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Gaggia OWC - (Very Old) Old White Coffee - new mods
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Discussions > Espresso > Espresso Mods > Gaggia OWC -...  
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AndyPanda
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AndyPanda
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Posted Fri Jun 15, 2012, 6:51pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

The dimmer mod takes all of 5 minutes and hardly requires any tools.  I didn't want to drill holes in the front of the cabinet so I just poked the shaft of the dimmer out the back through one of those vent slots.  I had to widen one little bit of the vent enough (I used a reamer just because I happened to have one and it was quick/easy - but you could use a small, rat-tail file or any number of simple tools would do the job).

The reason I picked brass the first time, it is soft enough I could cut it with a normal (well heavy duty) pair of scissors.  And the stainless would probably need a real pair of tinsnips.

My hardware store had all sorts of metal tubing and sheets and rods in all shapes and sizes and all sorts of materials --- this was not in your standard, plumbing section - it's more of a hobby/fabrication sort of section that maybe only exists in the kind of "old time" hardware store like the one near me.

Here is a pic of just one small bit of this section in the local, old time hardware store

AndyPanda: hardware.jpg
(Click for larger image)
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
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Location: San Francisco Bay Area
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Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
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Roaster: BreadMachine/HeatGun
Posted Sat Jun 16, 2012, 8:42am
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

I posted a YouTube video of a bottomless pour with this OWC.  I started the shot with the dimmer set very low and gradually brought up the pressure.  About 10 seconds of preinfusion and then the pour starts at a full 9.5 bars and I gradually drop the pressure as the shot progresses.  I don't always do this - but wanted to try emulating the profile of a spring lever machine.  Usually I simply set the dimmer to where the pump gives a gentle build up to 9.5 bars and then I just leave it alone.. I've got a mark filed into the knob so I can feel where that setting is since I mounted the knob at the back of the machine where you can't see it.  

I know this will seem like a way overextracted shot (10 seconds preinfuse and then another 30+ second pull) but this gives a really tasty shot.  Though I probably would have stopped sooner if I had been paying more attention to pulling the shot and less attention to trying to make the video.

At the end of the shot, I show the surface of the spent puck so you can see how well the dispersion mods have improved on that flaw in the OWC stock design.

http://youtu.be/mAzvEbQPw4s
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Sat Jun 16, 2012, 9:07am
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

Snowboarder27118 Said:

Any pictures or further direction that you could help me with on the dimmer and/or the water inlet re-rout mods would be greatly appreciated.

Posted June 15, 2012 link

Here is a picture of how I mounted the dimmer.  I only used one screw (through the vent slot) and I bent the mounting ear on the other side so I could push the dimmer further towards that corner and get it to sit down lower - next to the terminal block.

Notice that this old model has a diode coming out of the main screw terminal block and then a little screw terminal coupler that used to go straight to the pump - this is where I put one leg of the dimmer.  Then the other leg of the dimmer goes to the pump (the wire that previously would have connected to the diode in the terminal block).  I happened to have two of these little screw terminal couplers (borrowed the one from my second OWC) but you could use a wire nut, or you could just twist the wires together (or solder them if you have the tools) and wrap with electrical tape or use a crimp type splice.  

There is a spot on the terminal block for ground (this old model has a three prong power cord) so I went ahead and connected the dimmer ground wire to that terminal.  But it makes no difference either way - you can also simply cut off or tape up the ground wire since the dimmer doesn't really use it. Only the two black wires are needed.

I don't mind having it in the back - it's easy enough to reach - and I wanted to make it as reversible as possible so I didn't want to drill holes in the front of the cabinet.  It's a "stealth mod" that unless you show someone the secret it looks stock - let them wonder how you are able pull great shots - let them think it's your superior barista skills.

AndyPanda: OWC_Dimmer.jpg
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D4F
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Espresso: Gaggia Classic PID
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Posted Sat Jun 16, 2012, 10:48am
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

AndyPanda Said:

My hardware store had all sorts of metal tubing and sheets and rods in all shapes and sizes and all sorts of materials --- this was not in your standard, plumbing section - it's more of a hobby/fabrication sort of section that maybe only exists in the kind of "old time" hardware store like the one near me.

Here is a pic of just one small bit of this section in the local, old time hardware store

Posted June 15, 2012 link

I have seen similar metal displays in some hobby, radio control, shops.  

Nice display of the dimmer mod and mod in use.

