# Brass dispersion plate drilled out



## timmyjj21 (May 10, 2015)

A bit of tangential discussion was happening on another thread regarding the Gaggia Classic brass dispersion plate and the IMS screen. The issue being some nasty jetting into the puck right below the outlets if the dispersion plate, straight through the IMS screen.

http://coffeeforums.co.uk/showthread.php?27950-seeking-a-silicon-8mm-Group-gasket/page4

I drilled out the existing holes of my brass plate a little, and added 2 extra ones centrally. I couldn't see a great change to the water dispersion coming out if the shower screen. My understanding is that Gaggias don't create a lovely drip through an IMS (From what I have seen and what other forum members have said?)









The result my drilling was a mild improvement to the appearance of the puck. I still love the coffee this being produced, but as you can see from the 2 pucks below, there is some nasty jetting happening that I just cant understand. It's consistent and constant, even between different beans. The photos below are from 2 different shots, hours apart. Dosing 16.9 to 17g into standard 14g basket.









Any advice or comments?


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## timmyjj21 (May 10, 2015)

Just thinking, I did my milk steaming with the group handle still on, so there is a bit of boiling happening on the puck surface. I should see how it looks straight after a pour...


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## risky (May 11, 2015)

Well as came up on the last discussion, the query is if it is having any affect on the taste in the cup.

It was also suggested that it may not be jetting but might be back pressure caused when the brew switch is turned off?


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## Khashy (Mar 10, 2015)

Hi,

Any luck with this?

I have just installed the brass dispersino plate and the IMS screen. I am not getting four jets coming out of the IMS screen but post making the shot, I have four very distinct dents in my puck!

I'll take a photo tonight and send across but basically exactly the same as your photo, except at each corner and probably not as deep and wide.

Thanks,

K.


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## timmyjj21 (May 10, 2015)

Yeah, the 4 dents in the puck were standard but stopped after the expansion of the existing holes. The back of the IMS screen no longer shows the 4 jet cleaned spots either.

You probably don't need to add the 2 extra holes like I did, but opening up the exits would likely help reduce water exiit velocity. The original aluminium piece actually has cone shaped holes if you look carefully, so the exit is bigger.

Also note that the brass plate is a short cylinder, while the original is actually a slight cone shape. This is important for holding the group seal in! I have had the seal blow off on my machine with the brass plate, as it will inexplicable build up pressure when steaming straight after a pour. I have been unable to determine why, but it only happens with the IMS screen. Wierd. (And yes, my solenoid is working perfectly!)

My single edge jet is always there. I can't explain it. It has moved positions after a clean, but doesn't seem to relate to anything specific. I have no idea if it is water jet leakage around the edge of the IMS screen or from under the brass plate, suction from the solenoid activation, or true channelling... Who knows, but I still like the coffee produced!


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## Khashy (Mar 10, 2015)

I'm going to do some experiments over the weekend to get to the bottom of this. Not too keen to bore out my piece of brass.


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## Ciocc (Mar 9, 2020)

Hi, I also had this problem but cured it last week. I took the brass plate off for cleaning and compared it to the old aluminium one and found that the brass plate has 2.5 mm holes whereas the originals holes are 3.5 mm for the first third opening up to 4 mm for the rest .2 minutes with a drill and problem solved


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## Abcan (Jan 10, 2020)

Ciocc said:


> Hi, I also had this problem but cured it last week. I took the brass plate off for cleaning and compared it to the old aluminium one and found that the brass plate has 2.5 mm holes whereas the originals holes are 3.5 mm for the first third opening up to 4 mm for the rest .2 minutes with a drill and problem solved


 I'm having this problem too. Did you open up to the same as the original?


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## Ciocc (Mar 9, 2020)

Yes . I drilled the holes out to 3.5 then put a 4 mm drill bit in the old plate and marked the depth with a piece of tape and drilled down to the tape


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## shodjoe1 (Apr 25, 2018)

Forget about brass (my opinion and experience)and go back to original alloy. Better extraction, faster heat ups and cools down. No channeling. I removed brass, no worth it.


