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Classic - Adding PID, seals at the same time?


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Agree with El carajillo. 

If you haven't taken it apart before and it was second hand, it's totally worth replacing all the seals. And gives you a chance to properly check it out internally if you haven't before. 

Think a new set of seals is only a fiver or so including delivery on ebay. 

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Judging from what other people have experienced when stripping an older GC, you might want to think about using new fasteners when you reassemble it. Good luck with the strip, mod and rebuild btw!

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Ok, thanks all.
 

anyone have any idea of what new fasteners are likely? I don’t really want to get part way through and have to wait for another delivery of bits to be able to get going again. Plus with a toddler, leaving parts and machines anywhere except ceiling level is taking a risk 🤣

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Open it up and see what all the bolts look like. They're often pretty rusty! 

I bought some to redo my classic recently. I haven't put it all back together yet and I can't actually remember how many bolts I bought. 

If I have any spare I might be able to send you some of each size if you want? Postage is probably a couple of quid max. 

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2 hours ago, jaffro said:

Agree with El carajillo. 

If you haven't taken it apart before and it was second hand, it's totally worth replacing all the seals. And gives you a chance to properly check it out internally if you haven't before. 

Think a new set of seals is only a fiver or so including delivery on ebay. 

Do you happen to have a recommended ebay seller for gasket and seals pack? 

 

14 minutes ago, MartinB said:

Boiler bolts - m6x18mm I think. They can rust and corrode, and ocasionally get themselves stuck. Hopefully not in your case!

 

Theespressoshop sell them.

I'll also link @ratty here who has been enjoying refurbishing some machines. 

I'd be interested in compiling a list of necessary tools (wrench sizes, etc.), recommended resellers/sources, bolt sizes, etc. when doing a teardown and rebuild of the Gaggia. Do you know whether such a list has been created? (Obviously we can also inspect the parts diagram, but I'm referring to a forum text version where people can easily click and assemble a to-buy list). 

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23 minutes ago, MartinB said:

Boiler bolts - m6x18mm I think. They can rust and corrode, and ocasionally get themselves stuck. Hopefully not in your case!

 

Theespressoshop sell them.

The espresso shop and some other shops have the wrong lengths stated for the boiler bolts. Seems like there was some incorrect copying going on! They can bottom out at these lengths.

The correct size is M6 x 16mm

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38 minutes ago, ratty said:

The espresso shop and some other shops have the wrong lengths stated for the boiler bolts. Seems like there was some incorrect copying going on! They can bottom out at these lengths.

The correct size is M6 x 16mm

Balls, think I bought M5x10 and M6x18 as per the espresso shop! 

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Also this may be obvious but if you're getting some M6x16mm boiler screws, buy six. Four for the boiler/group seal, and two for the boiler/steam valve seal. They can also be stripped and pretty grubby if there's any leakage at the top. 

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4 hours ago, jaffro said:

Balls, think I bought M5x10 and M6x18 as per the espresso shop! 

My first thought would be to grind them down to the 16mm length.

Don't do that, it will set up an easy corrosion point where its been ground.

Bite the bullet and buy new, again!

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26 minutes ago, ratty said:

My first thought would be to grind them down to the 16mm length.

Don't do that, it will set up an easy corrosion point where its been ground.

Bite the bullet and buy new, again!

Yeah fair. They were only a couple of quid including delivery from ebay! 

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8 hours ago, jaffro said:

Open it up and see what all the bolts look like. They're often pretty rusty! 

I bought some to redo my classic recently. I haven't put it all back together yet and I can't actually remember how many bolts I bought. 

If I have any spare I might be able to send you some of each size if you want? Postage is probably a couple of quid max. 

Will do @jaffro and will take you up on the offer should things look a little crusty 🤣

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6 hours ago, ratty said:

My first thought would be to grind them down to the 16mm length.

Don't do that, it will set up an easy corrosion point where its been ground.

Bite the bullet and buy new, again!

Yep, if you bought galved steel bolts then don't cut them. If you bought stainless though, you can use two nuts locked against each other as a guide to cut against with a hacksaw. 

