# Group head screws



## Kyle548 (Jan 24, 2013)

A while ago I replaced my shower head with one of those ims screens and needed to also replace my screw as the shower plate is secured with the same screw, which was too short.

Bought some new ones from somewhere (screwfix?) and they are apparently galvanised, but cleaning my group today, they are still starting to rot.

Anyone know any longish screws, noble enough to not rot and resist the pretty harrowing conditions inside a group?


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## Glenn (Jun 14, 2008)

Try stainless steel ones if you can.

What machine do you have?


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## Kyle548 (Jan 24, 2013)

It's a Bezzera.

I think the screws I'm using are stainless with a zinc plating.


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## TonyW (Jul 17, 2012)

Hi Kyle.

I am struggling to visualise this. Any chance of posting a picture or a link to the Specific IMS shower screen your using.

The BZ02 stock build has a flat shower screen held in place by a central screw that goes through the centre of the screen and dispersion plate into the group head, so the screw clamps all three parts together. I can't recall if the dispersion plate is countersunk to take the screw, but the stock screw is countersunk, yes?

So, are you holding the IMS screen in place with an (undersized?) gasket and discarding the original shower screen? If so, what's stoping you using the original screw to hold the dispersion plate in place? That original screw (stainless steel, iirc) is designed to cope with exactly those harrowing conditions

Anyway, it sounds like a really interesting modification.


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## Kyle548 (Jan 24, 2013)

The ims screens are slightly cup shaped and have a bigger dia than the stock one screen.

So it fits outside the dispersion plate (I'm using the stock gasket).

The plate even has a groove for this, the only problem is that the ims sticks out a little too far and is inflexible like a regular screen, so I can't just tighten the screw all the way


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## El carajillo (Mar 16, 2013)

Kyle they do not galvanise stainless, only on mild steel (for protection) you need a good quality stainless steel screw, try an engineering supplies company. Doubtful you will obtain one from D I Y /Screwfix type outlets. Alternatively you may get away with brass.


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## TonyW (Jul 17, 2012)

Aha. Thanks Kyle. I get it now - exactly like you said originally, the screw is just too short.

The Bezzera BZ02 parts manual lists the standard screw as "Screw TPS M5x16 DIN963 A2" if that helps (also listed here: http://www.1st-line.com/store/pc/Bezzera-Screw-TPS-M5-x-16-DIN-963-A2-Ref-A-131-p1283.htm ), so I guess your looking for a countersunk stainless steel M5x18 equivalent to give you a couple of extra mm, yes?


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## Kyle548 (Jan 24, 2013)

The IMS screen doesn't have a countersunk hole, so a Roundhead would fit better.


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## TonyW (Jul 17, 2012)

Something like this then?

Item: M5 (5mm) A2 STAINLESS MACHINE SCREW POZI PAN HEAD POZIDRIVE BOLTS POSI DIN7985


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## espressotechno (Apr 11, 2011)

Take these screw specs. to an engineering / fasteners supply place and get one of each in industrial grade stainless steel - they'll cost only a few pence. The you can test countersunk v. round head.


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## TonyW (Jul 17, 2012)

+1 to that...


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## Kyle548 (Jan 24, 2013)

Sure, I'll try that.


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## TonyW (Jul 17, 2012)

Good luck Kyle and please update us on how you get on. I am trying to recall if that screw goes into a blind hole in the group, in which case too long a screw could bottom out before it clamps the dispersion plate up against the group. It may be useful for anyone who comes across this thread later to know what spec screw works best for you.


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