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## Abcan (Jan 10, 2020)

shodjoe1 said:


> Forget about brass (my opinion and experience)and go back to original alloy. Better extraction, faster heat ups and cools down. No channeling. I removed brass, no worth it.


 Interesting. What shower screen did you use with the alloy head?


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## Abcan (Jan 10, 2020)

@shodjoe1 thanks for the advice. I've been playing around with this today. Firstly I drilled out the brass plate to as near to the original as possible. Using the IMS screen I pulled a shot and got the same results as before it was drilled (first photo) I then used the original alloy plate, with the IMS screen, to pull another shot. I can't believe the difference in taste! (Second photo) the puck was way better!


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## shodjoe1 (Apr 25, 2018)

Im not using IMS shower screen, also using the original one. But you can keep that IMS or try original one and compare and then you can choose. I'm glad to see nice difference on your pics


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## Skizz (Feb 10, 2020)

timmyjj21 said:


> ... http://coffeeforums.co.uk/showthread.php?27950-seeking-a-silicon-8mm-Group-gasket/page4
> 
> I drilled out the existing holes of my brass plate a little, and added 2 extra ones centrally. I couldn't see a great change to the water dispersion coming out if the shower screen. My understanding is that Gaggias don't create a lovely drip through an IMS (From what I have seen and what other forum members have said?)
> 
> ...


 In an effort to get more even dispersion across the screen and correct some minor channelling I did this mod today, with the only change being being that I countersunk the holes rather than counterbored them. I've not got a pic of the shot running but there's definitely an improvement, with less observed channelling and the flow centring earlier in the shot.

For reference, this is on a PID'd 2004 Classic with OPV set to 10bar static, the brass dispersion block from theespressoshop.co.uk, the IMS screen and a VST 18g basket in a naked PF.

I gave up trying to ensure the two additional holes weren't in line with the screen clusters and just hoped for the best. The small dent you can see near the PF handle was there before the mod so not concerned about that.


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## islandlad (Feb 8, 2019)

Run into this same problem myself after swapping a stainless steel dispersion plate . Holes are uniform ~2.5mm diameter, whereas stock holes are tapered from 3 to 4mm. Am therefore looking to bore the holes out to approach stock hole dimensions. Has anyone succeeded in laying their hands on a suitable (cobalt) tapered drill bit?


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## El carajillo (Mar 16, 2013)

The reason the alloy ones have tapered holes is because they are '' die-cast''. the taper helps release from mould.


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## islandlad (Feb 8, 2019)

El carajillo said:


> The reason the alloy ones have tapered holes is because they are '' die-cast''. the taper helps release from mould.


 Yes, that did occur to me. Nevertheless, I wonder why Skizz's boring to a wider diameter didn't improve things significantly (vs benefits when adding a counterbore). Obviously appreciate that post-shot puck appearance holds little to no value, and all that matters is naked pf extraction appearance and what's in the cup.


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## SirGrindsalot (May 28, 2020)

I installed the silicon ring/IMS screen/6-hole brass dispersion plate kit and have the a divot in my puck at the 1o'clock position. Taste and consistency seem to be better, but not sure whether that's due to the better seal, screen, or brass plate. As islandlad said, what matters is pf extraction and taste, which both are great, but I get a bit compulsive when I see the divot.


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## timb (Jun 7, 2020)

I also had all this faff when "Upgrading" to the brass and ims screen. As I chucked the originals I had to buy the stock parts again but it was worth it.

I am considering offering up my brass plate and IMS screen to be passed around the community of people contemplating the upgrade before they pull the trigger as it seams like an expensive down grade to me.


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## MrShades (Jul 29, 2009)

You should try the stainless dispersion plate - as Gaggia now ship the Classic Pro / Classic 2019 with a machined stainless dispersion plate rather than the old aluminium one.

We've managed to get a few of them at Shades of Coffee, and they have 4 larger diameter water holes than many of the brass ones. Not cheap, but possibly a worthwhile upgrade for anyone struggling with a brass one.

Take a look here if you're interested: Gaggia OEM stainless steel dispersion plate


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## RossD (Feb 6, 2021)

@MrShades

Will the steel shower plate holder work with the original shower plate from an older classic (2005)? Heard there might be some issues with new shower plate holders not fitting original parts... Cheers.


