Category Archives: Coffee

Filter Basket on Gaggia Classic

About a month ago I updated my OPV setting on my Gaggia Classic based on the information that I had come across online.  My espresso’s appear to have improved because of this, although I am still a tiny bit scheptical.

The thing that initially kicked things off was my initial frustrations when first getting the Gaggia Classic, something wasn’t ringing true and my coffee would not improve no matter waht I did to the grind, tamp, coffee.  Then I read about the fact that the basket itself may be the problem.  So I looked in the portafilter and checked the basket.

The basket appeared to have many holes and looked pretty normal to me.  In my haste I thought there was nothing to worry about.  Then I read in another post that there is a single hole in the POD portafilters and it’s visible from the underside.  So I removed the basket from the portafilter and “Hey Presto”

So my machine was supplied with ONLY POD compatible baskets.  They make an espresso but not a very good one and  it explains why not much was changing when I altered the grind and never had any discernable change in shot pull times.  Basically everything has to come through the tiny hole and the plastic bit ends up being a throttle so that the high pressure fluid from the hole does not spray up your walls.  (DO NOT TRY THIS AT HOME IF YOU LIKE YOUR KITCHEN, CHILDREN, EYES…ETC You can test this buy removing the plastic plug and leaving the POD compatible basket in.  When you run the machine you will have coffee going everywhere)

So online to CoffeeHit and new basket arrives, quite a difference

I put my new basket into the portafilter and then ground some of my coffee.  I then switched on and the coffee gushed out of my portafilter with no crema and was the most awful espresso ever.  Not all bad though as now the coffee is the restriction in the basket (I think) rather than the little hole in the POD compatible basket.

So redial the grinder to a finer grind and try again, shot pull is still fast but there is the first noticeable change since having the machine.  Espresso is still bloody awful but there was a hint of crema and the pull took 10 seconds.  After a bit of fun and some dialling in the pour started to get closer to the 25 second mark and real crema emulsion is flowing from the portafilter.

So, in summary, the change of the basket has made a hell of a difference and I can now taste my espresso and get a really good pour.  I didn’t realise that you truly can have floral notes, hints of caramel, blackcurrent flavours all mixed in with the brown coffee liquid.  I think regulating the OPV has helped but the biggest difference has been using the machine as intended with the correct basket.  Why Gaggia supply them like this I will never know as it is impossible to make an espresso with the POD baskets.  Maybe Gaggia know better and there is a knack but I can’t find it and my coffee taste like never before now the machine is like it was originally designed.

Hope this is of use to some of you.


Modifying Gaggia Classic OPV to 9 Bar

This week I decided that, to pass the time, I would modify my Gaggia Classic in pursuit of the “God Shot”.  Now by all means I will be years from my “God Shot” as I barely understand the variation in beans, freshness, grind, the requirements of temperature and all manner of tamping skills.  However, I know that my machine has been delivered ready for POD compatibility and the Internet more or less commands me to reset the OPV (Over Pressure Valve).

Previously I have discovered that my Gaggia Classic came delivered with baskets which are specific to using POD’s.  This in itself set me back a few months as because I have never had a Coffee machine before I did not realise that there was anything wrong with these baskets.  When researching why my shots were so poor I came across a description of how the Portafilter basket should look and realised that I should have many holes in the bottom of my basket not just 1 and a plastic frother.

So I ordered a new basket from coffeehit this was promptly delivered and I put this in machine.  My shots changed instantly and although far from perfect the taste changed instantly.  They also flowed very fast even on the finest grind of my Gaggia MDF.  (I will post something about this issue, here)

Walk-through of Modification to Gaggia Classic

(CAUTION All of the things that I describe in this walk-through are of my own doing and will have invalidated any warranty I have with Gaggia, I am fully aware of the risks and Hazards.  If you decide to try to replicate any of the described modifications you do so at your own risk and I cannot take any responsibility for your actions or any injuries, damage and any other outcome due to you performing the modifications and the risks you expose yourself to (Electricity, Water, High Temperature Metal))

  1. Hopefully no one is reading this without knowing that this is purely an experiment and my Gaggia Classic is now an engineering toy.
  2. Ensure that the Gaggia Classic is disconnected from the Electricity supply and that the Machine is has been allowed to cool for 1 hour. (Machine gets to over 100 Degrees Celsius and can cause severe burning to skin.  Ideally only attempt after leaving machine off for several hours)
  3. Remove the lid to the Gaggia Classic by removing the two Philips Screws on the top
  4. Remove the Earth wire from the cover whilst lifting the cover away from the Main unit

    (Optical illusion here due to Stainless Steel, but remove clip by depressing the “tang” and pulling on the crimp)
  5. Locate the Over Pressure Valve (OPV), centre of the unit with rubber tube, for return, leaving through the top and high pressure line from pump entering from the left through red Bung (as viewed from rear of Gaggia Classic)
  6. Remove the Overflow tube from the top of the OPV, do not try to touch any other tube.
  7. Using 17mm socket or 17mm Spanner, carefully remove the the OPV cover by unscrewing Anti-clockwise (CAUTION: The 17mm head is made from soft metal and using a spanner may lead to damage to the Nut head)
  8. Here is the OPV with the Adjustable 5mm Hex pressure control visible, there will be water present
  9. Insert the 5mm Hex key and turn the Anticlockwise 270 degrees.  (This was a setting initially found after trawling the forums, some further tinkering can be done if this initial setting is not enough)
  10. Now perform the actions in reverse to put the Gaggia Classic back together, remembering to connect the overflow tube onto the OPV
  11. Reconnect the Earth lead to the cover and replace the cover onto the Gaggia Classic
  12. Test the machine by reconnecting the Electrical supply and trying to pull a shot

Observations / Comments

  1.  I have performed the modification on the commonly posted 270 Degree’s anti-clockwise technique.  I have not used a pressure gauge.
  2. However, I have tested using the flow technique.  This involves putting the overflow from the OPV into an empty glass and measuring the amount of flow over 30 seconds with the Portafilter blanked (i.e. blocked)  To block the portafilter, either get a special portafilter or press the steam button which actuates the 3 way valve and perform the same function.  This is not perfect, because each valve and pump combination will have differing overflow volumes.  You are looking for ~125ml in 30 seconds.
  3. When I got close to these values I then tested the espresso by pulling a shot and checking it’s formation and flow.


The modification has made a phenomenal difference to the taste of my espresso shots and I have been getting far better flavour and consistency.  Also my pour is taking around 25 seconds rather than 15 before.

I’m using very fresh beans, 1 week since roasting, and still have the MDF set to the lowest setting, this has surprised me, however if I don’t I get horrid espresso.  (I get the feeling this is where my next research should be focussed)

This did take numerous tweaks of the OPV valve and I think I ended up nearly 400 degree’s anti-clockwise of the factory setting point.  Each valve will be different due to the pump, valve combinations.

I have been very poor in my measuring of pressure and I know that I may well not be getting 9 Bar.  Therefore I will have to modify my portafilter and measure the pressure at the Brew Head to find anymore improvements.

Overall it’s been a fun experience and my espresso has improved.  Within a few more years I may get good at it.