...can see the finish line now!!

I wanted to update a few things - I'm waiting for the derusting process to finish, which will hopefully be later today, and after that is just group assembly and then finally testing. Almost done!

So wanted to share a few glamor shots and the method to get there..

Upper group - was fully degreased, scrubbed, rinsed and dried and now will be polished to spice up the already quite excellent condition chrome (shockingly this machine has better chrome condition than my 2009 Brewtus )



These two bits that go with the spring in the piston - fully degreased (was tough...), scrubbed, and then I threw them in a light citric warm bath to take off the zinc and some oxides, I know that doesnt help but I like the brass pink and fresh


I decided I was not satisfied with the sightglass cover, so took it off. Sanded it a good bit first with a 3M fine scotch brite type pad, then with 00 wool, then with 0000 wool, and finally with mag polish and buffed out. All this was done with hand, took a good 2 hrs, but happy how it turned out. I have applied a mineral oil coat for now to protect it, but will be clear coating this with Rustoleum clear coat to seal it up so it doesnt oxidize as easily again.



Finally - also polished up in-situ, all the panels and the drip tray on the machine, including the bakelite. The sightglass in this photo was not yet polished as above. Coming together!!

Hit a snag today ... and can't figure out what's going on, hoping perhaps this group can help!

I added the new gasket stack. Opted for the 2nd gasket facing upwards, the rest facing downwards as others have done on this forum.

Then, I setup the upper group, rack, piston and spring assembly and attached the spring tool again. All surfaces were coated with mineral oil, the racks moving parts in a bit of grease and the racks teeth half to 3/4 full with grease.

I then compressed the spring with the spring tool until I could see the racks teeth, and then I installed the pinion gear and right bearing (right bearing was already pulled completely onto the new pinion gear). The bearing/pinion combo went in quite easily on the right side. A few whacks on the bearing inner ring snd it was in. I then tightened the pinion cap on the right side.





I then installed the left side bearing - positioned in place, and then used a 12 mm socket to gently tap it until it was in, flush with the pinion gear.



At this point, the next step would be to pull the lever, raise the rack , remove the spring tool and install the top nut.

However I can't pull the lever! I applied a good amount of force, more and I would worry about the teeth / gears - it wouldn't budge. I tried compressing the spring a bit more to try different teeth , that didn't work either.

Any ideas what could be going on?




Photo from front with tool installed, current state of machine:

Well, I compressed the spring a bit more, and then I was able to lift the lever.

Sadly, likely while torquing the spring, it seems the jacket where the rack mounts to the piston was too weak and broke, There are some options from here

(1) Get a new piston, new inner connecting piece and use existing rack and pin (120 EUR)
(2) find a way to remove this (trying PB oil right now, with heat and perhaps thermal shock to see) and just get this piece new (24 EUR)
(3) Wildcard option - try to remove this and just drill new holes for the pin

In any case, sadly my wife put her foot down, I think she has been quite patient with me taking over our kitchen counter for months but I've been asked to put this up for sale while I figure this out

Well, thanks to the amazing Thijs at Brooks-espresso (highly recommend him - excellent communicator, and has been very responsive and helpful!) is saving me!

Will be ordering a new piston, and have located at a rack with another friend, just figuring out compatibility but looks like it should work.

To be continued, and almost at the finish line!

Its been a while since I posted, but thanks to Thijs and IamOiman, I was able to procure the parts needed to reassemble the group. New piston, new piston, new bolt.

Bolt was threaded and locked into the piston. Sharing some more info just in case there is something I'm not seeing. Essentially at a similar spot as before, but proceeding with caution...

(1) photo of gasket stack
I opted for all rubber gaskets facing downards


(2) rack, bolt new piston assembly assembled:


(3) Upper group threaded in, spring tool installed, ready to start compressing the spring:
photo of start point (close up):



(4) starting setup of rack teeth - spring was compressed and at this point, the pinion gear and bearing (bearing already pulled on to the pinion gear) was inserted in, and then gently tapped into place. Pinion could move on bearing smoothly, I checked before installation. pinion gear teeth also slid in fairly easily, only needed hammering for the bearing.
after this, the cover was installed and threaded into place


pinion gear installed:


(5) then, the other side - bearing was positioned over the pinion gear tip, and then hammered in gently with a socket, until inner bearing ring was flush with the pinion gear tip.
after this, the cover was installed on the left side as well.



(6) after this, the next step would have been to pull the lever, lift the rack and remove the spring tool. Sadly, this is where I am stuck and need some help and ideas of what could be happening.
The spring cannot be compressed by the lever, it feels stuck. If I loosen the spring tool fastening nut, I can get some range of motion but it is only a few mm of rise. here is a video:

If I tighten the spring tool nut fully, there is almost no compression. this is the EXACT way, my last piston broke, because the force of the lever pulling up, something got stuck and shore off the center bolt of the piston (which was a bit weak from rust but still).

here is another mystery - out of an abundance of caution, before assembling everything, I just installed the rack/piston assembly WITHOUT the spring, and then I just inserted the pinion gear/bearing about half way and pulled the lever to see if the whole range of motion was fine.

you can see here:
It moves completely fine.

I am wondering, something is preventing the piston from coming up with the spring and spring tool installed, or otherwise preventing compression by lever or by spring tool beyond a certain point. the last time when the piston broke, I noticed one of the rubber group gaskets was torn - I am a bit at a loss here, for now I have just left the the group as is with the tool installed.

