# Gaggia Classic IMS shower screen upgrade?



## timb (Jun 7, 2020)

I was finding my original shower screen would often squirt water at high pressure/speed and believed I could see the channelling in the puck.

With it removed I noticed hardly any brew water coming out the back of the screen holder so I replaced both.

The IMS shower screen and brass dispersion block looked like an upgrade but after fitting, it looks pretty bad.

Had I installed this correctly? Should I just go back to the original shower screen?

Original shower screen with new brass dispersion block:

https://photos.app.goo.gl/nXUe8nob88CMUiYU9

IMS screen:

https://photos.app.goo.gl/Ct8Br1pqGNijffib6

Shot looked okay though:

https://photos.app.goo.gl/qQcddjhaS7nEbDhv6


----------



## Blue_Cafe (Jun 22, 2020)

I preferred the soundtrack in the last video 🙂


----------



## Blue_Cafe (Jun 22, 2020)

Don't really get the idea behind "competition" screens and brass holders myself but then again I am new to this so....


----------



## CantChipForCoffee (Apr 16, 2020)

I don't know as much as others but the shot does look like it pours ok.

Weird water direction when there's no PF though.


----------



## cuprajake (Mar 30, 2020)

I dont think you can gauge with pf off as theres no back pressure,


----------



## cuprajake (Mar 30, 2020)

Could also be too tight with the screw too


----------



## Agentb (Feb 11, 2017)

timb said:


> Had I installed this correctly? Should I just go back to the original shower screen?


 If it makes good coffee - don't worry.

With the IMS screen you can rotate the screen a few degrees and re-tighten - stops the exit hole in the dispersion block aligning with the screen. You'll probably find that helps a little bit (or make it worse - lol ). If you are happy with the results and see four dimples in the puck - don't worry.

Also do not over tighten the screen they are easily twisted and then they don't seal. They just have to be snug and clean. Take them off, clean them often, it's quick. 👍


----------



## timb (Jun 7, 2020)

Blue_Cafe said:


> Don't really get the idea behind "competition" screens and brass holders myself but then again I am new to this so....


 My stock holder was needing replaced anyway as really corroded so thought I'd try upgrading.
I think brass should suffer from corrosion less (I have really soft water) and supposed to improve temp stability? I also found my stock screen would keep blocking, maybe I should try take soaking in Cafiza to get it spotless.



CantChipForCoffee said:


> I don't know as much as others but the shot does look like it pours ok.
> 
> Weird water direction when there's no PF though.


 I think it is an improvement over when the standard screen blocks and creates a jet, just doesn't seam to quite meet my expectations.



Cuprajake said:


> I dont think you can gauge with pf off as theres no back pressure,


 I do see four little craters/dimples in the puck so I think when the water first comes out it might disturb the puck but I do agree without back pressure it must behave very differently.

Thinking the dimmer mod might help wet the bed without disturbing it.



Cuprajake said:


> Could also be too tight with the screw too





Agentb said:


> If it makes good coffee - don't worry.
> 
> With the IMS screen you can rotate the screen a few degrees and re-tighten - stops the exit hole in the dispersion block aligning with the screen. You'll probably find that helps a little bit (or make it worse - lol ). If you are happy with the results and see four dimples in the puck - don't worry.
> 
> Also do not over tighten the screen they are easily twisted and then they don't seal. They just have to be snug and clean. Take them off, clean them often, it's quick. 👍


 I have played with the screw tightness and rotation a bit but this is about as good as I can get it.

It arrived new with a slight buckle but I don't think its affecting it much - the screw is very loose and it is sealing.
Thanks for the advice, I'll keep playing with the position and tightness of the screw as I clean. It definitely looks easer to clean than the original.

Will try comparing a perfectly clean original shower screen with the IMS to see if the bed is less disturbed and if I can taste the difference.


----------



## Blue_Cafe (Jun 22, 2020)

timb said:


> My stock holder was needing replaced anyway as really corroded so thought I'd try upgrading.
> I think brass should suffer from corrosion less (I have really soft water) and supposed to improve temp stability? I also found my stock screen would keep blocking, maybe I should try take soaking in Cafiza to get it spotless.
> 
> I think it is an improvement over when the standard screen blocks and creates a jet, just doesn't seam to quite meet my expectations.
> ...