 
D4F also at
http://www.gaggiausersgroup.com/
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Sat Jun 16, 2012, 12:11pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

Thanks ... I just finished posting that video you requested in the other thread.  YouTube is still processing it but it should be available by the time you read this post.
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Sat Jun 16, 2012, 1:56pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

Here is a rear view of the OWC with the knob removed from the dimmer so you can see how I reamed the vent slot for the shaft.  Once you've tested it and lived with it for awhile you may prefer it mounted up front ... but you may find that you set it once and forget it and prefer it hidden away in the back.

AndyPanda: OWC_DimmerBack.jpg
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zazz
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Joined: 5 Jul 2012
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Location: GA
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Posted Fri Jul 6, 2012, 1:20pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

Question, i took apart my boiler and found a lot of debris from scaling.  but also notice there seems to be a paint on the inside of the upper part (brown coating), the coating is also chipping away causing debris in the boiler.

Have you noticed this before with the OWC?
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Fri Jul 6, 2012, 1:59pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

zazz Said:

Question, i took apart my boiler and found a lot of debris from scaling.  but also notice there seems to be a paint on the inside of the upper part (brown coating), the coating is also chipping away causing debris in the boiler.

Have you noticed this before with the OWC?

Posted July 6, 2012 link

No ... I have seen deeply corroded aluminum (rough texture) - and I've seen various colors of scale built up.  Never paint.  Something else I've seen frequently in Gaggia boilers is that the inside surface is soft (like mud) and scrapes off like gray/black peanut butter.  I believe (but just a guess) that this is from previous owner letting descaler sit in the boiler long enough to dissolve the aluminum.

Generally the aluminum will develop an oxide coating which is very hard.  It looks ugly and way too many people think they are doing a good thing by grinding/sanding it off to get down to the shiny aluminum.  The aluminum oxide is a hard coating and, although it is ugly, it is very good to protect the aluminum.  But if you do get down to the bare aluminium, it will quickly get a new oxide coating all by itself.

I usually find reddish brown coating all over the bottom half of the boiler (iron/rust -  from the water - nothing inside the boiler will rust) and also usually a pile of green or blue and white scale.  Sometimes the scale is really built up and you have to chisel it out.

Somewhere on this site is a picture of a boiler that is full of something that looks like butterscotch pudding in the photo - so scale and mineral deposits come in all colors.  Ah ... found it:
"Inside of Boiler Looks like Butterscotch Pudding"
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zazz
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Location: GA
Expertise: I love coffee

Posted Fri Jul 6, 2012, 2:55pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

Hmmm, the bottom half is fairly clean with a bit of scaling. The upper half is more scaled though. I don't understand why the upper half is coated with some brown coating, it is on the flange that mates with the other half so I think it is a coating. I will descale and see what happens. Would it be terrible to sand off the coating so it does not flake into the water?
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Fri Jul 6, 2012, 5:36pm
Subject: Re: Gaggia OWC - (Very Old) Old White Coffee - new mods
 

The bottom half is chrome plated brass - the upper half is bare aluminum.  I suspect the coating you are seeing is aluminum oxide.

Do you have a picture you can post?

If you can't brush it off with a wire brush, it isn't likely to flake off into your water.  

You do generally need to file or sand the mating surface smooth - that frequently gets pitted to the point where it doesn't make a good seal and the boiler can leak between the two halves.  I generally just use a flat file - other people have posted about using a glass surface with wet/dry sandpaper and others (with access to fancy tools) mill it down with a lathe or other high tech stuff.   For me, a simple bastard file and some care (skill helps) gets it nice and smooth.  I usually can reuse the old o-ring - but if it is shot, I think you can still get new ones for that old model ... but it might be hard to find.

Lots of people scrape away the build up, some grind with a dremel, some use a file, or a chisel ... some use a sandblaster.  I've done most of those things in the past but not recently -- if it isn't bad, I just use a toothbrush now and get anything that that is flakey.  If it is worse, I'll use a wire brush.  I haven't had one in ages that was bad enough to need hard scraping.  But I've seen plenty of pictures of ridiculously scaled up boilers where there was no room for any water inside.

I have heard and read so many different stories about what descaler is safe for the aluminum and which ones aren't --- I have no idea what to believe.  I have seen several aluminum Gaggia boilers where the aluminum was soft enough to scrape off like putty and the water from the boiler was dirty gray.  Those really disturb me - so I really never use any descaler on the Gaggia aluminum boilers these days (though I'm not positive that descaler is what caused the soft aluminum - that's just my suspicion) - or if I do, I don't leave it very long.  It is so easy to split the halves of the boiler and brush out the scale with a toothbrush or a wire brush - I just clean them that way.
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