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4 hours ago, Skizz said:

Yep, if you bought galved steel bolts then don't cut them. If you bought stainless though, you can use two nuts locked against each other as a guide to cut against with a hacksaw. 

I was talking about not cutting down the stainless steel bolts.

Cutting them down will leave potential stress risers in the material by introducing stress concentration areas. This, in a chlorine environment can lead to corrosion of the steel even with only minimal PPM of chlorine present in an elevated temperature environment.

The stainless steel bolts are inexpensive and to save a couple of £'s seems pointless in this instance.

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2 hours ago, ratty said:

I was talking about not cutting down the stainless steel bolts.

Cutting them down will leave potential stress risers in the material by introducing stress concentration areas. This, in a chlorine environment can lead to corrosion of the steel even with only minimal PPM of chlorine present in an elevated temperature environment.

The stainless steel bolts are inexpensive and to save a couple of £'s seems pointless in this instance.

Any material change would be at the point of the cut, i.e. the very end of the newly shortened bolt, and so under no significant load. If it means you can get on with the job in hand then there's no problem doing this.

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Just ask people who have removed stainless steel bolts from boilers after a few years, where they have 'locked' in position through corrosion of the steel. That is common particularly in austenitic stainless steel that is apt to corrode on grain boundaries. Cutting the material leaves grain boundaries exposed on cold forged steel components.

Stainless steel is a material that will corrode given the right conditions, and corrosion can spread through the material.

It also needs to be properly lubricated with an anti seize paste for best longevity usage.

Edited by ratty
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50 minutes ago, ratty said:

Just ask people who have removed stainless steel bolts from boilers after a few years, where they have 'locked' in position through corrosion of the steel. That is common particularly in austenitic stainless steel that is apt to corrode on grain boundaries. Cutting the material leaves grain boundaries exposed.

Stainless steel is a material that will corrode given the right conditions, and corrosion can spread through the material.

It also needs to be properly lubricated with an anti seize paste for best longevity usage.

Sound advice Ratty. Stainless steel is not corrosion proof. I know it's not the same in a coffee machine, but even stainless steel has cracked in high temperature / humidity atmospheres of power station steam circuits. But the important thing to remember is that your going into dissimilar metals with a bit of warm moisture thrown in to speed up corrosion.

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Yes, well aware that stainless, in its many varieties, is not corrosion-proof. Spent years working on product development for watersports equipment used in salt-water environments. In practical terms though, trimming 2mm off the end of an A2 M5 bolt is unlikely to cause issue in this use-case,  even less so if, as you say @ratty, you use a suitable anti-seizing compound.

But damn you for prompting me to read this: Design and Optimization of Screwed Fasteners to Reduce Stress Concentration Factor 😄

Edited by Skizz
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Most the problems arise in Classics due to seized bolts in the boiler, head group and OPV.

Use best practice to mitigate these problems to provide easier dismantling in the future.

I worked at Standard Pressed Steel for 20 years on fasteners. SPS have a claim to inventing the cap head screw in 1911 much debated in the States with Allen.

I also studied Material Science at College and University for 10 years, as a mature student.

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  • 3 weeks later...

@ratty @Skizz evening gents!

So the OPV/Solenoid bolts are.....M5 x 10mm or 12mm? I'm bit confused by the below:

https://www.mrbean2cup.co.uk/m5-x-12-socket-cap-headed-bolt

https://www.theespressoshop.co.uk/en/Gaggia-Classic-Stainless-Body-to-Boiler-Hex-Screw-M5x10mm/m-3102.aspx

p.s. ordered the m6 x 16mm a4 you suggested @ratty ;)

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On 18/06/2020 at 12:39, ratty said:

Most the problems arise in Classics due to seized bolts in the boiler, head group and OPV.

Use best practice to mitigate these problems to provide easier dismantling in the future.

I worked at Standard Pressed Steel for 20 years on fasteners. SPS have a claim to inventing the cap head screw in 1911 much debated in the States with Allen.

I also studied Material Science at College and University for 10 years, as a mature student.

Proper material engineers are a dying breed and utterly priceless in engineering.

Nuts and bolts man, huh? Handy to know :)

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