 Re: Brass shower head.

Why is this a good change? What does thermal stability actually mean or do?

During the shot, are you wanting heat to go from the machine to the water, or vice versa or neither?

Aluminium conducts heat better than brass (x2)

Aluminium has a lower specific heat capacity than Brass (x2)

All things being equal, you want the heat in the shower head to remain constant during the pull, yet the temperature in the portafilter will will the temperature down during the shot as it will be colder than the group, especially so with the coffee. You want the heat from the head to get to the group as quickly as possible to transfer to the brewing puck, no?

A brass head will be slower to give up its heat whilst being much slower to get up to temperature.

I can't help but think the aluminium is a better choice. Its better at allowing energy to move through it from the boiler to the brew head than brass.

An even better idea, is to not have one at all, but bolt up the shower screen directly to the boiler, like in the V2 classics....


----------



## Valkyrie88 (May 3, 2020)

@Blue_Cafe I can follow your logic and what your saying is, to me, quite rational.

However eveytime I read these type of comments I finnish the sentence with "in theory". And 10/10 times go with what's been tried and tested, bit like science.

Science accepts it can be wrong and you can go against the grain as much as you like but it would be nice if you substantiate some of the things you suggest - else it's just confusing!


----------



## Blue_Cafe (Jun 22, 2020)

Valkyrie88 said:


> @Blue_Cafe I can follow your logic and what your saying is, to me, quite rational.
> 
> However eveytime I read these type of comments I finnish the sentence with "in theory". And 10/10 times go with what's been tried and tested, bit like science.
> 
> Science accepts it can be wrong and you can go against the grain as much as you like but it would be nice if you substantiate some of the things you suggest - else it's just confusing!


 Oh agreed 100%.

Good science is backed up by empirical testing.

To substantiate my thoughts empirically...

I have the V2 classic. The "Hive" hates it for reasons i am still trying to fathom, atm, all i can come up with is thats its different..

I was looking at the specs and design for the V1 vs V2 Vs V3 to try to figure out where this ire comes from and i notice that the V2 has quite a different brew temp set point (95C) to the V1/V3 (107C) i think this is because the pathway to the puck is different in the two, as the heavy aluminium boiler and screen holder in the V1/V3 will suck out a fair bit of heat from the brew water as opposed to the V2 which is just a straight pathway to the puck with very little in the way of heat sink to drop the temps.

It seems that for espresso, you want water, at the right temp hitting the puck. without any temp drop on the way. In the V2 classic, this is easy as the design of the boiler is as perfect as one could get to do this. Its a large volume (250ml) and opens straight to the puck with the shower screen bolted directly to its thin wall. In the V1/V3, it has to go through the ginnals of the boiler and through the heavy screen holder which is a heat sink.

So, that brew temp of 107c is set by the manufacturer to allow for the natural heat transfer in the system. By changing the thermal response of the system by using heavy brass instead of aluminium, you upset the balance in the system, and the output.

The cynic in me thinks this is just vendors peddling Woo and Voodoo to make a buck (brass is always better than aluminium right?).

I am sure after spending ££ on these "upgrades", confirmation bias will convince you that it really is a better coffee.

It may well be, who knows?


----------



## Valkyrie88 (May 3, 2020)

The hive you actually made me LOL!

Ok, now understanding the V2's group head design a little better I get your advice on going commando.

Cynic or not, I think its great to hear an opposing view mate (I really do) it's just that when it comes down to decision time newbie's like myself will go with closest thing we deem as "evidence" - sometimes that's actual examples and other times its simply consensus.

I guess the question now is have you tried going commando on a v1/v3? how did it work out for you  haha


----------



## ChrisinHove (Jul 11, 2020)

I had two aluminium shower screen holders show significant corrosion in the 12 years I'd had my Gaggia before I decided that I had ingested enough aluminium oxide....

Stainless is a darn sight easier to keep scale free, but I have noticed no other discernible differences in use. YMMV.