Any ideas what could be causing this and how to proceed?

One thing to add
1) when lever is down, the spring tool is completely centered and vertical - definitely not catching on anything

2) turning the upper group (and piston) requires a lot of force - I am wondering if the piston is catching on a gasket or some part of the stack

A couple of things stick out for me. I wonder why the old piston and that rusty top nut sheared off like it did. That section of the piston and that rusty nut should not be under any kind of pressure from the spring. With the spring installed, the piston should still wobble around. The spring force is resting on the top hat shaped brass piece, which is held in place by the actual rack. The top hat does not touch the inner bottom of the piston or that piece that sheared off.

I would also loosen up the top 2 sections of the group, those big parts that thread into the group. See if that helps. When they are tightened they compress the seals and pinch the piston.

Then it is worth checking very simple obvious stuff. Like make sure the pinion gear is inserted at the top of the rack teeth. Also make sure that the spring steels are not catching anywhere (if you have them on) and that the spring steel screws are not fouling anywhere - I have done that numerous times

Paul! Thank you for weighing in!!

Thanks to you and Iamoimans help, i figured out my mistake.

I let the piston top rim go below the first seal while assembling. The piston rim would shear the group gasket on the way up, and the shorn gasket would then prevent the spring and piston assembly from moving properly.

Thank god - I had spare group gaskets a plenty (I read Paul's comment somewhere to have tons of spare parts haha).

I only have one remaining issue to resolve with the group.

The lever starting position has the piston about 4-5 mm above the group sleeve at the bottom - this 4-5 mm also prevents the preinfusion mechanism from engaging because the spring cannot be compressed far enough for it to engage.

Video of successfully assembled group, the gap in piston start height, and the gap to preinfusion engagement at the bottom of the lever (max compression) here:

I am hoping I can get there by lowering the upper group into the big nut hopefully no other more painful adjustments needed...

A quick update: this project is nearing completion, this beautiful gaggia will soon be making tasty shots I feel thought I'd post some photos and share updates, as well as the remaining issues (where help and input is welcome!)

I configured the group to have a comfortable pre-infusion action with the lever angled backwards for aesthetic reasons (not a fan of some vintage machines of levers pointing straight up), and piston flush with the group piston sleeve. I opted to remove the stock screen since it likes to spray water sideways, and opted to install a blue cafelat group gasket and a modded e61 screen for now.


while I was waiting for pressure testing, I figured - these beauties needed a good polishing, all shined up


remaining issues to resolve
Mostly, the pressure test went amazingly, pulled several shots. Here is a shot video with some honduras decaf dialed in very similarly as my bosco:

(1) I got zapped as I tried to adjust the feet height and touched the frame. The grounding is crimped to the frame, I have to test where the grounding is wrong - ideas welcome on this: Plan to switch on and test voltage difference between live element terminal and the crimp pictured below, the frame, and the part I touched to figure out where and how the voltage leak is happening.



(2) From video above, the shot volume was a tad lower than expected, yielded about 30-35 g before flow got very slow, on bosco that would be closer to 40-45g, I am wondering if this thing at the back of the group adjusts flow? Anyone familiar with this, and how to use it? what is the sensitivity? feel free to link other threads I don't particularly recall this piece one on the Gaggia group head being discussed in threads I've read...


(3) Other very small things, I heard a hiss from the sight glass gasket and the occasional drip from it (brand new rubber gasket) so I tightened that up once the machine cooled, not putting too much pressure as its still glass and don't want this to be another game-over and 5 week wait to get a part. elsewhere, the steam wand tip I installed (2 hole instead of 4) was a bit leaky at the rim, need to redo the teflon tape and make a tighter seal.

(4) on temperature, very interesting that I had to set the Pstat to cycle from 0.65 to 0.85 Kg/cm2 for shots to not taste burned/astringent (bosco is set to 1.2bar). Group idles at 189F (bosco would idle at 169-172F), and intrashot group temp goes from 189F to 194F on Gaggia (measured via thermocouple terminals flue taped to grouphead right above PF on the side of lower group). Again, Pstat deadband/config/temp preferences welcome, this is what worked for me. I believe the group's thermal mass, and the bigger 10L boiler explain these observations.

Other than this, performed beautifully. The Vac breaker I installed (on the compression fitting connecting cup warmer) worked well, no drama from the new safety valve either. This is truly a spectacular machine, both to use and behold, so I leave you with a a photo of our handsome brute:

sheedapistawl wrote: From video above, the shot volume was a tad lower than expected, yielded about 30-35 g before flow got very slow, on bosco that would be closer to 40-45g, I am wondering if this thing at the back of the group adjusts flow? Anyone familiar with this, and how to use it? what is the sensitivity? feel free to link other threads I don't particularly recall this piece one on the Gaggia group head being discussed in threads I've read...

Looks to be the same or similar type of valve that's on your Bosco. Main function according to Roberta is so you can shut off the water flow & service one group on a multigroup machine without turning off the machine. With the valve in it's highest position the flow path is wide open & it gets smaller as you screw it down. The Bosco's valve has a ball down in there. If you haven't removed that valve previously the pathway openings could be partially scaled up.

One thing to note is that later Boscos like yours do produce a higher cup volume then earlier models like mine (38 ml). The cup volume your getting with the Gaggia might be normal?? I'm sure Paul could tell us what volume you should expect.