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## MrShades (Jul 29, 2009)

RossD said:


> @MrShades
> Will the steel shower plate holder work with the original shower plate from an older classic (2005)? Heard there might be some issues with new shower plate holders not fitting original parts... Cheers.


I'm pretty sure it's completely compatible across the board - though I can fit one to an older machine and try it if you'd like me to?


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## RossD (Feb 6, 2021)

MrShades said:


> I'm pretty sure it's completely compatible across the board - though I can fit one to an older machine and try it if you'd like me to?


 No it should be okay thanks though! Sure it'll be grand


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## TomHughes (Dec 16, 2019)

I just bought a brass holder as my one and was naffed, thinking I made the wrong choice! 
it's got the 6 small holes which I was going to drill out a bit to prevent jetting


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## Michael87 (Sep 20, 2019)

6 holes must be a new design I bought one last year and it has 4. My advice before drilling is adjust the shower screen screw tension, has a huge impact on water distribution.


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## SupraMan (Mar 9, 2021)

Michael87 said:


> 6 holes must be a new design I bought one last year and it has 4. My advice before drilling is adjust the shower screen screw tension, has a huge impact on water distribution.


 Sorry, do you mind explaining what you mean by screen screw tension? I have a new stainless one but I've not fitted it yet.


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## Michael87 (Sep 20, 2019)

The screw that holds the shower screen in, you can tighten or loosen it. It might depend on your screen but mine has some flex to it, so if you tighten the screw you can force the screen flatter (rather than plate shaped). Which in turn seems to affect water distribution. I'm general, looser allows the screen to come away from the dispersion block which might reduce jetting (as some of the water coming out the block spreads out rather than being forced straight through).


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## Zeak (Jun 12, 2017)

I had this cratering issue eith the 4 hole brass plate up until I switched from Gaggia stock 18g to a 18g VST basket. Never had anything like it after 👀


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## SupraMan (Mar 9, 2021)

Michael87 said:


> The screw that holds the shower screen in, you can tighten or loosen it. It might depend on your screen but mine has some flex to it, so if you tighten the screw you can force the screen flatter (rather than plate shaped). Which in turn seems to affect water distribution. I'm general, looser allows the screen to come away from the dispersion block which might reduce jetting (as some of the water coming out the block spreads out rather than being forced straight through).


 Ah ok thanks. I am going to keep the stock screen as I don't rate the IMS ones.
I'll see how I get on with it.


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## RossD (Feb 6, 2021)

Anyone having issues with their brass plate I'd highly recommend the official steel ones @MrShades is selling!

Was having issues with channeling from water jetting into the puck from the small holes in the brass one. Opted to go for one with the same size holes as the original and its been perfect with no issues at all!


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## byjoshuawilliams (Nov 25, 2020)

RossD said:


> Anyone having issues with their brass plate I'd highly recommend the official steel ones @MrShades is selling!
> 
> Was having issues with channeling from water jetting into the puck from the small holes in the brass one. Opted to go for one with the same size holes as the original and its been perfect with no issues at all!


 Nice, might help sort my channelling issues


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## larkim (Sep 3, 2018)

What does "channelling" look like when it happens? I bought the brass plate a few weeks ago and don't *think* it's causing me any issues, but maybe I don't know what to look for!


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## RossD (Feb 6, 2021)

larkim said:


> What does "channelling" look like when it happens? I bought the brass plate a few weeks ago and don't *think* it's causing me any issues, but maybe I don't know what to look for!


 I didn't happen every time with mines - but would leave a crater at the top of the puck quite often. It would look likes small holes (channels) forming in the puck or in my cases big dents or craters

But if the coffee tastes good I wouldn't worry


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## Pavel (Jul 5, 2020)

RossD said:


> Anyone having issues with their brass plate I'd highly recommend the official steel ones @MrShades is selling!
> 
> Was having issues with channeling from water jetting into the puck from the small holes in the brass one. Opted to go for one with the same size holes as the original and its been perfect with no issues at all!


 Hello!
What is diameter of the holes you have now?
4.4 mm? Or some different?


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