was inserted - then remove the tape.

If you'd have been around my place this past weekend sampling the espressi flowing forth from my Ponte Vecchio you would have added incentive to get the Export up and running!

PC

[docktowndavid]

It also might help to warm the seals in hot water, as hot as you can stand it to be and still work with it easily-- it makes the seals more flexible.

[SJM]

Whoopeeee!
It's in past the problem spot.
Heat, grease, the little jewelers screwdriver, and a little help from y'all....

Time for dinner
Susan

[espressme]

Ya done good!
Sincerely
richard

[SJM]

Yeah, well not as good as I'd a liked.
A few more twists of the clamp and it all came apart and took off the top of my thumb nail.

Time to go and sit with some ice, and it'll be a couple of days until I can use my left hand to be useful again.

Sigh...
Susan

[espressme]

Dang!
emphatically yours
richard

[timo888]

Reseating the piston in these domestic spring-levers needs a special rig -- like a miniature version of the medieval rack, only working in reverse. Otherwise, it's torture.

Regards
Timo

[HB]

Reseating the piston in these domestic spring-levers needs a special rig... Otherwise, it's torture.

Except for recent model Olympia Creminas:

New pistons = tight seal and the biggest headache with most designs is how to get the lip of the top gasket into the grouphead. Now with other machines I have used a scribe to help with the rubber washer but with this harder material I was a bit concerned whether it would flex enough to keep me from marring the gasket or the grouphead.

And then it dawns on you. With a multi-piece piston, you can simply insert the piston shaft, insert the first gasket and then add the rest of the piston and tighten the piston IN the grouphead.



My hat's off to Markus and the Olympia engineers for that trick.

From Olympia Cremina 2002: The evolution of design

[SJM]

Reseating the piston in these domestic spring-levers needs a special rig -- like a miniature version of the medieval rack, only working in reverse. Otherwise, it's torture.

Regards
Timo

Way short of torture, but a bloody ouch for sure.

From Olympia Cremina 2002: The evolution of design

Oh, my thumb for a multi-part piston !

Meanwhile, if anyone has any ideas for that special rig, send them my way. I'm going to try to go at this more safely and scientifically this time.

Susan

[peacecup]

I have had the good fortune to have not had to remove the piston from my machine. I have been thinking of a design like timo's suggestion, wherein the wooden dowel is used like in your photo, but instead of the c-clamp to the top of the piston, an EXTENDED screw arrangement is placed between the dowel and the drip tray area.

Alternately, you could devise a piece of wood that would better hold the clamp on top of the piston. Having the dowel be as short as is necessary, and a wide a diameter as possible will help in either case.


PC

[timo888]

Yes, those multi-part pistons do make the gasket-job much easier. But I was also thinking of the spring. And the piston must be kept from turning so that the holes on the rod line-up perfectly for the pins ...

Respek

[ntwkgestapo]

Don't know the diameter of the piston but MAYBE this would work? http://www.daf.com/daftrpcatalogus/en/-165381.htm

The size 0 compressor works within the 40-75mm range. You'd still need your wooden dowel to do the push, but the compressor would POSSIBLY keep the gaskets/seals in place?!?