----------



## ChilledMatt (May 9, 2015)

ChrisinHove said:


> I had two aluminium shower screen holders show significant corrosion in the 12 years I'd had my Gaggia before I decided that I had ingested enough aluminium oxide....
> Stainless is a darn sight easier to keep scale free, but I have noticed no other discernible differences in use. YMMV.


I have a stainless one allegedly specifically made for IMS screens (has more holes) and to me the primary advantage is in cleaning. The aluminium block and Cafiza are not a good mix.

Sent from my SM-A705FN using Tapatalk


----------



## timb (Jun 7, 2020)

Really interesting discussion.

I had bad corrosion on my aluminium holder so thought brass would be a better choice on this regard.

I have a PID fitted so can choose my brew temp easily.

I like the idea that brass holds a lot of heat, so hopefully as the water passes through it, it's temp is less affected by the brew water and so the temperature of the brew water/puck changes less during the shot.

The only think I've noticed is less jets/channeling from the IMS shower screen as apposed to the stock one that would block all the time.


----------



## phario (May 7, 2017)

(Accidental post.)


----------



## ting_tang (Jul 26, 2020)

Hi All!

Didn't want to start a new similar topic. Just additional information to analyze for more experienced guys.

My set up: Gaggia classic 2014(RI8161), OPV 10 bar static, Kinu Phoenix grinder. Some cheap tampers for 22€ (58mm for double, and 41mm for single). Scarlet distribution tool - 58.5mm. LM1 single basket. Last months I normally have been making singles only. Usually single 7.5gr in - 15 out in 27 sec. For double 17gr in - 34 out in 27sec.

Process kind of standard, grind, draw eights with back of straw cleaning brush to remove lumps, knock once, WDT and tamp.

I have recently fitted IMS brass holder and shower screen, and got the same issues described multiple times.

1. Spinning streams on the edge of shower screen - fixed with rotating of shower screen. I didn't make a shot until it was fixed, so can't say is it cause of 4 craters on the edge of basket or not.

2. Crater in the center of puck - appeared after single and double shot for the first time. I couldn't reproduce with single basket later. But I got 2 shots in a row with double basket, and I had shorter time of extractions (19 secs, against normal 25-27, with Kinu settings 0-7-2for single and 0-8-0 for double, these settings were fine before IMS)... and then my coffee ended, and I had to start the different blend.

I had to go finer with the new coffee, to get extraction between 25-30 secs, otherwise I continuously was getting channeling, spilling etc. . Before I was using on my Kinu 0-7-2, now I'm using 0-6-0. Before IMS I had not such big changes with the different blends. Settings were surfing between 0-7-0 and 0-8-0. Now I have a coffee from different roastery for the first time, so can't say for sure, had to go finer because of IMS or not.

So, to check is it water jet or weak part of the puck causing crater, I made 2 tests:

1. Grinded too fine, 1.5 times finer, like 0-4-0. First drop appeared in 15 seconds, I turned off machine, and checked. The puck looking was 'healthy', no crater, everything even.

2. Grinded too coarse, 1-1-0, I got 30 mm out in 7 seconds, again puck was healthy.

3. Grinded with proper settings, and crater appeared again in double basket, but not on single anymore. I thought maybe my WDT tool has a weak point in the center, so tried without WDT, but had the same result. And crater always approx at the same place.

Some interesting notes: With IMS, drops on the bottom of basket during the extraction started to appear more evenly, without donut effect. Attaching photo of crater in double basket. I don't care much about it, as I make usually single only. But some information to consider. When I was preparing tests with too fine and too coarse grind, I was sure that crater will appear, but it didn't.


----------



## ting_tang (Jul 26, 2020)

Another update: I fitted IMS shower screen over the standard shower screen and got real consistent shower. No modifications to the brass holder etc.

Result by the link: IMS shower screen above the standard

Few bulbs around 2 o'clock looks like cause of overheating, as they don't appear always.

I have not any streams on the sides, but 1 crater appeared anyway - so, as have been discussed multiple times, it looks like a result of solenoid work. Because of smaller holes soaking effect stronger probably?


----------

